Repo created

TMessagesProj/jni/voip/webrtc/base/synchronization/lock_impl_posix.cc

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+// Copyright (c) 2011 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "base/synchronization/lock_impl.h"
+
+#include <string>
+
+#include "base/debug/activity_tracker.h"
+#include "base/logging.h"
+#include "base/posix/safe_strerror.h"
+#include "base/strings/stringprintf.h"
+#include "base/synchronization/lock.h"
+#include "base/synchronization/synchronization_buildflags.h"
+#include "build/build_config.h"
+
+namespace base {
+namespace internal {
+
+namespace {
+
+#if DCHECK_IS_ON()
+const char* AdditionalHintForSystemErrorCode(int error_code) {
+  switch (error_code) {
+    case EINVAL:
+      return "Hint: This is often related to a use-after-free.";
+    default:
+      return "";
+  }
+}
+#endif  // DCHECK_IS_ON()
+
+std::string SystemErrorCodeToString(int error_code) {
+#if DCHECK_IS_ON()
+  return base::safe_strerror(error_code) + ". " +
+         AdditionalHintForSystemErrorCode(error_code);
+#else   // DCHECK_IS_ON()
+  return std::string();
+#endif  // DCHECK_IS_ON()
+}
+
+}  // namespace
+
+// Determines which platforms can consider using priority inheritance locks. Use
+// this define for platform code that may not compile if priority inheritance
+// locks aren't available. For this platform code,
+// PRIORITY_INHERITANCE_LOCKS_POSSIBLE() is a necessary but insufficient check.
+// Lock::PriorityInheritanceAvailable still must be checked as the code may
+// compile but the underlying platform still may not correctly support priority
+// inheritance locks.
+#if defined(OS_NACL) || defined(OS_ANDROID) || defined(OS_FUCHSIA)
+#define PRIORITY_INHERITANCE_LOCKS_POSSIBLE() 0
+#else
+#define PRIORITY_INHERITANCE_LOCKS_POSSIBLE() 1
+#endif
+
+LockImpl::LockImpl() {
+  pthread_mutexattr_t mta;
+  int rv = pthread_mutexattr_init(&mta);
+  DCHECK_EQ(rv, 0) << ". " << SystemErrorCodeToString(rv);
+#if PRIORITY_INHERITANCE_LOCKS_POSSIBLE()
+  if (PriorityInheritanceAvailable()) {
+    rv = pthread_mutexattr_setprotocol(&mta, PTHREAD_PRIO_INHERIT);
+    DCHECK_EQ(rv, 0) << ". " << SystemErrorCodeToString(rv);
+  }
+#endif
+#ifndef NDEBUG
+  // In debug, setup attributes for lock error checking.
+  rv = pthread_mutexattr_settype(&mta, PTHREAD_MUTEX_ERRORCHECK);
+  DCHECK_EQ(rv, 0) << ". " << SystemErrorCodeToString(rv);
+#endif
+  rv = pthread_mutex_init(&native_handle_, &mta);
+  DCHECK_EQ(rv, 0) << ". " << SystemErrorCodeToString(rv);
+  rv = pthread_mutexattr_destroy(&mta);
+  DCHECK_EQ(rv, 0) << ". " << SystemErrorCodeToString(rv);
+}
+
+LockImpl::~LockImpl() {
+  int rv = pthread_mutex_destroy(&native_handle_);
+  DCHECK_EQ(rv, 0) << ". " << SystemErrorCodeToString(rv);
+}
+
+bool LockImpl::Try() {
+  int rv = pthread_mutex_trylock(&native_handle_);
+  DCHECK(rv == 0 || rv == EBUSY) << ". " << SystemErrorCodeToString(rv);
+  return rv == 0;
+}
+
+void LockImpl::Lock() {
+  // The ScopedLockAcquireActivity below is relatively expensive and so its
+  // actions can become significant due to the very large number of locks
+  // that tend to be used throughout the build. To avoid this cost in the
+  // vast majority of the calls, simply "try" the lock first and only do the
+  // (tracked) blocking call if that fails. Since "try" itself is a system
+  // call, and thus also somewhat expensive, don't bother with it unless
+  // tracking is actually enabled.
+  if (base::debug::GlobalActivityTracker::IsEnabled())
+    if (Try())
+      return;
+
+  base::debug::ScopedLockAcquireActivity lock_activity(this);
+  int rv = pthread_mutex_lock(&native_handle_);
+  DCHECK_EQ(rv, 0) << ". " << SystemErrorCodeToString(rv);
+}
+
+// static
+bool LockImpl::PriorityInheritanceAvailable() {
+#if BUILDFLAG(ENABLE_MUTEX_PRIORITY_INHERITANCE)
+  return true;
+#elif PRIORITY_INHERITANCE_LOCKS_POSSIBLE() && defined(OS_MACOSX)
+  return true;
+#else
+  // Security concerns prevent the use of priority inheritance mutexes on Linux.
+  //   * CVE-2010-0622 - Linux < 2.6.33-rc7, wake_futex_pi possible DoS.
+  //     https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2010-0622
+  //   * CVE-2012-6647 - Linux < 3.5.1, futex_wait_requeue_pi possible DoS.
+  //     https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2012-6647
+  //   * CVE-2014-3153 - Linux <= 3.14.5, futex_requeue, privilege escalation.
+  //     https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2014-3153
+  //
+  // If the above were all addressed, we still need a runtime check to deal with
+  // the bug below.
+  //   * glibc Bug 14652: https://sourceware.org/bugzilla/show_bug.cgi?id=14652
+  //     Fixed in glibc 2.17.
+  //     Priority inheritance mutexes may deadlock with condition variables
+  //     during reacquisition of the mutex after the condition variable is
+  //     signalled.
+  return false;
+#endif
+}
+
+}  // namespace internal
+}  // namespace base