ppapi/cpp/private/pass_file_handle.h

   1 // Copyright (c) 2013 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 PPAPI_CPP_PRIVATE_PASS_FILE_HANDLE_H_
   6 #define PPAPI_CPP_PRIVATE_PASS_FILE_HANDLE_H_
   7
   8 #include <string.h>
   9
  10 #include "ppapi/c/private/pp_file_handle.h"
  11 #include "ppapi/cpp/output_traits.h"
  12
  13 namespace pp {
  14
  15 // A wrapper class for PP_FileHandle to make sure a file handle is
  16 // closed. This object takes the ownership of the file handle when it
  17 // is constructed. This loses the ownership when this object is
  18 // assigned to another object, just like auto_ptr.
  19 class PassFileHandle {
  20  public:
  21   PassFileHandle();
  22   // This constructor takes the ownership of |handle|.
  23   explicit PassFileHandle(PP_FileHandle handle);
  24   // Moves the ownership of |handle| to this object.
  25   PassFileHandle(PassFileHandle& handle);
  26   ~PassFileHandle();
  27
  28   // Releases |handle_|. The caller must close the file handle returned.
  29   PP_FileHandle Release();
  30
  31  private:
  32   // PassFileHandleRef allows users to return PassFileHandle as a
  33   // value. This technique is also used by auto_ptr_ref.
  34   struct PassFileHandleRef {
  35     PP_FileHandle handle;
  36     explicit PassFileHandleRef(PP_FileHandle h)
  37         : handle(h) {
  38     }
  39   };
  40
  41  public:
  42   PassFileHandle(PassFileHandleRef ref)
  43       : handle_(ref.handle) {
  44   }
  45
  46   operator PassFileHandleRef() {
  47     return PassFileHandleRef(Release());
  48   }
  49
  50  private:
  51   void operator=(const PassFileHandle&);
  52
  53   void Close();
  54
  55   PP_FileHandle handle_;
  56 };
  57
  58 namespace internal {
  59
  60 template<>
  61 struct CallbackOutputTraits<PassFileHandle> {
  62   typedef PP_FileHandle* APIArgType;
  63   typedef PP_FileHandle StorageType;
  64
  65   static inline APIArgType StorageToAPIArg(StorageType& t) {
  66     return &t;
  67   }
  68
  69   static inline PassFileHandle StorageToPluginArg(StorageType& t) {
  70     return PassFileHandle(t);
  71   }
  72
  73   static inline void Initialize(StorageType* t) {
  74     memset(t, 0, sizeof(*t));
  75   }
  76 };
  77
  78 }  // namespace internal
  79 }  // namespace pp
  80
  81 #endif  // PPAPI_CPP_PRIVATE_PASS_FILE_HANDLE_H_