base/memory/shared_memory_nacl.cc

   1 // Copyright (c) 2012 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 #include "base/memory/shared_memory.h"
   6
   7 #include <errno.h>
   8 #include <fcntl.h>
   9 #include <sys/mman.h>
  10 #include <sys/stat.h>
  11 #include <unistd.h>
  12
  13 #include <limits>
  14
  15 #include "base/logging.h"
  16
  17 namespace base {
  18
  19 SharedMemory::SharedMemory()
  20     : mapped_file_(-1),
  21       inode_(0),
  22       mapped_size_(0),
  23       memory_(NULL),
  24       read_only_(false),
  25       requested_size_(0) {
  26 }
  27
  28 SharedMemory::SharedMemory(SharedMemoryHandle handle, bool read_only)
  29     : mapped_file_(handle.fd),
  30       inode_(0),
  31       mapped_size_(0),
  32       memory_(NULL),
  33       read_only_(read_only),
  34       requested_size_(0) {
  35 }
  36
  37 SharedMemory::SharedMemory(SharedMemoryHandle handle, bool read_only,
  38                            ProcessHandle process)
  39     : mapped_file_(handle.fd),
  40       inode_(0),
  41       mapped_size_(0),
  42       memory_(NULL),
  43       read_only_(read_only),
  44       requested_size_(0) {
  45   NOTREACHED();
  46 }
  47
  48 SharedMemory::~SharedMemory() {
  49   Unmap();
  50   Close();
  51 }
  52
  53 // static
  54 bool SharedMemory::IsHandleValid(const SharedMemoryHandle& handle) {
  55   return handle.fd >= 0;
  56 }
  57
  58 // static
  59 SharedMemoryHandle SharedMemory::NULLHandle() {
  60   return SharedMemoryHandle();
  61 }
  62
  63 // static
  64 void SharedMemory::CloseHandle(const SharedMemoryHandle& handle) {
  65   DCHECK_GE(handle.fd, 0);
  66   if (close(handle.fd) < 0)
  67     DPLOG(ERROR) << "close";
  68 }
  69
  70 bool SharedMemory::CreateAndMapAnonymous(size_t size) {
  71   // Untrusted code can't create descriptors or handles.
  72   return false;
  73 }
  74
  75 bool SharedMemory::Create(const SharedMemoryCreateOptions& options) {
  76   // Untrusted code can't create descriptors or handles.
  77   return false;
  78 }
  79
  80 bool SharedMemory::Delete(const std::string& name) {
  81   return false;
  82 }
  83
  84 bool SharedMemory::Open(const std::string& name, bool read_only) {
  85   return false;
  86 }
  87
  88 bool SharedMemory::MapAt(off_t offset, size_t bytes) {
  89   if (mapped_file_ == -1)
  90     return false;
  91
  92   if (bytes > static_cast<size_t>(std::numeric_limits<int>::max()))
  93     return false;
  94
  95   if (memory_)
  96     return false;
  97
  98   memory_ = mmap(NULL, bytes, PROT_READ | (read_only_ ? 0 : PROT_WRITE),
  99                  MAP_SHARED, mapped_file_, offset);
 100
 101   bool mmap_succeeded = memory_ != MAP_FAILED && memory_ != NULL;
 102   if (mmap_succeeded) {
 103     mapped_size_ = bytes;
 104     DCHECK_EQ(0U, reinterpret_cast<uintptr_t>(memory_) &
 105         (SharedMemory::MAP_MINIMUM_ALIGNMENT - 1));
 106   } else {
 107     memory_ = NULL;
 108   }
 109
 110   return mmap_succeeded;
 111 }
 112
 113 bool SharedMemory::Unmap() {
 114   if (memory_ == NULL)
 115     return false;
 116
 117   if (munmap(memory_, mapped_size_) < 0)
 118     DPLOG(ERROR) << "munmap";
 119   memory_ = NULL;
 120   mapped_size_ = 0;
 121   return true;
 122 }
 123
 124 SharedMemoryHandle SharedMemory::handle() const {
 125   return FileDescriptor(mapped_file_, false);
 126 }
 127
 128 void SharedMemory::Close() {
 129   if (mapped_file_ > 0) {
 130     if (close(mapped_file_) < 0)
 131       DPLOG(ERROR) << "close";
 132     mapped_file_ = -1;
 133   }
 134 }
 135
 136 void SharedMemory::LockDeprecated() {
 137   NOTIMPLEMENTED();
 138 }
 139
 140 void SharedMemory::UnlockDeprecated() {
 141   NOTIMPLEMENTED();
 142 }
 143
 144 bool SharedMemory::ShareToProcessCommon(ProcessHandle process,
 145                                         SharedMemoryHandle *new_handle,
 146                                         bool close_self,
 147                                         ShareMode share_mode) {
 148   if (share_mode == SHARE_READONLY) {
 149     // Untrusted code can't create descriptors or handles, which is needed to
 150     // drop permissions.
 151     return false;
 152   }
 153   const int new_fd = dup(mapped_file_);
 154   if (new_fd < 0) {
 155     DPLOG(ERROR) << "dup() failed.";
 156     return false;
 157   }
 158
 159   new_handle->fd = new_fd;
 160   new_handle->auto_close = true;
 161
 162   if (close_self) {
 163     Unmap();
 164     Close();
 165   }
 166   return true;
 167 }
 168
 169 }  // namespace base