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      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 #include <wincrypt.h>
     10 
     11 #include <algorithm>
     12 
     13 #include "base/logging.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_
    122