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/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
  25 using namespace llvm;
  26
  27 #if LLVM_ENABLE_ZLIB == 1 && HAVE_LIBZ
  28 static 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
  38 static 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
  49 bool zlib::isAvailable() { return true; }
  50 zlib::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->getBufferStart(), CompressedSize);
  64   }
  65   return Res;
  66 }
  67
  68 zlib::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->getBufferStart(), UncompressedSize);
  80   }
  81   return Res;
  82 }
  83
  84 uint32_t zlib::crc32(StringRef Buffer) {
  85   return ::crc32(0, (const Bytef *)Buffer.data(), Buffer.size());
  86 }
  87
  88 #else
  89 bool zlib::isAvailable() { return false; }
  90 zlib::Status zlib::compress(StringRef InputBuffer,
  91                             OwningPtr<MemoryBuffer> &CompressedBuffer,
  92                             CompressionLevel Level) {
  93   return zlib::StatusUnsupported;
  94 }
  95 zlib::Status zlib::uncompress(StringRef InputBuffer,
  96                               OwningPtr<MemoryBuffer> &UncompressedBuffer,
  97                               size_t UncompressedSize) {
  98   return zlib::StatusUnsupported;
  99 }
 100 uint32_t zlib::crc32(StringRef Buffer) {
 101   llvm_unreachable("zlib::crc32 is unavailable");
 102 }
 103 #endif
 104