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// Copyright 2013 The Chromium Authors
// 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};
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_COPY:
flags = File::FLAG_OPEN | File::FLAG_READ;
#if BUILDFLAG(IS_FUCHSIA)
// Fuchsia's mmap() implementation does not allow us to create a
// copy-on-write mapping of a file opened as read-only.
flags |= File::FLAG_WRITE;
#endif
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();
#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:
case READ_WRITE_COPY:
// 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:
DCHECK(Region::kWholeFile == region);
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 !bytes_.empty();
}
// 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 CHECK 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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