crypto/scoped_capi_types.h

   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 #ifndef CRYPTO_SCOPED_CAPI_TYPES_H_
   6 #define CRYPTO_SCOPED_CAPI_TYPES_H_
   7
   8 #include <windows.h>
   9
  10 #include <algorithm>
  11
  12 #include "base/logging.h"
  13 #include "crypto/wincrypt_shim.h"
  14
  15 namespace crypto {
  16
  17 // Simple destructor for the Free family of CryptoAPI functions, such as
  18 // CryptDestroyHash, which take only a single argument to release.
  19 template <typename CAPIHandle, BOOL (WINAPI *Destroyer)(CAPIHandle)>
  20 struct CAPIDestroyer {
  21   void operator()(CAPIHandle handle) const {
  22     if (handle) {
  23       BOOL ok = Destroyer(handle);
  24       DCHECK(ok);
  25     }
  26   }
  27 };
  28
  29 // Destructor for the Close/Release family of CryptoAPI functions, which take
  30 // a second DWORD parameter indicating flags to use when closing or releasing.
  31 // This includes functions like CertCloseStore or CryptReleaseContext.
  32 template <typename CAPIHandle, BOOL (WINAPI *Destroyer)(CAPIHandle, DWORD),
  33           DWORD flags>
  34 struct CAPIDestroyerWithFlags {
  35   void operator()(CAPIHandle handle) const {
  36     if (handle) {
  37       BOOL ok = Destroyer(handle, flags);
  38       DCHECK(ok);
  39     }
  40   }
  41 };
  42
  43 // scoped_ptr-like class for the CryptoAPI cryptography and certificate
  44 // handles. Because these handles are defined as integer types, and not
  45 // pointers, the existing scoped classes, such as scoped_ptr, are insufficient.
  46 // The semantics are the same as scoped_ptr.
  47 template <class CAPIHandle, typename FreeProc>
  48 class ScopedCAPIHandle {
  49  public:
  50   explicit ScopedCAPIHandle(CAPIHandle handle = NULL) : handle_(handle) {}
  51
  52   ~ScopedCAPIHandle() {
  53     reset();
  54   }
  55
  56   void reset(CAPIHandle handle = NULL) {
  57     if (handle_ != handle) {
  58       FreeProc free_proc;
  59       free_proc(handle_);
  60       handle_ = handle;
  61     }
  62   }
  63
  64   operator CAPIHandle() const { return handle_; }
  65   CAPIHandle get() const { return handle_; }
  66
  67   CAPIHandle* receive() {
  68     CHECK(handle_ == NULL);
  69     return &handle_;
  70   }
  71
  72   bool operator==(CAPIHandle handle) const {
  73     return handle_ == handle;
  74   }
  75
  76   bool operator!=(CAPIHandle handle) const {
  77     return handle_ != handle;
  78   }
  79
  80   void swap(ScopedCAPIHandle& b) {
  81     CAPIHandle tmp = b.handle_;
  82     b.handle_ = handle_;
  83     handle_ = tmp;
  84   }
  85
  86   CAPIHandle release() {
  87     CAPIHandle tmp = handle_;
  88     handle_ = NULL;
  89     return tmp;
  90   }
  91
  92  private:
  93   CAPIHandle handle_;
  94
  95   DISALLOW_COPY_AND_ASSIGN(ScopedCAPIHandle);
  96 };
  97
  98 template<class CH, typename FP> inline
  99 bool operator==(CH h, const ScopedCAPIHandle<CH, FP>& b) {
 100   return h == b.get();
 101 }
 102
 103 template<class CH, typename FP> inline
 104 bool operator!=(CH h, const ScopedCAPIHandle<CH, FP>& b) {
 105   return h != b.get();
 106 }
 107
 108 typedef ScopedCAPIHandle<
 109     HCRYPTPROV,
 110     CAPIDestroyerWithFlags<HCRYPTPROV,
 111                            CryptReleaseContext, 0> > ScopedHCRYPTPROV;
 112
 113 typedef ScopedCAPIHandle<
 114     HCRYPTKEY, CAPIDestroyer<HCRYPTKEY, CryptDestroyKey> > ScopedHCRYPTKEY;
 115
 116 typedef ScopedCAPIHandle<
 117     HCRYPTHASH, CAPIDestroyer<HCRYPTHASH, CryptDestroyHash> > ScopedHCRYPTHASH;
 118
 119 }  // namespace crypto
 120
 121 #endif  // CRYPTO_SCOPED_CAPI_TYPES_H_