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110 lines
3.2 KiB
C++
110 lines
3.2 KiB
C++
// Copyright 2013 The Chromium Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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#include "base/files/memory_mapped_file.h"
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#include <stddef.h>
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#include <stdint.h>
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#include <limits>
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#include "base/files/file_path.h"
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#include "base/strings/string16.h"
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#include "base/threading/thread_restrictions.h"
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#include <windows.h>
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namespace base {
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MemoryMappedFile::MemoryMappedFile() : data_(NULL), length_(0) {
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}
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bool MemoryMappedFile::MapFileRegionToMemory(
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const MemoryMappedFile::Region& region,
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Access access) {
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AssertBlockingAllowed();
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if (!file_.IsValid())
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return false;
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int flags = 0;
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ULARGE_INTEGER size = {};
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switch (access) {
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case READ_ONLY:
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flags |= PAGE_READONLY;
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break;
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case READ_WRITE:
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flags |= PAGE_READWRITE;
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break;
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case READ_WRITE_EXTEND:
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flags |= PAGE_READWRITE;
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size.QuadPart = region.size;
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break;
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}
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file_mapping_.Set(::CreateFileMapping(file_.GetPlatformFile(), NULL, flags,
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size.HighPart, size.LowPart, NULL));
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if (!file_mapping_.IsValid())
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return false;
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LARGE_INTEGER map_start = {};
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SIZE_T map_size = 0;
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int32_t data_offset = 0;
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if (region == MemoryMappedFile::Region::kWholeFile) {
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DCHECK_NE(READ_WRITE_EXTEND, access);
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int64_t file_len = file_.GetLength();
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if (file_len <= 0 || !IsValueInRangeForNumericType<size_t>(file_len))
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return false;
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length_ = static_cast<size_t>(file_len);
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} else {
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// The region can be arbitrarily aligned. MapViewOfFile, instead, requires
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// that the start address is aligned to the VM granularity (which is
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// typically larger than a page size, for instance 32k).
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// Also, conversely to POSIX's mmap, the |map_size| doesn't have to be
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// aligned and must be less than or equal the mapped file size.
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// We map here the outer region [|aligned_start|, |aligned_start+size|]
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// which contains |region| and then add up the |data_offset| displacement.
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int64_t aligned_start = 0;
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size_t ignored = 0U;
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CalculateVMAlignedBoundaries(
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region.offset, region.size, &aligned_start, &ignored, &data_offset);
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int64_t full_map_size = region.size + data_offset;
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// Ensure that the casts below in the MapViewOfFile call are sane.
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if (aligned_start < 0 || full_map_size < 0 ||
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!IsValueInRangeForNumericType<SIZE_T>(
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static_cast<uint64_t>(full_map_size))) {
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DLOG(ERROR) << "Region bounds are not valid for MapViewOfFile";
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return false;
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}
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map_start.QuadPart = aligned_start;
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map_size = static_cast<SIZE_T>(full_map_size);
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length_ = region.size;
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}
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data_ = static_cast<uint8_t*>(
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::MapViewOfFile(file_mapping_.Get(),
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(flags & PAGE_READONLY) ? FILE_MAP_READ : FILE_MAP_WRITE,
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map_start.HighPart, map_start.LowPart, map_size));
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if (data_ == NULL)
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return false;
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data_ += data_offset;
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return true;
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}
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void MemoryMappedFile::CloseHandles() {
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if (data_)
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::UnmapViewOfFile(data_);
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if (file_mapping_.IsValid())
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file_mapping_.Close();
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if (file_.IsValid())
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file_.Close();
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data_ = NULL;
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length_ = 0;
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}
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} // namespace base
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