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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 <utility>
- #include "base/files/file_path.h"
- #include "base/logging.h"
- #include "base/notreached.h"
- #include "base/numerics/safe_math.h"
- #include "base/system/sys_info.h"
- #include "build/build_config.h"
- namespace base {
- const MemoryMappedFile::Region MemoryMappedFile::Region::kWholeFile = {0, 0};
- bool MemoryMappedFile::Region::operator==(
- const MemoryMappedFile::Region& other) const {
- return other.offset == offset && other.size == size;
- }
- bool MemoryMappedFile::Region::operator!=(
- const MemoryMappedFile::Region& other) const {
- return other.offset != offset || other.size != size;
- }
- MemoryMappedFile::~MemoryMappedFile() {
- CloseHandles();
- }
- #if !BUILDFLAG(IS_NACL)
- bool MemoryMappedFile::Initialize(const FilePath& file_name, Access access) {
- if (IsValid())
- return false;
- uint32_t flags = 0;
- switch (access) {
- case READ_ONLY:
- flags = File::FLAG_OPEN | File::FLAG_READ;
- break;
- case READ_WRITE:
- flags = File::FLAG_OPEN | File::FLAG_READ | File::FLAG_WRITE;
- break;
- case READ_WRITE_EXTEND:
- // Can't open with "extend" because no maximum size is known.
- NOTREACHED();
- break;
- #if BUILDFLAG(IS_WIN)
- case READ_CODE_IMAGE:
- flags |= File::FLAG_OPEN | File::FLAG_READ |
- File::FLAG_WIN_EXCLUSIVE_WRITE | File::FLAG_WIN_EXECUTE;
- break;
- #endif
- }
- file_.Initialize(file_name, flags);
- if (!file_.IsValid()) {
- DLOG(ERROR) << "Couldn't open " << file_name.AsUTF8Unsafe();
- return false;
- }
- if (!MapFileRegionToMemory(Region::kWholeFile, access)) {
- CloseHandles();
- return false;
- }
- return true;
- }
- bool MemoryMappedFile::Initialize(File file, Access access) {
- DCHECK_NE(READ_WRITE_EXTEND, access);
- return Initialize(std::move(file), Region::kWholeFile, access);
- }
- bool MemoryMappedFile::Initialize(File file,
- const Region& region,
- Access access) {
- switch (access) {
- case READ_WRITE_EXTEND:
- DCHECK(Region::kWholeFile != region);
- {
- CheckedNumeric<int64_t> region_end(region.offset);
- region_end += region.size;
- if (!region_end.IsValid()) {
- DLOG(ERROR) << "Region bounds exceed maximum for base::File.";
- return false;
- }
- }
- [[fallthrough]];
- case READ_ONLY:
- case READ_WRITE:
- // Ensure that the region values are valid.
- if (region.offset < 0) {
- DLOG(ERROR) << "Region bounds are not valid.";
- return false;
- }
- break;
- #if BUILDFLAG(IS_WIN)
- case READ_CODE_IMAGE:
- // Can't open with "READ_CODE_IMAGE", not supported outside Windows
- // or with a |region|.
- NOTREACHED();
- break;
- #endif
- }
- if (IsValid())
- return false;
- if (region != Region::kWholeFile)
- DCHECK_GE(region.offset, 0);
- file_ = std::move(file);
- if (!MapFileRegionToMemory(region, access)) {
- CloseHandles();
- return false;
- }
- return true;
- }
- bool MemoryMappedFile::IsValid() const {
- return data_ != nullptr;
- }
- // static
- void MemoryMappedFile::CalculateVMAlignedBoundaries(int64_t start,
- size_t size,
- int64_t* aligned_start,
- size_t* aligned_size,
- int32_t* offset) {
- // Sadly, on Windows, the mmap alignment is not just equal to the page size.
- uint64_t mask = SysInfo::VMAllocationGranularity() - 1;
- CHECK(IsValueInRangeForNumericType<int32_t>(mask));
- *offset = static_cast<int32_t>(static_cast<uint64_t>(start) & mask);
- *aligned_start = static_cast<int64_t>(static_cast<uint64_t>(start) & ~mask);
- // The DCHECK above means bit 31 is not set in `mask`, which in turn means
- // *offset is positive. Therefore casting it to a size_t is safe.
- *aligned_size =
- (size + static_cast<size_t>(*offset) + static_cast<size_t>(mask)) & ~mask;
- }
- #endif // !BUILDFLAG(IS_NACL)
- } // namespace base
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