mojo/embedder/simple_platform_shared_buffer.h

   1 // Copyright 2014 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 MOJO_SYSTEM_SIMPLE_PLATFORM_SHARED_BUFFER_H_
   6 #define MOJO_SYSTEM_SIMPLE_PLATFORM_SHARED_BUFFER_H_
   7
   8 #include <stddef.h>
   9
  10 #include "base/macros.h"
  11 #include "mojo/embedder/platform_shared_buffer.h"
  12 #include "mojo/system/system_impl_export.h"
  13
  14 namespace mojo {
  15 namespace embedder {
  16
  17 // A simple implementation of |PlatformSharedBuffer|.
  18 class MOJO_SYSTEM_IMPL_EXPORT SimplePlatformSharedBuffer
  19     : public PlatformSharedBuffer {
  20  public:
  21   // Creates a shared buffer of size |num_bytes| bytes (initially zero-filled).
  22   // |num_bytes| must be nonzero. Returns null on failure.
  23   static SimplePlatformSharedBuffer* Create(size_t num_bytes);
  24
  25   static SimplePlatformSharedBuffer* CreateFromPlatformHandle(
  26       size_t num_bytes,
  27       ScopedPlatformHandle platform_handle);
  28
  29   // |PlatformSharedBuffer| implementation:
  30   virtual size_t GetNumBytes() const OVERRIDE;
  31   virtual scoped_ptr<PlatformSharedBufferMapping> Map(size_t offset,
  32                                                       size_t length) OVERRIDE;
  33   virtual bool IsValidMap(size_t offset, size_t length) OVERRIDE;
  34   virtual scoped_ptr<PlatformSharedBufferMapping> MapNoCheck(
  35       size_t offset,
  36       size_t length) OVERRIDE;
  37   virtual ScopedPlatformHandle DuplicatePlatformHandle() OVERRIDE;
  38   virtual ScopedPlatformHandle PassPlatformHandle() OVERRIDE;
  39
  40  private:
  41   explicit SimplePlatformSharedBuffer(size_t num_bytes);
  42   virtual ~SimplePlatformSharedBuffer();
  43
  44   // Implemented in simple_platform_shared_buffer_{posix,win}.cc:
  45
  46   // This is called by |Create()| before this object is given to anyone.
  47   bool Init();
  48
  49   // This is like |Init()|, but for |CreateFromPlatformHandle()|. (Note: It
  50   // should verify that |platform_handle| is an appropriate handle for the
  51   // claimed |num_bytes_|.)
  52   bool InitFromPlatformHandle(ScopedPlatformHandle platform_handle);
  53
  54   // The platform-dependent part of |Map()|; doesn't check arguments.
  55   scoped_ptr<PlatformSharedBufferMapping> MapImpl(size_t offset, size_t length);
  56
  57   const size_t num_bytes_;
  58
  59   // This is set in |Init()|/|InitFromPlatformHandle()| and never modified
  60   // (except by |PassPlatformHandle()|; see the comments above its declaration),
  61   // hence does not need to be protected by a lock.
  62   ScopedPlatformHandle handle_;
  63
  64   DISALLOW_COPY_AND_ASSIGN(SimplePlatformSharedBuffer);
  65 };
  66
  67 // An implementation of |PlatformSharedBufferMapping|, produced by
  68 // |SimplePlatformSharedBuffer|.
  69 class MOJO_SYSTEM_IMPL_EXPORT SimplePlatformSharedBufferMapping
  70     : public PlatformSharedBufferMapping {
  71  public:
  72   virtual ~SimplePlatformSharedBufferMapping();
  73
  74   virtual void* GetBase() const OVERRIDE;
  75   virtual size_t GetLength() const OVERRIDE;
  76
  77  private:
  78   friend class SimplePlatformSharedBuffer;
  79
  80   SimplePlatformSharedBufferMapping(void* base,
  81                                     size_t length,
  82                                     void* real_base,
  83                                     size_t real_length)
  84       : base_(base),
  85         length_(length),
  86         real_base_(real_base),
  87         real_length_(real_length) {}
  88   void Unmap();
  89
  90   void* const base_;
  91   const size_t length_;
  92
  93   void* const real_base_;
  94   const size_t real_length_;
  95
  96   DISALLOW_COPY_AND_ASSIGN(SimplePlatformSharedBufferMapping);
  97 };
  98
  99 }  // namespace embedder
 100 }  // namespace mojo
 101
 102 #endif  // MOJO_SYSTEM_SIMPLE_PLATFORM_SHARED_BUFFER_H_