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   Close();
  50 }
  51
  52 // static
  53 bool SharedMemory::IsHandleValid(const SharedMemoryHandle& handle) {
  54   return handle.fd >= 0;
  55 }
  56
  57 // static
  58 SharedMemoryHandle SharedMemory::NULLHandle() {
  59   return SharedMemoryHandle();
  60 }
  61
  62 // static
  63 void SharedMemory::CloseHandle(const SharedMemoryHandle& handle) {
  64   DCHECK_GE(handle.fd, 0);
  65   if (close(handle.fd) < 0)
  66     DPLOG(ERROR) << "close";
  67 }
  68
  69 bool SharedMemory::CreateAndMapAnonymous(size_t size) {
  70   // Untrusted code can't create descriptors or handles.
  71   return false;
  72 }
  73
  74 bool SharedMemory::Create(const SharedMemoryCreateOptions& options) {
  75   // Untrusted code can't create descriptors or handles.
  76   return false;
  77 }
  78
  79 bool SharedMemory::Delete(const std::string& name) {
  80   return false;
  81 }
  82
  83 bool SharedMemory::Open(const std::string& name, bool read_only) {
  84   return false;
  85 }
  86
  87 bool SharedMemory::MapAt(off_t offset, size_t bytes) {
  88   if (mapped_file_ == -1)
  89     return false;
  90
  91   if (bytes > static_cast<size_t>(std::numeric_limits<int>::max()))
  92     return false;
  93
  94   memory_ = mmap(NULL, bytes, PROT_READ | (read_only_ ? 0 : PROT_WRITE),
  95                  MAP_SHARED, mapped_file_, offset);
  96
  97   bool mmap_succeeded = memory_ != MAP_FAILED && memory_ != NULL;
  98   if (mmap_succeeded) {
  99     mapped_size_ = bytes;
 100     DCHECK_EQ(0U, reinterpret_cast<uintptr_t>(memory_) &
 101         (SharedMemory::MAP_MINIMUM_ALIGNMENT - 1));
 102   } else {
 103     memory_ = NULL;
 104   }
 105
 106   return mmap_succeeded;
 107 }
 108
 109 bool SharedMemory::Unmap() {
 110   if (memory_ == NULL)
 111     return false;
 112
 113   if (munmap(memory_, mapped_size_) < 0)
 114     DPLOG(ERROR) << "munmap";
 115   memory_ = NULL;
 116   mapped_size_ = 0;
 117   return true;
 118 }
 119
 120 SharedMemoryHandle SharedMemory::handle() const {
 121   return FileDescriptor(mapped_file_, false);
 122 }
 123
 124 void SharedMemory::Close() {
 125   Unmap();
 126   if (mapped_file_ > 0) {
 127     if (close(mapped_file_) < 0)
 128       DPLOG(ERROR) << "close";
 129     mapped_file_ = -1;
 130   }
 131 }
 132
 133 void SharedMemory::LockDeprecated() {
 134   NOTIMPLEMENTED();
 135 }
 136
 137 void SharedMemory::UnlockDeprecated() {
 138   NOTIMPLEMENTED();
 139 }
 140
 141 bool SharedMemory::ShareToProcessCommon(ProcessHandle process,
 142                                         SharedMemoryHandle *new_handle,
 143                                         bool close_self,
 144                                         ShareMode share_mode) {
 145   if (share_mode == SHARE_READONLY) {
 146     // Untrusted code can't create descriptors or handles, which is needed to
 147     // drop permissions.
 148     return false;
 149   }
 150   const int new_fd = dup(mapped_file_);
 151   if (new_fd < 0) {
 152     DPLOG(ERROR) << "dup() failed.";
 153     return false;
 154   }
 155
 156   new_handle->fd = new_fd;
 157   new_handle->auto_close = true;
 158
 159   if (close_self)
 160     Close();
 161   return true;
 162 }
 163
 164 }  // namespace base