1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/ipc/chromium/src/chrome/common/transport_dib.h Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,124 @@
1.4 +// Copyright (c) 2006-2009 The Chromium Authors. All rights reserved.
1.5 +// Use of this source code is governed by a BSD-style license that can be
1.6 +// found in the LICENSE file.
1.7 +
1.8 +#ifndef CHROME_COMMON_TRANSPORT_DIB_H_
1.9 +#define CHROME_COMMON_TRANSPORT_DIB_H_
1.10 +
1.11 +#include "base/basictypes.h"
1.12 +
1.13 +#if defined(OS_WIN) || defined(OS_MACOSX) || defined(OS_BSD)
1.14 +#include "base/shared_memory.h"
1.15 +#endif
1.16 +
1.17 +#if defined(OS_WIN)
1.18 +#include <windows.h>
1.19 +#elif defined(OS_LINUX)
1.20 +#include "chrome/common/x11_util.h"
1.21 +#endif
1.22 +
1.23 +// -----------------------------------------------------------------------------
1.24 +// A TransportDIB is a block of memory that is used to transport pixels
1.25 +// between processes: from the renderer process to the browser, and
1.26 +// between renderer and plugin processes.
1.27 +// -----------------------------------------------------------------------------
1.28 +class TransportDIB {
1.29 + public:
1.30 + ~TransportDIB();
1.31 +
1.32 + // Two typedefs are defined. A Handle is the type which can be sent over
1.33 + // the wire so that the remote side can map the transport DIB. The Id typedef
1.34 + // is sufficient to identify the transport DIB when you know that the remote
1.35 + // side already may have it mapped.
1.36 +#if defined(OS_WIN)
1.37 + typedef HANDLE Handle;
1.38 + // On Windows, the Id type includes a sequence number (epoch) to solve an ABA
1.39 + // issue:
1.40 + // 1) Process A creates a transport DIB with HANDLE=1 and sends to B.
1.41 + // 2) Process B maps the transport DIB and caches 1 -> DIB.
1.42 + // 3) Process A closes the transport DIB and creates a new one. The new DIB
1.43 + // is also assigned HANDLE=1.
1.44 + // 4) Process A sends the Handle to B, but B incorrectly believes that it
1.45 + // already has it cached.
1.46 + struct HandleAndSequenceNum {
1.47 + HandleAndSequenceNum()
1.48 + : handle(NULL),
1.49 + sequence_num(0) {
1.50 + }
1.51 +
1.52 + HandleAndSequenceNum(HANDLE h, uint32_t seq_num)
1.53 + : handle(h),
1.54 + sequence_num(seq_num) {
1.55 + }
1.56 +
1.57 + bool operator< (const HandleAndSequenceNum& other) const {
1.58 + // Use the lexicographic order on the tuple <handle, sequence_num>.
1.59 + if (other.handle != handle)
1.60 + return other.handle < handle;
1.61 + return other.sequence_num < sequence_num;
1.62 + }
1.63 +
1.64 + HANDLE handle;
1.65 + uint32_t sequence_num;
1.66 + };
1.67 + typedef HandleAndSequenceNum Id;
1.68 +#elif defined(OS_MACOSX) || defined(OS_BSD)
1.69 + typedef base::SharedMemoryHandle Handle;
1.70 + // On Mac, the inode number of the backing file is used as an id.
1.71 + typedef base::SharedMemoryId Id;
1.72 +#elif defined(OS_LINUX)
1.73 + typedef int Handle; // These two ints are SysV IPC shared memory keys
1.74 + typedef int Id;
1.75 +#endif
1.76 +
1.77 + // Create a new TransportDIB
1.78 + // size: the minimum size, in bytes
1.79 + // epoch: Windows only: a global counter. See comment above.
1.80 + // returns: NULL on failure
1.81 + static TransportDIB* Create(size_t size, uint32_t sequence_num);
1.82 +
1.83 + // Map the referenced transport DIB. Returns NULL on failure.
1.84 + static TransportDIB* Map(Handle transport_dib);
1.85 +
1.86 + // Return a pointer to the shared memory
1.87 + void* memory() const;
1.88 +
1.89 + // Return the maximum size of the shared memory. This is not the amount of
1.90 + // data which is valid, you have to know that via other means, this is simply
1.91 + // the maximum amount that /could/ be valid.
1.92 + size_t size() const { return size_; }
1.93 +
1.94 + // Return the identifier which can be used to refer to this shared memory
1.95 + // on the wire.
1.96 + Id id() const;
1.97 +
1.98 + // Return a handle to the underlying shared memory. This can be sent over the
1.99 + // wire to give this transport DIB to another process.
1.100 + Handle handle() const;
1.101 +
1.102 +#if defined(OS_LINUX)
1.103 + // Map the shared memory into the X server and return an id for the shared
1.104 + // segment.
1.105 + XID MapToX(Display* connection);
1.106 +#endif
1.107 +
1.108 + private:
1.109 + TransportDIB();
1.110 +#if defined(OS_WIN) || defined(OS_MACOSX) || defined(OS_BSD)
1.111 + explicit TransportDIB(base::SharedMemoryHandle dib);
1.112 + base::SharedMemory shared_memory_;
1.113 +#elif defined(OS_LINUX)
1.114 + int key_; // SysV shared memory id
1.115 + void* address_; // mapped address
1.116 + XID x_shm_; // X id for the shared segment
1.117 + Display* display_; // connection to the X server
1.118 +#endif
1.119 +#ifdef OS_WIN
1.120 + uint32_t sequence_num_;
1.121 +#endif
1.122 + size_t size_; // length, in bytes
1.123 +};
1.124 +
1.125 +class MessageLoop;
1.126 +
1.127 +#endif // CHROME_COMMON_TRANSPORT_DIB_H_
