contrib/llvm/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/SmallVector.h"
  16 #include "llvm/ADT/StringRef.h"
  17 #include "llvm/Config/config.h"
  18 #include "llvm/Support/Compiler.h"
  19 #include "llvm/Support/Error.h"
  20 #include "llvm/Support/ErrorHandling.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 Error createError(StringRef Err) {
  29   return make_error<StringError>(Err, inconvertibleErrorCode());
  30 }
  31
  32 static int encodeZlibCompressionLevel(zlib::CompressionLevel Level) {
  33   switch (Level) {
  34     case zlib::NoCompression: return 0;
  35     case zlib::BestSpeedCompression: return 1;
  36     case zlib::DefaultCompression: return Z_DEFAULT_COMPRESSION;
  37     case zlib::BestSizeCompression: return 9;
  38   }
  39   llvm_unreachable("Invalid zlib::CompressionLevel!");
  40 }
  41
  42 static StringRef convertZlibCodeToString(int Code) {
  43   switch (Code) {
  44   case Z_MEM_ERROR:
  45     return "zlib error: Z_MEM_ERROR";
  46   case Z_BUF_ERROR:
  47     return "zlib error: Z_BUF_ERROR";
  48   case Z_STREAM_ERROR:
  49     return "zlib error: Z_STREAM_ERROR";
  50   case Z_DATA_ERROR:
  51     return "zlib error: Z_DATA_ERROR";
  52   case Z_OK:
  53   default:
  54     llvm_unreachable("unknown or unexpected zlib status code");
  55   }
  56 }
  57
  58 bool zlib::isAvailable() { return true; }
  59
  60 Error zlib::compress(StringRef InputBuffer,
  61                      SmallVectorImpl<char> &CompressedBuffer,
  62                      CompressionLevel Level) {
  63   unsigned long CompressedSize = ::compressBound(InputBuffer.size());
  64   CompressedBuffer.resize(CompressedSize);
  65   int CLevel = encodeZlibCompressionLevel(Level);
  66   int Res = ::compress2((Bytef *)CompressedBuffer.data(), &CompressedSize,
  67                         (const Bytef *)InputBuffer.data(), InputBuffer.size(),
  68                         CLevel);
  69   // Tell MemorySanitizer that zlib output buffer is fully initialized.
  70   // This avoids a false report when running LLVM with uninstrumented ZLib.
  71   __msan_unpoison(CompressedBuffer.data(), CompressedSize);
  72   CompressedBuffer.resize(CompressedSize);
  73   return Res ? createError(convertZlibCodeToString(Res)) : Error::success();
  74 }
  75
  76 Error zlib::uncompress(StringRef InputBuffer, char *UncompressedBuffer,
  77                        size_t &UncompressedSize) {
  78   int Res =
  79       ::uncompress((Bytef *)UncompressedBuffer, (uLongf *)&UncompressedSize,
  80                    (const Bytef *)InputBuffer.data(), InputBuffer.size());
  81   // Tell MemorySanitizer that zlib output buffer is fully initialized.
  82   // This avoids a false report when running LLVM with uninstrumented ZLib.
  83   __msan_unpoison(UncompressedBuffer, UncompressedSize);
  84   return Res ? createError(convertZlibCodeToString(Res)) : Error::success();
  85 }
  86
  87 Error zlib::uncompress(StringRef InputBuffer,
  88                        SmallVectorImpl<char> &UncompressedBuffer,
  89                        size_t UncompressedSize) {
  90   UncompressedBuffer.resize(UncompressedSize);
  91   Error E =
  92       uncompress(InputBuffer, UncompressedBuffer.data(), UncompressedSize);
  93   UncompressedBuffer.resize(UncompressedSize);
  94   return E;
  95 }
  96
  97 uint32_t zlib::crc32(StringRef Buffer) {
  98   return ::crc32(0, (const Bytef *)Buffer.data(), Buffer.size());
  99 }
 100
 101 #else
 102 bool zlib::isAvailable() { return false; }
 103 Error zlib::compress(StringRef InputBuffer,
 104                      SmallVectorImpl<char> &CompressedBuffer,
 105                      CompressionLevel Level) {
 106   llvm_unreachable("zlib::compress is unavailable");
 107 }
 108 Error zlib::uncompress(StringRef InputBuffer, char *UncompressedBuffer,
 109                        size_t &UncompressedSize) {
 110   llvm_unreachable("zlib::uncompress is unavailable");
 111 }
 112 Error zlib::uncompress(StringRef InputBuffer,
 113                        SmallVectorImpl<char> &UncompressedBuffer,
 114                        size_t UncompressedSize) {
 115   llvm_unreachable("zlib::uncompress is unavailable");
 116 }
 117 uint32_t zlib::crc32(StringRef Buffer) {
 118   llvm_unreachable("zlib::crc32 is unavailable");
 119 }
 120 #endif
 121