js/xpconnect/src/xpcpublic.h
author Bill McCloskey <wmccloskey@mozilla.com>
Fri, 30 Nov 2012 12:20:24 -0800
changeset 123751 a4c6aedf00deb3d3683a5253c88e42acb3b22e29
parent 123680 a6b60491669479843bf270cf79cea8bd2af03f49
child 123914 ce24dbcb88b3796a11b900134826c6f07ab82b07
permissions -rw-r--r--
Backout a6b604916694 (bug 747066) because it's broken

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
 * vim: set ts=8 sw=4 et tw=78:
 *
 * 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/. */

#ifndef xpcpublic_h
#define xpcpublic_h

#include "jsapi.h"
#include "js/MemoryMetrics.h"
#include "jsclass.h"
#include "jsfriendapi.h"
#include "jspubtd.h"
#include "jsproxy.h"
#include "js/HeapAPI.h"

#include "nsISupports.h"
#include "nsIPrincipal.h"
#include "nsWrapperCache.h"
#include "nsStringGlue.h"
#include "nsTArray.h"
#include "mozilla/dom/DOMJSClass.h"
#include "nsMathUtils.h"

class nsIPrincipal;
class nsIXPConnectWrappedJS;
class nsScriptNameSpaceManager;

#ifndef BAD_TLS_INDEX
#define BAD_TLS_INDEX ((uint32_t) -1)
#endif

namespace xpc {
JSObject *
TransplantObject(JSContext *cx, JSObject *origobj, JSObject *target);

JSObject *
TransplantObjectWithWrapper(JSContext *cx,
                            JSObject *origobj, JSObject *origwrapper,
                            JSObject *targetobj, JSObject *targetwrapper);
} /* namespace xpc */

#define XPCONNECT_GLOBAL_FLAGS                                                \
    JSCLASS_DOM_GLOBAL | JSCLASS_HAS_PRIVATE |                                \
    JSCLASS_PRIVATE_IS_NSISUPPORTS | JSCLASS_IMPLEMENTS_BARRIERS |            \
    JSCLASS_GLOBAL_FLAGS_WITH_SLOTS(2)

void
TraceXPCGlobal(JSTracer *trc, JSObject *obj);

// XXX where should this live?
NS_EXPORT_(void)
xpc_LocalizeContext(JSContext *cx);

nsresult
xpc_MorphSlimWrapper(JSContext *cx, nsISupports *tomorph);

static inline bool IS_WRAPPER_CLASS(js::Class* clazz)
{
    return clazz->ext.isWrappedNative;
}

// If IS_WRAPPER_CLASS for the JSClass of an object is true, the object can be
// a slim wrapper, holding a native in its private slot, or a wrappednative
// wrapper, holding the XPCWrappedNative in its private slot. A slim wrapper
// also holds a pointer to its XPCWrappedNativeProto in a reserved slot, we can
// check that slot for a private value (i.e. a double) to distinguish between
// the two. This allows us to store a JSObject in that slot for non-slim wrappers
// while still being able to distinguish the two cases.

// NB: This slot isn't actually reserved for us on globals, because SpiderMonkey
// uses the first N slots on globals internally. The fact that we use it for
// wrapped global objects is totally broken. But due to a happy coincidence, the
// JS engine never uses that slot. This still needs fixing though. See bug 760095.
#define WRAPPER_MULTISLOT 0

static inline bool IS_WN_WRAPPER_OBJECT(JSObject *obj)
{
    MOZ_ASSERT(IS_WRAPPER_CLASS(js::GetObjectClass(obj)));
    return !js::GetReservedSlot(obj, WRAPPER_MULTISLOT).isDouble();
}
static inline bool IS_SLIM_WRAPPER_OBJECT(JSObject *obj)
{
    return !IS_WN_WRAPPER_OBJECT(obj);
}

// Use these functions if IS_WRAPPER_CLASS(GetObjectClass(obj)) might be false.
// Avoid calling them if IS_WRAPPER_CLASS(GetObjectClass(obj)) can only be
// true, as we'd do a redundant call to IS_WRAPPER_CLASS.
static inline bool IS_WN_WRAPPER(JSObject *obj)
{
    return IS_WRAPPER_CLASS(js::GetObjectClass(obj)) && IS_WN_WRAPPER_OBJECT(obj);
}
static inline bool IS_SLIM_WRAPPER(JSObject *obj)
{
    return IS_WRAPPER_CLASS(js::GetObjectClass(obj)) && IS_SLIM_WRAPPER_OBJECT(obj);
}

extern bool
xpc_OkToHandOutWrapper(nsWrapperCache *cache);

inline JSObject*
xpc_FastGetCachedWrapper(nsWrapperCache *cache, JSObject *scope, jsval *vp)
{
    if (cache) {
        JSObject* wrapper = cache->GetWrapper();
        NS_ASSERTION(!wrapper ||
                     !cache->IsDOMBinding() ||
                     !IS_SLIM_WRAPPER(wrapper),
                     "Should never have a slim wrapper when IsDOMBinding()");
        if (wrapper &&
            js::GetObjectCompartment(wrapper) == js::GetObjectCompartment(scope) &&
            (IS_SLIM_WRAPPER(wrapper) || cache->IsDOMBinding() ||
             xpc_OkToHandOutWrapper(cache))) {
            *vp = OBJECT_TO_JSVAL(wrapper);
            return wrapper;
        }
    }

    return nullptr;
}

// The JS GC marks objects gray that are held alive directly or
// indirectly by an XPConnect root. The cycle collector explores only
// this subset of the JS heap.
inline JSBool
xpc_IsGrayGCThing(void *thing)
{
    return js::GCThingIsMarkedGray(thing);
}

// The cycle collector only cares about some kinds of GCthings that are
// reachable from an XPConnect root. Implemented in nsXPConnect.cpp.
extern JSBool
xpc_GCThingIsGrayCCThing(void *thing);

// Implemented in nsXPConnect.cpp.
extern void
xpc_UnmarkGrayGCThingRecursive(void *thing, JSGCTraceKind kind);

// Unmark gray for known-nonnull cases
MOZ_ALWAYS_INLINE void
xpc_UnmarkNonNullGrayObject(JSObject *obj)
{
    if (xpc_IsGrayGCThing(obj))
        xpc_UnmarkGrayGCThingRecursive(obj, JSTRACE_OBJECT);
    else if (js::IsIncrementalBarrierNeededOnObject(obj))
        js::IncrementalReferenceBarrier(obj);
}

// Remove the gray color from the given JSObject and any other objects that can
// be reached through it.
MOZ_ALWAYS_INLINE JSObject *
xpc_UnmarkGrayObject(JSObject *obj)
{
    if (obj)
        xpc_UnmarkNonNullGrayObject(obj);
    return obj;
}

inline JSScript *
xpc_UnmarkGrayScript(JSScript *script)
{
    if (script) {
        if (xpc_IsGrayGCThing(script))
            xpc_UnmarkGrayGCThingRecursive(script, JSTRACE_SCRIPT);
        else if (js::IsIncrementalBarrierNeededOnScript(script))
            js::IncrementalReferenceBarrier(script);
    }
    return script;
}

inline JSContext *
xpc_UnmarkGrayContext(JSContext *cx)
{
    if (cx) {
        JSObject *global = JS_GetGlobalObject(cx);
        xpc_UnmarkGrayObject(global);
        if (global && JS_IsInRequest(JS_GetRuntime(cx))) {
            JSObject *scope = JS_GetGlobalForScopeChain(cx);
            if (scope != global)
                xpc_UnmarkGrayObject(scope);
        }
    }
    return cx;
}

#ifdef __cplusplus
class XPCAutoRequest : public JSAutoRequest {
public:
    XPCAutoRequest(JSContext *cx) : JSAutoRequest(cx) {
        xpc_UnmarkGrayContext(cx);
    }
};
#endif

// If aVariant is an XPCVariant, this marks the object to be in aGeneration.
// This also unmarks the gray JSObject.
extern void
xpc_MarkInCCGeneration(nsISupports* aVariant, uint32_t aGeneration);

// If aWrappedJS is a JS wrapper, unmark its JSObject.
extern void
xpc_TryUnmarkWrappedGrayObject(nsISupports* aWrappedJS);

extern void
xpc_UnmarkSkippableJSHolders();

// No JS can be on the stack when this is called. Probably only useful from
// xpcshell.
NS_EXPORT_(void)
xpc_ActivateDebugMode();

class nsIMemoryMultiReporterCallback;

namespace xpc {

bool DeferredRelease(nsISupports *obj);

// If these functions return false, then an exception will be set on cx.
NS_EXPORT_(bool) Base64Encode(JSContext *cx, JS::Value val, JS::Value *out);
NS_EXPORT_(bool) Base64Decode(JSContext *cx, JS::Value val, JS::Value *out);

/**
 * Convert an nsString to jsval, returning true on success.
 * Note, the ownership of the string buffer may be moved from str to rval.
 * If that happens, str will point to an empty string after this call.
 */
bool NonVoidStringToJsval(JSContext *cx, nsAString &str, JS::Value *rval);
inline bool StringToJsval(JSContext *cx, nsAString &str, JS::Value *rval)
{
    // From the T_DOMSTRING case in XPCConvert::NativeData2JS.
    if (str.IsVoid()) {
        *rval = JSVAL_NULL;
        return true;
    }
    return NonVoidStringToJsval(cx, str, rval);
}

nsIPrincipal *GetCompartmentPrincipal(JSCompartment *compartment);

void DumpJSHeap(FILE* file);

void SetLocationForGlobal(JSObject *global, const nsACString& location);
void SetLocationForGlobal(JSObject *global, nsIURI *locationURI);

/**
 * Define quick stubs on the given object, @a proto.
 *
 * @param cx
 *     A context.  Requires request.
 * @param proto
 *     The (newly created) prototype object for a DOM class.  The JS half
 *     of an XPCWrappedNativeProto.
 * @param flags
 *     Property flags for the quick stub properties--should be either
 *     JSPROP_ENUMERATE or 0.
 * @param interfaceCount
 *     The number of interfaces the class implements.
 * @param interfaceArray
 *     The interfaces the class implements; interfaceArray and
 *     interfaceCount are like what nsIClassInfo.getInterfaces returns.
 */
bool
DOM_DefineQuickStubs(JSContext *cx, JSObject *proto, uint32_t flags,
                     uint32_t interfaceCount, const nsIID **interfaceArray);

// This reports all the stats in |rtStats| that belong in the "explicit" tree,
// (which isn't all of them).
nsresult
ReportJSRuntimeExplicitTreeStats(const JS::RuntimeStats &rtStats,
                                 const nsACString &rtPath,
                                 nsIMemoryMultiReporterCallback *cb,
                                 nsISupports *closure, size_t *rtTotal = NULL);

/**
 * Given an arbitrary object, Unwrap will return the wrapped object if the
 * passed-in object is a wrapper that Unwrap knows about *and* the
 * currently running code has permission to access both the wrapper and
 * wrapped object.
 *
 * Since this is meant to be called from functions like
 * XPCWrappedNative::GetWrappedNativeOfJSObject, it does not set an
 * exception on |cx|.
 */
JSObject *
Unwrap(JSContext *cx, JSObject *wrapper, bool stopAtOuter = true);

/**
 * Throws an exception on cx and returns false.
 */
bool
Throw(JSContext *cx, nsresult rv);

} // namespace xpc

nsCycleCollectionParticipant *
xpc_JSCompartmentParticipant();

namespace mozilla {
namespace dom {

extern int HandlerFamily;
inline void* ProxyFamily() { return &HandlerFamily; }

inline bool IsDOMProxy(JSObject *obj, const js::Class* clasp)
{
    MOZ_ASSERT(js::GetObjectClass(obj) == clasp);
    return (js::IsObjectProxyClass(clasp) || js::IsFunctionProxyClass(clasp)) &&
           js::GetProxyHandler(obj)->family() == ProxyFamily();
}

inline bool IsDOMProxy(JSObject *obj)
{
    return IsDOMProxy(obj, js::GetObjectClass(obj));
}

typedef JSObject*
(*DefineInterface)(JSContext *cx, JSObject *global, bool *enabled);

typedef bool
(*PrefEnabled)();

extern bool
DefineStaticJSVals(JSContext *cx);
void
Register(nsScriptNameSpaceManager* aNameSpaceManager);

} // namespace dom
} // namespace mozilla

#endif