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      1 // Copyright 2014 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 "mojo/system/raw_shared_buffer.h"
      6 
      7 #include <windows.h>
      8 
      9 #include <limits>
     10 
     11 #include "base/logging.h"
     12 #include "base/sys_info.h"
     13 #include "mojo/embedder/platform_handle.h"
     14 #include "mojo/embedder/scoped_platform_handle.h"
     15 
     16 namespace mojo {
     17 namespace system {
     18 
     19 // RawSharedBuffer -------------------------------------------------------------
     20 
     21 bool RawSharedBuffer::Init() {
     22   DCHECK(!handle_.is_valid());
     23 
     24   // TODO(vtl): Currently, we only support mapping up to 2^32-1 bytes.
     25   if (static_cast<uint64_t>(num_bytes_) >
     26           static_cast<uint64_t>(std::numeric_limits<DWORD>::max())) {
     27     return false;
     28   }
     29 
     30   // IMPORTANT NOTE: Unnamed objects are NOT SECURABLE. Thus if we ever want to
     31   // share read-only to other processes, we'll have to name our file mapping
     32   // object.
     33   // TODO(vtl): Unlike |base::SharedMemory|, we don't round up the size (to a
     34   // multiple of 64 KB). This may cause problems with NaCl. Cross this bridge
     35   // when we get there. crbug.com/210609
     36   handle_.reset(embedder::PlatformHandle(CreateFileMapping(
     37       INVALID_HANDLE_VALUE, NULL, PAGE_READWRITE, 0,
     38       static_cast<DWORD>(num_bytes_), NULL)));
     39   if (!handle_.is_valid()) {
     40     PLOG(ERROR) << "CreateFileMapping";
     41     return false;
     42   }
     43 
     44   return true;
     45 }
     46 
     47 bool RawSharedBuffer::InitFromPlatformHandle(
     48     embedder::ScopedPlatformHandle platform_handle) {
     49   DCHECK(!handle_.is_valid());
     50 
     51   // TODO(vtl): Implement.
     52   NOTIMPLEMENTED();
     53   return false;
     54 }
     55 
     56 scoped_ptr<RawSharedBufferMapping> RawSharedBuffer::MapImpl(size_t offset,
     57                                                             size_t length) {
     58   size_t offset_rounding = offset % base::SysInfo::VMAllocationGranularity();
     59   size_t real_offset = offset - offset_rounding;
     60   size_t real_length = length + offset_rounding;
     61 
     62   // This should hold (since we checked |num_bytes| versus the maximum value of
     63   // |off_t| on creation, but it never hurts to be paranoid.
     64   DCHECK_LE(static_cast<uint64_t>(real_offset),
     65             static_cast<uint64_t>(std::numeric_limits<DWORD>::max()));
     66 
     67   void* real_base = MapViewOfFile(
     68       handle_.get().handle, FILE_MAP_READ | FILE_MAP_WRITE, 0,
     69       static_cast<DWORD>(real_offset), real_length);
     70   if (!real_base) {
     71     PLOG(ERROR) << "MapViewOfFile";
     72     return scoped_ptr<RawSharedBufferMapping>();
     73   }
     74 
     75   void* base = static_cast<char*>(real_base) + offset_rounding;
     76   return make_scoped_ptr(
     77       new RawSharedBufferMapping(base, length, real_base, real_length));
     78 }
     79 
     80 // RawSharedBufferMapping ------------------------------------------------------
     81 
     82 void RawSharedBufferMapping::Unmap() {
     83   BOOL result = UnmapViewOfFile(real_base_);
     84   PLOG_IF(ERROR, !result) << "UnmapViewOfFile";
     85 }
     86 
     87 }  // namespace system
     88 }  // namespace mojo
     89