storage/mozStorageStatement.cpp
author Masayuki Nakano <masayuki@d-toybox.com>
Thu, 10 Jan 2019 08:50:41 +0000
changeset 453219 99a977d519a0b78e267d3dce4afb009b8d3be769
parent 448947 6f3709b3878117466168c40affa7bca0b60cf75b
child 458963 b4258349e68b37138bc1e926105cce0b8e1db569
permissions -rw-r--r--
Bug 181137 - part 8: Make ContentIteratorBase and its subclasses non-refcountable r=smaug This patch makes ContentIteratorBase, PostContentIterator, PreContentIterator and ContentSubtreeIterator classes non-refcountable because most users can create their instances in stack and such users may be in a hot path. So, we can save a lot of cost of instantiation. Unfortunately, only ScriptableContentIterator creates one of the concrete classes and needs to destroy it properly. Therefore, its EnsureContentIterator(), destructor, traverse and unlink code becomes messy. However, ScriptableContentIterator was designed for automated tests and we need to maintain it not so many times. Therefore, improvement of other users must be worthwhiler than this demerit. Differential Revision: https://phabricator.services.mozilla.com/D15928

/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
 * vim: sw=2 ts=2 et lcs=trail\:.,tab\:>~ :
 * 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/. */

#include <limits.h>
#include <stdio.h>

#include "nsError.h"
#include "nsMemory.h"
#include "nsThreadUtils.h"
#include "nsIClassInfoImpl.h"
#include "Variant.h"

#include "mozIStorageError.h"

#include "mozStorageBindingParams.h"
#include "mozStorageConnection.h"
#include "mozStorageStatementJSHelper.h"
#include "mozStoragePrivateHelpers.h"
#include "mozStorageStatementParams.h"
#include "mozStorageStatementRow.h"
#include "mozStorageStatement.h"
#include "GeckoProfiler.h"

#include "mozilla/Logging.h"
#include "mozilla/Printf.h"

extern mozilla::LazyLogModule gStorageLog;

namespace mozilla {
namespace storage {

////////////////////////////////////////////////////////////////////////////////
//// nsIClassInfo

NS_IMPL_CI_INTERFACE_GETTER(Statement, mozIStorageStatement,
                            mozIStorageBaseStatement, mozIStorageBindingParams,
                            mozIStorageValueArray,
                            mozilla::storage::StorageBaseStatementInternal)

class StatementClassInfo : public nsIClassInfo {
 public:
  constexpr StatementClassInfo() {}

  NS_DECL_ISUPPORTS_INHERITED

  NS_IMETHOD
  GetInterfaces(uint32_t *_count, nsIID ***_array) override {
    return NS_CI_INTERFACE_GETTER_NAME(Statement)(_count, _array);
  }

  NS_IMETHOD
  GetScriptableHelper(nsIXPCScriptable **_helper) override {
    static StatementJSHelper sJSHelper;
    *_helper = &sJSHelper;
    return NS_OK;
  }

  NS_IMETHOD
  GetContractID(nsACString &aContractID) override {
    aContractID.SetIsVoid(true);
    return NS_OK;
  }

  NS_IMETHOD
  GetClassDescription(nsACString &aDesc) override {
    aDesc.SetIsVoid(true);
    return NS_OK;
  }

  NS_IMETHOD
  GetClassID(nsCID **_id) override {
    *_id = nullptr;
    return NS_OK;
  }

  NS_IMETHOD
  GetFlags(uint32_t *_flags) override {
    *_flags = 0;
    return NS_OK;
  }

  NS_IMETHOD
  GetClassIDNoAlloc(nsCID *_cid) override { return NS_ERROR_NOT_AVAILABLE; }
};

NS_IMETHODIMP_(MozExternalRefCountType) StatementClassInfo::AddRef() {
  return 2;
}
NS_IMETHODIMP_(MozExternalRefCountType) StatementClassInfo::Release() {
  return 1;
}
NS_IMPL_QUERY_INTERFACE(StatementClassInfo, nsIClassInfo)

static StatementClassInfo sStatementClassInfo;

////////////////////////////////////////////////////////////////////////////////
//// Statement

Statement::Statement()
    : StorageBaseStatementInternal(),
      mDBStatement(nullptr),
      mParamCount(0),
      mResultColumnCount(0),
      mColumnNames(),
      mExecuting(false) {}

nsresult Statement::initialize(Connection *aDBConnection,
                               sqlite3 *aNativeConnection,
                               const nsACString &aSQLStatement) {
  MOZ_ASSERT(aDBConnection, "No database connection given!");
  MOZ_ASSERT(aDBConnection->isConnectionReadyOnThisThread(),
             "Database connection should be valid");
  MOZ_ASSERT(!mDBStatement, "Statement already initialized!");
  MOZ_ASSERT(aNativeConnection, "No native connection given!");

  int srv = aDBConnection->prepareStatement(
      aNativeConnection, PromiseFlatCString(aSQLStatement), &mDBStatement);
  if (srv != SQLITE_OK) {
    MOZ_LOG(gStorageLog, LogLevel::Error,
            ("Sqlite statement prepare error: %d '%s'", srv,
             ::sqlite3_errmsg(aNativeConnection)));
    MOZ_LOG(gStorageLog, LogLevel::Error,
            ("Statement was: '%s'", PromiseFlatCString(aSQLStatement).get()));
    return NS_ERROR_FAILURE;
  }

  MOZ_LOG(gStorageLog, LogLevel::Debug,
          ("Initialized statement '%s' (0x%p)",
           PromiseFlatCString(aSQLStatement).get(), mDBStatement));

  mDBConnection = aDBConnection;
  mNativeConnection = aNativeConnection;
  mParamCount = ::sqlite3_bind_parameter_count(mDBStatement);
  mResultColumnCount = ::sqlite3_column_count(mDBStatement);
  mColumnNames.Clear();

  nsCString *columnNames = mColumnNames.AppendElements(mResultColumnCount);
  for (uint32_t i = 0; i < mResultColumnCount; i++) {
    const char *name = ::sqlite3_column_name(mDBStatement, i);
    columnNames[i].Assign(name);
  }

#ifdef DEBUG
  // We want to try and test for LIKE and that consumers are using
  // escapeStringForLIKE instead of just trusting user input.  The idea to
  // check to see if they are binding a parameter after like instead of just
  // using a string.  We only do this in debug builds because it's expensive!
  const nsCaseInsensitiveCStringComparator c;
  nsACString::const_iterator start, end, e;
  aSQLStatement.BeginReading(start);
  aSQLStatement.EndReading(end);
  e = end;
  while (::FindInReadable(NS_LITERAL_CSTRING(" LIKE"), start, e, c)) {
    // We have a LIKE in here, so we perform our tests
    // FindInReadable moves the iterator, so we have to get a new one for
    // each test we perform.
    nsACString::const_iterator s1, s2, s3;
    s1 = s2 = s3 = start;

    if (!(::FindInReadable(NS_LITERAL_CSTRING(" LIKE ?"), s1, end, c) ||
          ::FindInReadable(NS_LITERAL_CSTRING(" LIKE :"), s2, end, c) ||
          ::FindInReadable(NS_LITERAL_CSTRING(" LIKE @"), s3, end, c))) {
      // At this point, we didn't find a LIKE statement followed by ?, :,
      // or @, all of which are valid characters for binding a parameter.
      // We will warn the consumer that they may not be safely using LIKE.
      NS_WARNING(
          "Unsafe use of LIKE detected!  Please ensure that you "
          "are using mozIStorageStatement::escapeStringForLIKE "
          "and that you are binding that result to the statement "
          "to prevent SQL injection attacks.");
    }

    // resetting start and e
    start = e;
    e = end;
  }
#endif

  return NS_OK;
}

mozIStorageBindingParams *Statement::getParams() {
  nsresult rv;

  // If we do not have an array object yet, make it.
  if (!mParamsArray) {
    nsCOMPtr<mozIStorageBindingParamsArray> array;
    rv = NewBindingParamsArray(getter_AddRefs(array));
    NS_ENSURE_SUCCESS(rv, nullptr);

    mParamsArray = static_cast<BindingParamsArray *>(array.get());
  }

  // If there isn't already any rows added, we'll have to add one to use.
  if (mParamsArray->length() == 0) {
    RefPtr<BindingParams> params(new BindingParams(mParamsArray, this));
    NS_ENSURE_TRUE(params, nullptr);

    rv = mParamsArray->AddParams(params);
    NS_ENSURE_SUCCESS(rv, nullptr);

    // We have to unlock our params because AddParams locks them.  This is safe
    // because no reference to the params object was, or ever will be given out.
    params->unlock(this);

    // We also want to lock our array at this point - we don't want anything to
    // be added to it.  Nothing has, or will ever get a reference to it, but we
    // will get additional safety checks via assertions by doing this.
    mParamsArray->lock();
  }

  return *mParamsArray->begin();
}

Statement::~Statement() { (void)internalFinalize(true); }

////////////////////////////////////////////////////////////////////////////////
//// nsISupports

NS_IMPL_ADDREF(Statement)
NS_IMPL_RELEASE(Statement)

NS_INTERFACE_MAP_BEGIN(Statement)
  NS_INTERFACE_MAP_ENTRY(mozIStorageStatement)
  NS_INTERFACE_MAP_ENTRY(mozIStorageBaseStatement)
  NS_INTERFACE_MAP_ENTRY(mozIStorageBindingParams)
  NS_INTERFACE_MAP_ENTRY(mozIStorageValueArray)
  NS_INTERFACE_MAP_ENTRY(mozilla::storage::StorageBaseStatementInternal)
  if (aIID.Equals(NS_GET_IID(nsIClassInfo))) {
    foundInterface = static_cast<nsIClassInfo *>(&sStatementClassInfo);
  } else
    NS_INTERFACE_MAP_ENTRY_AMBIGUOUS(nsISupports, mozIStorageStatement)
NS_INTERFACE_MAP_END

////////////////////////////////////////////////////////////////////////////////
//// StorageBaseStatementInternal

Connection *Statement::getOwner() { return mDBConnection; }

int Statement::getAsyncStatement(sqlite3_stmt **_stmt) {
  // If we have no statement, we shouldn't be calling this method!
  NS_ASSERTION(mDBStatement != nullptr, "We have no statement to clone!");

  // If we do not yet have a cached async statement, clone our statement now.
  if (!mAsyncStatement) {
    nsDependentCString sql(::sqlite3_sql(mDBStatement));
    int rc = mDBConnection->prepareStatement(mNativeConnection, sql,
                                             &mAsyncStatement);
    if (rc != SQLITE_OK) {
      *_stmt = nullptr;
      return rc;
    }

    MOZ_LOG(gStorageLog, LogLevel::Debug,
            ("Cloned statement 0x%p to 0x%p", mDBStatement, mAsyncStatement));
  }

  *_stmt = mAsyncStatement;
  return SQLITE_OK;
}

nsresult Statement::getAsynchronousStatementData(StatementData &_data) {
  if (!mDBStatement) return NS_ERROR_UNEXPECTED;

  sqlite3_stmt *stmt;
  int rc = getAsyncStatement(&stmt);
  if (rc != SQLITE_OK) return convertResultCode(rc);

  _data = StatementData(stmt, bindingParamsArray(), this);

  return NS_OK;
}

already_AddRefed<mozIStorageBindingParams> Statement::newBindingParams(
    mozIStorageBindingParamsArray *aOwner) {
  nsCOMPtr<mozIStorageBindingParams> params = new BindingParams(aOwner, this);
  return params.forget();
}

////////////////////////////////////////////////////////////////////////////////
//// mozIStorageStatement

// proxy to StorageBaseStatementInternal using its define helper.
MIXIN_IMPL_STORAGEBASESTATEMENTINTERNAL(Statement, (void)0;)

NS_IMETHODIMP
Statement::Clone(mozIStorageStatement **_statement) {
  RefPtr<Statement> statement(new Statement());
  NS_ENSURE_TRUE(statement, NS_ERROR_OUT_OF_MEMORY);

  nsAutoCString sql(::sqlite3_sql(mDBStatement));
  nsresult rv = statement->initialize(mDBConnection, mNativeConnection, sql);
  NS_ENSURE_SUCCESS(rv, rv);

  statement.forget(_statement);
  return NS_OK;
}

NS_IMETHODIMP
Statement::Finalize() { return internalFinalize(false); }

nsresult Statement::internalFinalize(bool aDestructing) {
  if (!mDBStatement) return NS_OK;

  int srv = SQLITE_OK;

  {
    // If the statement ends up being finalized twice, the second finalization
    // would apply to a dangling pointer and may cause unexpected consequences.
    // Thus we must be sure that the connection state won't change during this
    // operation, to avoid racing with finalizations made by the closing
    // connection.  See Connection::internalClose().
    MutexAutoLock lockedScope(mDBConnection->sharedAsyncExecutionMutex);
    if (!mDBConnection->isClosed(lockedScope)) {
      MOZ_LOG(gStorageLog, LogLevel::Debug,
              ("Finalizing statement '%s' during garbage-collection",
               ::sqlite3_sql(mDBStatement)));
      srv = ::sqlite3_finalize(mDBStatement);
    }
#ifdef DEBUG
    else {
      // The database connection is closed. The sqlite
      // statement has either been finalized already by the connection
      // or is about to be finalized by the connection.
      //
      // Finalizing it here would be useless and segfaultish.
      //
      // Note that we can't display the statement itself, as the data structure
      // is not valid anymore. However, the address shown here should help
      // developers correlate with the more complete debug message triggered
      // by AsyncClose().

      SmprintfPointer msg = ::mozilla::Smprintf(
          "SQL statement (%p) should have been finalized"
          " before garbage-collection. For more details on this statement, set"
          " NSPR_LOG_MESSAGES=mozStorage:5 .",
          mDBStatement);
      NS_WARNING(msg.get());

      // Use %s so we aren't exposing random strings to printf interpolation.
      MOZ_LOG(gStorageLog, LogLevel::Warning, ("%s", msg.get()));
    }
#endif  // DEBUG
  }

  mDBStatement = nullptr;

  if (mAsyncStatement) {
    // If the destructor called us, there are no pending async statements (they
    // hold a reference to us) and we can/must just kill the statement directly.
    if (aDestructing)
      destructorAsyncFinalize();
    else
      asyncFinalize();
  }

  // Release the holders, so they can release the reference to us.
  mStatementParamsHolder = nullptr;
  mStatementRowHolder = nullptr;

  return convertResultCode(srv);
}

NS_IMETHODIMP
Statement::GetParameterCount(uint32_t *_parameterCount) {
  if (!mDBStatement) return NS_ERROR_NOT_INITIALIZED;

  *_parameterCount = mParamCount;
  return NS_OK;
}

NS_IMETHODIMP
Statement::GetParameterName(uint32_t aParamIndex, nsACString &_name) {
  if (!mDBStatement) return NS_ERROR_NOT_INITIALIZED;
  ENSURE_INDEX_VALUE(aParamIndex, mParamCount);

  const char *name =
      ::sqlite3_bind_parameter_name(mDBStatement, aParamIndex + 1);
  if (name == nullptr) {
    // this thing had no name, so fake one
    nsAutoCString fakeName(":");
    fakeName.AppendInt(aParamIndex);
    _name.Assign(fakeName);
  } else {
    _name.Assign(nsDependentCString(name));
  }

  return NS_OK;
}

NS_IMETHODIMP
Statement::GetParameterIndex(const nsACString &aName, uint32_t *_index) {
  if (!mDBStatement) return NS_ERROR_NOT_INITIALIZED;

  // We do not accept any forms of names other than ":name", but we need to add
  // the colon for SQLite.
  nsAutoCString name(":");
  name.Append(aName);
  int ind = ::sqlite3_bind_parameter_index(mDBStatement, name.get());
  if (ind == 0)  // Named parameter not found.
    return NS_ERROR_INVALID_ARG;

  *_index = ind - 1;  // SQLite indexes are 1-based, we are 0-based.

  return NS_OK;
}

NS_IMETHODIMP
Statement::GetColumnCount(uint32_t *_columnCount) {
  if (!mDBStatement) return NS_ERROR_NOT_INITIALIZED;

  *_columnCount = mResultColumnCount;
  return NS_OK;
}

NS_IMETHODIMP
Statement::GetColumnName(uint32_t aColumnIndex, nsACString &_name) {
  if (!mDBStatement) return NS_ERROR_NOT_INITIALIZED;
  ENSURE_INDEX_VALUE(aColumnIndex, mResultColumnCount);

  const char *cname = ::sqlite3_column_name(mDBStatement, aColumnIndex);
  _name.Assign(nsDependentCString(cname));

  return NS_OK;
}

NS_IMETHODIMP
Statement::GetColumnIndex(const nsACString &aName, uint32_t *_index) {
  if (!mDBStatement) return NS_ERROR_NOT_INITIALIZED;

  // Surprisingly enough, SQLite doesn't provide an API for this.  We have to
  // determine it ourselves sadly.
  for (uint32_t i = 0; i < mResultColumnCount; i++) {
    if (mColumnNames[i].Equals(aName)) {
      *_index = i;
      return NS_OK;
    }
  }

  return NS_ERROR_INVALID_ARG;
}

NS_IMETHODIMP
Statement::Reset() {
  if (!mDBStatement) return NS_ERROR_NOT_INITIALIZED;

#ifdef DEBUG
  MOZ_LOG(gStorageLog, LogLevel::Debug,
          ("Resetting statement: '%s'", ::sqlite3_sql(mDBStatement)));

  checkAndLogStatementPerformance(mDBStatement);
#endif

  mParamsArray = nullptr;
  (void)sqlite3_reset(mDBStatement);
  (void)sqlite3_clear_bindings(mDBStatement);

  mExecuting = false;

  return NS_OK;
}

NS_IMETHODIMP
Statement::BindParameters(mozIStorageBindingParamsArray *aParameters) {
  NS_ENSURE_ARG_POINTER(aParameters);

  if (!mDBStatement) return NS_ERROR_NOT_INITIALIZED;

  BindingParamsArray *array = static_cast<BindingParamsArray *>(aParameters);
  if (array->getOwner() != this) return NS_ERROR_UNEXPECTED;

  if (array->length() == 0) return NS_ERROR_UNEXPECTED;

  mParamsArray = array;
  mParamsArray->lock();

  return NS_OK;
}

NS_IMETHODIMP
Statement::Execute() {
  if (!mDBStatement) return NS_ERROR_NOT_INITIALIZED;

  bool ret;
  nsresult rv = ExecuteStep(&ret);
  nsresult rv2 = Reset();

  return NS_FAILED(rv) ? rv : rv2;
}

NS_IMETHODIMP
Statement::ExecuteStep(bool *_moreResults) {
  AUTO_PROFILER_LABEL("Statement::ExecuteStep", OTHER);

  if (!mDBStatement) return NS_ERROR_NOT_INITIALIZED;

  // Bind any parameters first before executing.
  if (mParamsArray) {
    // If we have more than one row of parameters to bind, they shouldn't be
    // calling this method (and instead use executeAsync).
    if (mParamsArray->length() != 1) return NS_ERROR_UNEXPECTED;

    BindingParamsArray::iterator row = mParamsArray->begin();
    nsCOMPtr<IStorageBindingParamsInternal> bindingInternal =
        do_QueryInterface(*row);
    nsCOMPtr<mozIStorageError> error = bindingInternal->bind(mDBStatement);
    if (error) {
      int32_t srv;
      (void)error->GetResult(&srv);
      return convertResultCode(srv);
    }

    // We have bound, so now we can clear our array.
    mParamsArray = nullptr;
  }
  int srv = mDBConnection->stepStatement(mNativeConnection, mDBStatement);

  if (srv != SQLITE_ROW && srv != SQLITE_DONE &&
      MOZ_LOG_TEST(gStorageLog, LogLevel::Debug)) {
    nsAutoCString errStr;
    (void)mDBConnection->GetLastErrorString(errStr);
    MOZ_LOG(gStorageLog, LogLevel::Debug,
            ("Statement::ExecuteStep error: %s", errStr.get()));
  }

  // SQLITE_ROW and SQLITE_DONE are non-errors
  if (srv == SQLITE_ROW) {
    // we got a row back
    mExecuting = true;
    *_moreResults = true;
    return NS_OK;
  } else if (srv == SQLITE_DONE) {
    // statement is done (no row returned)
    mExecuting = false;
    *_moreResults = false;
    return NS_OK;
  } else if (srv == SQLITE_BUSY || srv == SQLITE_MISUSE) {
    mExecuting = false;
  } else if (mExecuting) {
    MOZ_LOG(gStorageLog, LogLevel::Error,
            ("SQLite error after mExecuting was true!"));
    mExecuting = false;
  }

  return convertResultCode(srv);
}

NS_IMETHODIMP
Statement::GetState(int32_t *_state) {
  if (!mDBStatement)
    *_state = MOZ_STORAGE_STATEMENT_INVALID;
  else if (mExecuting)
    *_state = MOZ_STORAGE_STATEMENT_EXECUTING;
  else
    *_state = MOZ_STORAGE_STATEMENT_READY;

  return NS_OK;
}

////////////////////////////////////////////////////////////////////////////////
//// mozIStorageValueArray (now part of mozIStorageStatement too)

NS_IMETHODIMP
Statement::GetNumEntries(uint32_t *_length) {
  *_length = mResultColumnCount;
  return NS_OK;
}

NS_IMETHODIMP
Statement::GetTypeOfIndex(uint32_t aIndex, int32_t *_type) {
  if (!mDBStatement) return NS_ERROR_NOT_INITIALIZED;

  ENSURE_INDEX_VALUE(aIndex, mResultColumnCount);

  if (!mExecuting) return NS_ERROR_UNEXPECTED;

  int t = ::sqlite3_column_type(mDBStatement, aIndex);
  switch (t) {
    case SQLITE_INTEGER:
      *_type = mozIStorageStatement::VALUE_TYPE_INTEGER;
      break;
    case SQLITE_FLOAT:
      *_type = mozIStorageStatement::VALUE_TYPE_FLOAT;
      break;
    case SQLITE_TEXT:
      *_type = mozIStorageStatement::VALUE_TYPE_TEXT;
      break;
    case SQLITE_BLOB:
      *_type = mozIStorageStatement::VALUE_TYPE_BLOB;
      break;
    case SQLITE_NULL:
      *_type = mozIStorageStatement::VALUE_TYPE_NULL;
      break;
    default:
      return NS_ERROR_FAILURE;
  }

  return NS_OK;
}

NS_IMETHODIMP
Statement::GetInt32(uint32_t aIndex, int32_t *_value) {
  if (!mDBStatement) return NS_ERROR_NOT_INITIALIZED;

  ENSURE_INDEX_VALUE(aIndex, mResultColumnCount);

  if (!mExecuting) return NS_ERROR_UNEXPECTED;

  *_value = ::sqlite3_column_int(mDBStatement, aIndex);
  return NS_OK;
}

NS_IMETHODIMP
Statement::GetInt64(uint32_t aIndex, int64_t *_value) {
  if (!mDBStatement) return NS_ERROR_NOT_INITIALIZED;

  ENSURE_INDEX_VALUE(aIndex, mResultColumnCount);

  if (!mExecuting) return NS_ERROR_UNEXPECTED;

  *_value = ::sqlite3_column_int64(mDBStatement, aIndex);

  return NS_OK;
}

NS_IMETHODIMP
Statement::GetDouble(uint32_t aIndex, double *_value) {
  if (!mDBStatement) return NS_ERROR_NOT_INITIALIZED;

  ENSURE_INDEX_VALUE(aIndex, mResultColumnCount);

  if (!mExecuting) return NS_ERROR_UNEXPECTED;

  *_value = ::sqlite3_column_double(mDBStatement, aIndex);

  return NS_OK;
}

NS_IMETHODIMP
Statement::GetUTF8String(uint32_t aIndex, nsACString &_value) {
  // Get type of Index will check aIndex for us, so we don't have to.
  int32_t type;
  nsresult rv = GetTypeOfIndex(aIndex, &type);
  NS_ENSURE_SUCCESS(rv, rv);
  if (type == mozIStorageStatement::VALUE_TYPE_NULL) {
    // NULL columns should have IsVoid set to distinguish them from the empty
    // string.
    _value.SetIsVoid(true);
  } else {
    const char *value = reinterpret_cast<const char *>(
        ::sqlite3_column_text(mDBStatement, aIndex));
    _value.Assign(value, ::sqlite3_column_bytes(mDBStatement, aIndex));
  }
  return NS_OK;
}

NS_IMETHODIMP
Statement::GetString(uint32_t aIndex, nsAString &_value) {
  // Get type of Index will check aIndex for us, so we don't have to.
  int32_t type;
  nsresult rv = GetTypeOfIndex(aIndex, &type);
  NS_ENSURE_SUCCESS(rv, rv);
  if (type == mozIStorageStatement::VALUE_TYPE_NULL) {
    // NULL columns should have IsVoid set to distinguish them from the empty
    // string.
    _value.SetIsVoid(true);
  } else {
    const char16_t *value = static_cast<const char16_t *>(
        ::sqlite3_column_text16(mDBStatement, aIndex));
    _value.Assign(value, ::sqlite3_column_bytes16(mDBStatement, aIndex) / 2);
  }
  return NS_OK;
}

NS_IMETHODIMP
Statement::GetBlob(uint32_t aIndex, uint32_t *_size, uint8_t **_blob) {
  if (!mDBStatement) return NS_ERROR_NOT_INITIALIZED;

  ENSURE_INDEX_VALUE(aIndex, mResultColumnCount);

  if (!mExecuting) return NS_ERROR_UNEXPECTED;

  int size = ::sqlite3_column_bytes(mDBStatement, aIndex);
  void *blob = nullptr;
  if (size) {
    blob = moz_xmemdup(::sqlite3_column_blob(mDBStatement, aIndex), size);
  }

  *_blob = static_cast<uint8_t *>(blob);
  *_size = size;
  return NS_OK;
}

NS_IMETHODIMP
Statement::GetBlobAsString(uint32_t aIndex, nsAString &aValue) {
  return DoGetBlobAsString(this, aIndex, aValue);
}

NS_IMETHODIMP
Statement::GetBlobAsUTF8String(uint32_t aIndex, nsACString &aValue) {
  return DoGetBlobAsString(this, aIndex, aValue);
}

NS_IMETHODIMP
Statement::GetSharedUTF8String(uint32_t aIndex, uint32_t *_length,
                               const char **_value) {
  if (_length) *_length = ::sqlite3_column_bytes(mDBStatement, aIndex);

  *_value = reinterpret_cast<const char *>(
      ::sqlite3_column_text(mDBStatement, aIndex));
  return NS_OK;
}

NS_IMETHODIMP
Statement::GetSharedString(uint32_t aIndex, uint32_t *_length,
                           const char16_t **_value) {
  if (_length) *_length = ::sqlite3_column_bytes16(mDBStatement, aIndex);

  *_value = static_cast<const char16_t *>(
      ::sqlite3_column_text16(mDBStatement, aIndex));
  return NS_OK;
}

NS_IMETHODIMP
Statement::GetSharedBlob(uint32_t aIndex, uint32_t *_size,
                         const uint8_t **_blob) {
  *_size = ::sqlite3_column_bytes(mDBStatement, aIndex);
  *_blob =
      static_cast<const uint8_t *>(::sqlite3_column_blob(mDBStatement, aIndex));
  return NS_OK;
}

NS_IMETHODIMP
Statement::GetIsNull(uint32_t aIndex, bool *_isNull) {
  // Get type of Index will check aIndex for us, so we don't have to.
  int32_t type;
  nsresult rv = GetTypeOfIndex(aIndex, &type);
  NS_ENSURE_SUCCESS(rv, rv);
  *_isNull = (type == mozIStorageStatement::VALUE_TYPE_NULL);
  return NS_OK;
}

////////////////////////////////////////////////////////////////////////////////
//// mozIStorageBindingParams

BOILERPLATE_BIND_PROXIES(Statement,
                         if (!mDBStatement) return NS_ERROR_NOT_INITIALIZED;)

}  // namespace storage
}  // namespace mozilla