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// Copyright 2013 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/files/memory_mapped_file.h"
#include "base/files/file_path.h"
#include "base/strings/string16.h"
#include "base/threading/thread_restrictions.h"
namespace base {
MemoryMappedFile::MemoryMappedFile() : data_(NULL), length_(0), image_(false) {
}
bool MemoryMappedFile::InitializeAsImageSection(const FilePath& file_name) {
image_ = true;
return Initialize(file_name);
}
bool MemoryMappedFile::MapFileRegionToMemory(
const MemoryMappedFile::Region& region) {
ThreadRestrictions::AssertIOAllowed();
if (!file_.IsValid())
return false;
int flags = image_ ? SEC_IMAGE | PAGE_READONLY : PAGE_READONLY;
file_mapping_.Set(::CreateFileMapping(file_.GetPlatformFile(), NULL,
flags, 0, 0, NULL));
if (!file_mapping_.IsValid())
return false;
LARGE_INTEGER map_start = {0};
SIZE_T map_size = 0;
int32 data_offset = 0;
if (region == MemoryMappedFile::Region::kWholeFile) {
int64 file_len = file_.GetLength();
if (file_len <= 0 || file_len > kint32max)
return false;
length_ = static_cast<size_t>(file_len);
} else {
// The region can be arbitrarily aligned. MapViewOfFile, instead, requires
// that the start address is aligned to the VM granularity (which is
// typically larger than a page size, for instance 32k).
// Also, conversely to POSIX's mmap, the |map_size| doesn't have to be
// aligned and must be less than or equal the mapped file size.
// We map here the outer region [|aligned_start|, |aligned_start+size|]
// which contains |region| and then add up the |data_offset| displacement.
int64 aligned_start = 0;
int64 ignored = 0;
CalculateVMAlignedBoundaries(
region.offset, region.size, &aligned_start, &ignored, &data_offset);
int64 size = region.size + data_offset;
// Ensure that the casts below in the MapViewOfFile call are sane.
if (aligned_start < 0 || size < 0 ||
static_cast<uint64>(size) > std::numeric_limits<SIZE_T>::max()) {
DLOG(ERROR) << "Region bounds are not valid for MapViewOfFile";
return false;
}
map_start.QuadPart = aligned_start;
map_size = static_cast<SIZE_T>(size);
length_ = static_cast<size_t>(region.size);
}
data_ = static_cast<uint8*>(::MapViewOfFile(file_mapping_.Get(),
FILE_MAP_READ,
map_start.HighPart,
map_start.LowPart,
map_size));
if (data_ == NULL)
return false;
data_ += data_offset;
return true;
}
void MemoryMappedFile::CloseHandles() {
if (data_)
::UnmapViewOfFile(data_);
if (file_mapping_.IsValid())
file_mapping_.Close();
if (file_.IsValid())
file_.Close();
data_ = NULL;
length_ = 0;
}
} // namespace base
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