Compression.cpp revision a0bd5df0867e054b9740bc734325cdeabfe3825a 
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/ErrorHandling.h"
19#include "llvm/Support/MemoryBuffer.h"
20#if LLVM_ENABLE_ZLIB == 1 && HAVE_ZLIB_H
21#include <zlib.h>
22#endif
23
24using namespace llvm;
25
26#if LLVM_ENABLE_ZLIB == 1 && HAVE_LIBZ
27static int encodeZlibCompressionLevel(zlib::CompressionLevel Level) {
28  switch (Level) {
29    case zlib::NoCompression: return 0;
30    case zlib::BestSpeedCompression: return 1;
31    case zlib::DefaultCompression: return Z_DEFAULT_COMPRESSION;
32    case zlib::BestSizeCompression: return 9;
33  }
34}
35
36static zlib::Status encodeZlibReturnValue(int ReturnValue) {
37  switch (ReturnValue) {
38    case Z_OK: return zlib::StatusOK;
39    case Z_MEM_ERROR: return zlib::StatusOutOfMemory;
40    case Z_BUF_ERROR: return zlib::StatusBufferTooShort;
41    case Z_STREAM_ERROR: return zlib::StatusInvalidArg;
42    case Z_DATA_ERROR: return zlib::StatusInvalidData;
43    default: llvm_unreachable("unknown zlib return status!");
44  }
45}
46
47bool zlib::isAvailable() { return true; }
48zlib::Status zlib::compress(StringRef InputBuffer,
49                            OwningPtr<MemoryBuffer> &CompressedBuffer,
50                            CompressionLevel Level) {
51  unsigned long CompressedSize = ::compressBound(InputBuffer.size());
52  OwningArrayPtr<char> TmpBuffer(new char[CompressedSize]);
53  int CLevel = encodeZlibCompressionLevel(Level);
54  Status Res = encodeZlibReturnValue(::compress2(
55      (Bytef *)TmpBuffer.get(), &CompressedSize,
56      (const Bytef *)InputBuffer.data(), InputBuffer.size(), CLevel));
57  if (Res == StatusOK)
58    CompressedBuffer.reset(MemoryBuffer::getMemBufferCopy(
59        StringRef(TmpBuffer.get(), CompressedSize)));
60  return Res;
61}
62
63zlib::Status zlib::uncompress(StringRef InputBuffer,
64                              OwningPtr<MemoryBuffer> &UncompressedBuffer,
65                              size_t UncompressedSize) {
66  OwningArrayPtr<char> TmpBuffer(new char[UncompressedSize]);
67  Status Res = encodeZlibReturnValue(
68      ::uncompress((Bytef *)TmpBuffer.get(), (uLongf *)&UncompressedSize,
69                   (const Bytef *)InputBuffer.data(), InputBuffer.size()));
70  if (Res == StatusOK)
71    UncompressedBuffer.reset(MemoryBuffer::getMemBufferCopy(
72        StringRef(TmpBuffer.get(), UncompressedSize)));
73  return Res;
74}
75
76#else
77bool zlib::isAvailable() { return false; }
78zlib::Status zlib::compress(StringRef InputBuffer,
79                            OwningPtr<MemoryBuffer> &CompressedBuffer,
80                            CompressionLevel Level) {
81  return zlib::StatusUnsupported;
82}
83zlib::Status zlib::uncompress(StringRef InputBuffer,
84                              OwningPtr<MemoryBuffer> &UncompressedBuffer,
85                              size_t UncompressedSize) {
86  return zlib::StatusUnsupported;
87}
88#endif
89
90