base/memory/shared_memory_win.cc

   1 // Copyright (c) 2011 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 <aclapi.h>
   8
   9 #include "base/logging.h"
  10 #include "base/memory/scoped_ptr.h"
  11 #include "base/rand_util.h"
  12 #include "base/strings/stringprintf.h"
  13 #include "base/strings/utf_string_conversions.h"
  14
  15 namespace {
  16
  17 // Returns the length of the memory section starting at the supplied address.
  18 size_t GetMemorySectionSize(void* address) {
  19   MEMORY_BASIC_INFORMATION memory_info;
  20   if (!::VirtualQuery(address, &memory_info, sizeof(memory_info)))
  21     return 0;
  22   return memory_info.RegionSize - (static_cast<char*>(address) -
  23          static_cast<char*>(memory_info.AllocationBase));
  24 }
  25
  26 }  // namespace.
  27
  28 namespace base {
  29
  30 SharedMemory::SharedMemory()
  31     : mapped_file_(NULL),
  32       memory_(NULL),
  33       read_only_(false),
  34       mapped_size_(0),
  35       requested_size_(0) {
  36 }
  37
  38 SharedMemory::SharedMemory(const std::wstring& name)
  39     : mapped_file_(NULL),
  40       memory_(NULL),
  41       read_only_(false),
  42       requested_size_(0),
  43       mapped_size_(0),
  44       name_(name) {
  45 }
  46
  47 SharedMemory::SharedMemory(SharedMemoryHandle handle, bool read_only)
  48     : mapped_file_(handle),
  49       memory_(NULL),
  50       read_only_(read_only),
  51       requested_size_(0),
  52       mapped_size_(0) {
  53 }
  54
  55 SharedMemory::SharedMemory(SharedMemoryHandle handle,
  56                            bool read_only,
  57                            ProcessHandle process)
  58     : mapped_file_(NULL),
  59       memory_(NULL),
  60       read_only_(read_only),
  61       requested_size_(0),
  62       mapped_size_(0) {
  63   ::DuplicateHandle(process, handle,
  64                     GetCurrentProcess(), &mapped_file_,
  65                     read_only_ ? FILE_MAP_READ : FILE_MAP_READ |
  66                         FILE_MAP_WRITE,
  67                     FALSE, 0);
  68 }
  69
  70 SharedMemory::~SharedMemory() {
  71   Unmap();
  72   Close();
  73 }
  74
  75 // static
  76 bool SharedMemory::IsHandleValid(const SharedMemoryHandle& handle) {
  77   return handle != NULL;
  78 }
  79
  80 // static
  81 SharedMemoryHandle SharedMemory::NULLHandle() {
  82   return NULL;
  83 }
  84
  85 // static
  86 void SharedMemory::CloseHandle(const SharedMemoryHandle& handle) {
  87   DCHECK(handle != NULL);
  88   ::CloseHandle(handle);
  89 }
  90
  91 // static
  92 size_t SharedMemory::GetHandleLimit() {
  93   // Rounded down from value reported here:
  94   // http://blogs.technet.com/b/markrussinovich/archive/2009/09/29/3283844.aspx
  95   return static_cast<size_t>(1 << 23);
  96 }
  97
  98 // static
  99 SharedMemoryHandle SharedMemory::DuplicateHandle(
 100     const SharedMemoryHandle& handle) {
 101   ProcessHandle process = GetCurrentProcess();
 102   SharedMemoryHandle duped_handle;
 103   BOOL success = ::DuplicateHandle(process, handle, process, &duped_handle, 0,
 104                                    FALSE, DUPLICATE_SAME_ACCESS);
 105   if (success)
 106     return duped_handle;
 107   return NULLHandle();
 108 }
 109
 110 bool SharedMemory::CreateAndMapAnonymous(size_t size) {
 111   return CreateAnonymous(size) && Map(size);
 112 }
 113
 114 bool SharedMemory::Create(const SharedMemoryCreateOptions& options) {
 115   // TODO(bsy,sehr): crbug.com/210609 NaCl forces us to round up 64k here,
 116   // wasting 32k per mapping on average.
 117   static const size_t kSectionMask = 65536 - 1;
 118   DCHECK(!options.executable);
 119   DCHECK(!mapped_file_);
 120   if (options.size == 0)
 121     return false;
 122
 123   // Check maximum accounting for overflow.
 124   if (options.size >
 125       static_cast<size_t>(std::numeric_limits<int>::max()) - kSectionMask)
 126     return false;
 127
 128   size_t rounded_size = (options.size + kSectionMask) & ~kSectionMask;
 129   name_ = options.name_deprecated ?
 130       ASCIIToUTF16(*options.name_deprecated) : L"";
 131   SECURITY_ATTRIBUTES sa = { sizeof(sa), NULL, FALSE };
 132   SECURITY_DESCRIPTOR sd;
 133   ACL dacl;
 134
 135   if (options.share_read_only && name_.empty()) {
 136     // Add an empty DACL to enforce anonymous read-only sections.
 137     sa.lpSecurityDescriptor = &sd;
 138     if (!InitializeAcl(&dacl, sizeof(dacl), ACL_REVISION))
 139       return false;
 140     if (!InitializeSecurityDescriptor(&sd, SECURITY_DESCRIPTOR_REVISION))
 141       return false;
 142     if (!SetSecurityDescriptorDacl(&sd, TRUE, &dacl, FALSE))
 143       return false;
 144
 145     // Windows ignores DACLs on certain unnamed objects (like shared sections).
 146     // So, we generate a random name when we need to enforce read-only.
 147     uint64_t rand_values[4];
 148     RandBytes(&rand_values, sizeof(rand_values));
 149     name_ = StringPrintf(L"CrSharedMem_%016x%016x%016x%016x",
 150                          rand_values[0], rand_values[1],
 151                          rand_values[2], rand_values[3]);
 152   }
 153   mapped_file_ = CreateFileMapping(INVALID_HANDLE_VALUE, &sa,
 154       PAGE_READWRITE, 0, static_cast<DWORD>(rounded_size),
 155       name_.empty() ? nullptr : name_.c_str());
 156   if (!mapped_file_)
 157     return false;
 158
 159   requested_size_ = options.size;
 160
 161   // Check if the shared memory pre-exists.
 162   if (GetLastError() == ERROR_ALREADY_EXISTS) {
 163     // If the file already existed, set requested_size_ to 0 to show that
 164     // we don't know the size.
 165     requested_size_ = 0;
 166     if (!options.open_existing_deprecated) {
 167       Close();
 168       return false;
 169     }
 170   }
 171
 172   return true;
 173 }
 174
 175 bool SharedMemory::Delete(const std::string& name) {
 176   // intentionally empty -- there is nothing for us to do on Windows.
 177   return true;
 178 }
 179
 180 bool SharedMemory::Open(const std::string& name, bool read_only) {
 181   DCHECK(!mapped_file_);
 182
 183   name_ = ASCIIToUTF16(name);
 184   read_only_ = read_only;
 185   mapped_file_ = OpenFileMapping(
 186       read_only_ ? FILE_MAP_READ : FILE_MAP_READ | FILE_MAP_WRITE,
 187       false, name_.empty() ? NULL : name_.c_str());
 188   if (mapped_file_ != NULL) {
 189     // Note: size_ is not set in this case.
 190     return true;
 191   }
 192   return false;
 193 }
 194
 195 bool SharedMemory::MapAt(off_t offset, size_t bytes) {
 196   if (mapped_file_ == NULL)
 197     return false;
 198
 199   if (bytes > static_cast<size_t>(std::numeric_limits<int>::max()))
 200     return false;
 201
 202   if (memory_)
 203     return false;
 204
 205   memory_ = MapViewOfFile(mapped_file_,
 206                           read_only_ ? FILE_MAP_READ : FILE_MAP_READ |
 207                               FILE_MAP_WRITE,
 208                           static_cast<uint64>(offset) >> 32,
 209                           static_cast<DWORD>(offset),
 210                           bytes);
 211   if (memory_ != NULL) {
 212     DCHECK_EQ(0U, reinterpret_cast<uintptr_t>(memory_) &
 213         (SharedMemory::MAP_MINIMUM_ALIGNMENT - 1));
 214     mapped_size_ = GetMemorySectionSize(memory_);
 215     return true;
 216   }
 217   return false;
 218 }
 219
 220 bool SharedMemory::Unmap() {
 221   if (memory_ == NULL)
 222     return false;
 223
 224   UnmapViewOfFile(memory_);
 225   memory_ = NULL;
 226   return true;
 227 }
 228
 229 bool SharedMemory::ShareToProcessCommon(ProcessHandle process,
 230                                         SharedMemoryHandle* new_handle,
 231                                         bool close_self,
 232                                         ShareMode share_mode) {
 233   *new_handle = 0;
 234   DWORD access = FILE_MAP_READ;
 235   DWORD options = 0;
 236   HANDLE mapped_file = mapped_file_;
 237   HANDLE result;
 238   if (share_mode == SHARE_CURRENT_MODE && !read_only_)
 239     access |= FILE_MAP_WRITE;
 240   if (close_self) {
 241     // DUPLICATE_CLOSE_SOURCE causes DuplicateHandle to close mapped_file.
 242     options = DUPLICATE_CLOSE_SOURCE;
 243     mapped_file_ = NULL;
 244     Unmap();
 245   }
 246
 247   if (process == GetCurrentProcess() && close_self) {
 248     *new_handle = mapped_file;
 249     return true;
 250   }
 251
 252   if (!::DuplicateHandle(GetCurrentProcess(), mapped_file, process, &result,
 253                          access, FALSE, options)) {
 254     return false;
 255   }
 256   *new_handle = result;
 257   return true;
 258 }
 259
 260
 261 void SharedMemory::Close() {
 262   if (mapped_file_ != NULL) {
 263     CloseHandle(mapped_file_);
 264     mapped_file_ = NULL;
 265   }
 266 }
 267
 268 SharedMemoryHandle SharedMemory::handle() const {
 269   return mapped_file_;
 270 }
 271
 272 }  // namespace base