ipc/glue/SharedMemoryBasic_android.cpp

   1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
   2  * vim: sw=2 ts=8 et :
   3  */
   4 /* This Source Code Form is subject to the terms of the Mozilla Public
   5  * License, v. 2.0. If a copy of the MPL was not distributed with this
   6  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   7
   8 #include <android/log.h>
   9 #include <errno.h>
  10 #include <fcntl.h>
  11 #include <string.h>
  12 #include <sys/ioctl.h>
  13 #include <sys/mman.h>
  14 #include <sys/stat.h>
  15 #include <sys/types.h>
  16 #include <unistd.h>
  17
  18 #include "base/process_util.h"
  19
  20 #include "SharedMemoryBasic.h"
  21
  22 //
  23 // Temporarily go directly to the kernel interface until we can
  24 // interact better with libcutils.
  25 //
  26 #include <linux/ashmem.h>
  27
  28 namespace mozilla {
  29 namespace ipc {
  30
  31 static void
  32 LogError(const char* what)
  33 {
  34   __android_log_print(ANDROID_LOG_ERROR, "Gecko",
  35                       "%s: %s (%d)", what, strerror(errno), errno);
  36 }
  37
  38 SharedMemoryBasic::SharedMemoryBasic()
  39   : mShmFd(-1)
  40   , mMemory(nullptr)
  41 { }
  42
  43 SharedMemoryBasic::SharedMemoryBasic(const Handle& aHandle)
  44   : mShmFd(aHandle.fd)
  45   , mMemory(nullptr)
  46 { }
  47
  48 SharedMemoryBasic::~SharedMemoryBasic()
  49 {
  50   Unmap();
  51   Destroy();
  52 }
  53
  54 bool
  55 SharedMemoryBasic::Create(size_t aNbytes)
  56 {
  57   NS_ABORT_IF_FALSE(-1 == mShmFd, "Already Create()d");
  58
  59   // Carve a new instance off of /dev/ashmem
  60   int shmfd = open("/" ASHMEM_NAME_DEF, O_RDWR, 0600);
  61   if (-1 == shmfd) {
  62     LogError("ShmemAndroid::Create():open");
  63     return false;
  64   }
  65
  66   if (ioctl(shmfd, ASHMEM_SET_SIZE, aNbytes)) {
  67     LogError("ShmemAndroid::Unmap():ioctl(SET_SIZE)");
  68     close(shmfd);
  69     return false;
  70   }
  71
  72   mShmFd = shmfd;
  73   Created(aNbytes);
  74   return true;
  75 }
  76
  77 bool
  78 SharedMemoryBasic::Map(size_t nBytes)
  79 {
  80   NS_ABORT_IF_FALSE(nullptr == mMemory, "Already Map()d");
  81
  82   mMemory = mmap(nullptr, nBytes,
  83                  PROT_READ | PROT_WRITE,
  84                  MAP_SHARED,
  85                  mShmFd,
  86                  0);
  87   if (MAP_FAILED == mMemory) {
  88     LogError("ShmemAndroid::Map()");
  89     mMemory = nullptr;
  90     return false;
  91   }
  92
  93   Mapped(nBytes);
  94   return true;
  95 }
  96
  97 bool
  98 SharedMemoryBasic::ShareToProcess(base::ProcessHandle/*unused*/,
  99                                   Handle* aNewHandle)
 100 {
 101   NS_ABORT_IF_FALSE(mShmFd >= 0, "Should have been Create()d by now");
 102
 103   int shmfdDup = dup(mShmFd);
 104   if (-1 == shmfdDup) {
 105     LogError("ShmemAndroid::ShareToProcess()");
 106     return false;
 107   }
 108
 109   aNewHandle->fd = shmfdDup;
 110   aNewHandle->auto_close = true;
 111   return true;
 112 }
 113
 114 void
 115 SharedMemoryBasic::Unmap()
 116 {
 117   if (!mMemory) {
 118     return;
 119   }
 120
 121   if (munmap(mMemory, Size())) {
 122     LogError("ShmemAndroid::Unmap()");
 123   }
 124   mMemory = nullptr;
 125 }
 126
 127 void
 128 SharedMemoryBasic::Destroy()
 129 {
 130   if (mShmFd > 0) {
 131     close(mShmFd);
 132   }
 133 }
 134
 135 } // namespace ipc
 136 } // namespace mozilla