Improve the ScopedHandle verifier.

base/win/scoped_handle.cc

Index: base/win/scoped_handle.cc
diff --git a/base/win/scoped_handle.cc b/base/win/scoped_handle.cc
index 7b38369d5aa2706a8f7469f994ed1c1d48801846..280302169209b637129fe85e6cbbb15fc9854e23 100644
--- a/base/win/scoped_handle.cc
+++ b/base/win/scoped_handle.cc
@@ -4,25 +4,69 @@
 
 #include "base/win/scoped_handle.h"
 
-#include <map>
+#include <unordered_map>
 
 #include "base/debug/alias.h"
+#include "base/hash.h"
 #include "base/lazy_instance.h"
-#include "base/synchronization/lock.h"
-#include "base/win/windows_version.h"
+#include "base/logging.h"
+#include "base/synchronization/lock_impl.h"
 
 namespace {
 
+struct HandleHash {
+  size_t operator()(const HANDLE& handle) const {
+    char buffer[sizeof(handle)];
+    memcpy(buffer, &handle, sizeof(handle));
+    return base::Hash(buffer, sizeof(buffer));
+  }
+};
+
 struct Info {
   const void* owner;
   const void* pc1;
   const void* pc2;
   DWORD thread_id;
 };
-typedef std::map<HANDLE, Info> HandleMap;
+typedef std::unordered_map<HANDLE, Info, HandleHash> HandleMap;
 
+// g_lock protects g_handle_map and g_closing.
+typedef base::internal::LockImpl NativeLock;
+base::LazyInstance<NativeLock>::Leaky g_lock = LAZY_INSTANCE_INITIALIZER;
 base::LazyInstance<HandleMap>::Leaky g_handle_map = LAZY_INSTANCE_INITIALIZER;
-base::LazyInstance<base::Lock>::Leaky g_lock = LAZY_INSTANCE_INITIALIZER;
+bool g_closing = false;
+
+// g_verifier_enabled is not protected by g_lock because that would require
+// using the lock (hence, synchornizing multiple threads) even when the
+// verifier is not in use. Note that this variable is initialized to track all
+// handles, and it should only move to the disabled state, and never back to
+// enabled, because that would crash when seeing handles created while the
+// verifier was disabled. This also implies that it is OK if the value change is
+// not propagated immediately to all CPUs (as would happen with a lock).
+bool g_verifier_enabled = true;
+
+bool CloseHandleWrapper(HANDLE handle) {
+  if (!::CloseHandle(handle))
+    CHECK(false);
+  return true;
+}
+
+// Simple automatic locking using a native critical section so it supports
+// recursive locking.
+class AutoNativeLock {
+ public:
+  explicit AutoNativeLock(NativeLock& lock) : lock_(lock) {
+    lock_.Lock();
+  }
+
+  ~AutoNativeLock() {
+    lock_.Unlock();
+  }
+
+ private:
+  NativeLock& lock_;
+  DISALLOW_COPY_AND_ASSIGN(AutoNativeLock);
+};
 
 }  // namespace
 
@@ -30,12 +74,28 @@ namespace base {
 namespace win {
 
 // Static.
+bool HandleTraits::CloseHandle(HANDLE handle) {
+  if (!g_verifier_enabled)
+    return CloseHandleWrapper(handle);
+
+  AutoNativeLock lock(g_lock.Get());
+  g_closing = true;
+  CloseHandleWrapper(handle);
+  g_closing = false;
+
+  return true;
+}
+
+// Static.
 void VerifierTraits::StartTracking(HANDLE handle, const void* owner,
                                    const void* pc1, const void* pc2) {
+  if (!g_verifier_enabled)
+    return;
+
   // Grab the thread id before the lock.
   DWORD thread_id = GetCurrentThreadId();
 
-  AutoLock lock(g_lock.Get());
+  AutoNativeLock lock(g_lock.Get());
 
   Info handle_info = { owner, pc1, pc2, thread_id };
   std::pair<HANDLE, Info> item(handle, handle_info);
@@ -50,7 +110,10 @@ void VerifierTraits::StartTracking(HANDLE handle, const void* owner,
 // Static.
 void VerifierTraits::StopTracking(HANDLE handle, const void* owner,
                                   const void* pc1, const void* pc2) {
-  AutoLock lock(g_lock.Get());
+  if (!g_verifier_enabled)
+    return;
+
+  AutoNativeLock lock(g_lock.Get());
   HandleMap::iterator i = g_handle_map.Get().find(handle);
   if (i == g_handle_map.Get().end())
     CHECK(false);
@@ -64,5 +127,23 @@ void VerifierTraits::StopTracking(HANDLE handle, const void* owner,
   g_handle_map.Get().erase(i);
 }
 
+void DisableHandleVerifier() {
+  g_verifier_enabled = false;
+}
+
+void OnHandleBeingClosed(HANDLE handle) {
+  AutoNativeLock lock(g_lock.Get());
+  if (g_closing)
+    return;
+
+  HandleMap::iterator i = g_handle_map.Get().find(handle);
+  if (i == g_handle_map.Get().end())
+    return;
+
+  Info other = i->second;
+  debug::Alias(&other);
+  CHECK(false);
+}
+
 }  // namespace win
 }  // namespace base