Added SharedMemory::MapFrom.

base/shared_memory_win.cc

 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "base/shared_memory.h"
 
 #include "base/logging.h"
+#include "base/sys_info.h"
 #include "base/utf_string_conversions.h"
 
 namespace base {
 
 SharedMemory::SharedMemory()
     : mapped_file_(NULL),
       memory_(NULL),
       read_only_(false),
       created_size_(0),
       lock_(NULL) {
@@ skipping 109 matching lines @@
   mapped_file_ = OpenFileMapping(
       read_only_ ? FILE_MAP_READ : FILE_MAP_ALL_ACCESS, false,
       name_.empty() ? NULL : name_.c_str());
   if (mapped_file_ != NULL) {
     // Note: size_ is not set in this case.
     return true;
   }
   return false;
 }
 
-bool SharedMemory::Map(size_t bytes) {
+bool SharedMemory::MapFrom(off_t offset, size_t bytes) {
   if (mapped_file_ == NULL)
     return false;
 
   if (bytes > static_cast<size_t>(std::numeric_limits<int>::max()))
     return false;
 
+  DCHECK_EQ(0U, offset & (SysInfo::VMAllocationGranularity() - 1));

[Mark Mentovai, 2013/01/15 21:51:42]

Same.

[Vitaly Buka (NO REVIEWS), 2013/01/15 22:13:05]

So do you advise to remove DCHECK?

   memory_ = MapViewOfFile(mapped_file_,
-      read_only_ ? FILE_MAP_READ : FILE_MAP_ALL_ACCESS, 0, 0, bytes);
+                          read_only_ ? FILE_MAP_READ : FILE_MAP_ALL_ACCESS,
+                          static_cast<uint64>(offset) >> 32,
+                          static_cast<DWORD>(offset),
+                          bytes);
+  int e = GetLastError();

[Mark Mentovai, 2013/01/15 21:51:42]

Unused.

[Vitaly Buka (NO REVIEWS), 2013/01/15 22:13:05]

Done.

   if (memory_ != NULL) {
     DCHECK_EQ(0U, reinterpret_cast<uintptr_t>(memory_) &
         (SharedMemory::MAP_MINIMUM_ALIGNMENT - 1));
     return true;
   }
   return false;
 }
 
 bool SharedMemory::Unmap() {
   if (memory_ == NULL)
@@ skipping 69 matching lines @@
 void SharedMemory::Unlock() {
   DCHECK(lock_ != NULL);
   ReleaseMutex(lock_);
 }
 
 SharedMemoryHandle SharedMemory::handle() const {
   return mapped_file_;
 }
 
 }  // namespace base