1 // Copyright 2013 The Chromium Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style license that can be 3 // found in the LICENSE file. 4 5 #include "base/files/memory_mapped_file.h" 6 7 #include "base/files/file_path.h" 8 #include "base/logging.h" 9 #include "base/sys_info.h" 10 11 namespace base { 12 13 const MemoryMappedFile::Region MemoryMappedFile::Region::kWholeFile( 14 base::LINKER_INITIALIZED); 15 16 MemoryMappedFile::Region::Region(base::LinkerInitialized) : offset(0), size(0) { 17 } 18 19 MemoryMappedFile::Region::Region(int64 offset, int64 size) 20 : offset(offset), size(size) { 21 DCHECK_GE(offset, 0); 22 DCHECK_GT(size, 0); 23 } 24 25 bool MemoryMappedFile::Region::operator==( 26 const MemoryMappedFile::Region& other) const { 27 return other.offset == offset && other.size == size; 28 } 29 30 MemoryMappedFile::~MemoryMappedFile() { 31 CloseHandles(); 32 } 33 34 bool MemoryMappedFile::Initialize(const FilePath& file_name) { 35 if (IsValid()) 36 return false; 37 38 file_.Initialize(file_name, File::FLAG_OPEN | File::FLAG_READ); 39 40 if (!file_.IsValid()) { 41 DLOG(ERROR) << "Couldn't open " << file_name.AsUTF8Unsafe(); 42 return false; 43 } 44 45 if (!MapFileRegionToMemory(Region::kWholeFile)) { 46 CloseHandles(); 47 return false; 48 } 49 50 return true; 51 } 52 53 bool MemoryMappedFile::Initialize(File file) { 54 return Initialize(file.Pass(), Region::kWholeFile); 55 } 56 57 bool MemoryMappedFile::Initialize(File file, const Region& region) { 58 if (IsValid()) 59 return false; 60 61 file_ = file.Pass(); 62 63 if (!MapFileRegionToMemory(region)) { 64 CloseHandles(); 65 return false; 66 } 67 68 return true; 69 } 70 71 bool MemoryMappedFile::IsValid() const { 72 return data_ != NULL; 73 } 74 75 // static 76 void MemoryMappedFile::CalculateVMAlignedBoundaries(int64 start, 77 int64 size, 78 int64* aligned_start, 79 int64* aligned_size, 80 int32* offset) { 81 // Sadly, on Windows, the mmap alignment is not just equal to the page size. 82 const int64 mask = static_cast<int64>(SysInfo::VMAllocationGranularity()) - 1; 83 DCHECK_LT(mask, std::numeric_limits<int32>::max()); 84 *offset = start & mask; 85 *aligned_start = start & ~mask; 86 *aligned_size = (size + *offset + mask) & ~mask; 87 } 88 89 } // namespace base 90