1 files changed, 100 insertions, 0 deletions
diff --git a/lib/asan/asan_lock.h b/lib/asan/asan_lock.h
new file mode 100644
index 000000000000..030fae613c23
--- /dev/null
+++ b/lib/asan/asan_lock.h
@@ -0,0 +1,100 @@
+//===-- asan_lock.h ---------------------------------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file is a part of AddressSanitizer, an address sanity checker.
+//
+// A wrapper for a simple lock.
+//===----------------------------------------------------------------------===//
+#ifndef ASAN_LOCK_H
+#define ASAN_LOCK_H
+
+#include "asan_internal.h"
+
+// The locks in ASan are global objects and they are never destroyed to avoid
+// at-exit races (that is, a lock is being used by other threads while the main
+// thread is doing atexit destructors).
+
+#ifdef __APPLE__
+#include <pthread.h>
+
+#include <libkern/OSAtomic.h>
+namespace __asan {
+class AsanLock {
+ public:
+  explicit AsanLock(LinkerInitialized) :
+    mu_(OS_SPINLOCK_INIT),
+    owner_(0),
+    is_locked_(false) {}
+
+  void Lock() {
+    CHECK(owner_ != pthread_self());
+    OSSpinLockLock(&mu_);
+    is_locked_ = true;
+    owner_ = pthread_self();
+  }
+  void Unlock() {
+    owner_ = 0;
+    is_locked_ = false;
+    OSSpinLockUnlock(&mu_);
+  }
+
+  bool IsLocked() {
+    // This is not atomic, e.g. one thread may get different values if another
+    // one is about to release the lock.
+    return is_locked_;
+  }
+ private:
+  OSSpinLock mu_;
+  volatile pthread_t owner_;  // for debugging purposes
+  bool is_locked_;  // for silly malloc_introspection_t interface
+};
+}  // namespace __asan
+
+#else  // assume linux
+#include <pthread.h>
+namespace __asan {
+class AsanLock {
+ public:
+  explicit AsanLock(LinkerInitialized) {
+    // We assume that pthread_mutex_t initialized to all zeroes is a valid
+    // unlocked mutex. We can not use PTHREAD_MUTEX_INITIALIZER as it triggers
+    // a gcc warning:
+    // extended initializer lists only available with -std=c++0x or -std=gnu++0x
+  }
+  void Lock() {
+    pthread_mutex_lock(&mu_);
+    // pthread_spin_lock(&mu_);
+  }
+  void Unlock() {
+    pthread_mutex_unlock(&mu_);
+    // pthread_spin_unlock(&mu_);
+  }
+ private:
+  pthread_mutex_t mu_;
+  // pthread_spinlock_t mu_;
+};
+}  // namespace __asan
+#endif
+
+namespace __asan {
+class ScopedLock {
+ public:
+  explicit ScopedLock(AsanLock *mu) : mu_(mu) {
+    mu_->Lock();
+  }
+  ~ScopedLock() {
+    mu_->Unlock();
+  }
+ private:
+  AsanLock *mu_;
+};
+
+}  // namespace __asan
+
+#endif  // ASAN_LOCK_H