Compression.cpp revision 39dd5aafb0a92536a8872ac4a9c39a56442c8023 
1//===--- Compression.cpp - Compression implementation ---------------------===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9//
10//  This file implements compression functions.
11//
12//===----------------------------------------------------------------------===//
13
14#include "llvm/Support/Compression.h"
15#include "llvm/ADT/OwningPtr.h"
16#include "llvm/ADT/StringRef.h"
17#include "llvm/Config/config.h"
18#include "llvm/Support/Compiler.h"
19#include "llvm/Support/ErrorHandling.h"
20#include "llvm/Support/MemoryBuffer.h"
21#if LLVM_ENABLE_ZLIB == 1 && HAVE_ZLIB_H
22#include <zlib.h>
23#endif
24
25using namespace llvm;
26
27#if LLVM_ENABLE_ZLIB == 1 && HAVE_LIBZ
28static int encodeZlibCompressionLevel(zlib::CompressionLevel Level) {
29  switch (Level) {
30    case zlib::NoCompression: return 0;
31    case zlib::BestSpeedCompression: return 1;
32    case zlib::DefaultCompression: return Z_DEFAULT_COMPRESSION;
33    case zlib::BestSizeCompression: return 9;
34  }
35  llvm_unreachable("Invalid zlib::CompressionLevel!");
36}
37
38static zlib::Status encodeZlibReturnValue(int ReturnValue) {
39  switch (ReturnValue) {
40    case Z_OK: return zlib::StatusOK;
41    case Z_MEM_ERROR: return zlib::StatusOutOfMemory;
42    case Z_BUF_ERROR: return zlib::StatusBufferTooShort;
43    case Z_STREAM_ERROR: return zlib::StatusInvalidArg;
44    case Z_DATA_ERROR: return zlib::StatusInvalidData;
45    default: llvm_unreachable("unknown zlib return status!");
46  }
47}
48
49bool zlib::isAvailable() { return true; }
50zlib::Status zlib::compress(StringRef InputBuffer,
51                            OwningPtr<MemoryBuffer> &CompressedBuffer,
52                            CompressionLevel Level) {
53  unsigned long CompressedSize = ::compressBound(InputBuffer.size());
54  OwningArrayPtr<char> TmpBuffer(new char[CompressedSize]);
55  int CLevel = encodeZlibCompressionLevel(Level);
56  Status Res = encodeZlibReturnValue(::compress2(
57      (Bytef *)TmpBuffer.get(), &CompressedSize,
58      (const Bytef *)InputBuffer.data(), InputBuffer.size(), CLevel));
59  if (Res == StatusOK) {
60    CompressedBuffer.reset(MemoryBuffer::getMemBufferCopy(
61        StringRef(TmpBuffer.get(), CompressedSize)));
62    // Tell MSan that memory initialized by zlib is valid.
63    __msan_unpoison(CompressedBuffer.data(), CompressedBuffer.size());
64  }
65  return Res;
66}
67
68zlib::Status zlib::uncompress(StringRef InputBuffer,
69                              OwningPtr<MemoryBuffer> &UncompressedBuffer,
70                              size_t UncompressedSize) {
71  OwningArrayPtr<char> TmpBuffer(new char[UncompressedSize]);
72  Status Res = encodeZlibReturnValue(
73      ::uncompress((Bytef *)TmpBuffer.get(), (uLongf *)&UncompressedSize,
74                   (const Bytef *)InputBuffer.data(), InputBuffer.size()));
75  if (Res == StatusOK) {
76    UncompressedBuffer.reset(MemoryBuffer::getMemBufferCopy(
77        StringRef(TmpBuffer.get(), UncompressedSize)));
78    // Tell MSan that memory initialized by zlib is valid.
79    __msan_unpoison(UncompressedBuffer.data(), UncompressedBuffer.size());
80  }
81  return Res;
82}
83
84#else
85bool zlib::isAvailable() { return false; }
86zlib::Status zlib::compress(StringRef InputBuffer,
87                            OwningPtr<MemoryBuffer> &CompressedBuffer,
88                            CompressionLevel Level) {
89  return zlib::StatusUnsupported;
90}
91zlib::Status zlib::uncompress(StringRef InputBuffer,
92                              OwningPtr<MemoryBuffer> &UncompressedBuffer,
93                              size_t UncompressedSize) {
94  return zlib::StatusUnsupported;
95}
96#endif
97
98