111 lines
3.0 KiB
C++
111 lines
3.0 KiB
C++
// Copyright 2013 The Chromium Authors
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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 <fcntl.h>
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#include <stddef.h>
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#include <stdint.h>
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#include <sys/mman.h>
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#include <sys/stat.h>
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#include <unistd.h>
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#include "base/files/file_util.h"
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#include "base/logging.h"
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#include "base/numerics/safe_conversions.h"
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#include "base/threading/scoped_blocking_call.h"
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#include "build/build_config.h"
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namespace base {
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MemoryMappedFile::MemoryMappedFile() = default;
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#if !BUILDFLAG(IS_NACL)
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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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ScopedBlockingCall scoped_blocking_call(FROM_HERE, BlockingType::MAY_BLOCK);
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off_t map_start = 0;
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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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int64_t file_len = file_.GetLength();
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if (file_len < 0) {
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DPLOG(ERROR) << "fstat " << file_.GetPlatformFile();
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return false;
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}
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if (!IsValueInRangeForNumericType<size_t>(file_len))
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return false;
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map_size = static_cast<size_t>(file_len);
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length_ = map_size;
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} else {
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// The region can be arbitrarily aligned. mmap, instead, requires both the
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// start and size to be page-aligned. Hence, we map here the page-aligned
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// outer region [|aligned_start|, |aligned_start| + |size|] which contains
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// |region| and then add up the |data_offset| displacement.
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int64_t aligned_start = 0;
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size_t aligned_size = 0;
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CalculateVMAlignedBoundaries(region.offset,
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region.size,
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&aligned_start,
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&aligned_size,
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&data_offset);
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// Ensure that the casts in the mmap call below are sane.
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if (aligned_start < 0 ||
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!IsValueInRangeForNumericType<off_t>(aligned_start)) {
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DLOG(ERROR) << "Region bounds are not valid for mmap";
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return false;
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}
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map_start = static_cast<off_t>(aligned_start);
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map_size = aligned_size;
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length_ = region.size;
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}
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int flags = 0;
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switch (access) {
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case READ_ONLY:
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flags |= PROT_READ;
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break;
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case READ_WRITE:
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flags |= PROT_READ | PROT_WRITE;
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break;
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case READ_WRITE_EXTEND:
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flags |= PROT_READ | PROT_WRITE;
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if (!AllocateFileRegion(&file_, region.offset, region.size))
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return false;
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break;
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}
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data_ = static_cast<uint8_t*>(mmap(nullptr, map_size, flags, MAP_SHARED,
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file_.GetPlatformFile(), map_start));
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if (data_ == MAP_FAILED) {
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DPLOG(ERROR) << "mmap " << file_.GetPlatformFile();
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return false;
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}
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data_ += data_offset;
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return true;
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}
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#endif
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void MemoryMappedFile::CloseHandles() {
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ScopedBlockingCall scoped_blocking_call(FROM_HERE, BlockingType::MAY_BLOCK);
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if (data_ != nullptr) {
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munmap(data_.ExtractAsDangling(), length_);
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}
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file_.Close();
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length_ = 0;
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}
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} // namespace base
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