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       mapped_size_(0),
  22       memory_(NULL),
  23       read_only_(false),
  24       requested_size_(0) {
  25 }
  26
  27 SharedMemory::SharedMemory(SharedMemoryHandle handle, bool read_only)
  28     : mapped_file_(handle.fd),
  29       mapped_size_(0),
  30       memory_(NULL),
  31       read_only_(read_only),
  32       requested_size_(0) {
  33 }
  34
  35 SharedMemory::SharedMemory(SharedMemoryHandle handle, bool read_only,
  36                            ProcessHandle process)
  37     : mapped_file_(handle.fd),
  38       mapped_size_(0),
  39       memory_(NULL),
  40       read_only_(read_only),
  41       requested_size_(0) {
  42   NOTREACHED();
  43 }
  44
  45 SharedMemory::~SharedMemory() {
  46   Unmap();
  47   Close();
  48 }
  49
  50 // static
  51 bool SharedMemory::IsHandleValid(const SharedMemoryHandle& handle) {
  52   return handle.fd >= 0;
  53 }
  54
  55 // static
  56 SharedMemoryHandle SharedMemory::NULLHandle() {
  57   return SharedMemoryHandle();
  58 }
  59
  60 // static
  61 void SharedMemory::CloseHandle(const SharedMemoryHandle& handle) {
  62   DCHECK_GE(handle.fd, 0);
  63   if (close(handle.fd) < 0)
  64     DPLOG(ERROR) << "close";
  65 }
  66
  67 // static
  68 SharedMemoryHandle SharedMemory::DuplicateHandle(
  69     const SharedMemoryHandle& handle) {
  70   int duped_handle = HANDLE_EINTR(dup(handle.fd));
  71   if (duped_handle < 0)
  72     return base::SharedMemory::NULLHandle();
  73   return base::FileDescriptor(duped_handle, true);
  74 }
  75
  76 bool SharedMemory::CreateAndMapAnonymous(size_t size) {
  77   // Untrusted code can't create descriptors or handles.
  78   return false;
  79 }
  80
  81 bool SharedMemory::Create(const SharedMemoryCreateOptions& options) {
  82   // Untrusted code can't create descriptors or handles.
  83   return false;
  84 }
  85
  86 bool SharedMemory::Delete(const std::string& name) {
  87   return false;
  88 }
  89
  90 bool SharedMemory::Open(const std::string& name, bool read_only) {
  91   return false;
  92 }
  93
  94 bool SharedMemory::MapAt(off_t offset, size_t bytes) {
  95   if (mapped_file_ == -1)
  96     return false;
  97
  98   if (bytes > static_cast<size_t>(std::numeric_limits<int>::max()))
  99     return false;
 100
 101   if (memory_)
 102     return false;
 103
 104   memory_ = mmap(NULL, bytes, PROT_READ | (read_only_ ? 0 : PROT_WRITE),
 105                  MAP_SHARED, mapped_file_, offset);
 106
 107   bool mmap_succeeded = memory_ != MAP_FAILED && memory_ != NULL;
 108   if (mmap_succeeded) {
 109     mapped_size_ = bytes;
 110     DCHECK_EQ(0U, reinterpret_cast<uintptr_t>(memory_) &
 111         (SharedMemory::MAP_MINIMUM_ALIGNMENT - 1));
 112   } else {
 113     memory_ = NULL;
 114   }
 115
 116   return mmap_succeeded;
 117 }
 118
 119 bool SharedMemory::Unmap() {
 120   if (memory_ == NULL)
 121     return false;
 122
 123   if (munmap(memory_, mapped_size_) < 0)
 124     DPLOG(ERROR) << "munmap";
 125   memory_ = NULL;
 126   mapped_size_ = 0;
 127   return true;
 128 }
 129
 130 SharedMemoryHandle SharedMemory::handle() const {
 131   return FileDescriptor(mapped_file_, false);
 132 }
 133
 134 void SharedMemory::Close() {
 135   if (mapped_file_ > 0) {
 136     if (close(mapped_file_) < 0)
 137       DPLOG(ERROR) << "close";
 138     mapped_file_ = -1;
 139   }
 140 }
 141
 142 void SharedMemory::LockDeprecated() {
 143   NOTIMPLEMENTED();
 144 }
 145
 146 void SharedMemory::UnlockDeprecated() {
 147   NOTIMPLEMENTED();
 148 }
 149
 150 bool SharedMemory::ShareToProcessCommon(ProcessHandle process,
 151                                         SharedMemoryHandle *new_handle,
 152                                         bool close_self,
 153                                         ShareMode share_mode) {
 154   if (share_mode == SHARE_READONLY) {
 155     // Untrusted code can't create descriptors or handles, which is needed to
 156     // drop permissions.
 157     return false;
 158   }
 159   const int new_fd = dup(mapped_file_);
 160   if (new_fd < 0) {
 161     DPLOG(ERROR) << "dup() failed.";
 162     return false;
 163   }
 164
 165   new_handle->fd = new_fd;
 166   new_handle->auto_close = true;
 167
 168   if (close_self) {
 169     Unmap();
 170     Close();
 171   }
 172   return true;
 173 }
 174
 175 }  // namespace base