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      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_
     82