tor-browser

The Tor Browser
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ClientDirectoryLockHandle.cpp (4326B)

      1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
      2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
      3 /* This Source Code Form is subject to the terms of the Mozilla Public
      4 * License, v. 2.0. If a copy of the MPL was not distributed with this file,
      5 * You can obtain one at http://mozilla.org/MPL/2.0/. */
      6 
      7 #include "mozilla/dom/quota/ClientDirectoryLockHandle.h"
      8 
      9 #include "mozilla/dom/quota/ClientDirectoryLock.h"
     10 #include "mozilla/dom/quota/DirectoryLock.h"
     11 #include "mozilla/dom/quota/DirectoryLockInlines.h"
     12 #include "mozilla/dom/quota/QuotaManager.h"
     13 
     14 namespace mozilla::dom::quota {
     15 
     16 ClientDirectoryLockHandle::ClientDirectoryLockHandle() {
     17  MOZ_COUNT_CTOR(mozilla::dom::quota::ClientDirectoryLockHandle);
     18 }
     19 
     20 ClientDirectoryLockHandle::ClientDirectoryLockHandle(
     21    RefPtr<ClientDirectoryLock> aClientDirectoryLock) {
     22  aClientDirectoryLock->AssertIsOnOwningThread();
     23 
     24  mClientDirectoryLock = std::move(aClientDirectoryLock);
     25 
     26  MOZ_COUNT_CTOR(mozilla::dom::quota::ClientDirectoryLockHandle);
     27 }
     28 
     29 ClientDirectoryLockHandle::ClientDirectoryLockHandle(
     30    ClientDirectoryLockHandle&& aOther) noexcept {
     31  aOther.AssertIsOnOwningThread();
     32 
     33  mClientDirectoryLock = std::move(aOther.mClientDirectoryLock);
     34 
     35  // Explicitly null aOther.mClientDirectoryLock so that aOther appears inert
     36  // immediately after the move. While RefPtr nulls out its mRawPtr internally,
     37  // the store may be reordered in optimized builds, possibly occurring only
     38  // just before RefPtr’s own destructor runs. Without this, the moved-from
     39  // handle’s destructor may observe a stale non-null value.
     40  aOther.mClientDirectoryLock = nullptr;
     41 
     42  mRegistered = std::exchange(aOther.mRegistered, false);
     43 
     44  MOZ_COUNT_CTOR(mozilla::dom::quota::ClientDirectoryLockHandle);
     45 }
     46 
     47 ClientDirectoryLockHandle::~ClientDirectoryLockHandle() {
     48  // If mClientDirectoryLock is null, this handle is in an inert state — either
     49  // it was default-constructed or moved.
     50  //
     51  // This check is safe here because destruction implies no other thread is
     52  // using the handle. Any use-after-destroy bugs would indicate a much more
     53  // serious issue (e.g., a dangling pointer), and should be caught by tools
     54  // like AddressSanitizer.
     55  if (mClientDirectoryLock) {
     56    AssertIsOnOwningThread();
     57 
     58    mClientDirectoryLock->MutableManagerRef().ClientDirectoryLockHandleDestroy(
     59        *this);
     60 
     61    DropDirectoryLock(mClientDirectoryLock);
     62  }
     63 
     64  MOZ_COUNT_DTOR(mozilla::dom::quota::ClientDirectoryLockHandle);
     65 }
     66 
     67 void ClientDirectoryLockHandle::AssertIsOnOwningThread() const {
     68  NS_ASSERT_OWNINGTHREAD(ClientDirectoryLockHandle);
     69 }
     70 
     71 ClientDirectoryLockHandle& ClientDirectoryLockHandle::operator=(
     72    ClientDirectoryLockHandle&& aOther) noexcept {
     73  AssertIsOnOwningThread();
     74  aOther.AssertIsOnOwningThread();
     75 
     76  if (this != &aOther) {
     77    mClientDirectoryLock = std::move(aOther.mClientDirectoryLock);
     78 
     79    // Explicitly null aOther.mClientDirectoryLock so that aOther appears inert
     80    // immediately after the move. While RefPtr nulls out its mRawPtr
     81    // internally, the store may be reordered in optimized builds, possibly
     82    // occurring only just before RefPtr’s own destructor runs. Without this,
     83    // the moved-from handle’s destructor may observe a stale non-null value.
     84    aOther.mClientDirectoryLock = nullptr;
     85 
     86    mRegistered = std::exchange(aOther.mRegistered, false);
     87  }
     88 
     89  return *this;
     90 }
     91 
     92 ClientDirectoryLockHandle::operator bool() const {
     93  AssertIsOnOwningThread();
     94 
     95  return !!mClientDirectoryLock;
     96 }
     97 
     98 ClientDirectoryLock* ClientDirectoryLockHandle::get() const {
     99  AssertIsOnOwningThread();
    100 
    101  return mClientDirectoryLock ? mClientDirectoryLock.get() : nullptr;
    102 }
    103 
    104 ClientDirectoryLock& ClientDirectoryLockHandle::operator*() const {
    105  AssertIsOnOwningThread();
    106 
    107  return *get();
    108 }
    109 
    110 ClientDirectoryLock* ClientDirectoryLockHandle::operator->() const {
    111  AssertIsOnOwningThread();
    112 
    113  return get();
    114 }
    115 
    116 bool ClientDirectoryLockHandle::IsRegistered() const {
    117  AssertIsOnOwningThread();
    118 
    119  return mRegistered;
    120 }
    121 
    122 void ClientDirectoryLockHandle::SetRegistered(bool aRegistered) {
    123  AssertIsOnOwningThread();
    124 
    125  mRegistered = aRegistered;
    126 }
    127 
    128 #ifdef MOZ_DIAGNOSTIC_ASSERT_ENABLED
    129 
    130 bool ClientDirectoryLockHandle::IsInert() const {
    131  return !mClientDirectoryLock;
    132 }
    133 
    134 #endif
    135 
    136 }  // namespace mozilla::dom::quota