lib/Support/Compression.cpp

   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/StringRef.h"
  16 #include "llvm/Config/config.h"
  17 #include "llvm/Support/Compiler.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
  24 using namespace llvm;
  25
  26 #if LLVM_ENABLE_ZLIB == 1 && HAVE_LIBZ
  27 static 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   llvm_unreachable("Invalid zlib::CompressionLevel!");
  35 }
  36
  37 static zlib::Status encodeZlibReturnValue(int ReturnValue) {
  38   switch (ReturnValue) {
  39     case Z_OK: return zlib::StatusOK;
  40     case Z_MEM_ERROR: return zlib::StatusOutOfMemory;
  41     case Z_BUF_ERROR: return zlib::StatusBufferTooShort;
  42     case Z_STREAM_ERROR: return zlib::StatusInvalidArg;
  43     case Z_DATA_ERROR: return zlib::StatusInvalidData;
  44     default: llvm_unreachable("unknown zlib return status!");
  45   }
  46 }
  47
  48 bool zlib::isAvailable() { return true; }
  49 zlib::Status zlib::compress(StringRef InputBuffer,
  50                             std::unique_ptr<MemoryBuffer> &CompressedBuffer,
  51                             CompressionLevel Level) {
  52   unsigned long CompressedSize = ::compressBound(InputBuffer.size());
  53   std::unique_ptr<char[]> TmpBuffer(new char[CompressedSize]);
  54   int CLevel = encodeZlibCompressionLevel(Level);
  55   Status Res = encodeZlibReturnValue(::compress2(
  56       (Bytef *)TmpBuffer.get(), &CompressedSize,
  57       (const Bytef *)InputBuffer.data(), InputBuffer.size(), CLevel));
  58   if (Res == StatusOK) {
  59     CompressedBuffer.reset(MemoryBuffer::getMemBufferCopy(
  60         StringRef(TmpBuffer.get(), CompressedSize)));
  61     // Tell MSan that memory initialized by zlib is valid.
  62     __msan_unpoison(CompressedBuffer->getBufferStart(), CompressedSize);
  63   }
  64   return Res;
  65 }
  66
  67 zlib::Status zlib::uncompress(StringRef InputBuffer,
  68                               SmallVectorImpl<char> &UncompressedBuffer,
  69                               size_t UncompressedSize) {
  70   UncompressedBuffer.resize(UncompressedSize);
  71   Status Res = encodeZlibReturnValue(::uncompress(
  72       (Bytef *)UncompressedBuffer.data(), (uLongf *)&UncompressedSize,
  73       (const Bytef *)InputBuffer.data(), InputBuffer.size()));
  74   UncompressedBuffer.resize(UncompressedSize);
  75   return Res;
  76 }
  77
  78 uint32_t zlib::crc32(StringRef Buffer) {
  79   return ::crc32(0, (const Bytef *)Buffer.data(), Buffer.size());
  80 }
  81
  82 #else
  83 bool zlib::isAvailable() { return false; }
  84 zlib::Status zlib::compress(StringRef InputBuffer,
  85                             std::unique_ptr<MemoryBuffer> &CompressedBuffer,
  86                             CompressionLevel Level) {
  87   return zlib::StatusUnsupported;
  88 }
  89 zlib::Status zlib::uncompress(StringRef InputBuffer,
  90                               std::unique_ptr<MemoryBuffer> &UncompressedBuffer,
  91                               size_t UncompressedSize) {
  92   return zlib::StatusUnsupported;
  93 }
  94 uint32_t zlib::crc32(StringRef Buffer) {
  95   llvm_unreachable("zlib::crc32 is unavailable");
  96 }
  97 #endif
  98