js/src/shell/js.cpp
author Till Schneidereit <till@tillschneidereit.net>
Fri, 28 Jul 2017 23:39:54 +0200
changeset 423002 64bbc26920aad951c81eb28d9b319be92f72aa4b
parent 422850 9bf3949a7ae8577007f7692cdb9beb3bc85fae8b
child 423911 e65e640970ef101defb3e75fb4186741157c8b11
child 424644 fa94c05940164dd5b82967d9e2c9c6c840f51d12
permissions -rw-r--r--
Bug 1272697 - Part 2: Add runtime pref to enable streams. r=jonco,baku MozReview-Commit-ID: FJMAxbtD3Uy

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
 * vim: set ts=8 sts=4 et sw=4 tw=99:
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

/* JS shell. */

#include "mozilla/ArrayUtils.h"
#include "mozilla/Atomics.h"
#include "mozilla/Attributes.h"
#include "mozilla/DebugOnly.h"
#include "mozilla/GuardObjects.h"
#include "mozilla/IntegerPrintfMacros.h"
#include "mozilla/mozalloc.h"
#include "mozilla/PodOperations.h"
#include "mozilla/ScopeExit.h"
#include "mozilla/Sprintf.h"
#include "mozilla/TimeStamp.h"

#ifdef XP_WIN
# include <direct.h>
# include <process.h>
#endif
#include <errno.h>
#include <fcntl.h>
#if defined(XP_WIN)
# include <io.h>     /* for isatty() */
#endif
#include <locale.h>
#if defined(MALLOC_H)
# include MALLOC_H    /* for malloc_usable_size, malloc_size, _msize */
#endif
#include <math.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/stat.h>
#include <sys/types.h>
#ifdef XP_UNIX
# include <sys/mman.h>
# include <sys/stat.h>
# include <sys/wait.h>
# include <unistd.h>
#endif

#include "jsapi.h"
#include "jsarray.h"
#include "jsatom.h"
#include "jscntxt.h"
#include "jsfriendapi.h"
#include "jsfun.h"
#include "jsobj.h"
#include "jsprf.h"
#include "jsscript.h"
#include "jstypes.h"
#include "jsutil.h"
#ifdef XP_WIN
# include "jswin.h"
#endif
#include "jswrapper.h"
#include "shellmoduleloader.out.h"

#include "builtin/ModuleObject.h"
#include "builtin/TestingFunctions.h"
#include "frontend/Parser.h"
#include "gc/GCInternals.h"
#include "jit/arm/Simulator-arm.h"
#include "jit/InlinableNatives.h"
#include "jit/Ion.h"
#include "jit/JitcodeMap.h"
#include "jit/OptimizationTracking.h"
#include "js/Debug.h"
#include "js/GCAPI.h"
#include "js/GCVector.h"
#include "js/Initialization.h"
#include "js/StructuredClone.h"
#include "js/SweepingAPI.h"
#include "js/TrackedOptimizationInfo.h"
#include "perf/jsperf.h"
#include "shell/jsoptparse.h"
#include "shell/jsshell.h"
#include "shell/OSObject.h"
#include "threading/ConditionVariable.h"
#include "threading/LockGuard.h"
#include "threading/Thread.h"
#include "vm/ArgumentsObject.h"
#include "vm/AsyncFunction.h"
#include "vm/AsyncIteration.h"
#include "vm/Compression.h"
#include "vm/Debugger.h"
#include "vm/HelperThreads.h"
#include "vm/Monitor.h"
#include "vm/MutexIDs.h"
#include "vm/Shape.h"
#include "vm/SharedArrayObject.h"
#include "vm/StringBuffer.h"
#include "vm/Time.h"
#include "vm/TypedArrayObject.h"
#include "vm/WrapperObject.h"
#include "wasm/WasmJS.h"

#include "jscompartmentinlines.h"
#include "jsobjinlines.h"

#include "vm/ErrorObject-inl.h"
#include "vm/Interpreter-inl.h"
#include "vm/Stack-inl.h"

using namespace js;
using namespace js::cli;
using namespace js::shell;

using js::shell::RCFile;

using mozilla::ArrayLength;
using mozilla::Atomic;
using mozilla::MakeScopeExit;
using mozilla::Maybe;
using mozilla::Nothing;
using mozilla::NumberEqualsInt32;
using mozilla::PodCopy;
using mozilla::PodEqual;
using mozilla::TimeDuration;
using mozilla::TimeStamp;

enum JSShellExitCode {
    EXITCODE_RUNTIME_ERROR      = 3,
    EXITCODE_FILE_NOT_FOUND     = 4,
    EXITCODE_OUT_OF_MEMORY      = 5,
    EXITCODE_TIMEOUT            = 6
};

static const size_t gStackChunkSize = 8192;

/*
 * Note: This limit should match the stack limit set by the browser in
 *       js/xpconnect/src/XPCJSContext.cpp
 */
#if defined(MOZ_ASAN) || (defined(DEBUG) && !defined(XP_WIN))
static const size_t gMaxStackSize = 2 * 128 * sizeof(size_t) * 1024;
#else
static const size_t gMaxStackSize = 128 * sizeof(size_t) * 1024;
#endif

/*
 * Limit the timeout to 30 minutes to prevent an overflow on platfoms
 * that represent the time internally in microseconds using 32-bit int.
 */
static const TimeDuration MAX_TIMEOUT_INTERVAL = TimeDuration::FromSeconds(1800.0);

// SharedArrayBuffer and Atomics are enabled by default (tracking Firefox).
#define SHARED_MEMORY_DEFAULT 1

bool
OffThreadState::startIfIdle(JSContext* cx, ScriptKind kind, ScopedJSFreePtr<char16_t>& newSource)
{
    AutoLockMonitor alm(monitor);
    if (state != IDLE)
        return false;

    MOZ_ASSERT(!token);

    source = newSource.forget();

    scriptKind = kind;
    state = COMPILING;
    return true;
}

bool
OffThreadState::startIfIdle(JSContext* cx, ScriptKind kind, JS::TranscodeBuffer&& newXdr)
{
    AutoLockMonitor alm(monitor);
    if (state != IDLE)
        return false;

    MOZ_ASSERT(!token);

    xdr = mozilla::Move(newXdr);

    scriptKind = kind;
    state = COMPILING;
    return true;
}

void
OffThreadState::abandon(JSContext* cx)
{
    AutoLockMonitor alm(monitor);
    MOZ_ASSERT(state == COMPILING);
    MOZ_ASSERT(!token);
    MOZ_ASSERT(source || !xdr.empty());

    if (source)
        js_free(source);
    source = nullptr;
    xdr.clearAndFree();

    state = IDLE;
}

void
OffThreadState::markDone(void* newToken)
{
    AutoLockMonitor alm(monitor);
    MOZ_ASSERT(state == COMPILING);
    MOZ_ASSERT(!token);
    MOZ_ASSERT(source || !xdr.empty());
    MOZ_ASSERT(newToken);

    token = newToken;
    state = DONE;
    alm.notify();
}

void*
OffThreadState::waitUntilDone(JSContext* cx, ScriptKind kind)
{
    AutoLockMonitor alm(monitor);
    if (state == IDLE || scriptKind != kind)
        return nullptr;

    if (state == COMPILING) {
        while (state != DONE)
            alm.wait();
    }

    MOZ_ASSERT(source || !xdr.empty());
    if (source)
        js_free(source);
    source = nullptr;
    xdr.clearAndFree();

    MOZ_ASSERT(token);
    void* holdToken = token;
    token = nullptr;
    state = IDLE;
    return holdToken;
}

struct ShellCompartmentPrivate {
    JS::Heap<JSObject*> grayRoot;
};

struct MOZ_STACK_CLASS EnvironmentPreparer : public js::ScriptEnvironmentPreparer {
    JSContext* cx;
    explicit EnvironmentPreparer(JSContext* cx)
      : cx(cx)
    {
        js::SetScriptEnvironmentPreparer(cx, this);
    }
    void invoke(JS::HandleObject scope, Closure& closure) override;
};

// Shell state set once at startup.
static bool enableCodeCoverage = false;
static bool enableDisassemblyDumps = false;
static bool offthreadCompilation = false;
static bool enableBaseline = false;
static bool enableIon = false;
static bool enableAsmJS = false;
static bool enableWasm = false;
static bool enableNativeRegExp = false;
static bool enableUnboxedArrays = false;
static bool enableSharedMemory = SHARED_MEMORY_DEFAULT;
static bool enableWasmAlwaysBaseline = false;
static bool enableAsyncStacks = false;
static bool enableStreams = false;
#ifdef JS_GC_ZEAL
static uint32_t gZealBits = 0;
static uint32_t gZealFrequency = 0;
#endif
static bool printTiming = false;
static const char* jsCacheDir = nullptr;
static const char* jsCacheAsmJSPath = nullptr;
static RCFile* gErrFile = nullptr;
static RCFile* gOutFile = nullptr;
static bool reportWarnings = true;
static bool compileOnly = false;
static bool fuzzingSafe = false;
static bool disableOOMFunctions = false;

#ifdef DEBUG
static bool dumpEntrainedVariables = false;
static bool OOM_printAllocationCount = false;
#endif

// Shell state this is only accessed on the main thread.
bool jsCachingEnabled = false;
mozilla::Atomic<bool> jsCacheOpened(false);

static bool
SetTimeoutValue(JSContext* cx, double t);

static void
KillWatchdog(JSContext* cx);

static bool
ScheduleWatchdog(JSContext* cx, double t);

static void
CancelExecution(JSContext* cx);

static JSObject*
NewGlobalObject(JSContext* cx, JS::CompartmentOptions& options,
                JSPrincipals* principals);

/*
 * A toy principals type for the shell.
 *
 * In the shell, a principal is simply a 32-bit mask: P subsumes Q if the
 * set bits in P are a superset of those in Q. Thus, the principal 0 is
 * subsumed by everything, and the principal ~0 subsumes everything.
 *
 * As a special case, a null pointer as a principal is treated like 0xffff.
 *
 * The 'newGlobal' function takes an option indicating which principal the
 * new global should have; 'evaluate' does for the new code.
 */
class ShellPrincipals final : public JSPrincipals {
    uint32_t bits;

    static uint32_t getBits(JSPrincipals* p) {
        if (!p)
            return 0xffff;
        return static_cast<ShellPrincipals*>(p)->bits;
    }

  public:
    explicit ShellPrincipals(uint32_t bits, int32_t refcount = 0) : bits(bits) {
        this->refcount = refcount;
    }

    bool write(JSContext* cx, JSStructuredCloneWriter* writer) override {
        // The shell doesn't have a read principals hook, so it doesn't really
        // matter what we write here, but we have to write something so the
        // fuzzer is happy.
        return JS_WriteUint32Pair(writer, bits, 0);
    }

    static void destroy(JSPrincipals* principals) {
        MOZ_ASSERT(principals != &fullyTrusted);
        MOZ_ASSERT(principals->refcount == 0);
        js_delete(static_cast<const ShellPrincipals*>(principals));
    }

    static bool subsumes(JSPrincipals* first, JSPrincipals* second) {
        uint32_t firstBits  = getBits(first);
        uint32_t secondBits = getBits(second);
        return (firstBits | secondBits) == firstBits;
    }

    static JSSecurityCallbacks securityCallbacks;

    // Fully-trusted principals singleton.
    static ShellPrincipals fullyTrusted;
};

JSSecurityCallbacks ShellPrincipals::securityCallbacks = {
    nullptr, // contentSecurityPolicyAllows
    subsumes
};

// The fully-trusted principal subsumes all other principals.
ShellPrincipals ShellPrincipals::fullyTrusted(-1, 1);

#ifdef EDITLINE
extern "C" {
extern JS_EXPORT_API(char*) readline(const char* prompt);
extern JS_EXPORT_API(void)   add_history(char* line);
} // extern "C"
#endif

ShellContext::ShellContext(JSContext* cx)
  : isWorker(false),
    timeoutInterval(-1.0),
    startTime(PRMJ_Now()),
    serviceInterrupt(false),
    haveInterruptFunc(false),
    interruptFunc(cx, NullValue()),
    lastWarningEnabled(false),
    lastWarning(cx, NullValue()),
    promiseRejectionTrackerCallback(cx, NullValue()),
    watchdogLock(mutexid::ShellContextWatchdog),
    exitCode(0),
    quitting(false),
    readLineBufPos(0),
    errFilePtr(nullptr),
    outFilePtr(nullptr)
{}

ShellContext*
js::shell::GetShellContext(JSContext* cx)
{
    ShellContext* sc = static_cast<ShellContext*>(JS_GetContextPrivate(cx));
    MOZ_ASSERT(sc);
    return sc;
}

static void
TraceGrayRoots(JSTracer* trc, void* data)
{
    JSRuntime* rt = trc->runtime();
    for (ZonesIter zone(rt, SkipAtoms); !zone.done(); zone.next()) {
        for (CompartmentsInZoneIter comp(zone); !comp.done(); comp.next()) {
            auto priv = static_cast<ShellCompartmentPrivate*>(JS_GetCompartmentPrivate(comp.get()));
            if (priv)
                JS::TraceEdge(trc, &priv->grayRoot, "test gray root");
        }
    }
}

static char*
GetLine(FILE* file, const char * prompt)
{
#ifdef EDITLINE
    /*
     * Use readline only if file is stdin, because there's no way to specify
     * another handle.  Are other filehandles interactive?
     */
    if (file == stdin) {
        char* linep = readline(prompt);
        /*
         * We set it to zero to avoid complaining about inappropriate ioctl
         * for device in the case of EOF. Looks like errno == 251 if line is
         * finished with EOF and errno == 25 (EINVAL on Mac) if there is
         * nothing left to read.
         */
        if (errno == 251 || errno == 25 || errno == EINVAL)
            errno = 0;
        if (!linep)
            return nullptr;
        if (linep[0] != '\0')
            add_history(linep);
        return linep;
    }
#endif

    size_t len = 0;
    if (*prompt != '\0' && gOutFile->isOpen()) {
        fprintf(gOutFile->fp, "%s", prompt);
        fflush(gOutFile->fp);
    }

    size_t size = 80;
    char* buffer = static_cast<char*>(malloc(size));
    if (!buffer)
        return nullptr;

    char* current = buffer;
    do {
        while (true) {
            if (fgets(current, size - len, file))
                break;
            if (errno != EINTR) {
                free(buffer);
                return nullptr;
            }
        }

        len += strlen(current);
        char* t = buffer + len - 1;
        if (*t == '\n') {
            /* Line was read. We remove '\n' and exit. */
            *t = '\0';
            return buffer;
        }

        if (len + 1 == size) {
            size = size * 2;
            char* tmp = static_cast<char*>(realloc(buffer, size));
            if (!tmp) {
                free(buffer);
                return nullptr;
            }
            buffer = tmp;
        }
        current = buffer + len;
    } while (true);
    return nullptr;
}

static bool
ShellInterruptCallback(JSContext* cx)
{
    ShellContext* sc = GetShellContext(cx);
    if (!sc->serviceInterrupt)
        return true;

    // Reset serviceInterrupt. CancelExecution or InterruptIf will set it to
    // true to distinguish watchdog or user triggered interrupts.
    // Do this first to prevent other interrupts that may occur while the
    // user-supplied callback is executing from re-entering the handler.
    sc->serviceInterrupt = false;

    bool result;
    if (sc->haveInterruptFunc) {
        bool wasAlreadyThrowing = cx->isExceptionPending();
        JS::AutoSaveExceptionState savedExc(cx);
        JSAutoCompartment ac(cx, &sc->interruptFunc.toObject());
        RootedValue rval(cx);

        // Report any exceptions thrown by the JS interrupt callback, but do
        // *not* keep it on the cx. The interrupt handler is invoked at points
        // that are not expected to throw catchable exceptions, like at
        // JSOP_RETRVAL.
        //
        // If the interrupted JS code was already throwing, any exceptions
        // thrown by the interrupt handler are silently swallowed.
        {
            Maybe<AutoReportException> are;
            if (!wasAlreadyThrowing)
                are.emplace(cx);
            result = JS_CallFunctionValue(cx, nullptr, sc->interruptFunc,
                                          JS::HandleValueArray::empty(), &rval);
        }
        savedExc.restore();

        if (rval.isBoolean())
            result = rval.toBoolean();
        else
            result = false;
    } else {
        result = false;
    }

    if (!result && sc->exitCode == 0)
        sc->exitCode = EXITCODE_TIMEOUT;

    return result;
}

/*
 * Some UTF-8 files, notably those written using Notepad, have a Unicode
 * Byte-Order-Mark (BOM) as their first character. This is useless (byte-order
 * is meaningless for UTF-8) but causes a syntax error unless we skip it.
 */
static void
SkipUTF8BOM(FILE* file)
{
    int ch1 = fgetc(file);
    int ch2 = fgetc(file);
    int ch3 = fgetc(file);

    // Skip the BOM
    if (ch1 == 0xEF && ch2 == 0xBB && ch3 == 0xBF)
        return;

    // No BOM - revert
    if (ch3 != EOF)
        ungetc(ch3, file);
    if (ch2 != EOF)
        ungetc(ch2, file);
    if (ch1 != EOF)
        ungetc(ch1, file);
}

void
EnvironmentPreparer::invoke(HandleObject scope, Closure& closure)
{
    MOZ_ASSERT(!JS_IsExceptionPending(cx));

    AutoCompartment ac(cx, scope);
    AutoReportException are(cx);
    if (!closure(cx))
        return;
}

static MOZ_MUST_USE bool
RunFile(JSContext* cx, const char* filename, FILE* file, bool compileOnly)
{
    SkipUTF8BOM(file);

    // To support the UNIX #! shell hack, gobble the first line if it starts
    // with '#'.
    int ch = fgetc(file);
    if (ch == '#') {
        while ((ch = fgetc(file)) != EOF) {
            if (ch == '\n' || ch == '\r')
                break;
        }
    }
    ungetc(ch, file);

    int64_t t1 = PRMJ_Now();
    RootedScript script(cx);

    {
        CompileOptions options(cx);
        options.setIntroductionType("js shell file")
               .setUTF8(true)
               .setFileAndLine(filename, 1)
               .setIsRunOnce(true)
               .setNoScriptRval(true);

        if (!JS::Compile(cx, options, file, &script))
            return false;
        MOZ_ASSERT(script);
    }

    #ifdef DEBUG
        if (dumpEntrainedVariables)
            AnalyzeEntrainedVariables(cx, script);
    #endif
    if (!compileOnly) {
        if (!JS_ExecuteScript(cx, script))
            return false;
        int64_t t2 = PRMJ_Now() - t1;
        if (printTiming)
            printf("runtime = %.3f ms\n", double(t2) / PRMJ_USEC_PER_MSEC);
    }
    return true;
}

static bool
InitModuleLoader(JSContext* cx)
{
    // Decompress and evaluate the embedded module loader source to initialize
    // the module loader for the current compartment.

    uint32_t srcLen = moduleloader::GetRawScriptsSize();
    ScopedJSFreePtr<char> src(cx->pod_malloc<char>(srcLen));
    if (!src || !DecompressString(moduleloader::compressedSources, moduleloader::GetCompressedSize(),
                                  reinterpret_cast<unsigned char*>(src.get()), srcLen))
    {
        return false;
    }

    CompileOptions options(cx);
    options.setIntroductionType("shell module loader");
    options.setFileAndLine("shell/ModuleLoader.js", 1);
    options.setSelfHostingMode(false);
    options.setCanLazilyParse(false);
    options.setVersion(JSVERSION_LATEST);
    options.werrorOption = true;
    options.strictOption = true;

    RootedValue rv(cx);
    return Evaluate(cx, options, src, srcLen, &rv);
}

static bool
GetLoaderObject(JSContext* cx, MutableHandleObject resultOut)
{
    // Look up the |Reflect.Loader| object that has been defined by the module
    // loader.

    RootedObject object(cx, cx->global());
    RootedValue value(cx);
    if (!JS_GetProperty(cx, object, "Reflect", &value) || !value.isObject())
        return false;

    object = &value.toObject();
    if (!JS_GetProperty(cx, object, "Loader", &value) || !value.isObject())
        return false;

    resultOut.set(&value.toObject());
    return true;
}

static bool
GetImportRootMethod(JSContext* cx, HandleObject loader, MutableHandleFunction resultOut)
{
    // Look up the module loader's |importRoot| method.

    RootedValue value(cx);
    if (!JS_GetProperty(cx, loader, "importRoot", &value) || !value.isObject())
        return false;

    RootedObject object(cx, &value.toObject());
    if (!object->is<JSFunction>())
        return false;

    resultOut.set(&object->as<JSFunction>());
    return true;
}

static MOZ_MUST_USE bool
RunModule(JSContext* cx, const char* filename, FILE* file, bool compileOnly)
{
    // Execute a module by calling Reflect.Loader.importRoot on the resolved
    // filename.

    RootedObject loaderObj(cx);
    if (!GetLoaderObject(cx, &loaderObj)) {
        JS_ReportErrorASCII(cx, "Failed to get Reflect.Loader");
        return false;
    }

    RootedFunction importFun(cx);
    if (!GetImportRootMethod(cx, loaderObj, &importFun)) {
        JS_ReportErrorASCII(cx, "Failed to get Reflect.Loader.importRoot method");
        return false;
    }

    RootedString path(cx, JS_NewStringCopyZ(cx, filename));
    if (!path)
        return false;

    path = ResolvePath(cx, path, RootRelative);
    if (!path)
        return false;

    JS::AutoValueArray<1> args(cx);
    args[0].setString(path);

    RootedValue value(cx);
    return JS_CallFunction(cx, loaderObj, importFun, args, &value);
}

static bool
DrainJobQueue(JSContext* cx, unsigned argc, Value* vp)
{
    CallArgs args = CallArgsFromVp(argc, vp);

    if (GetShellContext(cx)->quitting) {
        JS_ReportErrorASCII(cx, "Mustn't drain the job queue when the shell is quitting");
        return false;
    }

    js::RunJobs(cx);

    args.rval().setUndefined();
    return true;
}

static void
ForwardingPromiseRejectionTrackerCallback(JSContext* cx, JS::HandleObject promise,
                                          PromiseRejectionHandlingState state, void* data)
{
    RootedValue callback(cx, GetShellContext(cx)->promiseRejectionTrackerCallback);
    if (callback.isNull()) {
        return;
    }

    AutoCompartment ac(cx, &callback.toObject());

    FixedInvokeArgs<2> args(cx);
    args[0].setObject(*promise);
    args[1].setInt32(static_cast<int32_t>(state));

    if (!JS_WrapValue(cx, args[0]))
        return;

    RootedValue rval(cx);
    if (!Call(cx, callback, UndefinedHandleValue, args, &rval))
        JS_ClearPendingException(cx);
}

static bool
SetPromiseRejectionTrackerCallback(JSContext* cx, unsigned argc, Value* vp)
{
    CallArgs args = CallArgsFromVp(argc, vp);

    if (!IsCallable(args.get(0))) {
        JS_ReportErrorASCII(cx,
                            "setPromiseRejectionTrackerCallback expects a function as its sole "
                            "argument");
        return false;
    }

    GetShellContext(cx)->promiseRejectionTrackerCallback = args[0];
    JS::SetPromiseRejectionTrackerCallback(cx, ForwardingPromiseRejectionTrackerCallback);

    args.rval().setUndefined();
    return true;
}

#ifdef ENABLE_INTL_API
static bool
AddIntlExtras(JSContext* cx, unsigned argc, Value* vp)
{
    CallArgs args = CallArgsFromVp(argc, vp);
    if (!args.get(0).isObject()) {
        JS_ReportErrorASCII(cx, "addIntlExtras must be passed an object");
        return false;
    }
    JS::RootedObject intl(cx, &args[0].toObject());

    static const JSFunctionSpec funcs[] = {
        JS_SELF_HOSTED_FN("getCalendarInfo", "Intl_getCalendarInfo", 1, 0),
        JS_SELF_HOSTED_FN("getLocaleInfo", "Intl_getLocaleInfo", 1, 0),
        JS_SELF_HOSTED_FN("getDisplayNames", "Intl_getDisplayNames", 2, 0),
        JS_FS_END
    };

    if (!JS_DefineFunctions(cx, intl, funcs))
        return false;

    if (!js::AddPluralRulesConstructor(cx, intl))
        return false;

    if (!js::AddMozDateTimeFormatConstructor(cx, intl))
        return false;

    args.rval().setUndefined();
    return true;
}
#endif // ENABLE_INTL_API

static bool
EvalAndPrint(JSContext* cx, const char* bytes, size_t length,
             int lineno, bool compileOnly)
{
    // Eval.
    JS::CompileOptions options(cx);
    options.setIntroductionType("js shell interactive")
           .setUTF8(true)
           .setIsRunOnce(true)
           .setFileAndLine("typein", lineno);
    RootedScript script(cx);
    if (!JS::Compile(cx, options, bytes, length, &script))
        return false;
    if (compileOnly)
        return true;
    RootedValue result(cx);
    if (!JS_ExecuteScript(cx, script, &result))
        return false;

    if (!result.isUndefined() && gOutFile->isOpen()) {
        // Print.
        RootedString str(cx);
        str = JS_ValueToSource(cx, result);
        if (!str)
            return false;

        char* utf8chars = JS_EncodeStringToUTF8(cx, str);
        if (!utf8chars)
            return false;
        fprintf(gOutFile->fp, "%s\n", utf8chars);
        JS_free(cx, utf8chars);
    }
    return true;
}

static MOZ_MUST_USE bool
ReadEvalPrintLoop(JSContext* cx, FILE* in, bool compileOnly)
{
    ShellContext* sc = GetShellContext(cx);
    int lineno = 1;
    bool hitEOF = false;

    do {
        /*
         * Accumulate lines until we get a 'compilable unit' - one that either
         * generates an error (before running out of source) or that compiles
         * cleanly.  This should be whenever we get a complete statement that
         * coincides with the end of a line.
         */
        int startline = lineno;
        typedef Vector<char, 32> CharBuffer;
        RootedObject globalLexical(cx, &cx->global()->lexicalEnvironment());
        CharBuffer buffer(cx);
        do {
            ScheduleWatchdog(cx, -1);
            sc->serviceInterrupt = false;
            errno = 0;

            char* line = GetLine(in, startline == lineno ? "js> " : "");
            if (!line) {
                if (errno) {
                    /*
                     * Use Latin1 variant here because strerror(errno)'s
                     * encoding depends on the user's C locale.
                     */
                    JS_ReportErrorLatin1(cx, "%s", strerror(errno));
                    return false;
                }
                hitEOF = true;
                break;
            }

            if (!buffer.append(line, strlen(line)) || !buffer.append('\n'))
                return false;

            lineno++;
            if (!ScheduleWatchdog(cx, sc->timeoutInterval)) {
                hitEOF = true;
                break;
            }
        } while (!JS_BufferIsCompilableUnit(cx, cx->global(), buffer.begin(), buffer.length()));

        if (hitEOF && buffer.empty())
            break;

        {
            // Report exceptions but keep going.
            AutoReportException are(cx);
            (void) EvalAndPrint(cx, buffer.begin(), buffer.length(), startline, compileOnly);
        }

        // If a let or const fail to initialize they will remain in an unusable
        // without further intervention. This call cleans up the global scope,
        // setting uninitialized lexicals to undefined so that they may still
        // be used. This behavior is _only_ acceptable in the context of the repl.
        if (JS::ForceLexicalInitialization(cx, globalLexical) && gErrFile->isOpen()) {
            fputs("Warning: According to the standard, after the above exception,\n"
                  "Warning: the global bindings should be permanently uninitialized.\n"
                  "Warning: We have non-standard-ly initialized them to `undefined`"
                  "for you.\nWarning: This nicety only happens in the JS shell.\n",
                  stderr);
        }

        if (!GetShellContext(cx)->quitting)
            js::RunJobs(cx);

    } while (!hitEOF && !sc->quitting);

    if (gOutFile->isOpen())
        fprintf(gOutFile->fp, "\n");

    return true;
}

enum FileKind
{
    FileScript,
    FileModule
};

static void
ReportCantOpenErrorUnknownEncoding(JSContext* cx, const char* filename)
{
    /*
     * Filenames are in some random system encoding.  *Probably* it's UTF-8,
     * but no guarantees.
     *
     * strerror(errno)'s encoding, in contrast, depends on the user's C locale.
     *
     * Latin-1 is possibly wrong for both of these -- but at least if it's
     * wrong it'll produce mojibake *safely*.  Run with Latin-1 til someone
     * complains.
     */
    JS_ReportErrorNumberLatin1(cx, my_GetErrorMessage, nullptr, JSSMSG_CANT_OPEN,
                               filename, strerror(errno));
}

static MOZ_MUST_USE bool
Process(JSContext* cx, const char* filename, bool forceTTY, FileKind kind = FileScript)
{
    FILE* file;
    if (forceTTY || !filename || strcmp(filename, "-") == 0) {
        file = stdin;
    } else {
        file = fopen(filename, "rb");
        if (!file) {
            ReportCantOpenErrorUnknownEncoding(cx, filename);
            return false;
        }
    }
    AutoCloseFile autoClose(file);

    if (!forceTTY && !isatty(fileno(file))) {
        // It's not interactive - just execute it.
        if (kind == FileScript) {
            if (!RunFile(cx, filename, file, compileOnly))
                return false;
        } else {
            if (!RunModule(cx, filename, file, compileOnly))
                return false;
        }
    } else {
        // It's an interactive filehandle; drop into read-eval-print loop.
        MOZ_ASSERT(kind == FileScript);
        if (!ReadEvalPrintLoop(cx, file, compileOnly))
            return false;
    }
    return true;
}

static bool
Version(JSContext* cx, unsigned argc, Value* vp)
{
    CallArgs args = CallArgsFromVp(argc, vp);
    JSVersion origVersion = JS_GetVersion(cx);
    if (args.length() == 0 || args[0].isUndefined()) {
        /* Get version. */
        args.rval().setInt32(origVersion);
    } else {
        /* Set version. */
        int32_t v = -1;
        if (args[0].isInt32()) {
            v = args[0].toInt32();
        } else if (args[0].isDouble()) {
            double fv = args[0].toDouble();
            int32_t fvi;
            if (NumberEqualsInt32(fv, &fvi))
                v = fvi;
        }
        if (v < 0 || v > JSVERSION_LATEST) {
            JS_ReportErrorNumberASCII(cx, my_GetErrorMessage, nullptr, JSSMSG_INVALID_ARGS,
                                      "version");
            return false;
        }
        JS_SetVersionForCompartment(js::GetContextCompartment(cx), JSVersion(v));
        args.rval().setInt32(origVersion);
    }
    return true;
}

#ifdef XP_WIN
#  define GET_FD_FROM_FILE(a) int(_get_osfhandle(fileno(a)))
#else
#  define GET_FD_FROM_FILE(a) fileno(a)
#endif

static bool
CreateMappedArrayBuffer(JSContext* cx, unsigned argc, Value* vp)
{
    CallArgs args = CallArgsFromVp(argc, vp);

    if (args.length() < 1 || args.length() > 3) {
        JS_ReportErrorNumberASCII(cx, my_GetErrorMessage, nullptr,
                                  args.length() < 1 ? JSSMSG_NOT_ENOUGH_ARGS : JSSMSG_TOO_MANY_ARGS,
                                  "createMappedArrayBuffer");
        return false;
    }

    RootedString rawFilenameStr(cx, JS::ToString(cx, args[0]));
    if (!rawFilenameStr)
        return false;
    // It's a little bizarre to resolve relative to the script, but for testing
    // I need a file at a known location, and the only good way I know of to do
    // that right now is to include it in the repo alongside the test script.
    // Bug 944164 would introduce an alternative.
    JSString* filenameStr = ResolvePath(cx, rawFilenameStr, ScriptRelative);
    if (!filenameStr)
        return false;
    JSAutoByteString filename(cx, filenameStr);
    if (!filename)
        return false;

    uint32_t offset = 0;
    if (args.length() >= 2) {
        if (!JS::ToUint32(cx, args[1], &offset))
            return false;
    }

    bool sizeGiven = false;
    uint32_t size;
    if (args.length() >= 3) {
        if (!JS::ToUint32(cx, args[2], &size))
            return false;
        sizeGiven = true;
        if (size == 0) {
            JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr, JSMSG_BAD_ARRAY_LENGTH);
            return false;
        }
    }

    FILE* file = fopen(filename.ptr(), "rb");
    if (!file) {
        ReportCantOpenErrorUnknownEncoding(cx, filename.ptr());
        return false;
    }
    AutoCloseFile autoClose(file);

    if (!sizeGiven) {
        struct stat st;
        if (fstat(fileno(file), &st) < 0) {
            JS_ReportErrorASCII(cx, "Unable to stat file");
            return false;
        }
        if (off_t(offset) >= st.st_size) {
            JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr,
                                      JSMSG_ARG_INDEX_OUT_OF_RANGE, "2");
            return false;
        }
        size = st.st_size - offset;
    }

    void* contents = JS_CreateMappedArrayBufferContents(GET_FD_FROM_FILE(file), offset, size);
    if (!contents) {
        JS_ReportErrorASCII(cx, "failed to allocate mapped array buffer contents (possibly due to bad alignment)");
        return false;
    }

    RootedObject obj(cx, JS_NewMappedArrayBufferWithContents(cx, size, contents));
    if (!obj)
        return false;

    args.rval().setObject(*obj);
    return true;
}

#undef GET_FD_FROM_FILE

static bool
AddPromiseReactions(JSContext* cx, unsigned argc, Value* vp)
{
    CallArgs args = CallArgsFromVp(argc, vp);

    if (args.length() != 3) {
        JS_ReportErrorNumberASCII(cx, my_GetErrorMessage, nullptr,
                                  args.length() < 3 ? JSSMSG_NOT_ENOUGH_ARGS : JSSMSG_TOO_MANY_ARGS,
                                  "addPromiseReactions");
        return false;
    }

    RootedObject promise(cx);
    if (args[0].isObject())
        promise = &args[0].toObject();

    if (!promise || !JS::IsPromiseObject(promise)) {
        JS_ReportErrorNumberASCII(cx, my_GetErrorMessage, nullptr, JSSMSG_INVALID_ARGS,
                                  "addPromiseReactions");
        return false;
    }

    RootedObject onResolve(cx);
    if (args[1].isObject())
        onResolve = &args[1].toObject();

    RootedObject onReject(cx);
    if (args[2].isObject())
        onReject = &args[2].toObject();

    if (!onResolve || !onResolve->is<JSFunction>() || !onReject || !onReject->is<JSFunction>()) {
        JS_ReportErrorNumberASCII(cx, my_GetErrorMessage, nullptr, JSSMSG_INVALID_ARGS,
                                  "addPromiseReactions");
        return false;
    }

    return JS::AddPromiseReactions(cx, promise, onResolve, onReject);
}

static bool
Options(JSContext* cx, unsigned argc, Value* vp)
{
    CallArgs args = CallArgsFromVp(argc, vp);

    JS::ContextOptions oldContextOptions = JS::ContextOptionsRef(cx);
    for (unsigned i = 0; i < args.length(); i++) {
        RootedString str(cx, JS::ToString(cx, args[i]));
        if (!str)
            return false;
        args[i].setString(str);

        JSAutoByteString opt;
        if (!opt.encodeUtf8(cx, str))
            return false;

        if (strcmp(opt.ptr(), "strict") == 0)
            JS::ContextOptionsRef(cx).toggleExtraWarnings();
        else if (strcmp(opt.ptr(), "werror") == 0)
            JS::ContextOptionsRef(cx).toggleWerror();
        else if (strcmp(opt.ptr(), "throw_on_asmjs_validation_failure") == 0)
            JS::ContextOptionsRef(cx).toggleThrowOnAsmJSValidationFailure();
        else if (strcmp(opt.ptr(), "strict_mode") == 0)
            JS::ContextOptionsRef(cx).toggleStrictMode();
        else {
            JS_ReportErrorUTF8(cx,
                               "unknown option name '%s'."
                               " The valid names are strict,"
                               " werror, and strict_mode.",
                               opt.ptr());
            return false;
        }
    }

    UniqueChars names = DuplicateString("");
    bool found = false;
    if (names && oldContextOptions.extraWarnings()) {
        names = JS_sprintf_append(Move(names), "%s%s", found ? "," : "", "strict");
        found = true;
    }
    if (names && oldContextOptions.werror()) {
        names = JS_sprintf_append(Move(names), "%s%s", found ? "," : "", "werror");
        found = true;
    }
    if (names && oldContextOptions.throwOnAsmJSValidationFailure()) {
        names = JS_sprintf_append(Move(names), "%s%s", found ? "," : "", "throw_on_asmjs_validation_failure");
        found = true;
    }
    if (names && oldContextOptions.strictMode()) {
        names = JS_sprintf_append(Move(names), "%s%s", found ? "," : "", "strict_mode");
        found = true;
    }
    if (!names) {
        JS_ReportOutOfMemory(cx);
        return false;
    }

    JSString* str = JS_NewStringCopyZ(cx, names.get());
    if (!str)
        return false;
    args.rval().setString(str);
    return true;
}

static bool
LoadScript(JSContext* cx, unsigned argc, Value* vp, bool scriptRelative)
{
    CallArgs args = CallArgsFromVp(argc, vp);

    RootedString str(cx);
    for (unsigned i = 0; i < args.length(); i++) {
        str = JS::ToString(cx, args[i]);
        if (!str) {
            JS_ReportErrorNumberASCII(cx, my_GetErrorMessage, nullptr, JSSMSG_INVALID_ARGS,
                                      "load");
            return false;
        }
        str = ResolvePath(cx, str, scriptRelative ? ScriptRelative : RootRelative);
        if (!str) {
            JS_ReportErrorASCII(cx, "unable to resolve path");
            return false;
        }
        JSAutoByteString filename(cx, str);
        if (!filename)
            return false;
        errno = 0;
        CompileOptions opts(cx);
        opts.setIntroductionType("js shell load")
            .setUTF8(true)
            .setIsRunOnce(true)
            .setNoScriptRval(true);
        RootedScript script(cx);
        RootedValue unused(cx);
        if ((compileOnly && !Compile(cx, opts, filename.ptr(), &script)) ||
            !Evaluate(cx, opts, filename.ptr(), &unused))
        {
            return false;
        }
    }

    args.rval().setUndefined();
    return true;
}

static bool
Load(JSContext* cx, unsigned argc, Value* vp)
{
    return LoadScript(cx, argc, vp, false);
}

static bool
LoadScriptRelativeToScript(JSContext* cx, unsigned argc, Value* vp)
{
    return LoadScript(cx, argc, vp, true);
}

// Populate |options| with the options given by |opts|'s properties. If we
// need to convert a filename to a C string, let fileNameBytes own the
// bytes.
static bool
ParseCompileOptions(JSContext* cx, CompileOptions& options, HandleObject opts,
                    JSAutoByteString& fileNameBytes)
{
    RootedValue v(cx);
    RootedString s(cx);

    if (!JS_GetProperty(cx, opts, "isRunOnce", &v))
        return false;
    if (!v.isUndefined())
        options.setIsRunOnce(ToBoolean(v));

    if (!JS_GetProperty(cx, opts, "noScriptRval", &v))
        return false;
    if (!v.isUndefined())
        options.setNoScriptRval(ToBoolean(v));

    if (!JS_GetProperty(cx, opts, "fileName", &v))
        return false;
    if (v.isNull()) {
        options.setFile(nullptr);
    } else if (!v.isUndefined()) {
        s = ToString(cx, v);
        if (!s)
            return false;
        char* fileName = fileNameBytes.encodeLatin1(cx, s);
        if (!fileName)
            return false;
        options.setFile(fileName);
    }

    if (!JS_GetProperty(cx, opts, "element", &v))
        return false;
    if (v.isObject())
        options.setElement(&v.toObject());

    if (!JS_GetProperty(cx, opts, "elementAttributeName", &v))
        return false;
    if (!v.isUndefined()) {
        s = ToString(cx, v);
        if (!s)
            return false;
        options.setElementAttributeName(s);
    }

    if (!JS_GetProperty(cx, opts, "lineNumber", &v))
        return false;
    if (!v.isUndefined()) {
        uint32_t u;
        if (!ToUint32(cx, v, &u))
            return false;
        options.setLine(u);
    }

    if (!JS_GetProperty(cx, opts, "columnNumber", &v))
        return false;
    if (!v.isUndefined()) {
        int32_t c;
        if (!ToInt32(cx, v, &c))
            return false;
        options.setColumn(c);
    }

    if (!JS_GetProperty(cx, opts, "sourceIsLazy", &v))
        return false;
    if (v.isBoolean())
        options.setSourceIsLazy(v.toBoolean());

    return true;
}

static void
my_LargeAllocFailCallback()
{
    JSContext* cx = TlsContext.get();
    if (!cx || cx->helperThread())
        return;

    MOZ_ASSERT(!JS::CurrentThreadIsHeapBusy());

    JS::PrepareForFullGC(cx);
    cx->runtime()->gc.gc(GC_NORMAL, JS::gcreason::SHARED_MEMORY_LIMIT);
}

static const uint32_t CacheEntry_SOURCE = 0;
static const uint32_t CacheEntry_BYTECODE = 1;

static const JSClass CacheEntry_class = {
    "CacheEntryObject", JSCLASS_HAS_RESERVED_SLOTS(2)
};

static bool
CacheEntry(JSContext* cx, unsigned argc, JS::Value* vp)
{
    CallArgs args = CallArgsFromVp(argc, vp);

    if (args.length() != 1 || !args[0].isString()) {
        JS_ReportErrorNumberASCII(cx, my_GetErrorMessage, nullptr, JSSMSG_INVALID_ARGS,
                                  "CacheEntry");
        return false;
    }

    RootedObject obj(cx, JS_NewObject(cx, &CacheEntry_class));
    if (!obj)
        return false;

    SetReservedSlot(obj, CacheEntry_SOURCE, args[0]);
    SetReservedSlot(obj, CacheEntry_BYTECODE, UndefinedValue());
    args.rval().setObject(*obj);
    return true;
}

static bool
CacheEntry_isCacheEntry(JSObject* cache)
{
    return JS_GetClass(cache) == &CacheEntry_class;
}

static JSString*
CacheEntry_getSource(HandleObject cache)
{
    MOZ_ASSERT(CacheEntry_isCacheEntry(cache));
    Value v = JS_GetReservedSlot(cache, CacheEntry_SOURCE);
    if (!v.isString())
        return nullptr;

    return v.toString();
}

static uint8_t*
CacheEntry_getBytecode(HandleObject cache, uint32_t* length)
{
    MOZ_ASSERT(CacheEntry_isCacheEntry(cache));
    Value v = JS_GetReservedSlot(cache, CacheEntry_BYTECODE);
    if (!v.isObject() || !v.toObject().is<ArrayBufferObject>())
        return nullptr;

    ArrayBufferObject* arrayBuffer = &v.toObject().as<ArrayBufferObject>();
    *length = arrayBuffer->byteLength();
    return arrayBuffer->dataPointer();
}

static bool
CacheEntry_setBytecode(JSContext* cx, HandleObject cache, uint8_t* buffer, uint32_t length)
{
    MOZ_ASSERT(CacheEntry_isCacheEntry(cache));

    ArrayBufferObject::BufferContents contents =
        ArrayBufferObject::BufferContents::create<ArrayBufferObject::PLAIN>(buffer);
    Rooted<ArrayBufferObject*> arrayBuffer(cx, ArrayBufferObject::create(cx, length, contents));
    if (!arrayBuffer)
        return false;

    SetReservedSlot(cache, CacheEntry_BYTECODE, ObjectValue(*arrayBuffer));
    return true;
}

static bool
ConvertTranscodeResultToJSException(JSContext* cx, JS::TranscodeResult rv)
{
    switch (rv) {
      case JS::TranscodeResult_Ok:
        return true;

      default:
        MOZ_FALLTHROUGH;
      case JS::TranscodeResult_Failure:
        MOZ_ASSERT(!cx->isExceptionPending());
        JS_ReportErrorASCII(cx, "generic warning");
        return false;
      case JS::TranscodeResult_Failure_BadBuildId:
        MOZ_ASSERT(!cx->isExceptionPending());
        JS_ReportErrorASCII(cx, "the build-id does not match");
        return false;
      case JS::TranscodeResult_Failure_RunOnceNotSupported:
        MOZ_ASSERT(!cx->isExceptionPending());
        JS_ReportErrorASCII(cx, "run-once script are not supported by XDR");
        return false;
      case JS::TranscodeResult_Failure_AsmJSNotSupported:
        MOZ_ASSERT(!cx->isExceptionPending());
        JS_ReportErrorASCII(cx, "Asm.js is not supported by XDR");
        return false;
      case JS::TranscodeResult_Failure_UnknownClassKind:
        MOZ_ASSERT(!cx->isExceptionPending());
        JS_ReportErrorASCII(cx, "Unknown class kind, go fix it.");
        return false;
      case JS::TranscodeResult_Failure_WrongCompileOption:
        MOZ_ASSERT(!cx->isExceptionPending());
        JS_ReportErrorASCII(cx, "Compile options differs from Compile options of the encoding");
        return false;
      case JS::TranscodeResult_Failure_NotInterpretedFun:
        MOZ_ASSERT(!cx->isExceptionPending());
        JS_ReportErrorASCII(cx, "Only interepreted functions are supported by XDR");
        return false;

      case JS::TranscodeResult_Throw:
        MOZ_ASSERT(cx->isExceptionPending());
        return false;
    }
}

static bool
Evaluate(JSContext* cx, unsigned argc, Value* vp)
{
    CallArgs args = CallArgsFromVp(argc, vp);

    if (args.length() < 1 || args.length() > 2) {
        JS_ReportErrorNumberASCII(cx, my_GetErrorMessage, nullptr,
                                  args.length() < 1 ? JSSMSG_NOT_ENOUGH_ARGS : JSSMSG_TOO_MANY_ARGS,
                                  "evaluate");
        return false;
    }

    RootedString code(cx, nullptr);
    RootedObject cacheEntry(cx, nullptr);
    if (args[0].isString()) {
        code = args[0].toString();
    } else if (args[0].isObject() && CacheEntry_isCacheEntry(&args[0].toObject())) {
        cacheEntry = &args[0].toObject();
        code = CacheEntry_getSource(cacheEntry);
    }

    if (!code || (args.length() == 2 && args[1].isPrimitive())) {
        JS_ReportErrorNumberASCII(cx, my_GetErrorMessage, nullptr, JSSMSG_INVALID_ARGS, "evaluate");
        return false;
    }

    CompileOptions options(cx);
    JSAutoByteString fileNameBytes;
    RootedString displayURL(cx);
    RootedString sourceMapURL(cx);
    RootedObject global(cx, nullptr);
    bool catchTermination = false;
    bool loadBytecode = false;
    bool saveBytecode = false;
    bool saveIncrementalBytecode = false;
    bool assertEqBytecode = false;
    RootedObject callerGlobal(cx, cx->global());

    options.setIntroductionType("js shell evaluate")
           .setFileAndLine("@evaluate", 1);

    global = JS_GetGlobalForObject(cx, &args.callee());
    MOZ_ASSERT(global);

    if (args.length() == 2) {
        RootedObject opts(cx, &args[1].toObject());
        RootedValue v(cx);

        if (!ParseCompileOptions(cx, options, opts, fileNameBytes))
            return false;

        if (!JS_GetProperty(cx, opts, "displayURL", &v))
            return false;
        if (!v.isUndefined()) {
            displayURL = ToString(cx, v);
            if (!displayURL)
                return false;
        }

        if (!JS_GetProperty(cx, opts, "sourceMapURL", &v))
            return false;
        if (!v.isUndefined()) {
            sourceMapURL = ToString(cx, v);
            if (!sourceMapURL)
                return false;
        }

        if (!JS_GetProperty(cx, opts, "global", &v))
            return false;
        if (!v.isUndefined()) {
            if (v.isObject()) {
                global = js::UncheckedUnwrap(&v.toObject());
                if (!global)
                    return false;
            }
            if (!global || !(JS_GetClass(global)->flags & JSCLASS_IS_GLOBAL)) {
                JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr, JSMSG_UNEXPECTED_TYPE,
                                          "\"global\" passed to evaluate()", "not a global object");
                return false;
            }
        }

        if (!JS_GetProperty(cx, opts, "zoneGroup", &v))
            return false;
        if (!v.isUndefined()) {
            if (global != JS_GetGlobalForObject(cx, &args.callee())) {
                JS_ReportErrorASCII(cx, "zoneGroup and global cannot both be specified.");
                return false;
            }

            // Find all eligible globals to execute in: any global in another
            // zone group which has not been entered by a cooperative thread.
            JS::AutoObjectVector eligibleGlobals(cx);
            for (CompartmentsIter c(cx->runtime(), SkipAtoms); !c.done(); c.next()) {
                if (!c->zone()->group()->ownerContext().context() &&
                    c->maybeGlobal() &&
                    !cx->runtime()->isSelfHostingGlobal(c->maybeGlobal()))
                {
                    if (!eligibleGlobals.append(c->maybeGlobal()))
                        return false;
                }
            }

            if (eligibleGlobals.empty()) {
                JS_ReportErrorASCII(cx, "zoneGroup can only be used if another"
                                    " cooperative thread has called cooperativeYield(true).");
                return false;
            }

            // Pick an eligible global to use based on the value of the zoneGroup property.
            int32_t which;
            if (!ToInt32(cx, v, &which))
                return false;
            which = Min<int32_t>(Max(which, 0), eligibleGlobals.length() - 1);
            global = eligibleGlobals[which];
        }

        if (!JS_GetProperty(cx, opts, "catchTermination", &v))
            return false;
        if (!v.isUndefined())
            catchTermination = ToBoolean(v);

        if (!JS_GetProperty(cx, opts, "loadBytecode", &v))
            return false;
        if (!v.isUndefined())
            loadBytecode = ToBoolean(v);

        if (!JS_GetProperty(cx, opts, "saveBytecode", &v))
            return false;
        if (!v.isUndefined())
            saveBytecode = ToBoolean(v);

        if (!JS_GetProperty(cx, opts, "saveIncrementalBytecode", &v))
            return false;
        if (!v.isUndefined())
            saveIncrementalBytecode = ToBoolean(v);

        if (!JS_GetProperty(cx, opts, "assertEqBytecode", &v))
            return false;
        if (!v.isUndefined())
            assertEqBytecode = ToBoolean(v);

        // We cannot load or save the bytecode if we have no object where the
        // bytecode cache is stored.
        if (loadBytecode || saveBytecode || saveIncrementalBytecode) {
            if (!cacheEntry) {
                JS_ReportErrorNumberASCII(cx, my_GetErrorMessage, nullptr, JSSMSG_INVALID_ARGS,
                                          "evaluate");
                return false;
            }
            if (saveIncrementalBytecode && saveBytecode) {
                JS_ReportErrorASCII(cx, "saveIncrementalBytecode and saveBytecode cannot be used"
                                    " at the same time.");
                return false;
            }
        }
    }

    AutoStableStringChars codeChars(cx);
    if (!codeChars.initTwoByte(cx, code))
        return false;

    JS::TranscodeBuffer loadBuffer;
    JS::TranscodeBuffer saveBuffer;

    if (loadBytecode) {
        uint32_t loadLength = 0;
        uint8_t* loadData = nullptr;
        loadData = CacheEntry_getBytecode(cacheEntry, &loadLength);
        if (!loadData)
            return false;
        if (!loadBuffer.append(loadData, loadLength)) {
            JS_ReportOutOfMemory(cx);
            return false;
        }
    }

    {
        JSAutoCompartment ac(cx, global);
        RootedScript script(cx);

        {
            if (saveBytecode) {
                if (!JS::CompartmentCreationOptionsRef(cx).cloneSingletons()) {
                    JS_ReportErrorNumberASCII(cx, my_GetErrorMessage, nullptr,
                                              JSSMSG_CACHE_SINGLETON_FAILED);
                    return false;
                }

                // cloneSingletons implies that singletons are used as template objects.
                MOZ_ASSERT(JS::CompartmentBehaviorsRef(cx).getSingletonsAsTemplates());
            }

            if (loadBytecode) {
                JS::TranscodeResult rv = JS::DecodeScript(cx, loadBuffer, &script);
                if (!ConvertTranscodeResultToJSException(cx, rv))
                    return false;
            } else {
                mozilla::Range<const char16_t> chars = codeChars.twoByteRange();
                (void) JS::Compile(cx, options, chars.begin().get(), chars.length(), &script);
            }

            if (!script)
                return false;
        }

        if (displayURL && !script->scriptSource()->hasDisplayURL()) {
            JSFlatString* flat = displayURL->ensureFlat(cx);
            if (!flat)
                return false;

            AutoStableStringChars chars(cx);
            if (!chars.initTwoByte(cx, flat))
                return false;

            const char16_t* durl = chars.twoByteRange().begin().get();
            if (!script->scriptSource()->setDisplayURL(cx, durl))
                return false;
        }
        if (sourceMapURL && !script->scriptSource()->hasSourceMapURL()) {
            JSFlatString* flat = sourceMapURL->ensureFlat(cx);
            if (!flat)
                return false;

            AutoStableStringChars chars(cx);
            if (!chars.initTwoByte(cx, flat))
                return false;

            const char16_t* smurl = chars.twoByteRange().begin().get();
            if (!script->scriptSource()->setSourceMapURL(cx, smurl))
                return false;
        }

        // If we want to save the bytecode incrementally, then we should
        // register ahead the fact that every JSFunction which is being
        // delazified should be encoded at the end of the delazification.
        if (saveIncrementalBytecode) {
            if (!StartIncrementalEncoding(cx, script))
                return false;
        }

        if (!JS_ExecuteScript(cx, script, args.rval())) {
            if (catchTermination && !JS_IsExceptionPending(cx)) {
                JSAutoCompartment ac1(cx, callerGlobal);
                JSString* str = JS_NewStringCopyZ(cx, "terminated");
                if (!str)
                    return false;
                args.rval().setString(str);
                return true;
            }
            return false;
        }

        // Encode the bytecode after the execution of the script.
        if (saveBytecode) {
            JS::TranscodeResult rv = JS::EncodeScript(cx, saveBuffer, script);
            if (!ConvertTranscodeResultToJSException(cx, rv))
                return false;
        }

        // Serialize the encoded bytecode, recorded before the execution, into a
        // buffer which can be deserialized linearly.
        if (saveIncrementalBytecode) {
            if (!FinishIncrementalEncoding(cx, script, saveBuffer))
                return false;
        }
    }

    if (saveBytecode || saveIncrementalBytecode) {
        // If we are both loading and saving, we assert that we are going to
        // replace the current bytecode by the same stream of bytes.
        if (loadBytecode && assertEqBytecode) {
            if (saveBuffer.length() != loadBuffer.length()) {
                char loadLengthStr[16];
                SprintfLiteral(loadLengthStr, "%zu", loadBuffer.length());
                char saveLengthStr[16];
                SprintfLiteral(saveLengthStr,"%zu", saveBuffer.length());

                JS_ReportErrorNumberASCII(cx, my_GetErrorMessage, nullptr, JSSMSG_CACHE_EQ_SIZE_FAILED,
                                          loadLengthStr, saveLengthStr);
                return false;
            }

            if (!PodEqual(loadBuffer.begin(), saveBuffer.begin(), loadBuffer.length())) {
                JS_ReportErrorNumberASCII(cx, my_GetErrorMessage, nullptr,
                                          JSSMSG_CACHE_EQ_CONTENT_FAILED);
                return false;
            }
        }

        size_t saveLength = saveBuffer.length();
        if (saveLength >= INT32_MAX) {
            JS_ReportErrorASCII(cx, "Cannot save large cache entry content");
            return false;
        }
        uint8_t* saveData = saveBuffer.extractOrCopyRawBuffer();
        if (!CacheEntry_setBytecode(cx, cacheEntry, saveData, saveLength)) {
            js_free(saveData);
            return false;
        }
    }

    return JS_WrapValue(cx, args.rval());
}

JSString*
js::shell::FileAsString(JSContext* cx, JS::HandleString pathnameStr)
{
    JSAutoByteString pathname(cx, pathnameStr);
    if (!pathname)
        return nullptr;

    FILE* file;

    file = fopen(pathname.ptr(), "rb");
    if (!file) {
        ReportCantOpenErrorUnknownEncoding(cx, pathname.ptr());
        return nullptr;
    }

    AutoCloseFile autoClose(file);

    if (fseek(file, 0, SEEK_END) != 0) {
        pathname.clear();
        if (!pathname.encodeUtf8(cx, pathnameStr))
            return nullptr;
        JS_ReportErrorUTF8(cx, "can't seek end of %s", pathname.ptr());
        return nullptr;
    }

    size_t len = ftell(file);
    if (fseek(file, 0, SEEK_SET) != 0) {
        pathname.clear();
        if (!pathname.encodeUtf8(cx, pathnameStr))
            return nullptr;
        JS_ReportErrorUTF8(cx, "can't seek start of %s", pathname.ptr());
        return nullptr;
    }

    UniqueChars buf(static_cast<char*>(js_malloc(len + 1)));
    if (!buf)
        return nullptr;

    size_t cc = fread(buf.get(), 1, len, file);
    if (cc != len) {
        if (ptrdiff_t(cc) < 0) {
            ReportCantOpenErrorUnknownEncoding(cx, pathname.ptr());
        } else {
            pathname.clear();
            if (!pathname.encodeUtf8(cx, pathnameStr))
                return nullptr;
            JS_ReportErrorUTF8(cx, "can't read %s: short read", pathname.ptr());
        }
        return nullptr;
    }

    UniqueTwoByteChars ucbuf(
        JS::LossyUTF8CharsToNewTwoByteCharsZ(cx, JS::UTF8Chars(buf.get(), len), &len).get()
    );
    if (!ucbuf) {
        pathname.clear();
        if (!pathname.encodeUtf8(cx, pathnameStr))
            return nullptr;
        JS_ReportErrorUTF8(cx, "Invalid UTF-8 in file '%s'", pathname.ptr());
        return nullptr;
    }

    return JS_NewUCStringCopyN(cx, ucbuf.get(), len);
}

/*
 * Function to run scripts and return compilation + execution time. Semantics
 * are closely modelled after the equivalent function in WebKit, as this is used
 * to produce benchmark timings by SunSpider.
 */
static bool
Run(JSContext* cx, unsigned argc, Value* vp)
{
    CallArgs args = CallArgsFromVp(argc, vp);
    if (args.length() != 1) {
        JS_ReportErrorNumberASCII(cx, my_GetErrorMessage, nullptr, JSSMSG_INVALID_ARGS, "run");
        return false;
    }

    RootedString str(cx, JS::ToString(cx, args[0]));
    if (!str)
        return false;
    args[0].setString(str);

    str = FileAsString(cx, str);
    if (!str)
        return false;

    AutoStableStringChars chars(cx);
    if (!chars.initTwoByte(cx, str))
        return false;

    const char16_t* ucbuf = chars.twoByteRange().begin().get();
    size_t buflen = str->length();

    RootedScript script(cx);
    int64_t startClock = PRMJ_Now();
    {
        /* FIXME: This should use UTF-8 (bug 987069). */
        JSAutoByteString filename(cx, str);
        if (!filename)
            return false;

        JS::CompileOptions options(cx);
        options.setIntroductionType("js shell run")
               .setFileAndLine(filename.ptr(), 1)
               .setIsRunOnce(true)
               .setNoScriptRval(true);
        if (!JS_CompileUCScript(cx, ucbuf, buflen, options, &script))
            return false;
    }

    if (!JS_ExecuteScript(cx, script))
        return false;

    int64_t endClock = PRMJ_Now();

    args.rval().setDouble((endClock - startClock) / double(PRMJ_USEC_PER_MSEC));
    return true;
}

/*
 * function readline()
 * Provides a hook for scripts to read a line from stdin.
 */
static bool
ReadLine(JSContext* cx, unsigned argc, Value* vp)
{
    CallArgs args = CallArgsFromVp(argc, vp);

#define BUFSIZE 256
    FILE* from = stdin;
    size_t buflength = 0;
    size_t bufsize = BUFSIZE;
    char* buf = (char*) JS_malloc(cx, bufsize);
    if (!buf)
        return false;

    bool sawNewline = false;
    size_t gotlength;
    while ((gotlength = js_fgets(buf + buflength, bufsize - buflength, from)) > 0) {
        buflength += gotlength;

        /* Are we done? */
        if (buf[buflength - 1] == '\n') {
            buf[buflength - 1] = '\0';
            sawNewline = true;
            break;
        } else if (buflength < bufsize - 1) {
            break;
        }

        /* Else, grow our buffer for another pass. */
        char* tmp;
        bufsize *= 2;
        if (bufsize > buflength) {
            tmp = static_cast<char*>(JS_realloc(cx, buf, bufsize / 2, bufsize));
        } else {
            JS_ReportOutOfMemory(cx);
            tmp = nullptr;
        }

        if (!tmp) {
            JS_free(cx, buf);
            return false;
        }

        buf = tmp;
    }

    /* Treat the empty string specially. */
    if (buflength == 0) {
        args.rval().set(feof(from) ? NullValue() : JS_GetEmptyStringValue(cx));
        JS_free(cx, buf);
        return true;
    }

    /* Shrink the buffer to the real size. */
    char* tmp = static_cast<char*>(JS_realloc(cx, buf, bufsize, buflength));
    if (!tmp) {
        JS_free(cx, buf);
        return false;
    }

    buf = tmp;

    /*
     * Turn buf into a JSString. Note that buflength includes the trailing null
     * character.
     */
    JSString* str = JS_NewStringCopyN(cx, buf, sawNewline ? buflength - 1 : buflength);
    JS_free(cx, buf);
    if (!str)
        return false;

    args.rval().setString(str);
    return true;
}

/*
 * function readlineBuf()
 * Provides a hook for scripts to emulate readline() using a string object.
 */
static bool
ReadLineBuf(JSContext* cx, unsigned argc, Value* vp)
{
    CallArgs args = CallArgsFromVp(argc, vp);
    ShellContext* sc = GetShellContext(cx);

    if (!args.length()) {
        if (!sc->readLineBuf) {
            JS_ReportErrorASCII(cx, "No source buffer set. You must initially "
                                "call readlineBuf with an argument.");
            return false;
        }

        char* currentBuf = sc->readLineBuf.get() + sc->readLineBufPos;
        size_t buflen = strlen(currentBuf);

        if (!buflen) {
            args.rval().setNull();
            return true;
        }

        size_t len = 0;
        while(len < buflen) {
            if (currentBuf[len] == '\n')
                break;
            len++;
        }

        JSString* str = JS_NewStringCopyN(cx, currentBuf, len);
        if (!str)
            return false;

        if (currentBuf[len] == '\0')
            sc->readLineBufPos += len;
        else
            sc->readLineBufPos += len + 1;

        args.rval().setString(str);
        return true;
    }

    if (args.length() == 1) {
        if (sc->readLineBuf)
            sc->readLineBuf.reset();

        RootedString str(cx, JS::ToString(cx, args[0]));
        if (!str)
            return false;
        sc->readLineBuf = UniqueChars(JS_EncodeStringToUTF8(cx, str));
        if (!sc->readLineBuf)
            return false;

        sc->readLineBufPos = 0;
        return true;
    }

    JS_ReportErrorASCII(cx, "Must specify at most one argument");
    return false;
}

static bool
PutStr(JSContext* cx, unsigned argc, Value* vp)
{
    CallArgs args = CallArgsFromVp(argc, vp);

    if (args.length() != 0) {
        if (!gOutFile->isOpen()) {
            JS_ReportErrorASCII(cx, "output file is closed");
            return false;
        }

        RootedString str(cx, JS::ToString(cx, args[0]));
        if (!str)
            return false;
        char* bytes = JS_EncodeStringToUTF8(cx, str);
        if (!bytes)
            return false;
        fputs(bytes, gOutFile->fp);
        JS_free(cx, bytes);
        fflush(gOutFile->fp);
    }

    args.rval().setUndefined();
    return true;
}

static bool
Now(JSContext* cx, unsigned argc, Value* vp)
{
    CallArgs args = CallArgsFromVp(argc, vp);
    double now = PRMJ_Now() / double(PRMJ_USEC_PER_MSEC);
    args.rval().setDouble(now);
    return true;
}

static bool
PrintInternal(JSContext* cx, const CallArgs& args, RCFile* file)
{
    if (!file->isOpen()) {
        JS_ReportErrorASCII(cx, "output file is closed");
        return false;
    }

    for (unsigned i = 0; i < args.length(); i++) {
        RootedString str(cx, JS::ToString(cx, args[i]));
        if (!str)
            return false;
        char* bytes = JS_EncodeStringToUTF8(cx, str);
        if (!bytes)
            return false;
        fprintf(file->fp, "%s%s", i ? " " : "", bytes);
        JS_free(cx, bytes);
    }

    fputc('\n', file->fp);
    fflush(file->fp);

    args.rval().setUndefined();
    return true;
}

static bool
Print(JSContext* cx, unsigned argc, Value* vp)
{
    CallArgs args = CallArgsFromVp(argc, vp);
    return PrintInternal(cx, args, gOutFile);
}

static bool
PrintErr(JSContext* cx, unsigned argc, Value* vp)
{
    CallArgs args = CallArgsFromVp(argc, vp);
    return PrintInternal(cx, args, gErrFile);
}

static bool
Help(JSContext* cx, unsigned argc, Value* vp);

static bool
Quit(JSContext* cx, unsigned argc, Value* vp)
{
    ShellContext* sc = GetShellContext(cx);

#ifdef JS_MORE_DETERMINISTIC
    // Print a message to stderr in more-deterministic builds to help jsfunfuzz
    // find uncatchable-exception bugs.
    fprintf(stderr, "quit called\n");
#endif

    CallArgs args = CallArgsFromVp(argc, vp);
    int32_t code;
    if (!ToInt32(cx, args.get(0), &code))
        return false;

    // The fuzzers check the shell's exit code and assume a value >= 128 means
    // the process crashed (for instance, SIGSEGV will result in code 139). On
    // POSIX platforms, the exit code is 8-bit and negative values can also
    // result in an exit code >= 128. We restrict the value to range [0, 127] to
    // avoid false positives.
    if (code < 0 || code >= 128) {
        JS_ReportErrorASCII(cx, "quit exit code should be in range 0-127");
        return false;
    }

    js::StopDrainingJobQueue(cx);
    sc->exitCode = code;
    sc->quitting = true;
    return false;
}

static bool
StartTimingMutator(JSContext* cx, unsigned argc, Value* vp)
{
    CallArgs args = CallArgsFromVp(argc, vp);
    if (args.length() > 0) {
        JS_ReportErrorNumberASCII(cx, my_GetErrorMessage, nullptr, JSSMSG_TOO_MANY_ARGS,
                                  "startTimingMutator");
        return false;
    }

    if (!cx->runtime()->gc.stats().startTimingMutator()) {
        JS_ReportErrorASCII(cx, "StartTimingMutator should only be called from outside of GC");
        return false;
    }

    args.rval().setUndefined();
    return true;
}

static bool
StopTimingMutator(JSContext* cx, unsigned argc, Value* vp)
{
    CallArgs args = CallArgsFromVp(argc, vp);
    if (args.length() > 0) {
        JS_ReportErrorNumberASCII(cx, my_GetErrorMessage, nullptr, JSSMSG_TOO_MANY_ARGS,
                                  "stopTimingMutator");
        return false;
    }

    double mutator_ms, gc_ms;
    if (!cx->runtime()->gc.stats().stopTimingMutator(mutator_ms, gc_ms)) {
        JS_ReportErrorASCII(cx, "stopTimingMutator called when not timing the mutator");
        return false;
    }
    double total_ms = mutator_ms + gc_ms;
    if (total_ms > 0 && gOutFile->isOpen()) {
        fprintf(gOutFile->fp, "Mutator: %.3fms (%.1f%%), GC: %.3fms (%.1f%%)\n",
                mutator_ms, mutator_ms / total_ms * 100.0, gc_ms, gc_ms / total_ms * 100.0);
    }

    args.rval().setUndefined();
    return true;
}

static const char*
ToSource(JSContext* cx, MutableHandleValue vp, JSAutoByteString* bytes)
{
    JSString* str = JS_ValueToSource(cx, vp);
    if (str) {
        vp.setString(str);
        if (bytes->encodeLatin1(cx, str))
            return bytes->ptr();
    }
    JS_ClearPendingException(cx);
    return "<<error converting value to string>>";
}

static bool
AssertEq(JSContext* cx, unsigned argc, Value* vp)
{
    CallArgs args = CallArgsFromVp(argc, vp);
    if (!(args.length() == 2 || (args.length() == 3 && args[2].isString()))) {
        JS_ReportErrorNumberASCII(cx, my_GetErrorMessage, nullptr,
                                  (args.length() < 2)
                                  ? JSSMSG_NOT_ENOUGH_ARGS
                                  : (args.length() == 3)
                                  ? JSSMSG_INVALID_ARGS
                                  : JSSMSG_TOO_MANY_ARGS,
                                  "assertEq");
        return false;
    }

    bool same;
    if (!JS_SameValue(cx, args[0], args[1], &same))
        return false;
    if (!same) {
        JSAutoByteString bytes0, bytes1;
        const char* actual = ToSource(cx, args[0], &bytes0);
        const char* expected = ToSource(cx, args[1], &bytes1);
        if (args.length() == 2) {
            JS_ReportErrorNumberLatin1(cx, my_GetErrorMessage, nullptr, JSSMSG_ASSERT_EQ_FAILED,
                                       actual, expected);
        } else {
            JSAutoByteString bytes2(cx, args[2].toString());
            if (!bytes2)
                return false;
            JS_ReportErrorNumberLatin1(cx, my_GetErrorMessage, nullptr,
                                       JSSMSG_ASSERT_EQ_FAILED_MSG,
                                       actual, expected, bytes2.ptr());
        }
        return false;
    }
    args.rval().setUndefined();
    return true;
}

static JSScript*
ValueToScript(JSContext* cx, HandleValue v, JSFunction** funp = nullptr)
{
    if (v.isString()) {
        // To convert a string to a script, compile it. Parse it as an ES6 Program.
        RootedLinearString linearStr(cx, StringToLinearString(cx, v.toString()));
        if (!linearStr)
            return nullptr;
        size_t len = GetLinearStringLength(linearStr);
        AutoStableStringChars linearChars(cx);
        if (!linearChars.initTwoByte(cx, linearStr))
            return nullptr;
        const char16_t* chars = linearChars.twoByteRange().begin().get();

        RootedScript script(cx);
        CompileOptions options(cx);
        if (!JS::Compile(cx, options, chars, len, &script))
            return nullptr;
        return script;
    }

    RootedFunction fun(cx, JS_ValueToFunction(cx, v));
    if (!fun)
        return nullptr;

    // Unwrap bound functions.
    while (fun->isBoundFunction()) {
        JSObject* target = fun->getBoundFunctionTarget();
        if (target && target->is<JSFunction>())
            fun = &target->as<JSFunction>();
        else
            break;
    }

    // Get unwrapped async function.
    if (IsWrappedAsyncFunction(fun))
        fun = GetUnwrappedAsyncFunction(fun);
    if (IsWrappedAsyncGenerator(fun))
        fun = GetUnwrappedAsyncGenerator(fun);

    if (!fun->isInterpreted()) {
        JS_ReportErrorNumberASCII(cx, my_GetErrorMessage, nullptr, JSSMSG_SCRIPTS_ONLY);
        return nullptr;
    }

    JSScript* script = JSFunction::getOrCreateScript(cx, fun);
    if (!script)
        return nullptr;

    if (funp)
        *funp = fun;

    return script;
}

static JSScript*
GetTopScript(JSContext* cx)
{
    NonBuiltinScriptFrameIter iter(cx);
    return iter.done() ? nullptr : iter.script();
}

static bool
GetScriptAndPCArgs(JSContext* cx, CallArgs& args, MutableHandleScript scriptp,
                   int32_t* ip)
{
    RootedScript script(cx, GetTopScript(cx));
    *ip = 0;
    if (!args.get(0).isUndefined()) {
        HandleValue v = args[0];
        unsigned intarg = 0;
        if (v.isObject() &&
            JS_GetClass(&v.toObject()) == Jsvalify(&JSFunction::class_)) {
            script = ValueToScript(cx, v);
            if (!script)
                return false;
            intarg++;
        }
        if (!args.get(intarg).isUndefined()) {
            if (!JS::ToInt32(cx, args[intarg], ip))
                return false;
            if ((uint32_t)*ip >= script->length()) {
                JS_ReportErrorASCII(cx, "Invalid PC");
                return false;
            }
        }
    }

    scriptp.set(script);

    return true;
}

static bool
LineToPC(JSContext* cx, unsigned argc, Value* vp)
{
    CallArgs args = CallArgsFromVp(argc, vp);

    if (args.length() == 0) {
        JS_ReportErrorNumberASCII(cx, my_GetErrorMessage, nullptr, JSSMSG_LINE2PC_USAGE);
        return false;
    }

    RootedScript script(cx, GetTopScript(cx));
    int32_t lineArg = 0;
    if (args[0].isObject() && args[0].toObject().is<JSFunction>()) {
        script = ValueToScript(cx, args[0]);
        if (!script)
            return false;
        lineArg++;
    }

    uint32_t lineno;
    if (!ToUint32(cx, args.get(lineArg), &lineno))
         return false;

    jsbytecode* pc = LineNumberToPC(script, lineno);
    if (!pc)
        return false;
    args.rval().setInt32(script->pcToOffset(pc));
    return true;
}

static bool
PCToLine(JSContext* cx, unsigned argc, Value* vp)
{
    CallArgs args = CallArgsFromVp(argc, vp);
    RootedScript script(cx);
    int32_t i;
    unsigned lineno;

    if (!GetScriptAndPCArgs(cx, args, &script, &i))
        return false;
    lineno = PCToLineNumber(script, script->offsetToPC(i));
    if (!lineno)
        return false;
    args.rval().setInt32(lineno);
    return true;
}

#ifdef DEBUG

static void
UpdateSwitchTableBounds(JSContext* cx, HandleScript script, unsigned offset,
                        unsigned* start, unsigned* end)
{
    jsbytecode* pc;
    JSOp op;
    ptrdiff_t jmplen;
    int32_t low, high, n;

    pc = script->offsetToPC(offset);
    op = JSOp(*pc);
    switch (op) {
      case JSOP_TABLESWITCH:
        jmplen = JUMP_OFFSET_LEN;
        pc += jmplen;
        low = GET_JUMP_OFFSET(pc);
        pc += JUMP_OFFSET_LEN;
        high = GET_JUMP_OFFSET(pc);
        pc += JUMP_OFFSET_LEN;
        n = high - low + 1;
        break;

      default:
        /* [condswitch] switch does not have any jump or lookup tables. */
        MOZ_ASSERT(op == JSOP_CONDSWITCH);
        return;
    }

    *start = script->pcToOffset(pc);
    *end = *start + (unsigned)(n * jmplen);
}

static MOZ_MUST_USE bool
SrcNotes(JSContext* cx, HandleScript script, Sprinter* sp)
{
    if (!sp->put("\nSource notes:\n") ||
        !sp->jsprintf("%4s %4s %5s %6s %-8s %s\n",
                      "ofs", "line", "pc", "delta", "desc", "args") ||
        !sp->put("---- ---- ----- ------ -------- ------\n"))
    {
        return false;
    }

    unsigned offset = 0;
    unsigned colspan = 0;
    unsigned lineno = script->lineno();
    jssrcnote* notes = script->notes();
    unsigned switchTableEnd = 0, switchTableStart = 0;
    for (jssrcnote* sn = notes; !SN_IS_TERMINATOR(sn); sn = SN_NEXT(sn)) {
        unsigned delta = SN_DELTA(sn);
        offset += delta;
        SrcNoteType type = SN_TYPE(sn);
        const char* name = js_SrcNoteSpec[type].name;
        if (!sp->jsprintf("%3u: %4u %5u [%4u] %-8s",
                          unsigned(sn - notes), lineno, offset, delta, name))
        {
            return false;
        }

        switch (type) {
          case SRC_NULL:
          case SRC_IF:
          case SRC_CONTINUE:
          case SRC_BREAK:
          case SRC_BREAK2LABEL:
          case SRC_SWITCHBREAK:
          case SRC_ASSIGNOP:
          case SRC_XDELTA:
            break;

          case SRC_COLSPAN:
            colspan = SN_OFFSET_TO_COLSPAN(GetSrcNoteOffset(sn, 0));
            if (!sp->jsprintf("%d", colspan))
                return false;
            break;

          case SRC_SETLINE:
            lineno = GetSrcNoteOffset(sn, 0);
            if (!sp->jsprintf(" lineno %u", lineno))
                return false;
            break;

          case SRC_NEWLINE:
            ++lineno;
            break;

          case SRC_FOR:
            if (!sp->jsprintf(" cond %u update %u tail %u",
                              unsigned(GetSrcNoteOffset(sn, 0)),
                              unsigned(GetSrcNoteOffset(sn, 1)),
                              unsigned(GetSrcNoteOffset(sn, 2))))
            {
                return false;
            }
            break;

          case SRC_IF_ELSE:
            if (!sp->jsprintf(" else %u", unsigned(GetSrcNoteOffset(sn, 0))))
                return false;
            break;

          case SRC_FOR_IN:
          case SRC_FOR_OF:
            if (!sp->jsprintf(" closingjump %u", unsigned(GetSrcNoteOffset(sn, 0))))
                return false;
            break;

          case SRC_COND:
          case SRC_WHILE:
          case SRC_NEXTCASE:
            if (!sp->jsprintf(" offset %u", unsigned(GetSrcNoteOffset(sn, 0))))
                return false;
            break;

          case SRC_TABLESWITCH: {
            JSOp op = JSOp(script->code()[offset]);
            MOZ_ASSERT(op == JSOP_TABLESWITCH);
            if (!sp->jsprintf(" length %u", unsigned(GetSrcNoteOffset(sn, 0))))
                return false;
            UpdateSwitchTableBounds(cx, script, offset,
                                    &switchTableStart, &switchTableEnd);
            break;
          }
          case SRC_CONDSWITCH: {
            JSOp op = JSOp(script->code()[offset]);
            MOZ_ASSERT(op == JSOP_CONDSWITCH);
            if (!sp->jsprintf(" length %u", unsigned(GetSrcNoteOffset(sn, 0))))
                return false;
            if (unsigned caseOff = (unsigned) GetSrcNoteOffset(sn, 1)) {
                if (!sp->jsprintf(" first case offset %u", caseOff))
                    return false;
            }
            UpdateSwitchTableBounds(cx, script, offset,
                                    &switchTableStart, &switchTableEnd);
            break;
          }

          case SRC_TRY:
            MOZ_ASSERT(JSOp(script->code()[offset]) == JSOP_TRY);
            if (!sp->jsprintf(" offset to jump %u", unsigned(GetSrcNoteOffset(sn, 0))))
                return false;
            break;

          case SRC_CLASS_SPAN: {
            unsigned startOffset = GetSrcNoteOffset(sn, 0);
            unsigned endOffset = GetSrcNoteOffset(sn, 1);
            if (!sp->jsprintf(" %u %u", startOffset, endOffset))
                return false;
            break;
          }

          default:
            MOZ_ASSERT_UNREACHABLE("unrecognized srcnote");
        }
        if (!sp->put("\n"))
            return false;
    }

    return true;
}

static bool
Notes(JSContext* cx, unsigned argc, Value* vp)
{
    CallArgs args = CallArgsFromVp(argc, vp);
    Sprinter sprinter(cx);
    if (!sprinter.init())
        return false;

    for (unsigned i = 0; i < args.length(); i++) {
        RootedScript script (cx, ValueToScript(cx, args[i]));
        if (!script)
            return false;

        if (!SrcNotes(cx, script, &sprinter))
            return false;
    }

    JSString* str = JS_NewStringCopyZ(cx, sprinter.string());
    if (!str)
        return false;
    args.rval().setString(str);
    return true;
}

static const char*
TryNoteName(JSTryNoteKind kind)
{
    switch (kind) {
      case JSTRY_CATCH:
        return "catch";
      case JSTRY_FINALLY:
        return "finally";
      case JSTRY_FOR_IN:
        return "for-in";
      case JSTRY_FOR_OF:
        return "for-of";
      case JSTRY_LOOP:
        return "loop";
      case JSTRY_FOR_OF_ITERCLOSE:
        return "for-of-iterclose";
      case JSTRY_DESTRUCTURING_ITERCLOSE:
        return "dstr-iterclose";
    }

    MOZ_CRASH("Bad JSTryNoteKind");
}

static MOZ_MUST_USE bool
TryNotes(JSContext* cx, HandleScript script, Sprinter* sp)
{
    if (!script->hasTrynotes())
        return true;

    if (!sp->put("\nException table:\nkind               stack    start      end\n"))
        return false;

    JSTryNote* tn = script->trynotes()->vector;
    JSTryNote* tnlimit = tn + script->trynotes()->length;
    do {
        uint32_t startOff = script->pcToOffset(script->main()) + tn->start;
        if (!sp->jsprintf(" %-16s %6u %8u %8u\n",
                          TryNoteName(static_cast<JSTryNoteKind>(tn->kind)),
                          tn->stackDepth, startOff, startOff + tn->length))
        {
            return false;
        }
    } while (++tn != tnlimit);
    return true;
}

static MOZ_MUST_USE bool
ScopeNotes(JSContext* cx, HandleScript script, Sprinter* sp)
{
    if (!script->hasScopeNotes())
        return true;

    if (!sp->put("\nScope notes:\n   index   parent    start      end\n"))
        return false;

    ScopeNoteArray* notes = script->scopeNotes();
    for (uint32_t i = 0; i < notes->length; i++) {
        const ScopeNote* note = &notes->vector[i];
        if (note->index == ScopeNote::NoScopeIndex) {
            if (!sp->jsprintf("%8s ", "(none)"))
                return false;
        } else {
            if (!sp->jsprintf("%8u ", note->index))
                return false;
        }
        if (note->parent == ScopeNote::NoScopeIndex) {
            if (!sp->jsprintf("%8s ", "(none)"))
                return false;
        } else {
            if (!sp->jsprintf("%8u ", note->parent))
                return false;
        }
        if (!sp->jsprintf("%8u %8u\n", note->start, note->start + note->length))
            return false;
    }
    return true;
}

static MOZ_MUST_USE bool
DisassembleScript(JSContext* cx, HandleScript script, HandleFunction fun,
                  bool lines, bool recursive, bool sourceNotes, Sprinter* sp)
{
    if (fun) {
        if (!sp->put("flags:"))
            return false;
        if (fun->isLambda()) {
            if (!sp->put(" LAMBDA"))
                return false;
        }
        if (fun->needsCallObject()) {
            if (!sp->put(" NEEDS_CALLOBJECT"))
                return false;
        }
        if (fun->needsExtraBodyVarEnvironment()) {
            if (!sp->put(" NEEDS_EXTRABODYVARENV"))
                return false;
        }
        if (fun->needsNamedLambdaEnvironment()) {
            if (!sp->put(" NEEDS_NAMEDLAMBDAENV"))
                return false;
        }
        if (fun->isConstructor()) {
            if (!sp->put(" CONSTRUCTOR"))
                return false;
        }
        if (script->isExprBody()) {
            if (!sp->put(" EXPRESSION_CLOSURE"))
                return false;
        }
        if (fun->isSelfHostedBuiltin()) {
            if (!sp->put(" SELF_HOSTED"))
                return false;
        }
        if (fun->isArrow()) {
            if (!sp->put(" ARROW"))
                return false;
        }
        if (!sp->put("\n"))
            return false;
    }

    if (!Disassemble(cx, script, lines, sp))
        return false;
    if (sourceNotes) {
        if (!SrcNotes(cx, script, sp))
            return false;
    }
    if (!TryNotes(cx, script, sp))
        return false;
    if (!ScopeNotes(cx, script, sp))
        return false;

    if (recursive && script->hasObjects()) {
        ObjectArray* objects = script->objects();
        for (unsigned i = 0; i != objects->length; ++i) {
            JSObject* obj = objects->vector[i];
            if (obj->is<JSFunction>()) {
                if (!sp->put("\n"))
                    return false;

                RootedFunction fun(cx, &obj->as<JSFunction>());
                if (fun->isInterpreted()) {
                    RootedScript script(cx, JSFunction::getOrCreateScript(cx, fun));
                    if (script) {
                        if (!DisassembleScript(cx, script, fun, lines, recursive, sourceNotes, sp))
                            return false;
                    }
                } else {
                    if (!sp->put("[native code]\n"))
                        return false;
                }
            }
        }
    }

    return true;
}

namespace {

struct DisassembleOptionParser {
    unsigned argc;
    Value* argv;
    bool lines;
    bool recursive;
    bool sourceNotes;

    DisassembleOptionParser(unsigned argc, Value* argv)
      : argc(argc), argv(argv), lines(false), recursive(false), sourceNotes(true) {}

    bool parse(JSContext* cx) {
        /* Read options off early arguments */
        while (argc > 0 && argv[0].isString()) {
            JSString* str = argv[0].toString();
            JSFlatString* flatStr = JS_FlattenString(cx, str);
            if (!flatStr)
                return false;
            if (JS_FlatStringEqualsAscii(flatStr, "-l"))
                lines = true;
            else if (JS_FlatStringEqualsAscii(flatStr, "-r"))
                recursive = true;
            else if (JS_FlatStringEqualsAscii(flatStr, "-S"))
                sourceNotes = false;
            else
                break;
            argv++; argc--;
        }
        return true;
    }
};

} /* anonymous namespace */

static bool
DisassembleToSprinter(JSContext* cx, unsigned argc, Value* vp, Sprinter* sprinter)
{
    CallArgs args = CallArgsFromVp(argc, vp);
    DisassembleOptionParser p(args.length(), args.array());
    if (!p.parse(cx))
        return false;

    if (p.argc == 0) {
        /* Without arguments, disassemble the current script. */
        RootedScript script(cx, GetTopScript(cx));
        if (script) {
            JSAutoCompartment ac(cx, script);
            if (!Disassemble(cx, script, p.lines, sprinter))
                return false;
            if (!SrcNotes(cx, script, sprinter))
                return false;
            if (!TryNotes(cx, script, sprinter))
                return false;
            if (!ScopeNotes(cx, script, sprinter))
                return false;
        }
    } else {
        for (unsigned i = 0; i < p.argc; i++) {
            RootedFunction fun(cx);
            RootedScript script(cx);
            RootedValue value(cx, p.argv[i]);
            if (value.isObject() && value.toObject().is<ModuleObject>())
                script = value.toObject().as<ModuleObject>().script();
            else
                script = ValueToScript(cx, value, fun.address());
            if (!script)
                return false;
            if (!DisassembleScript(cx, script, fun, p.lines, p.recursive, p.sourceNotes, sprinter))
                return false;
        }
    }

    return !sprinter->hadOutOfMemory();
}

static bool
DisassembleToString(JSContext* cx, unsigned argc, Value* vp)
{
    CallArgs args = CallArgsFromVp(argc, vp);
    Sprinter sprinter(cx);
    if (!sprinter.init())
        return false;
    if (!DisassembleToSprinter(cx, args.length(), vp, &sprinter))
        return false;

    JSString* str = JS_NewStringCopyZ(cx, sprinter.string());
    if (!str)
        return false;
    args.rval().setString(str);
    return true;
}

static bool
Disassemble(JSContext* cx, unsigned argc, Value* vp)
{
    CallArgs args = CallArgsFromVp(argc, vp);

    if (!gOutFile->isOpen()) {
        JS_ReportErrorASCII(cx, "output file is closed");
        return false;
    }

    Sprinter sprinter(cx);
    if (!sprinter.init())
        return false;
    if (!DisassembleToSprinter(cx, args.length(), vp, &sprinter))
        return false;

    fprintf(gOutFile->fp, "%s\n", sprinter.string());
    args.rval().setUndefined();
    return true;
}

static bool
DisassFile(JSContext* cx, unsigned argc, Value* vp)
{
    CallArgs args = CallArgsFromVp(argc, vp);

    if (!gOutFile->isOpen()) {
        JS_ReportErrorASCII(cx, "output file is closed");
        return false;
    }

    /* Support extra options at the start, just like Disassemble. */
    DisassembleOptionParser p(args.length(), args.array());
    if (!p.parse(cx))
        return false;

    if (!p.argc) {
        args.rval().setUndefined();
        return true;
    }

    // We should change DisassembleOptionParser to store CallArgs.
    JSString* str = JS::ToString(cx, HandleValue::fromMarkedLocation(&p.argv[0]));
    if (!str)
        return false;
    JSAutoByteString filename(cx, str);
    if (!filename)
        return false;
    RootedScript script(cx);

    {
        CompileOptions options(cx);
        options.setIntroductionType("js shell disFile")
               .setUTF8(true)
               .setFileAndLine(filename.ptr(), 1)
               .setIsRunOnce(true)
               .setNoScriptRval(true);

        if (!JS::Compile(cx, options, filename.ptr(), &script))
            return false;
    }

    Sprinter sprinter(cx);
    if (!sprinter.init())
        return false;
    bool ok = DisassembleScript(cx, script, nullptr, p.lines, p.recursive, p.sourceNotes, &sprinter);
    if (ok)
        fprintf(gOutFile->fp, "%s\n", sprinter.string());
    if (!ok)
        return false;

    args.rval().setUndefined();
    return true;
}

static bool
DisassWithSrc(JSContext* cx, unsigned argc, Value* vp)
{
    CallArgs args = CallArgsFromVp(argc, vp);

    if (!gOutFile->isOpen()) {
        JS_ReportErrorASCII(cx, "output file is closed");
        return false;
    }

    const size_t lineBufLen = 512;
    unsigned len, line1, line2, bupline;
    char linebuf[lineBufLen];
    static const char sep[] = ";-------------------------";

    RootedScript script(cx);
    for (unsigned i = 0; i < args.length(); i++) {
        script = ValueToScript(cx, args[i]);
        if (!script)
           return false;

        if (!script->filename()) {
            JS_ReportErrorNumberASCII(cx, my_GetErrorMessage, nullptr, JSSMSG_FILE_SCRIPTS_ONLY);
            return false;
        }

        FILE* file = fopen(script->filename(), "rb");
        if (!file) {
            /* FIXME: script->filename() should become UTF-8 (bug 987069). */
            ReportCantOpenErrorUnknownEncoding(cx, script->filename());
            return false;
        }
        auto closeFile = MakeScopeExit([file]() { fclose(file); });

        jsbytecode* pc = script->code();
        jsbytecode* end = script->codeEnd();

        Sprinter sprinter(cx);
        if (!sprinter.init())
            return false;

        /* burn the leading lines */
        line2 = PCToLineNumber(script, pc);
        for (line1 = 0; line1 < line2 - 1; line1++) {
            char* tmp = fgets(linebuf, lineBufLen, file);
            if (!tmp) {
                /* FIXME: This should use UTF-8 (bug 987069). */
                JS_ReportErrorLatin1(cx, "failed to read %s fully", script->filename());
                return false;
            }
        }

        bupline = 0;
        while (pc < end) {
            line2 = PCToLineNumber(script, pc);

            if (line2 < line1) {
                if (bupline != line2) {
                    bupline = line2;
                    if (!sprinter.jsprintf("%s %3u: BACKUP\n", sep, line2))
                        return false;
                }
            } else {
                if (bupline && line1 == line2) {
                    if (!sprinter.jsprintf("%s %3u: RESTORE\n", sep, line2))
                        return false;
                }
                bupline = 0;
                while (line1 < line2) {
                    if (!fgets(linebuf, lineBufLen, file)) {
                        /*
                         * FIXME: script->filename() should become UTF-8
                         *        (bug 987069).
                         */
                        JS_ReportErrorNumberLatin1(cx, my_GetErrorMessage, nullptr,
                                                   JSSMSG_UNEXPECTED_EOF,
                                                   script->filename());
                        return false;
                    }
                    line1++;
                    if (!sprinter.jsprintf("%s %3u: %s", sep, line1, linebuf))
                        return false;
                }
            }

            len = Disassemble1(cx, script, pc, script->pcToOffset(pc), true, &sprinter);
            if (!len)
                return false;

            pc += len;
        }

        fprintf(gOutFile->fp, "%s\n", sprinter.string());
    }

    args.rval().setUndefined();
    return true;
}

#endif /* DEBUG */

/* Pretend we can always preserve wrappers for dummy DOM objects. */
static bool
DummyPreserveWrapperCallback(JSContext* cx, JSObject* obj)
{
    return true;
}

static bool
Intern(JSContext* cx, unsigned argc, Value* vp)
{
    CallArgs args = CallArgsFromVp(argc, vp);

    JSString* str = JS::ToString(cx, args.get(0));
    if (!str)
        return false;

    AutoStableStringChars strChars(cx);
    if (!strChars.initTwoByte(cx, str))
        return false;

    mozilla::Range<const char16_t> chars = strChars.twoByteRange();

    if (!JS_AtomizeAndPinUCStringN(cx, chars.begin().get(), chars.length()))
        return false;

    args.rval().setUndefined();
    return true;
}

static bool
Clone(JSContext* cx, unsigned argc, Value* vp)
{
    CallArgs args = CallArgsFromVp(argc, vp);
    RootedObject parent(cx);
    RootedObject funobj(cx);

    if (!args.length()) {
        JS_ReportErrorASCII(cx, "Invalid arguments to clone");
        return false;
    }

    {
        Maybe<JSAutoCompartment> ac;
        RootedObject obj(cx, args[0].isPrimitive() ? nullptr : &args[0].toObject());

        if (obj && obj->is<CrossCompartmentWrapperObject>()) {
            obj = UncheckedUnwrap(obj);
            ac.emplace(cx, obj);
            args[0].setObject(*obj);
        }
        if (obj && obj->is<JSFunction>()) {
            funobj = obj;
        } else {
            JSFunction* fun = JS_ValueToFunction(cx, args[0]);
            if (!fun)
                return false;
            funobj = JS_GetFunctionObject(fun);
        }
    }

    if (args.length() > 1) {
        if (!JS_ValueToObject(cx, args[1], &parent))
            return false;
    } else {
        parent = js::GetGlobalForObjectCrossCompartment(&args.callee());
    }

    // Should it worry us that we might be getting with wrappers
    // around with wrappers here?
    JS::AutoObjectVector scopeChain(cx);
    if (!parent->is<GlobalObject>() && !scopeChain.append(parent))
        return false;
    JSObject* clone = JS::CloneFunctionObject(cx, funobj, scopeChain);
    if (!clone)
        return false;
    args.rval().setObject(*clone);
    return true;
}

static bool
Crash(JSContext* cx, unsigned argc, Value* vp)
{
    CallArgs args = CallArgsFromVp(argc, vp);
    if (args.length() == 0)
        MOZ_CRASH("forced crash");
    RootedString message(cx, JS::ToString(cx, args[0]));
    if (!message)
        return false;
    char* utf8chars = JS_EncodeStringToUTF8(cx, message);
    if (!utf8chars)
        return false;
#ifndef DEBUG
    MOZ_ReportCrash(utf8chars, __FILE__, __LINE__);
#endif
    MOZ_CRASH_UNSAFE_OOL(utf8chars);
}

static bool
GetSLX(JSContext* cx, unsigned argc, Value* vp)
{
    CallArgs args = CallArgsFromVp(argc, vp);
    RootedScript script(cx);

    script = ValueToScript(cx, args.get(0));
    if (!script)
        return false;
    args.rval().setInt32(GetScriptLineExtent(script));
    return true;
}

static bool
ThrowError(JSContext* cx, unsigned argc, Value* vp)
{
    JS_ReportErrorASCII(cx, "This is an error");
    return false;
}

#define LAZY_STANDARD_CLASSES

/* A class for easily testing the inner/outer object callbacks. */
typedef struct ComplexObject {
    bool isInner;
    bool frozen;
    JSObject* inner;
    JSObject* outer;
} ComplexObject;

static bool
sandbox_enumerate(JSContext* cx, JS::HandleObject obj, JS::AutoIdVector& properties,
                  bool enumerableOnly)
{
    RootedValue v(cx);

    if (!JS_GetProperty(cx, obj, "lazy", &v))
        return false;

    if (!ToBoolean(v))
        return true;

    return JS_NewEnumerateStandardClasses(cx, obj, properties, enumerableOnly);
}

static bool
sandbox_resolve(JSContext* cx, HandleObject obj, HandleId id, bool* resolvedp)
{
    RootedValue v(cx);
    if (!JS_GetProperty(cx, obj, "lazy", &v))
        return false;

    if (ToBoolean(v))
        return JS_ResolveStandardClass(cx, obj, id, resolvedp);
    return true;
}

static const JSClassOps sandbox_classOps = {
    nullptr, nullptr, nullptr, nullptr,
    nullptr, sandbox_enumerate, sandbox_resolve,
    nullptr, nullptr,
    nullptr, nullptr, nullptr,
    JS_GlobalObjectTraceHook
};

static const JSClass sandbox_class = {
    "sandbox",
    JSCLASS_GLOBAL_FLAGS,
    &sandbox_classOps
};

static void
SetStandardCompartmentOptions(JS::CompartmentOptions& options)
{
    options.behaviors().setVersion(JSVERSION_DEFAULT);
    options.creationOptions().setSharedMemoryAndAtomicsEnabled(enableSharedMemory);
}

static JSObject*
NewSandbox(JSContext* cx, bool lazy)
{
    JS::CompartmentOptions options;
    SetStandardCompartmentOptions(options);
    RootedObject obj(cx, JS_NewGlobalObject(cx, &sandbox_class, nullptr,
                                            JS::DontFireOnNewGlobalHook, options));
    if (!obj)
        return nullptr;

    {
        JSAutoCompartment ac(cx, obj);
        if (!lazy && !JS_InitStandardClasses(cx, obj))
            return nullptr;

        RootedValue value(cx, BooleanValue(lazy));
        if (!JS_DefineProperty(cx, obj, "lazy", value, JSPROP_PERMANENT | JSPROP_READONLY))
            return nullptr;

        JS_FireOnNewGlobalObject(cx, obj);
    }

    if (!cx->compartment()->wrap(cx, &obj))
        return nullptr;
    return obj;
}

static bool
EvalInContext(JSContext* cx, unsigned argc, Value* vp)
{
    CallArgs args = CallArgsFromVp(argc, vp);
    if (!args.requireAtLeast(cx, "evalcx", 1))
        return false;

    RootedString str(cx, ToString(cx, args[0]));
    if (!str)
        return false;

    RootedObject sobj(cx);
    if (args.hasDefined(1)) {
        sobj = ToObject(cx, args[1]);
        if (!sobj)
            return false;
    }

    AutoStableStringChars strChars(cx);
    if (!strChars.initTwoByte(cx, str))
        return false;

    mozilla::Range<const char16_t> chars = strChars.twoByteRange();
    size_t srclen = chars.length();
    const char16_t* src = chars.begin().get();

    bool lazy = false;
    if (srclen == 4) {
        if (src[0] == 'l' && src[1] == 'a' && src[2] == 'z' && src[3] == 'y') {
            lazy = true;
            srclen = 0;
        }
    }

    if (!sobj) {
        sobj = NewSandbox(cx, lazy);
        if (!sobj)
            return false;
    }

    if (srclen == 0) {
        args.rval().setObject(*sobj);
        return true;
    }

    JS::AutoFilename filename;
    unsigned lineno;

    DescribeScriptedCaller(cx, &filename, &lineno);
    {
        Maybe<JSAutoCompartment> ac;
        unsigned flags;
        JSObject* unwrapped = UncheckedUnwrap(sobj, true, &flags);
        if (flags & Wrapper::CROSS_COMPARTMENT) {
            sobj = unwrapped;
            ac.emplace(cx, sobj);
        }

        sobj = ToWindowIfWindowProxy(sobj);

        if (!(sobj->getClass()->flags & JSCLASS_IS_GLOBAL)) {
            JS_ReportErrorASCII(cx, "Invalid scope argument to evalcx");
            return false;
        }
        JS::CompileOptions opts(cx);
        opts.setFileAndLine(filename.get(), lineno);
        if (!JS::Evaluate(cx, opts, src, srclen, args.rval())) {
            return false;
        }
    }

    if (!cx->compartment()->wrap(cx, args.rval()))
        return false;

    return true;
}

struct CooperationState
{
    CooperationState()
      : lock(mutexid::ShellThreadCooperation)
      , idle(false)
      , numThreads(0)
      , yieldCount(0)
      , singleThreaded(false)
    {}

    Mutex lock;
    ConditionVariable cvar;
    bool idle;
    size_t numThreads;
    uint64_t yieldCount;
    bool singleThreaded;
};
static CooperationState* cooperationState = nullptr;

static void
CooperativeBeginWait(JSContext* cx)
{
    MOZ_ASSERT(cx == TlsContext.get());
    JS_YieldCooperativeContext(cx);
}

static void
CooperativeEndWait(JSContext* cx)
{
    MOZ_ASSERT(cx == TlsContext.get());
    LockGuard<Mutex> lock(cooperationState->lock);

    cooperationState->cvar.wait(lock, [&] { return cooperationState->idle; });

    JS_ResumeCooperativeContext(cx);
    cooperationState->idle = false;
    cooperationState->yieldCount++;
    cooperationState->cvar.notify_all();
}

static void
CooperativeYield()
{
    LockGuard<Mutex> lock(cooperationState->lock);
    MOZ_ASSERT(!cooperationState->idle);
    cooperationState->idle = true;
    cooperationState->cvar.notify_all();

    // Wait until another thread takes over control before returning, if there
    // is another thread to do so.
    if (cooperationState->numThreads) {
        uint64_t count = cooperationState->yieldCount;
        cooperationState->cvar.wait(lock, [&] { return cooperationState->yieldCount != count; });
    }
}

static bool
CooperativeYieldThread(JSContext* cx, unsigned argc, Value* vp)
{
    CallArgs args = CallArgsFromVp(argc, vp);

    if (!cx->runtime()->gc.canChangeActiveContext(cx)) {
        JS_ReportErrorASCII(cx, "Cooperating multithreading context switches are not currently allowed");
        return false;
    }

    if (GetShellContext(cx)->isWorker) {
        JS_ReportErrorASCII(cx, "Worker threads cannot yield");
        return false;
    }

    if (cooperationState->singleThreaded) {
        JS_ReportErrorASCII(cx, "Yielding is not allowed while single threaded");
        return false;
    }

    // To avoid contention issues between threads, yields are not allowed while
    // a thread has access to zone groups other than its original one, i.e. if
    // the thread is inside an evaluate() call with a different zone group.
    // This is not a limit which the browser has, but is necessary in the
    // shell: the shell can have arbitrary interleavings between cooperative
    // threads, whereas the browser has more control over which threads are
    // running at different times.
    for (ZoneGroupsIter group(cx->runtime()); !group.done(); group.next()) {
        if (group->ownerContext().context() == cx && group != cx->zone()->group()) {
            JS_ReportErrorASCII(cx, "Yielding is not allowed while owning multiple zone groups");
            return false;
        }
    }

    {
        Maybe<JS::AutoRelinquishZoneGroups> artzg;
        if ((args.length() > 0) && ToBoolean(args[0]))
            artzg.emplace(cx);

        CooperativeBeginWait(cx);
        CooperativeYield();
        CooperativeEndWait(cx);
    }

    args.rval().setUndefined();
    return true;
}

static void
CooperativeBeginSingleThreadedExecution(JSContext* cx)
{
    MOZ_ASSERT(!cooperationState->singleThreaded);

    // Yield until all other threads have exited any zone groups they are in.
    while (true) {
        bool done = true;
        for (ZoneGroupsIter group(cx->runtime()); !group.done(); group.next()) {
            if (!group->ownedByCurrentThread() && group->ownerContext().context())
                done = false;
        }
        if (done)
            break;
        CooperativeBeginWait(cx);
        CooperativeYield();
        CooperativeEndWait(cx);
    }

    cooperationState->singleThreaded = true;
}

static void
CooperativeEndSingleThreadedExecution(JSContext* cx)
{
    if (cooperationState)
        cooperationState->singleThreaded = false;
}

static bool
EnsureGeckoProfilingStackInstalled(JSContext* cx, ShellContext* sc)
{
    if (cx->geckoProfiler().installed()) {
        MOZ_ASSERT(sc->geckoProfilingStack);
        return true;
    }

    MOZ_ASSERT(!sc->geckoProfilingStack);
    sc->geckoProfilingStack = MakeUnique<PseudoStack>();
    if (!sc->geckoProfilingStack) {
        JS_ReportOutOfMemory(cx);
        return false;
    }

    SetContextProfilingStack(cx, sc->geckoProfilingStack.get());
    return true;
}

struct WorkerInput
{
    JSRuntime* parentRuntime;
    JSContext* siblingContext;
    char16_t* chars;
    size_t length;

    WorkerInput(JSRuntime* parentRuntime, char16_t* chars, size_t length)
      : parentRuntime(parentRuntime), siblingContext(nullptr), chars(chars), length(length)
    {}

    WorkerInput(JSContext* siblingContext, char16_t* chars, size_t length)
      : parentRuntime(nullptr), siblingContext(siblingContext), chars(chars), length(length)
    {}

    ~WorkerInput() {
        js_free(chars);
    }
};

static void SetWorkerContextOptions(JSContext* cx);

static void
WorkerMain(void* arg)
{
    WorkerInput* input = (WorkerInput*) arg;
    MOZ_ASSERT(!!input->parentRuntime != !!input->siblingContext);

    JSContext* cx = input->parentRuntime
         ? JS_NewContext(8L * 1024L * 1024L, 2L * 1024L * 1024L, input->parentRuntime)
         : JS_NewCooperativeContext(input->siblingContext);
    if (!cx)
        return;

    UniquePtr<ShellContext> sc = MakeUnique<ShellContext>(cx);
    if (!sc)
        return;

    auto guard = mozilla::MakeScopeExit([&] {
        if (cx)
            JS_DestroyContext(cx);
        if (input->siblingContext) {
            cooperationState->numThreads--;
            CooperativeYield();
        }
        js_delete(input);
    });

    if (input->parentRuntime)
        sc->isWorker = true;
    JS_SetContextPrivate(cx, sc.get());
    SetWorkerContextOptions(cx);

    Maybe<EnvironmentPreparer> environmentPreparer;
    if (input->parentRuntime) {
        JS_SetFutexCanWait(cx);
        JS::SetWarningReporter(cx, WarningReporter);
        js::SetPreserveWrapperCallback(cx, DummyPreserveWrapperCallback);
        JS_InitDestroyPrincipalsCallback(cx, ShellPrincipals::destroy);

        js::UseInternalJobQueues(cx);

        if (!JS::InitSelfHostedCode(cx))
            return;

        environmentPreparer.emplace(cx);
    } else {
        JS_AddInterruptCallback(cx, ShellInterruptCallback);

        // The Gecko Profiler requires that all cooperating contexts have
        // profiling stacks installed.
        MOZ_ALWAYS_TRUE(EnsureGeckoProfilingStackInstalled(cx, sc.get()));
    }

    do {
        JSAutoRequest ar(cx);

        JS::CompartmentOptions compartmentOptions;
        SetStandardCompartmentOptions(compartmentOptions);
        if (input->siblingContext)
            compartmentOptions.creationOptions().setNewZoneInNewZoneGroup();

        RootedObject global(cx, NewGlobalObject(cx, compartmentOptions, nullptr));
        if (!global)
            break;

        JSAutoCompartment ac(cx, global);

        JS::CompileOptions options(cx);
        options.setFileAndLine("<string>", 1)
               .setIsRunOnce(true);

        AutoReportException are(cx);
        RootedScript script(cx);
        if (!JS::Compile(cx, options, input->chars, input->length, &script))
            break;
        RootedValue result(cx);
        JS_ExecuteScript(cx, script, &result);
    } while (0);

    KillWatchdog(cx);
    JS_SetGrayGCRootsTracer(cx, nullptr, nullptr);
}

// Workers can spawn other workers, so we need a lock to access workerThreads.
static Mutex* workerThreadsLock = nullptr;
static Vector<js::Thread*, 0, SystemAllocPolicy> workerThreads;

class MOZ_RAII AutoLockWorkerThreads : public LockGuard<Mutex>
{
    using Base = LockGuard<Mutex>;
  public:
    AutoLockWorkerThreads()
      : Base(*workerThreadsLock)
    {
        MOZ_ASSERT(workerThreadsLock);
    }
};

static bool
EvalInThread(JSContext* cx, unsigned argc, Value* vp, bool cooperative)
{
    if (!CanUseExtraThreads()) {
        JS_ReportErrorASCII(cx, "Can't create threads with --no-threads");
        return false;
    }

    CallArgs args = CallArgsFromVp(argc, vp);
    if (!args.get(0).isString()) {
        JS_ReportErrorASCII(cx, "Invalid arguments");
        return false;
    }

#if defined(DEBUG) || defined(JS_OOM_BREAKPOINT)
    if (cx->runningOOMTest) {
        JS_ReportErrorASCII(cx, "Can't create threads while running simulated OOM test");
        return false;
    }
#endif

    if (cooperative && GetShellContext(cx)->isWorker) {
        // Disallowing cooperative multithreading in worker runtimes allows
        // yield state to be process wide, and some other simplifications.
        // When we have a better idea of how cooperative multithreading will be
        // used in the browser this restriction might be relaxed.
        JS_ReportErrorASCII(cx, "Cooperative multithreading in worker runtimes is not supported");
        return false;
    }

    if (cooperative && !cx->runtime()->gc.canChangeActiveContext(cx)) {
        JS_ReportErrorASCII(cx, "Cooperating multithreading context switches are not currently allowed");
        return false;
    }

    if (cooperative && cooperationState->singleThreaded) {
        JS_ReportErrorASCII(cx, "Creating cooperative threads is not allowed while single threaded");
        return false;
    }

    if (!args[0].toString()->ensureLinear(cx))
        return false;

    if (!workerThreadsLock) {
        workerThreadsLock = js_new<Mutex>(mutexid::ShellWorkerThreads);
        if (!workerThreadsLock) {
            ReportOutOfMemory(cx);
            return false;
        }
    }

    JSLinearString* str = &args[0].toString()->asLinear();

    char16_t* chars = (char16_t*) js_malloc(str->length() * sizeof(char16_t));
    if (!chars) {
        ReportOutOfMemory(cx);
        return false;
    }

    CopyChars(chars, *str);

    WorkerInput* input =
        cooperative
        ? js_new<WorkerInput>(cx, chars, str->length())
        : js_new<WorkerInput>(JS_GetParentRuntime(cx), chars, str->length());
    if (!input) {
        ReportOutOfMemory(cx);
        return false;
    }

    if (cooperative) {
        cooperationState->numThreads++;
        CooperativeBeginWait(cx);
    }

    auto thread = js_new<Thread>(Thread::Options().setStackSize(gMaxStackSize + 128 * 1024));
    if (!thread || !thread->init(WorkerMain, input)) {
        ReportOutOfMemory(cx);
        if (cooperative) {
            cooperationState->numThreads--;
            CooperativeYield();
            CooperativeEndWait(cx);
        }
        return false;
    }

    if (cooperative) {
        CooperativeEndWait(cx);
    } else {
        AutoLockWorkerThreads alwt;
        if (!workerThreads.append(thread)) {
            ReportOutOfMemory(cx);
            thread->join();
            return false;
        }
    }

    args.rval().setUndefined();
    return true;
}

static bool
EvalInWorker(JSContext* cx, unsigned argc, Value* vp)
{
    return EvalInThread(cx, argc, vp, false);
}

static bool
EvalInCooperativeThread(JSContext* cx, unsigned argc, Value* vp)
{
    return EvalInThread(cx, argc, vp, true);
}

static bool
ShapeOf(JSContext* cx, unsigned argc, JS::Value* vp)
{
    CallArgs args = CallArgsFromVp(argc, vp);
    if (!args.get(0).isObject()) {
        JS_ReportErrorASCII(cx, "shapeOf: object expected");
        return false;
    }
    JSObject* obj = &args[0].toObject();
    args.rval().set(JS_NumberValue(double(uintptr_t(obj->maybeShape()) >> 3)));
    return true;
}

static bool
GroupOf(JSContext* cx, unsigned argc, JS::Value* vp)
{
    CallArgs args = CallArgsFromVp(argc, vp);
    if (!args.get(0).isObject()) {
        JS_ReportErrorASCII(cx, "groupOf: object expected");
        return false;
    }
    RootedObject obj(cx, &args[0].toObject());
    ObjectGroup* group = JSObject::getGroup(cx, obj);
    if (!group)
        return false;
    args.rval().set(JS_NumberValue(double(uintptr_t(group) >> 3)));
    return true;
}

static bool
UnwrappedObjectsHaveSameShape(JSContext* cx, unsigned argc, JS::Value* vp)
{
    CallArgs args = CallArgsFromVp(argc, vp);
    if (!args.get(0).isObject() || !args.get(1).isObject()) {
        JS_ReportErrorASCII(cx, "2 objects expected");
        return false;
    }

    RootedObject obj1(cx, UncheckedUnwrap(&args[0].toObject()));
    RootedObject obj2(cx, UncheckedUnwrap(&args[1].toObject()));

    if (!obj1->is<ShapedObject>() || !obj2->is<ShapedObject>()) {
        JS_ReportErrorASCII(cx, "object does not have a Shape");
        return false;
    }

    args.rval().setBoolean(obj1->as<ShapedObject>().shape() == obj2->as<ShapedObject>().shape());
    return true;
}

static bool
Sleep_fn(JSContext* cx, unsigned argc, Value* vp)
{
    ShellContext* sc = GetShellContext(cx);
    CallArgs args = CallArgsFromVp(argc, vp);

    TimeDuration duration = TimeDuration::FromSeconds(0.0);
    if (args.length() > 0) {
        double t_secs;
        if (!ToNumber(cx, args[0], &t_secs))
            return false;
        if (mozilla::IsNaN(t_secs)) {
            JS_ReportErrorASCII(cx, "sleep interval is not a number");
            return false;
        }

        duration = TimeDuration::FromSeconds(Max(0.0, t_secs));
        if (duration > MAX_TIMEOUT_INTERVAL) {
            JS_ReportErrorASCII(cx, "Excessive sleep interval");
            return false;
        }
    }
    {
        LockGuard<Mutex> guard(sc->watchdogLock);
        TimeStamp toWakeup = TimeStamp::Now() + duration;
        for (;;) {
            sc->sleepWakeup.wait_for(guard, duration);
            if (sc->serviceInterrupt)
                break;
            auto now = TimeStamp::Now();
            if (now >= toWakeup)
                break;
            duration = toWakeup - now;
        }
    }
    args.rval().setUndefined();
    return !sc->serviceInterrupt;
}

static void
KillWatchdog(JSContext* cx)
{
    ShellContext* sc = GetShellContext(cx);
    Maybe<Thread> thread;

    {
        LockGuard<Mutex> guard(sc->watchdogLock);
        Swap(sc->watchdogThread, thread);
        if (thread) {
            // The watchdog thread becoming Nothing is its signal to exit.
            sc->watchdogWakeup.notify_one();
        }
    }
    if (thread)
        thread->join();

    MOZ_ASSERT(!sc->watchdogThread);
}

static void
WatchdogMain(JSContext* cx)
{
    ThisThread::SetName("JS Watchdog");

    ShellContext* sc = GetShellContext(cx);

    LockGuard<Mutex> guard(sc->watchdogLock);
    while (sc->watchdogThread) {
        auto now = TimeStamp::Now();
        if (sc->watchdogTimeout && now >= sc->watchdogTimeout.value()) {
            /*
             * The timeout has just expired. Request an interrupt callback
             * outside the lock.
             */
            sc->watchdogTimeout = Nothing();
            {
                UnlockGuard<Mutex> unlock(guard);
                CancelExecution(cx);
            }

            /* Wake up any threads doing sleep. */
            sc->sleepWakeup.notify_all();
        } else {
            if (sc->watchdogTimeout) {
                /*
                 * Time hasn't expired yet. Simulate an interrupt callback
                 * which doesn't abort execution.
                 */
                JS_RequestInterruptCallback(cx);
            }

            TimeDuration sleepDuration = sc->watchdogTimeout
                                         ? TimeDuration::FromSeconds(0.1)
                                         : TimeDuration::Forever();
            sc->watchdogWakeup.wait_for(guard, sleepDuration);
        }
    }
}

static bool
ScheduleWatchdog(JSContext* cx, double t)
{
    ShellContext* sc = GetShellContext(cx);

    if (t <= 0) {
        LockGuard<Mutex> guard(sc->watchdogLock);
        sc->watchdogTimeout = Nothing();
        return true;
    }

    auto interval = TimeDuration::FromSeconds(t);
    auto timeout = TimeStamp::Now() + interval;
    LockGuard<Mutex> guard(sc->watchdogLock);
    if (!sc->watchdogThread) {
        MOZ_ASSERT(!sc->watchdogTimeout);
        sc->watchdogThread.emplace();
        AutoEnterOOMUnsafeRegion oomUnsafe;
        if (!sc->watchdogThread->init(WatchdogMain, cx))
            oomUnsafe.crash("watchdogThread.init");
    } else if (!sc->watchdogTimeout || timeout < sc->watchdogTimeout.value()) {
        sc->watchdogWakeup.notify_one();
    }
    sc->watchdogTimeout = Some(timeout);
    return true;
}

static void
KillWorkerThreads(JSContext* cx)
{
    MOZ_ASSERT_IF(!CanUseExtraThreads(), workerThreads.empty());

    if (!workerThreadsLock) {
        MOZ_ASSERT(workerThreads.empty());
        return;
    }

    while (true) {
        // We need to leave the AutoLockWorkerThreads scope before we call
        // js::Thread::join, to avoid deadlocks when AutoLockWorkerThreads is
        // used by the worker thread.
        Thread* thread;
        {
            AutoLockWorkerThreads alwt;
            if (workerThreads.empty())
                break;
            thread = workerThreads.popCopy();
        }
        thread->join();
    }

    js_delete(workerThreadsLock);
    workerThreadsLock = nullptr;

    // Yield until all other cooperative threads in the main runtime finish.
    while (cooperationState->numThreads) {
        CooperativeBeginWait(cx);
        CooperativeYield();
        CooperativeEndWait(cx);
    }

    js_delete(cooperationState);
    cooperationState = nullptr;
}

static void
CancelExecution(JSContext* cx)
{
    ShellContext* sc = GetShellContext(cx);
    sc->serviceInterrupt = true;
    JS_RequestInterruptCallback(cx);

    if (sc->haveInterruptFunc) {
        static const char msg[] = "Script runs for too long, terminating.\n";
        fputs(msg, stderr);
    }
}

static bool
SetTimeoutValue(JSContext* cx, double t)
{
    if (mozilla::IsNaN(t)) {
        JS_ReportErrorASCII(cx, "timeout is not a number");
        return false;
    }
    if (TimeDuration::FromSeconds(t) > MAX_TIMEOUT_INTERVAL) {
        JS_ReportErrorASCII(cx, "Excessive timeout value");
        return false;
    }
    GetShellContext(cx)->timeoutInterval = t;
    if (!ScheduleWatchdog(cx, t)) {
        JS_ReportErrorASCII(cx, "Failed to create the watchdog");
        return false;
    }
    return true;
}

static bool
Timeout(JSContext* cx, unsigned argc, Value* vp)
{
    ShellContext* sc = GetShellContext(cx);
    CallArgs args = CallArgsFromVp(argc, vp);

    if (args.length() == 0) {
        args.rval().setNumber(sc->timeoutInterval);
        return true;
    }

    if (args.length() > 2) {
        JS_ReportErrorASCII(cx, "Wrong number of arguments");
        return false;
    }

    double t;
    if (!ToNumber(cx, args[0], &t))
        return false;

    if (args.length() > 1) {
        RootedValue value(cx, args[1]);
        if (!value.isObject() || !value.toObject().is<JSFunction>()) {
            JS_ReportErrorASCII(cx, "Second argument must be a timeout function");
            return false;
        }
        sc->interruptFunc = value;
        sc->haveInterruptFunc = true;
    }

    args.rval().setUndefined();
    return SetTimeoutValue(cx, t);
}

static bool
InterruptIf(JSContext* cx, unsigned argc, Value* vp)
{
    CallArgs args = CallArgsFromVp(argc, vp);

    if (args.length() != 1) {
        JS_ReportErrorASCII(cx, "Wrong number of arguments");
        return false;
    }

    if (ToBoolean(args[0])) {
        GetShellContext(cx)->serviceInterrupt = true;
        JS_RequestInterruptCallback(cx);
    }

    args.rval().setUndefined();
    return true;
}

static bool
InvokeInterruptCallbackWrapper(JSContext* cx, unsigned argc, Value* vp)
{
    CallArgs args = CallArgsFromVp(argc, vp);
    if (args.length() != 1) {
        JS_ReportErrorASCII(cx, "Wrong number of arguments");
        return false;
    }

    GetShellContext(cx)->serviceInterrupt = true;
    JS_RequestInterruptCallback(cx);
    bool interruptRv = CheckForInterrupt(cx);

    // The interrupt handler could have set a pending exception. Since we call
    // back into JS, don't have it see the pending exception. If we have an
    // uncatchable exception that's not propagating a debug mode forced
    // return, return.
    if (!interruptRv && !cx->isExceptionPending() && !cx->isPropagatingForcedReturn())
        return false;

    JS::AutoSaveExceptionState savedExc(cx);

    FixedInvokeArgs<1> iargs(cx);

    iargs[0].setBoolean(interruptRv);

    RootedValue rv(cx);
    if (!js::Call(cx, args[0], UndefinedHandleValue, iargs, &rv))
        return false;

    args.rval().setUndefined();
    return interruptRv;
}

static bool
SetInterruptCallback(JSContext* cx, unsigned argc, Value* vp)
{
    CallArgs args = CallArgsFromVp(argc, vp);

    if (args.length() != 1) {
        JS_ReportErrorASCII(cx, "Wrong number of arguments");
        return false;
    }

    RootedValue value(cx, args[0]);
    if (!value.isObject() || !value.toObject().is<JSFunction>()) {
        JS_ReportErrorASCII(cx, "Argument must be a function");
        return false;
    }
    GetShellContext(cx)->interruptFunc = value;
    GetShellContext(cx)->haveInterruptFunc = true;

    args.rval().setUndefined();
    return true;
}

static bool
EnableLastWarning(JSContext* cx, unsigned argc, Value* vp)
{
    ShellContext* sc = GetShellContext(cx);
    CallArgs args = CallArgsFromVp(argc, vp);

    sc->lastWarningEnabled = true;
    sc->lastWarning.setNull();

    args.rval().setUndefined();
    return true;
}

static bool
DisableLastWarning(JSContext* cx, unsigned argc, Value* vp)
{
    ShellContext* sc = GetShellContext(cx);
    CallArgs args = CallArgsFromVp(argc, vp);

    sc->lastWarningEnabled = false;
    sc->lastWarning.setNull();

    args.rval().setUndefined();
    return true;
}

static bool
GetLastWarning(JSContext* cx, unsigned argc, Value* vp)
{
    ShellContext* sc = GetShellContext(cx);
    CallArgs args = CallArgsFromVp(argc, vp);

    if (!sc->lastWarningEnabled) {
        JS_ReportErrorASCII(cx, "Call enableLastWarning first.");
        return false;
    }

    if (!JS_WrapValue(cx, &sc->lastWarning))
        return false;

    args.rval().set(sc->lastWarning);
    return true;
}

static bool
ClearLastWarning(JSContext* cx, unsigned argc, Value* vp)
{
    ShellContext* sc = GetShellContext(cx);
    CallArgs args = CallArgsFromVp(argc, vp);

    if (!sc->lastWarningEnabled) {
        JS_ReportErrorASCII(cx, "Call enableLastWarning first.");
        return false;
    }

    sc->lastWarning.setNull();

    args.rval().setUndefined();
    return true;
}

#ifdef DEBUG
static bool
StackDump(JSContext* cx, unsigned argc, Value* vp)
{
    CallArgs args = CallArgsFromVp(argc, vp);

    if (!gOutFile->isOpen()) {
        JS_ReportErrorASCII(cx, "output file is closed");
        return false;
    }

    bool showArgs = ToBoolean(args.get(0));
    bool showLocals = ToBoolean(args.get(1));
    bool showThisProps = ToBoolean(args.get(2));

    JS::UniqueChars buf = JS::FormatStackDump(cx, nullptr, showArgs, showLocals, showThisProps);
    if (!buf) {
        fputs("Failed to format JavaScript stack for dump\n", gOutFile->fp);
        JS_ClearPendingException(cx);
    } else {
        fputs(buf.get(), gOutFile->fp);
    }

    args.rval().setUndefined();
    return true;
}
#endif

static bool
StackPointerInfo(JSContext* cx, unsigned argc, Value* vp)
{
    CallArgs args = CallArgsFromVp(argc, vp);

    // Copy the truncated stack pointer to the result.  This value is not used
    // as a pointer but as a way to measure frame-size from JS.
    args.rval().setInt32(int32_t(reinterpret_cast<size_t>(&args) & 0xfffffff));
    return true;
}


static bool
Elapsed(JSContext* cx, unsigned argc, Value* vp)
{
    CallArgs args = CallArgsFromVp(argc, vp);
    if (args.length() == 0) {
        double d = PRMJ_Now() - GetShellContext(cx)->startTime;
        args.rval().setDouble(d);
        return true;
    }
    JS_ReportErrorASCII(cx, "Wrong number of arguments");
    return false;
}

static bool
Compile(JSContext* cx, unsigned argc, Value* vp)
{
    CallArgs args = CallArgsFromVp(argc, vp);
    if (args.length() < 1) {
        JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr, JSMSG_MORE_ARGS_NEEDED,
                                  "compile", "0", "s");
        return false;
    }
    if (!args[0].isString()) {
        const char* typeName = InformalValueTypeName(args[0]);
        JS_ReportErrorASCII(cx, "expected string to compile, got %s", typeName);
        return false;
    }

    RootedObject global(cx, JS::CurrentGlobalOrNull(cx));
    JSFlatString* scriptContents = args[0].toString()->ensureFlat(cx);
    if (!scriptContents)
        return false;

    AutoStableStringChars stableChars(cx);
    if (!stableChars.initTwoByte(cx, scriptContents))
        return false;

    JS::CompileOptions options(cx);
    options.setIntroductionType("js shell compile")
           .setFileAndLine("<string>", 1)
           .setIsRunOnce(true)
           .setNoScriptRval(true);
    RootedScript script(cx);
    const char16_t* chars = stableChars.twoByteRange().begin().get();
    bool ok = JS_CompileUCScript(cx, chars, scriptContents->length(), options, &script);
    args.rval().setUndefined();
    return ok;
}

static bool
ParseModule(JSContext* cx, unsigned argc, Value* vp)
{
    CallArgs args = CallArgsFromVp(argc, vp);
    if (args.length() == 0) {
        JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr, JSMSG_MORE_ARGS_NEEDED,
                                  "parseModule", "0", "s");
        return false;
    }

    if (!args[0].isString()) {
        const char* typeName = InformalValueTypeName(args[0]);
        JS_ReportErrorASCII(cx, "expected string to compile, got %s", typeName);
        return false;
    }

    JSFlatString* scriptContents = args[0].toString()->ensureFlat(cx);
    if (!scriptContents)
        return false;

    UniqueChars filename;
    CompileOptions options(cx);
    if (args.length() > 1) {
        if (!args[1].isString()) {
            const char* typeName = InformalValueTypeName(args[1]);
            JS_ReportErrorASCII(cx, "expected filename string, got %s", typeName);
            return false;
        }

        RootedString str(cx, args[1].toString());
        filename.reset(JS_EncodeString(cx, str));
        if (!filename)
            return false;

        options.setFileAndLine(filename.get(), 1);
    } else {
        options.setFileAndLine("<string>", 1);
    }

    AutoStableStringChars stableChars(cx);
    if (!stableChars.initTwoByte(cx, scriptContents))
        return false;

    const char16_t* chars = stableChars.twoByteRange().begin().get();
    SourceBufferHolder srcBuf(chars, scriptContents->length(),
                              SourceBufferHolder::NoOwnership);

    RootedObject module(cx, frontend::CompileModule(cx, options, srcBuf));
    if (!module)
        return false;

    args.rval().setObject(*module);
    return true;
}

static bool
SetModuleResolveHook(JSContext* cx, unsigned argc, Value* vp)
{
    CallArgs args = CallArgsFromVp(argc, vp);
    if (args.length() != 1) {
        JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr, JSMSG_MORE_ARGS_NEEDED,
                                  "setModuleResolveHook", "0", "s");
        return false;
    }

    if (!args[0].isObject() || !args[0].toObject().is<JSFunction>()) {
        const char* typeName = InformalValueTypeName(args[0]);
        JS_ReportErrorASCII(cx, "expected hook function, got %s", typeName);
        return false;
    }

    RootedFunction hook(cx, &args[0].toObject().as<JSFunction>());
    Rooted<GlobalObject*> global(cx, cx->global());
    global->setModuleResolveHook(hook);
    args.rval().setUndefined();
    return true;
}

static bool
GetModuleLoadPath(JSContext* cx, unsigned argc, Value* vp)
{
    CallArgs args = CallArgsFromVp(argc, vp);

    ShellContext* sc = GetShellContext(cx);
    if (sc->moduleLoadPath) {
        JSString* str = JS_NewStringCopyZ(cx, sc->moduleLoadPath.get());
        if (!str)
            return false;

        args.rval().setString(str);
    } else {
        args.rval().setNull();
    }
    return true;
}

static bool
Parse(JSContext* cx, unsigned argc, Value* vp)
{
    using namespace js::frontend;

    CallArgs args = CallArgsFromVp(argc, vp);

    if (args.length() < 1) {
        JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr, JSMSG_MORE_ARGS_NEEDED,
                                  "parse", "0", "s");
        return false;
    }
    if (!args[0].isString()) {
        const char* typeName = InformalValueTypeName(args[0]);
        JS_ReportErrorASCII(cx, "expected string to parse, got %s", typeName);
        return false;
    }

    JSFlatString* scriptContents = args[0].toString()->ensureFlat(cx);
    if (!scriptContents)
        return false;

    AutoStableStringChars stableChars(cx);
    if (!stableChars.initTwoByte(cx, scriptContents))
        return false;

    size_t length = scriptContents->length();
    const char16_t* chars = stableChars.twoByteRange().begin().get();

    CompileOptions options(cx);
    options.setIntroductionType("js shell parse")
           .setFileAndLine("<string>", 1);
    UsedNameTracker usedNames(cx);
    if (!usedNames.init())
        return false;
    Parser<FullParseHandler, char16_t> parser(cx, cx->tempLifoAlloc(), options, chars, length,
                                              /* foldConstants = */ true, usedNames, nullptr,
                                              nullptr);
    if (!parser.checkOptions())
        return false;

    ParseNode* pn = parser.parse();
    if (!pn)
        return false;
#ifdef DEBUG
    DumpParseTree(pn);
    fputc('\n', stderr);
#endif
    args.rval().setUndefined();
    return true;
}

static bool
SyntaxParse(JSContext* cx, unsigned argc, Value* vp)
{
    using namespace js::frontend;

    CallArgs args = CallArgsFromVp(argc, vp);

    if (args.length() < 1) {
        JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr, JSMSG_MORE_ARGS_NEEDED,
                                  "parse", "0", "s");
        return false;
    }
    if (!args[0].isString()) {
        const char* typeName = InformalValueTypeName(args[0]);
        JS_ReportErrorASCII(cx, "expected string to parse, got %s", typeName);
        return false;
    }

    JSFlatString* scriptContents = args[0].toString()->ensureFlat(cx);
    if (!scriptContents)
        return false;
    CompileOptions options(cx);
    options.setIntroductionType("js shell syntaxParse")
           .setFileAndLine("<string>", 1);

    AutoStableStringChars stableChars(cx);
    if (!stableChars.initTwoByte(cx, scriptContents))
        return false;

    const char16_t* chars = stableChars.twoByteRange().begin().get();
    size_t length = scriptContents->length();
    UsedNameTracker usedNames(cx);
    if (!usedNames.init())
        return false;
    Parser<frontend::SyntaxParseHandler, char16_t> parser(cx, cx->tempLifoAlloc(),
                                                          options, chars, length, false,
                                                          usedNames, nullptr, nullptr);
    if (!parser.checkOptions())
        return false;

    bool succeeded = parser.parse();
    if (cx->isExceptionPending())
        return false;

    if (!succeeded && !parser.hadAbortedSyntaxParse()) {
        // If no exception is posted, either there was an OOM or a language
        // feature unhandled by the syntax parser was encountered.
        MOZ_ASSERT(cx->runtime()->hadOutOfMemory);
        return false;
    }

    args.rval().setBoolean(succeeded);
    return true;
}

static void
OffThreadCompileScriptCallback(void* token, void* callbackData)
{
    ShellContext* sc = static_cast<ShellContext*>(callbackData);
    sc->offThreadState.markDone(token);
}

static bool
OffThreadCompileScript(JSContext* cx, unsigned argc, Value* vp)
{
    if (!CanUseExtraThreads()) {
        JS_ReportErrorASCII(cx, "Can't use offThreadCompileScript with --no-threads");
        return false;
    }

    CallArgs args = CallArgsFromVp(argc, vp);

    if (args.length() < 1) {
        JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr, JSMSG_MORE_ARGS_NEEDED,
                                  "offThreadCompileScript", "0", "s");
        return false;
    }
    if (!args[0].isString()) {
        const char* typeName = InformalValueTypeName(args[0]);
        JS_ReportErrorASCII(cx, "expected string to parse, got %s", typeName);
        return false;
    }

    JSAutoByteString fileNameBytes;
    CompileOptions options(cx);
    options.setIntroductionType("js shell offThreadCompileScript")
           .setFileAndLine("<string>", 1);

    if (args.length() >= 2) {
        if (args[1].isPrimitive()) {
            JS_ReportErrorNumberASCII(cx, my_GetErrorMessage, nullptr, JSSMSG_INVALID_ARGS,
                                      "evaluate");
            return false;
        }

        RootedObject opts(cx, &args[1].toObject());
        if (!ParseCompileOptions(cx, options, opts, fileNameBytes))
            return false;
    }

    // These option settings must override whatever the caller requested.
    options.setIsRunOnce(true)
           .setSourceIsLazy(false);

    // We assume the caller wants caching if at all possible, ignoring
    // heuristics that make sense for a real browser.
    options.forceAsync = true;

    JSString* scriptContents = args[0].toString();
    AutoStableStringChars stableChars(cx);
    if (!stableChars.initTwoByte(cx, scriptContents))
        return false;

    size_t length = scriptContents->length();
    const char16_t* chars = stableChars.twoByteRange().begin().get();

    // Make sure we own the string's chars, so that they are not freed before
    // the compilation is finished.
    ScopedJSFreePtr<char16_t> ownedChars;
    if (stableChars.maybeGiveOwnershipToCaller()) {
        ownedChars = const_cast<char16_t*>(chars);
    } else {
        char16_t* copy = cx->pod_malloc<char16_t>(length);
        if (!copy)
            return false;

        mozilla::PodCopy(copy, chars, length);
        ownedChars = copy;
        chars = copy;
    }

    if (!JS::CanCompileOffThread(cx, options, length)) {
        JS_ReportErrorASCII(cx, "cannot compile code on worker thread");
        return false;
    }

    ShellContext* sc = GetShellContext(cx);
    if (!sc->offThreadState.startIfIdle(cx, ScriptKind::Script, ownedChars)) {
        JS_ReportErrorASCII(cx, "called offThreadCompileScript without calling runOffThreadScript"
                            " to receive prior off-thread compilation");
        return false;
    }

    if (!JS::CompileOffThread(cx, options, chars, length,
                              OffThreadCompileScriptCallback, sc))
    {
        sc->offThreadState.abandon(cx);
        return false;
    }

    args.rval().setUndefined();
    return true;
}

static bool
runOffThreadScript(JSContext* cx, unsigned argc, Value* vp)
{
    CallArgs args = CallArgsFromVp(argc, vp);

    if (OffThreadParsingMustWaitForGC(cx->runtime()))
        gc::FinishGC(cx);

    ShellContext* sc = GetShellContext(cx);
    void* token = sc->offThreadState.waitUntilDone(cx, ScriptKind::Script);
    if (!token) {
        JS_ReportErrorASCII(cx, "called runOffThreadScript when no compilation is pending");
        return false;
    }

    RootedScript script(cx, JS::FinishOffThreadScript(cx, token));
    if (!script)
        return false;

    return JS_ExecuteScript(cx, script, args.rval());
}

static bool
OffThreadCompileModule(JSContext* cx, unsigned argc, Value* vp)
{
    CallArgs args = CallArgsFromVp(argc, vp);

    if (args.length() != 1 || !args[0].isString()) {
        JS_ReportErrorNumberASCII(cx, my_GetErrorMessage, nullptr, JSSMSG_INVALID_ARGS,
                                  "offThreadCompileModule");
        return false;
    }

    JSAutoByteString fileNameBytes;
    CompileOptions options(cx);
    options.setIntroductionType("js shell offThreadCompileModule")
           .setFileAndLine("<string>", 1);
    options.setIsRunOnce(true)
           .setSourceIsLazy(false);
    options.forceAsync = true;

    JSString* scriptContents = args[0].toString();
    AutoStableStringChars stableChars(cx);
    if (!stableChars.initTwoByte(cx, scriptContents))
        return false;

    size_t length = scriptContents->length();
    const char16_t* chars = stableChars.twoByteRange().begin().get();

    // Make sure we own the string's chars, so that they are not freed before
    // the compilation is finished.
    ScopedJSFreePtr<char16_t> ownedChars;
    if (stableChars.maybeGiveOwnershipToCaller()) {
        ownedChars = const_cast<char16_t*>(chars);
    } else {
        char16_t* copy = cx->pod_malloc<char16_t>(length);
        if (!copy)
            return false;

        mozilla::PodCopy(copy, chars, length);
        ownedChars = copy;
        chars = copy;
    }

    if (!JS::CanCompileOffThread(cx, options, length)) {
        JS_ReportErrorASCII(cx, "cannot compile code on worker thread");
        return false;
    }

    ShellContext* sc = GetShellContext(cx);
    if (!sc->offThreadState.startIfIdle(cx, ScriptKind::Module, ownedChars)) {
        JS_ReportErrorASCII(cx, "called offThreadCompileModule without receiving prior off-thread "
                            "compilation");
        return false;
    }

    if (!JS::CompileOffThreadModule(cx, options, chars, length,
                                    OffThreadCompileScriptCallback, sc))
    {
        sc->offThreadState.abandon(cx);
        return false;
    }

    args.rval().setUndefined();
    return true;
}

static bool
FinishOffThreadModule(JSContext* cx, unsigned argc, Value* vp)
{
    CallArgs args = CallArgsFromVp(argc, vp);

    if (OffThreadParsingMustWaitForGC(cx->runtime()))
        gc::FinishGC(cx);

    ShellContext* sc = GetShellContext(cx);
    void* token = sc->offThreadState.waitUntilDone(cx, ScriptKind::Module);
    if (!token) {
        JS_ReportErrorASCII(cx, "called finishOffThreadModule when no compilation is pending");
        return false;
    }

    RootedObject module(cx, JS::FinishOffThreadModule(cx, token));
    if (!module)
        return false;

    args.rval().setObject(*module);
    return true;
}

static bool
OffThreadDecodeScript(JSContext* cx, unsigned argc, Value* vp)
{
    if (!CanUseExtraThreads()) {
        JS_ReportErrorASCII(cx, "Can't use offThreadDecodeScript with --no-threads");
        return false;
    }

    CallArgs args = CallArgsFromVp(argc, vp);

    if (args.length() < 1) {
        JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr, JSMSG_MORE_ARGS_NEEDED,
                                  "offThreadDecodeScript", "0", "s");
        return false;
    }
    if (!args[0].isObject() || !CacheEntry_isCacheEntry(&args[0].toObject())) {
        const char* typeName = InformalValueTypeName(args[0]);
        JS_ReportErrorASCII(cx, "expected cache entry, got %s", typeName);
        return false;
    }
    RootedObject cacheEntry(cx, &args[0].toObject());

    JSAutoByteString fileNameBytes;
    CompileOptions options(cx);
    options.setIntroductionType("js shell offThreadDecodeScript")
           .setFileAndLine("<string>", 1);

    if (args.length() >= 2) {
        if (args[1].isPrimitive()) {
            JS_ReportErrorNumberASCII(cx, my_GetErrorMessage, nullptr, JSSMSG_INVALID_ARGS,
                                      "evaluate");
            return false;
        }

        RootedObject opts(cx, &args[1].toObject());
        if (!ParseCompileOptions(cx, options, opts, fileNameBytes))
            return false;
    }

    // These option settings must override whatever the caller requested.
    options.setIsRunOnce(true)
           .setSourceIsLazy(false);

    // We assume the caller wants caching if at all possible, ignoring
    // heuristics that make sense for a real browser.
    options.forceAsync = true;

    JS::TranscodeBuffer loadBuffer;
    uint32_t loadLength = 0;
    uint8_t* loadData = nullptr;
    loadData = CacheEntry_getBytecode(cacheEntry, &loadLength);
    if (!loadData)
        return false;
    if (!loadBuffer.append(loadData, loadLength)) {
        JS_ReportOutOfMemory(cx);
        return false;
    }

    if (!JS::CanDecodeOffThread(cx, options, loadLength)) {
        JS_ReportErrorASCII(cx, "cannot compile code on worker thread");
        return false;
    }

    ShellContext* sc = GetShellContext(cx);
    if (!sc->offThreadState.startIfIdle(cx, ScriptKind::DecodeScript, mozilla::Move(loadBuffer))) {
        JS_ReportErrorASCII(cx, "called offThreadDecodeScript without calling "
                            "runOffThreadDecodedScript to receive prior off-thread compilation");
        return false;
    }

    if (!JS::DecodeOffThreadScript(cx, options, sc->offThreadState.xdrBuffer(), 0,
                                   OffThreadCompileScriptCallback, sc))
    {
        sc->offThreadState.abandon(cx);
        return false;
    }

    args.rval().setUndefined();
    return true;
}

static bool
runOffThreadDecodedScript(JSContext* cx, unsigned argc, Value* vp)
{
    CallArgs args = CallArgsFromVp(argc, vp);

    if (OffThreadParsingMustWaitForGC(cx->runtime()))
        gc::FinishGC(cx);

    ShellContext* sc = GetShellContext(cx);
    void* token = sc->offThreadState.waitUntilDone(cx, ScriptKind::DecodeScript);
    if (!token) {
        JS_ReportErrorASCII(cx, "called runOffThreadDecodedScript when no compilation is pending");
        return false;
    }

    RootedScript script(cx, JS::FinishOffThreadScriptDecoder(cx, token));
    if (!script)
        return false;

    return JS_ExecuteScript(cx, script, args.rval());
}

struct MOZ_RAII FreeOnReturn
{
    JSContext* cx;
    const char* ptr;
    MOZ_DECL_USE_GUARD_OBJECT_NOTIFIER

    explicit FreeOnReturn(JSContext* cx, const char* ptr = nullptr
                 MOZ_GUARD_OBJECT_NOTIFIER_PARAM)
      : cx(cx), ptr(ptr)
    {
        MOZ_GUARD_OBJECT_NOTIFIER_INIT;
    }

    void init(const char* ptr) {
        MOZ_ASSERT(!this->ptr);
        this->ptr = ptr;
    }

    ~FreeOnReturn() {
        JS_free(cx, (void*)ptr);
    }
};

static int sArgc;
static char** sArgv;

class AutoCStringVector
{
    Vector<char*> argv_;
  public:
    explicit AutoCStringVector(JSContext* cx) : argv_(cx) {}
    ~AutoCStringVector() {
        for (size_t i = 0; i < argv_.length(); i++)
            js_free(argv_[i]);
    }
    bool append(char* arg) {
        if (!argv_.append(arg)) {
            js_free(arg);
            return false;
        }
        return true;
    }
    char* const* get() const {
        return argv_.begin();
    }
    size_t length() const {
        return argv_.length();
    }
    char* operator[](size_t i) const {
        return argv_[i];
    }
    void replace(size_t i, char* arg) {
        js_free(argv_[i]);
        argv_[i] = arg;
    }
    char* back() const {
        return argv_.back();
    }
    void replaceBack(char* arg) {
        js_free(argv_.back());
        argv_.back() = arg;
    }
};

#if defined(XP_WIN)
static bool
EscapeForShell(AutoCStringVector& argv)
{
    // Windows will break arguments in argv by various spaces, so we wrap each
    // argument in quotes and escape quotes within. Even with quotes, \ will be
    // treated like an escape character, so inflate each \ to \\.

    for (size_t i = 0; i < argv.length(); i++) {
        if (!argv[i])
            continue;

        size_t newLen = 3;  // quotes before and after and null-terminator
        for (char* p = argv[i]; *p; p++) {
            newLen++;
            if (*p == '\"' || *p == '\\')
                newLen++;
        }

        char* escaped = (char*)js_malloc(newLen);
        if (!escaped)
            return false;

        char* src = argv[i];
        char* dst = escaped;
        *dst++ = '\"';
        while (*src) {
            if (*src == '\"' || *src == '\\')
                *dst++ = '\\';
            *dst++ = *src++;
        }
        *dst++ = '\"';
        *dst++ = '\0';
        MOZ_ASSERT(escaped + newLen == dst);

        argv.replace(i, escaped);
    }
    return true;
}
#endif

static Vector<const char*, 4, js::SystemAllocPolicy> sPropagatedFlags;

#if defined(JS_CODEGEN_X86) || defined(JS_CODEGEN_X64)
static bool
PropagateFlagToNestedShells(const char* flag)
{
    return sPropagatedFlags.append(flag);
}
#endif

static bool
NestedShell(JSContext* cx, unsigned argc, Value* vp)
{
    CallArgs args = CallArgsFromVp(argc, vp);

    AutoCStringVector argv(cx);

    // The first argument to the shell is its path, which we assume is our own
    // argv[0].
    if (sArgc < 1) {
        JS_ReportErrorNumberASCII(cx, my_GetErrorMessage, nullptr, JSSMSG_NESTED_FAIL);
        return false;
    }
    if (!argv.append(strdup(sArgv[0])))
        return false;

    // Propagate selected flags from the current shell
    for (unsigned i = 0; i < sPropagatedFlags.length(); i++) {
        char* cstr = strdup(sPropagatedFlags[i]);
        if (!cstr || !argv.append(cstr))
            return false;
    }

    // The arguments to nestedShell are stringified and append to argv.
    RootedString str(cx);
    for (unsigned i = 0; i < args.length(); i++) {
        str = ToString(cx, args[i]);
        if (!str || !argv.append(JS_EncodeString(cx, str)))
            return false;

        // As a special case, if the caller passes "--js-cache", replace that
        // with "--js-cache=$(jsCacheDir)"
        if (!strcmp(argv.back(), "--js-cache") && jsCacheDir) {
            UniqueChars newArg = JS_smprintf("--js-cache=%s", jsCacheDir);
            if (!newArg)
                return false;
            argv.replaceBack(newArg.release());
        }
    }

    // execv assumes argv is null-terminated
    if (!argv.append(nullptr))
        return false;

    int status = 0;
#if defined(XP_WIN)
    if (!EscapeForShell(argv))
        return false;
    status = _spawnv(_P_WAIT, sArgv[0], argv.get());
#else
    pid_t pid = fork();
    switch (pid) {
      case -1:
        JS_ReportErrorNumberASCII(cx, my_GetErrorMessage, nullptr, JSSMSG_NESTED_FAIL);
        return false;
      case 0:
        (void)execv(sArgv[0], argv.get());
        exit(-1);
      default: {
        while (waitpid(pid, &status, 0) < 0 && errno == EINTR)
            continue;
        break;
      }
    }
#endif

    if (status != 0) {
        JS_ReportErrorNumberASCII(cx, my_GetErrorMessage, nullptr, JSSMSG_NESTED_FAIL);
        return false;
    }

    args.rval().setUndefined();
    return true;
}

static bool
DecompileFunction(JSContext* cx, unsigned argc, Value* vp)
{
    CallArgs args = CallArgsFromVp(argc, vp);
    if (args.length() < 1 || !args[0].isObject() || !args[0].toObject().is<JSFunction>()) {
        args.rval().setUndefined();
        return true;
    }
    RootedFunction fun(cx, &args[0].toObject().as<JSFunction>());
    JSString* result = JS_DecompileFunction(cx, fun);
    if (!result)
        return false;
    args.rval().setString(result);
    return true;
}

static bool
DecompileThisScript(JSContext* cx, unsigned argc, Value* vp)
{
    CallArgs args = CallArgsFromVp(argc, vp);

    NonBuiltinScriptFrameIter iter(cx);
    if (iter.done()) {
        args.rval().setString(cx->runtime()->emptyString);
        return true;
    }

    {
        JSAutoCompartment ac(cx, iter.script());

        RootedScript script(cx, iter.script());
        JSString* result = JS_DecompileScript(cx, script);
        if (!result)
            return false;

        args.rval().setString(result);
    }

    return JS_WrapValue(cx, args.rval());
}

static bool
ThisFilename(JSContext* cx, unsigned argc, Value* vp)
{
    CallArgs args = CallArgsFromVp(argc, vp);

    JS::AutoFilename filename;
    if (!DescribeScriptedCaller(cx, &filename) || !filename.get()) {
        args.rval().setString(cx->runtime()->emptyString);
        return true;
    }

    JSString* str = JS_NewStringCopyZ(cx, filename.get());
    if (!str)
        return false;

    args.rval().setString(str);
    return true;
}

static bool
WrapWithProto(JSContext* cx, unsigned argc, Value* vp)
{
    CallArgs args = CallArgsFromVp(argc, vp);
    Value obj = UndefinedValue(), proto = UndefinedValue();
    if (args.length() == 2) {
        obj = args[0];
        proto = args[1];
    }
    if (!obj.isObject() || !proto.isObjectOrNull()) {
        JS_ReportErrorNumberASCII(cx, my_GetErrorMessage, nullptr, JSSMSG_INVALID_ARGS,
                                  "wrapWithProto");
        return false;
    }

    WrapperOptions options(cx);
    options.setProto(proto.toObjectOrNull());
    JSObject* wrapped = Wrapper::New(cx, &obj.toObject(),
                                     &Wrapper::singletonWithPrototype, options);
    if (!wrapped)
        return false;

    args.rval().setObject(*wrapped);
    return true;
}

static bool
NewGlobal(JSContext* cx, unsigned argc, Value* vp)
{
    JSPrincipals* principals = nullptr;

    JS::CompartmentOptions options;
    JS::CompartmentCreationOptions& creationOptions = options.creationOptions();
    JS::CompartmentBehaviors& behaviors = options.behaviors();

    SetStandardCompartmentOptions(options);
    options.creationOptions().setNewZoneInExistingZoneGroup(cx->global());

    CallArgs args = CallArgsFromVp(argc, vp);
    if (args.length() == 1 && args[0].isObject()) {
        RootedObject opts(cx, &args[0].toObject());
        RootedValue v(cx);

        if (!JS_GetProperty(cx, opts, "invisibleToDebugger", &v))
            return false;
        if (v.isBoolean())
            creationOptions.setInvisibleToDebugger(v.toBoolean());

        if (!JS_GetProperty(cx, opts, "cloneSingletons", &v))
            return false;
        if (v.isBoolean())
            creationOptions.setCloneSingletons(v.toBoolean());

        if (!JS_GetProperty(cx, opts, "experimentalNumberFormatFormatToPartsEnabled", &v))
            return false;
        if (v.isBoolean())
            creationOptions.setExperimentalNumberFormatFormatToPartsEnabled(v.toBoolean());

        if (!JS_GetProperty(cx, opts, "sameZoneAs", &v))
            return false;
        if (v.isObject())
            creationOptions.setExistingZone(UncheckedUnwrap(&v.toObject()));

        if (!JS_GetProperty(cx, opts, "disableLazyParsing", &v))
            return false;
        if (v.isBoolean())
            behaviors.setDisableLazyParsing(v.toBoolean());

        if (!JS_GetProperty(cx, opts, "principal", &v))
            return false;
        if (!v.isUndefined()) {
            uint32_t bits;
            if (!ToUint32(cx, v, &bits))
                return false;
            principals = cx->new_<ShellPrincipals>(bits);
            if (!principals)
                return false;
            JS_HoldPrincipals(principals);
        }
    }

    RootedObject global(cx, NewGlobalObject(cx, options, principals));
    if (principals)
        JS_DropPrincipals(cx, principals);
    if (!global)
        return false;

    if (!JS_WrapObject(cx, &global))
        return false;

    args.rval().setObject(*global);
    return true;
}

static bool
NukeCCW(JSContext* cx, unsigned argc, Value* vp)
{
    CallArgs args = CallArgsFromVp(argc, vp);

    if (args.length() != 1 || !args[0].isObject() ||
        !IsCrossCompartmentWrapper(&args[0].toObject()))
    {
        JS_ReportErrorNumberASCII(cx, my_GetErrorMessage, nullptr, JSSMSG_INVALID_ARGS,
                                  "nukeCCW");
        return false;
    }

    NukeCrossCompartmentWrapper(cx, &args[0].toObject());
    args.rval().setUndefined();
    return true;
}

static bool
GetMaxArgs(JSContext* cx, unsigned argc, Value* vp)
{
    CallArgs args = CallArgsFromVp(argc, vp);
    args.rval().setInt32(ARGS_LENGTH_MAX);
    return true;
}

static bool
ObjectEmulatingUndefined(JSContext* cx, unsigned argc, Value* vp)
{
    CallArgs args = CallArgsFromVp(argc, vp);

    static const JSClass cls = {
        "ObjectEmulatingUndefined",
        JSCLASS_EMULATES_UNDEFINED
    };

    RootedObject obj(cx, JS_NewObject(cx, &cls));
    if (!obj)
        return false;
    args.rval().setObject(*obj);
    return true;
}

static bool
GetSelfHostedValue(JSContext* cx, unsigned argc, Value* vp)
{
    CallArgs args = CallArgsFromVp(argc, vp);

    if (args.length() != 1 || !args[0].isString()) {
        JS_ReportErrorNumberASCII(cx, my_GetErrorMessage, nullptr, JSSMSG_INVALID_ARGS,
                                  "getSelfHostedValue");
        return false;
    }
    RootedAtom srcAtom(cx, ToAtom<CanGC>(cx, args[0]));
    if (!srcAtom)
        return false;
    RootedPropertyName srcName(cx, srcAtom->asPropertyName());
    return cx->runtime()->cloneSelfHostedValue(cx, srcName, args.rval());
}

class ShellSourceHook: public SourceHook {
    // The function we should call to lazily retrieve source code.
    PersistentRootedFunction fun;

  public:
    ShellSourceHook(JSContext* cx, JSFunction& fun) : fun(cx, &fun) {}

    bool load(JSContext* cx, const char* filename, char16_t** src, size_t* length) {
        RootedString str(cx, JS_NewStringCopyZ(cx, filename));
        if (!str)
            return false;
        RootedValue filenameValue(cx, StringValue(str));

        RootedValue result(cx);
        if (!Call(cx, UndefinedHandleValue, fun, HandleValueArray(filenameValue), &result))
            return false;

        str = JS::ToString(cx, result);
        if (!str)
            return false;

        *length = JS_GetStringLength(str);
        *src = cx->pod_malloc<char16_t>(*length);
        if (!*src)
            return false;

        JSLinearString* linear = str->ensureLinear(cx);
        if (!linear)
            return false;

        CopyChars(*src, *linear);
        return true;
    }
};

static bool
WithSourceHook(JSContext* cx, unsigned argc, Value* vp)
{
    CallArgs args = CallArgsFromVp(argc, vp);
    RootedObject callee(cx, &args.callee());

    if (args.length() != 2) {
        ReportUsageErrorASCII(cx, callee, "Wrong number of arguments.");
        return false;
    }

    if (!args[0].isObject() || !args[0].toObject().is<JSFunction>()
        || !args[1].isObject() || !args[1].toObject().is<JSFunction>()) {
        ReportUsageErrorASCII(cx, callee, "First and second arguments must be functions.");
        return false;
    }

    mozilla::UniquePtr<ShellSourceHook> hook =
        mozilla::MakeUnique<ShellSourceHook>(cx, args[0].toObject().as<JSFunction>());
    if (!hook)
        return false;

    mozilla::UniquePtr<SourceHook> savedHook = js::ForgetSourceHook(cx);
    js::SetSourceHook(cx, Move(hook));

    RootedObject fun(cx, &args[1].toObject());
    bool result = Call(cx, UndefinedHandleValue, fun, JS::HandleValueArray::empty(), args.rval());
    js::SetSourceHook(cx, Move(savedHook));
    return result;
}

static bool
IsCachingEnabled(JSContext* cx, unsigned argc, Value* vp)
{
    CallArgs args = CallArgsFromVp(argc, vp);
    args.rval().setBoolean(jsCachingEnabled && jsCacheAsmJSPath != nullptr);
    return true;
}

static bool
SetCachingEnabled(JSContext* cx, unsigned argc, Value* vp)
{
    CallArgs args = CallArgsFromVp(argc, vp);
    if (GetShellContext(cx)->isWorker) {
        JS_ReportErrorASCII(cx, "Caching is not supported in workers");
        return false;
    }

    jsCachingEnabled = ToBoolean(args.get(0));
    args.rval().setUndefined();
    return true;
}

static void
PrintProfilerEvents_Callback(const char* msg)
{
    fprintf(stderr, "PROFILER EVENT: %s\n", msg);
}

static bool
PrintProfilerEvents(JSContext* cx, unsigned argc, Value* vp)
{
    CallArgs args = CallArgsFromVp(argc, vp);
    if (cx->runtime()->geckoProfiler().enabled())
        js::RegisterContextProfilingEventMarker(cx, &PrintProfilerEvents_Callback);
    args.rval().setUndefined();
    return true;
}

#ifdef SINGLESTEP_PROFILING
static void
SingleStepCallback(void* arg, jit::Simulator* sim, void* pc)
{
    JSContext* cx = reinterpret_cast<JSContext*>(arg);

    // If profiling is not enabled, don't do anything.
    if (!cx->runtime()->geckoProfiler().enabled())
        return;

    JS::ProfilingFrameIterator::RegisterState state;
    state.pc = pc;
#if defined(JS_SIMULATOR_ARM)
    state.sp = (void*)sim->get_register(jit::Simulator::sp);
    state.lr = (void*)sim->get_register(jit::Simulator::lr);
    state.fp = (void*)sim->get_register(jit::Simulator::fp);
#elif defined(JS_SIMULATOR_MIPS64)
    state.sp = (void*)sim->getRegister(jit::Simulator::sp);
    state.lr = (void*)sim->getRegister(jit::Simulator::ra);
    state.fp = (void*)sim->getRegister(jit::Simulator::fp);
#else
#  error "NYI: Single-step profiling support"
#endif

    mozilla::DebugOnly<void*> lastStackAddress = nullptr;
    StackChars stack;
    uint32_t frameNo = 0;
    AutoEnterOOMUnsafeRegion oomUnsafe;
    for (JS::ProfilingFrameIterator i(cx, state); !i.done(); ++i) {
        MOZ_ASSERT(i.stackAddress() != nullptr);
        MOZ_ASSERT(lastStackAddress <= i.stackAddress());
        lastStackAddress = i.stackAddress();
        JS::ProfilingFrameIterator::Frame frames[16];
        uint32_t nframes = i.extractStack(frames, 0, 16);
        for (uint32_t i = 0; i < nframes; i++) {
            if (frameNo > 0) {
                if (!stack.append(",", 1))
                    oomUnsafe.crash("stack.append");
            }
            if (!stack.append(frames[i].label, strlen(frames[i].label)))
                oomUnsafe.crash("stack.append");
            frameNo++;
        }
    }

    ShellContext* sc = GetShellContext(cx);

    // Only append the stack if it differs from the last stack.
    if (sc->stacks.empty() ||
        sc->stacks.back().length() != stack.length() ||
        !PodEqual(sc->stacks.back().begin(), stack.begin(), stack.length()))
    {
        if (!sc->stacks.append(Move(stack)))
            oomUnsafe.crash("stacks.append");
    }
}
#endif

static bool
EnableSingleStepProfiling(JSContext* cx, unsigned argc, Value* vp)
{
#ifdef SINGLESTEP_PROFILING
    CallArgs args = CallArgsFromVp(argc, vp);

    jit::Simulator* sim = cx->simulator();
    sim->enable_single_stepping(SingleStepCallback, cx);

    args.rval().setUndefined();
    return true;
#else
    JS_ReportErrorASCII(cx, "single-step profiling not enabled on this platform");
    return false;
#endif
}

static bool
DisableSingleStepProfiling(JSContext* cx, unsigned argc, Value* vp)
{
#ifdef SINGLESTEP_PROFILING
    CallArgs args = CallArgsFromVp(argc, vp);

    jit::Simulator* sim = cx->simulator();
    sim->disable_single_stepping();

    ShellContext* sc = GetShellContext(cx);

    AutoValueVector elems(cx);
    for (size_t i = 0; i < sc->stacks.length(); i++) {
        JSString* stack = JS_NewUCStringCopyN(cx, sc->stacks[i].begin(), sc->stacks[i].length());
        if (!stack)
            return false;
        if (!elems.append(StringValue(stack)))
            return false;
    }

    JSObject* array = JS_NewArrayObject(cx, elems);
    if (!array)
        return false;

    sc->stacks.clear();
    args.rval().setObject(*array);
    return true;
#else
    JS_ReportErrorASCII(cx, "single-step profiling not enabled on this platform");
    return false;
#endif
}

static bool
IsLatin1(JSContext* cx, unsigned argc, Value* vp)
{
    CallArgs args = CallArgsFromVp(argc, vp);
    bool isLatin1 = args.get(0).isString() && args[0].toString()->hasLatin1Chars();
    args.rval().setBoolean(isLatin1);
    return true;
}

// Set the profiling stack for each cooperating context in a runtime.
static bool
EnsureAllContextProfilingStacks(JSContext* cx)
{
    for (const CooperatingContext& target : cx->runtime()->cooperatingContexts()) {
        ShellContext* sc = GetShellContext(target.context());
        if (!EnsureGeckoProfilingStackInstalled(target.context(), sc))
            return false;
    }

    return true;
}

static bool
EnableGeckoProfiling(JSContext* cx, unsigned argc, Value* vp)
{
    CallArgs args = CallArgsFromVp(argc, vp);

    if (!EnsureAllContextProfilingStacks(cx))
        return false;

    cx->runtime()->geckoProfiler().enableSlowAssertions(false);
    cx->runtime()->geckoProfiler().enable(true);

    args.rval().setUndefined();
    return true;
}

static bool
EnableGeckoProfilingWithSlowAssertions(JSContext* cx, unsigned argc, Value* vp)
{
    CallArgs args = CallArgsFromVp(argc, vp);
    args.rval().setUndefined();

    if (cx->runtime()->geckoProfiler().enabled()) {
        // If profiling already enabled with slow assertions disabled,
        // this is a no-op.
        if (cx->runtime()->geckoProfiler().slowAssertionsEnabled())
            return true;

        // Slow assertions are off.  Disable profiling before re-enabling
        // with slow assertions on.
        cx->runtime()->geckoProfiler().enable(false);
    }

    if (!EnsureAllContextProfilingStacks(cx))
        return false;

    cx->runtime()->geckoProfiler().enableSlowAssertions(true);
    cx->runtime()->geckoProfiler().enable(true);

    return true;
}

static bool
DisableGeckoProfiling(JSContext* cx, unsigned argc, Value* vp)
{
    CallArgs args = CallArgsFromVp(argc, vp);
    args.rval().setUndefined();

    if (!cx->runtime()->geckoProfiler().enabled())
        return true;

    cx->runtime()->geckoProfiler().enable(false);
    return true;
}

// Global mailbox that is used to communicate a SharedArrayBuffer
// value from one worker to another.
//
// For simplicity we store only the SharedArrayRawBuffer; retaining
// the SAB object would require per-runtime storage, and would have no
// real benefits.
//
// Invariant: when a SARB is in the mailbox its reference count is at
// least 1, accounting for the reference from the mailbox.
//
// The lock guards the mailbox variable and prevents a race where two
// workers try to set the mailbox at the same time to replace a SARB
// that is only referenced from the mailbox: the workers will both
// decrement the reference count on the old SARB, and one of those
// decrements will be on a garbage object.  We could implement this
// with atomics and a CAS loop but it's not worth the bother.

static Mutex* sharedArrayBufferMailboxLock;
static SharedArrayRawBuffer* sharedArrayBufferMailbox;

static bool
InitSharedArrayBufferMailbox()
{
    sharedArrayBufferMailboxLock = js_new<Mutex>(mutexid::ShellArrayBufferMailbox);
    return sharedArrayBufferMailboxLock != nullptr;
}

static void
DestructSharedArrayBufferMailbox()
{
    // All workers need to have terminated at this point.
    if (sharedArrayBufferMailbox)
        sharedArrayBufferMailbox->dropReference();
    js_delete(sharedArrayBufferMailboxLock);
}

static bool
GetSharedArrayBuffer(JSContext* cx, unsigned argc, Value* vp)
{
    CallArgs args = CallArgsFromVp(argc, vp);
    JSObject* newObj = nullptr;

    {
        sharedArrayBufferMailboxLock->lock();
        auto unlockMailbox = MakeScopeExit([]() { sharedArrayBufferMailboxLock->unlock(); });

        SharedArrayRawBuffer* buf = sharedArrayBufferMailbox;
        if (buf) {
            if (!buf->addReference()) {
                JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr, JSMSG_SC_SAB_REFCNT_OFLO);
                return false;
            }

            // Shared memory is enabled globally in the shell: there can't be a worker
            // that does not enable it if the main thread has it.
            MOZ_ASSERT(cx->compartment()->creationOptions().getSharedMemoryAndAtomicsEnabled());
            newObj = SharedArrayBufferObject::New(cx, buf);
            if (!newObj) {
                buf->dropReference();
                return false;
            }
        }
    }

    args.rval().setObjectOrNull(newObj);
    return true;
}

static bool
SetSharedArrayBuffer(JSContext* cx, unsigned argc, Value* vp)
{
    CallArgs args = CallArgsFromVp(argc, vp);
    SharedArrayRawBuffer* newBuffer = nullptr;

    if (argc == 0 || args.get(0).isNullOrUndefined()) {
        // Clear out the mailbox
    }
    else if (args.get(0).isObject() && args[0].toObject().is<SharedArrayBufferObject>()) {
        newBuffer = args[0].toObject().as<SharedArrayBufferObject>().rawBufferObject();
        if (!newBuffer->addReference()) {
            JS_ReportErrorASCII(cx, "Reference count overflow on SharedArrayBuffer");
            return false;
        }
    } else {
        JS_ReportErrorASCII(cx, "Only a SharedArrayBuffer can be installed in the global mailbox");
        return false;
    }

    {
        sharedArrayBufferMailboxLock->lock();
        auto unlockMailbox = MakeScopeExit([]() { sharedArrayBufferMailboxLock->unlock(); });

        SharedArrayRawBuffer* oldBuffer = sharedArrayBufferMailbox;
        if (oldBuffer)
            oldBuffer->dropReference();
        sharedArrayBufferMailbox = newBuffer;
    }

    args.rval().setUndefined();
    return true;
}

class SprintOptimizationTypeInfoOp : public JS::ForEachTrackedOptimizationTypeInfoOp
{
    Sprinter* sp;
    bool startedTypes_;
    bool hadError_;

  public:
    explicit SprintOptimizationTypeInfoOp(Sprinter* sp)
      : sp(sp),
        startedTypes_(false),
        hadError_(false)
    { }

    void readType(const char* keyedBy, const char* name,
                  const char* location, const Maybe<unsigned>& lineno) override
    {
        if (hadError_)
            return;

        do {
            if (!startedTypes_) {
                startedTypes_ = true;
                if (!sp->put("{\"typeset\": ["))
                    break;
            }

            if (!sp->jsprintf("{\"keyedBy\":\"%s\"", keyedBy))
                break;

            if (name) {
                if (!sp->jsprintf(",\"name\":\"%s\"", name))
                    break;
            }

            if (location) {
                char buf[512];
                PutEscapedString(buf, mozilla::ArrayLength(buf), location, strlen(location), '"');
                if (!sp->jsprintf(",\"location\":%s", buf))
                    break;
            }
            if (lineno.isSome()) {
                if (!sp->jsprintf(",\"line\":%u", *lineno))
                    break;
            }
            if (!sp->put("},"))
                break;

            return;
        } while (false);

        hadError_ = true;
    }

    void operator()(JS::TrackedTypeSite site, const char* mirType) override {
        if (hadError_)
            return;

        do {
            if (startedTypes_) {
                // Clear trailing ,
                if ((*sp)[sp->getOffset() - 1] == ',')
                    (*sp)[sp->getOffset() - 1] = ' ';
                if (!sp->put("],"))
                    break;

                startedTypes_ = false;
            } else {
                if (!sp->put("{"))
                    break;
            }

            if (!sp->jsprintf("\"site\":\"%s\",\"mirType\":\"%s\"},",
                              TrackedTypeSiteString(site), mirType))
            {
                break;
            }

            return;
        } while (false);

        hadError_ = true;
    }

    bool hadError() const {
        return hadError_;
    }
};

class SprintOptimizationAttemptsOp : public JS::ForEachTrackedOptimizationAttemptOp
{
    Sprinter* sp;
    bool hadError_;

  public:
    explicit SprintOptimizationAttemptsOp(Sprinter* sp)
      : sp(sp), hadError_(false)
    { }

    void operator()(JS::TrackedStrategy strategy, JS::TrackedOutcome outcome) override {
        if (hadError_)
            return;

        hadError_ = !sp->jsprintf("{\"strategy\":\"%s\",\"outcome\":\"%s\"},",
                                  TrackedStrategyString(strategy), TrackedOutcomeString(outcome));
    }

    bool hadError() const {
        return hadError_;
    }
};

static bool
ReflectTrackedOptimizations(JSContext* cx, unsigned argc, Value* vp)
{
    CallArgs args = CallArgsFromVp(argc, vp);
    RootedObject callee(cx, &args.callee());
    JSRuntime* rt = cx->runtime();

    if (!rt->hasJitRuntime() || !rt->jitRuntime()->isOptimizationTrackingEnabled(cx->zone()->group())) {
        JS_ReportErrorASCII(cx, "Optimization tracking is off.");
        return false;
    }

    if (args.length() != 1) {
        ReportUsageErrorASCII(cx, callee, "Wrong number of arguments");
        return false;
    }

    if (!args[0].isObject() || !args[0].toObject().is<JSFunction>()) {
        ReportUsageErrorASCII(cx, callee, "Argument must be a function");
        return false;
    }

    RootedFunction fun(cx, &args[0].toObject().as<JSFunction>());
    if (!fun->hasScript() || !fun->nonLazyScript()->hasIonScript()) {
        args.rval().setNull();
        return true;
    }

    // Suppress GC for the unrooted JitcodeGlobalEntry below.
    gc::AutoSuppressGC suppress(cx);

    jit::JitcodeGlobalTable* table = rt->jitRuntime()->getJitcodeGlobalTable();
    jit::IonScript* ion = fun->nonLazyScript()->ionScript();
    jit::JitcodeGlobalEntry& entry = table->lookupInfallible(ion->method()->raw());

    if (!entry.hasTrackedOptimizations()) {
        JSObject* obj = JS_NewPlainObject(cx);
        if (!obj)
            return false;
        args.rval().setObject(*obj);
        return true;
    }

    Sprinter sp(cx);
    if (!sp.init())
        return false;

    const jit::IonTrackedOptimizationsRegionTable* regions =
        entry.ionEntry().trackedOptimizationsRegionTable();

    if (!sp.put("{\"regions\": ["))
        return false;

    for (uint32_t i = 0; i < regions->numEntries(); i++) {
        jit::IonTrackedOptimizationsRegion region = regions->entry(i);
        jit::IonTrackedOptimizationsRegion::RangeIterator iter = region.ranges();
        while (iter.more()) {
            uint32_t startOffset, endOffset;
            uint8_t index;
            iter.readNext(&startOffset, &endOffset, &index);

            JSScript* script;
            jsbytecode* pc;
            // Use endOffset, as startOffset may be associated with a