// 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 #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 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(mask)); *offset = static_cast(static_cast(start) & mask); *aligned_start = static_cast(static_cast(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(*offset) + static_cast(mask)) & ~mask; } #endif // !BUILDFLAG(IS_NACL) } // namespace base