Add a locked version of CryptAcquireContext

The function is not thread-safe when called with certain flags. This will be
useful when we move keygen onto a worker thread.

BUG=none
TEST=KeygenHandlerTest.SmokeTest (existing)

Review URL: http://codereview.chromium.org/2828019

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@50661 0039d316-1c4b-4281-b951-d872f2087c98

2 files changed, 81 insertions, 0 deletions

diff --git a/base/crypto/capi_util.cc b/base/crypto/capi_util.cc
new file mode 100644
index 0000000..0499492
--- /dev/null
+++ b/base/crypto/capi_util.cc
@@ -0,0 +1,50 @@
+// Copyright (c) 2010 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/crypto/capi_util.h"
+
+#include "base/basictypes.h"
+#include "base/lock.h"
+#include "base/singleton.h"
+
+namespace {
+
+class CAPIUtilSingleton {
+ public:
+  static CAPIUtilSingleton* GetInstance() {
+    return Singleton<CAPIUtilSingleton>::get();
+  }
+
+  // Returns a lock to guard calls to CryptAcquireContext with
+  // CRYPT_DELETEKEYSET or CRYPT_NEWKEYSET.
+  Lock& acquire_context_lock() {
+    return acquire_context_lock_;
+  }
+
+ private:
+  friend class Singleton<CAPIUtilSingleton>;
+  friend struct DefaultSingletonTraits<CAPIUtilSingleton>;
+
+  CAPIUtilSingleton() {}
+
+  Lock acquire_context_lock_;
+
+  DISALLOW_COPY_AND_ASSIGN(CAPIUtilSingleton);
+};
+
+}  // namespace
+
+namespace base {
+
+BOOL CryptAcquireContextLocked(HCRYPTPROV* prov,
+                               const TCHAR* container,
+                               const TCHAR* provider,
+                               DWORD prov_type,
+                               DWORD flags)
+{
+  AutoLock lock(CAPIUtilSingleton::GetInstance()->acquire_context_lock());
+  return CryptAcquireContext(prov, container, provider, prov_type, flags);
+}
+
+}  // namespace base
diff --git a/base/crypto/capi_util.h b/base/crypto/capi_util.h
new file mode 100644
index 0000000..9f26403
--- /dev/null
+++ b/base/crypto/capi_util.h
@@ -0,0 +1,31 @@
+// Copyright (c) 2010 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_CRYPTO_CAPI_UTIL_H_
+#define BASE_CRYPTO_CAPI_UTIl_H_
+
+#include <windows.h>
+#include <wincrypt.h>
+
+namespace base {
+
+// CryptAcquireContext when passed CRYPT_NEWKEYSET or CRYPT_DELETEKEYSET in
+// flags is not thread-safe. For such calls, we create a global lock to
+// synchronize it.
+//
+// From "Threading Issues with Cryptographic Service Providers",
+// <http://msdn.microsoft.com/en-us/library/aa388149(v=VS.85).aspx>:
+//
+// "The CryptAcquireContext function is generally thread safe unless
+// CRYPT_NEWKEYSET or CRYPT_DELETEKEYSET is specified in the dwFlags
+// parameter."
+BOOL CryptAcquireContextLocked(HCRYPTPROV* prov,
+                               const TCHAR* container,
+                               const TCHAR* provider,
+                               DWORD prov_type,
+                               DWORD flags);
+
+}  // namespace base
+
+#endif  // BASE_CRYPTO_CAPI_UTIl_H_