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Diffstat (limited to 'security/sandbox/chromium/base/sequence_checker.h')
| -rw-r--r-- | security/sandbox/chromium/base/sequence_checker.h | 143 |
1 files changed, 143 insertions, 0 deletions
diff --git a/security/sandbox/chromium/base/sequence_checker.h b/security/sandbox/chromium/base/sequence_checker.h new file mode 100644 index 0000000000..60ffd75a4f --- /dev/null +++ b/security/sandbox/chromium/base/sequence_checker.h @@ -0,0 +1,143 @@ +// Copyright (c) 2012 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. + +#ifndef BASE_SEQUENCE_CHECKER_H_ +#define BASE_SEQUENCE_CHECKER_H_ + +#include "base/compiler_specific.h" +#include "base/logging.h" +#include "base/sequence_checker_impl.h" +#include "base/strings/string_piece.h" +#include "build/build_config.h" + +// SequenceChecker is a helper class used to help verify that some methods of a +// class are called sequentially (for thread-safety). It supports thread safety +// annotations (see base/thread_annotations.h). +// +// Use the macros below instead of the SequenceChecker directly so that the +// unused member doesn't result in an extra byte (four when padded) per +// instance in production. +// +// This class is much prefered to ThreadChecker for thread-safety checks. +// ThreadChecker should only be used for classes that are truly thread-affine +// (use thread-local-storage or a third-party API that does). +// +// Usage: +// class MyClass { +// public: +// MyClass() { +// // It's sometimes useful to detach on construction for objects that are +// // constructed in one place and forever after used from another +// // sequence. +// DETACH_FROM_SEQUENCE(my_sequence_checker_); +// } +// +// ~MyClass() { +// // SequenceChecker doesn't automatically check it's destroyed on origin +// // sequence for the same reason it's sometimes detached in the +// // constructor. It's okay to destroy off sequence if the owner +// // otherwise knows usage on the associated sequence is done. If you're +// // not detaching in the constructor, you probably want to explicitly +// // check in the destructor. +// DCHECK_CALLED_ON_VALID_SEQUENCE(my_sequence_checker_); +// } +// void MyMethod() { +// DCHECK_CALLED_ON_VALID_SEQUENCE(my_sequence_checker_); +// ... (do stuff) ... +// MyOtherMethod(); +// } +// +// void MyOtherMethod() +// VALID_CONTEXT_REQUIRED(my_sequence_checker_) { +// foo_ = 42; +// } +// +// private: +// // GUARDED_BY_CONTEXT() enforces that this member is only +// // accessed from a scope that invokes DCHECK_CALLED_ON_VALID_SEQUENCE() +// // or from a function annotated with VALID_CONTEXT_REQUIRED(). A +// // DCHECK build will not compile if the member is accessed and these +// // conditions are not met. +// int foo_ GUARDED_BY_CONTEXT(my_sequence_checker_); +// +// SEQUENCE_CHECKER(my_sequence_checker_); +// } + +#define SEQUENCE_CHECKER_INTERNAL_CONCAT2(a, b) a##b +#define SEQUENCE_CHECKER_INTERNAL_CONCAT(a, b) \ + SEQUENCE_CHECKER_INTERNAL_CONCAT2(a, b) +#define SEQUENCE_CHECKER_INTERNAL_UID(prefix) \ + SEQUENCE_CHECKER_INTERNAL_CONCAT(prefix, __LINE__) + +#if DCHECK_IS_ON() +#define SEQUENCE_CHECKER(name) base::SequenceChecker name +#define DCHECK_CALLED_ON_VALID_SEQUENCE(name, ...) \ + base::ScopedValidateSequenceChecker SEQUENCE_CHECKER_INTERNAL_UID( \ + scoped_validate_sequence_checker_)(name, ##__VA_ARGS__); +#define DETACH_FROM_SEQUENCE(name) (name).DetachFromSequence() +#else // DCHECK_IS_ON() +#if __OBJC__ && defined(OS_IOS) && !HAS_FEATURE(objc_cxx_static_assert) +// TODO(thakis): Remove this branch once Xcode's clang has clang r356148. +#define SEQUENCE_CHECKER(name) +#else +#define SEQUENCE_CHECKER(name) static_assert(true, "") +#endif +#define DCHECK_CALLED_ON_VALID_SEQUENCE(name, ...) EAT_STREAM_PARAMETERS +#define DETACH_FROM_SEQUENCE(name) +#endif // DCHECK_IS_ON() + +namespace base { + +// Do nothing implementation, for use in release mode. +// +// Note: You should almost always use the SequenceChecker class (through the +// above macros) to get the right version for your build configuration. +// Note: This is only a check, not a "lock". It is marked "LOCKABLE" only in +// order to support thread_annotations.h. +class LOCKABLE SequenceCheckerDoNothing { + public: + SequenceCheckerDoNothing() = default; + + // Moving between matching sequences is allowed to help classes with + // SequenceCheckers that want a default move-construct/assign. + SequenceCheckerDoNothing(SequenceCheckerDoNothing&& other) = default; + SequenceCheckerDoNothing& operator=(SequenceCheckerDoNothing&& other) = + default; + + bool CalledOnValidSequence() const WARN_UNUSED_RESULT { return true; } + void DetachFromSequence() {} + + private: + DISALLOW_COPY_AND_ASSIGN(SequenceCheckerDoNothing); +}; + +#if DCHECK_IS_ON() +class SequenceChecker : public SequenceCheckerImpl { +}; +#else +class SequenceChecker : public SequenceCheckerDoNothing { +}; +#endif // DCHECK_IS_ON() + +class SCOPED_LOCKABLE ScopedValidateSequenceChecker { + public: + explicit ScopedValidateSequenceChecker(const SequenceChecker& checker) + EXCLUSIVE_LOCK_FUNCTION(checker) { + DCHECK(checker.CalledOnValidSequence()); + } + + explicit ScopedValidateSequenceChecker(const SequenceChecker& checker, + const StringPiece& msg) + EXCLUSIVE_LOCK_FUNCTION(checker) { + DCHECK(checker.CalledOnValidSequence()) << msg; + } + + ~ScopedValidateSequenceChecker() UNLOCK_FUNCTION() {} + + private: +}; + +} // namespace base + +#endif // BASE_SEQUENCE_CHECKER_H_ |