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