base/win/scoped_handle.cc

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "base/win/scoped_handle.h"
   6
   7 #include <unordered_map>
   8
   9 #include "base/debug/alias.h"
  10 #include "base/hash.h"
  11 #include "base/lazy_instance.h"
  12 #include "base/logging.h"
  13 #include "base/synchronization/lock_impl.h"
  14
  15 namespace {
  16
  17 struct HandleHash {
  18   size_t operator()(const HANDLE& handle) const {
  19     char buffer[sizeof(handle)];
  20     memcpy(buffer, &handle, sizeof(handle));
  21     return base::Hash(buffer, sizeof(buffer));
  22   }
  23 };
  24
  25 struct Info {
  26   const void* owner;
  27   const void* pc1;
  28   const void* pc2;
  29   DWORD thread_id;
  30 };
  31 typedef std::unordered_map<HANDLE, Info, HandleHash> HandleMap;
  32
  33 // g_lock protects g_handle_map and g_closing.
  34 typedef base::internal::LockImpl NativeLock;
  35 base::LazyInstance<NativeLock>::Leaky g_lock = LAZY_INSTANCE_INITIALIZER;
  36 base::LazyInstance<HandleMap>::Leaky g_handle_map = LAZY_INSTANCE_INITIALIZER;
  37 bool g_closing = false;
  38
  39 // g_verifier_enabled is not protected by g_lock because that would require
  40 // using the lock (hence, synchornizing multiple threads) even when the
  41 // verifier is not in use. Note that this variable is initialized to track all
  42 // handles, and it should only move to the disabled state, and never back to
  43 // enabled, because that would crash when seeing handles created while the
  44 // verifier was disabled. This also implies that it is OK if the value change is
  45 // not propagated immediately to all CPUs (as would happen with a lock).
  46 bool g_verifier_enabled = true;
  47
  48 bool CloseHandleWrapper(HANDLE handle) {
  49   if (!::CloseHandle(handle))
  50     CHECK(false);
  51   return true;
  52 }
  53
  54 // Simple automatic locking using a native critical section so it supports
  55 // recursive locking.
  56 class AutoNativeLock {
  57  public:
  58   explicit AutoNativeLock(NativeLock& lock) : lock_(lock) {
  59     lock_.Lock();
  60   }
  61
  62   ~AutoNativeLock() {
  63     lock_.Unlock();
  64   }
  65
  66  private:
  67   NativeLock& lock_;
  68   DISALLOW_COPY_AND_ASSIGN(AutoNativeLock);
  69 };
  70
  71 }  // namespace
  72
  73 namespace base {
  74 namespace win {
  75
  76 // Static.
  77 bool HandleTraits::CloseHandle(HANDLE handle) {
  78   if (!g_verifier_enabled)
  79     return CloseHandleWrapper(handle);
  80
  81   AutoNativeLock lock(g_lock.Get());
  82   g_closing = true;
  83   CloseHandleWrapper(handle);
  84   g_closing = false;
  85
  86   return true;
  87 }
  88
  89 // Static.
  90 void VerifierTraits::StartTracking(HANDLE handle, const void* owner,
  91                                    const void* pc1, const void* pc2) {
  92   if (!g_verifier_enabled)
  93     return;
  94
  95   // Grab the thread id before the lock.
  96   DWORD thread_id = GetCurrentThreadId();
  97
  98   AutoNativeLock lock(g_lock.Get());
  99
 100   Info handle_info = { owner, pc1, pc2, thread_id };
 101   std::pair<HANDLE, Info> item(handle, handle_info);
 102   std::pair<HandleMap::iterator, bool> result = g_handle_map.Get().insert(item);
 103   if (!result.second) {
 104     Info other = result.first->second;
 105     debug::Alias(&other);
 106     CHECK(false);
 107   }
 108 }
 109
 110 // Static.
 111 void VerifierTraits::StopTracking(HANDLE handle, const void* owner,
 112                                   const void* pc1, const void* pc2) {
 113   if (!g_verifier_enabled)
 114     return;
 115
 116   AutoNativeLock lock(g_lock.Get());
 117   HandleMap::iterator i = g_handle_map.Get().find(handle);
 118   if (i == g_handle_map.Get().end())
 119     CHECK(false);
 120
 121   Info other = i->second;
 122   if (other.owner != owner) {
 123     debug::Alias(&other);
 124     CHECK(false);
 125   }
 126
 127   g_handle_map.Get().erase(i);
 128 }
 129
 130 void DisableHandleVerifier() {
 131   g_verifier_enabled = false;
 132 }
 133
 134 void OnHandleBeingClosed(HANDLE handle) {
 135   AutoNativeLock lock(g_lock.Get());
 136   if (g_closing)
 137     return;
 138
 139   HandleMap::iterator i = g_handle_map.Get().find(handle);
 140   if (i == g_handle_map.Get().end())
 141     return;
 142
 143   Info other = i->second;
 144   debug::Alias(&other);
 145   CHECK(false);
 146 }
 147
 148 }  // namespace win
 149 }  // namespace base