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//===--- Compression.cpp - Compression implementation ---------------------===// 
// 
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 
// See https://llvm.org/LICENSE.txt for license information. 
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 
// 
//===----------------------------------------------------------------------===// 
// 
//  This file implements compression functions. 
// 
//===----------------------------------------------------------------------===// 
 
#include "llvm/Support/Compression.h" 
#include "llvm/ADT/SmallVector.h" 
#include "llvm/ADT/StringRef.h" 
#include "llvm/Config/config.h" 
#include "llvm/Support/Compiler.h" 
#include "llvm/Support/Error.h" 
#include "llvm/Support/ErrorHandling.h" 
#if LLVM_ENABLE_ZLIB
#include <zlib.h> 
#endif 
 
using namespace llvm; 
 
#if LLVM_ENABLE_ZLIB
static Error createError(StringRef Err) { 
  return make_error<StringError>(Err, inconvertibleErrorCode()); 
} 
 
static StringRef convertZlibCodeToString(int Code) { 
  switch (Code) { 
  case Z_MEM_ERROR: 
    return "zlib error: Z_MEM_ERROR"; 
  case Z_BUF_ERROR: 
    return "zlib error: Z_BUF_ERROR"; 
  case Z_STREAM_ERROR: 
    return "zlib error: Z_STREAM_ERROR"; 
  case Z_DATA_ERROR: 
    return "zlib error: Z_DATA_ERROR"; 
  case Z_OK: 
  default: 
    llvm_unreachable("unknown or unexpected zlib status code"); 
  } 
} 
 
bool zlib::isAvailable() { return true; } 
 
Error zlib::compress(StringRef InputBuffer, 
                     SmallVectorImpl<char> &CompressedBuffer, int Level) { 
  unsigned long CompressedSize = ::compressBound(InputBuffer.size()); 
  CompressedBuffer.reserve(CompressedSize); 
  int Res = 
      ::compress2((Bytef *)CompressedBuffer.data(), &CompressedSize, 
                  (const Bytef *)InputBuffer.data(), InputBuffer.size(), Level); 
  // Tell MemorySanitizer that zlib output buffer is fully initialized. 
  // This avoids a false report when running LLVM with uninstrumented ZLib. 
  __msan_unpoison(CompressedBuffer.data(), CompressedSize); 
  CompressedBuffer.set_size(CompressedSize); 
  return Res ? createError(convertZlibCodeToString(Res)) : Error::success(); 
} 
 
Error zlib::uncompress(StringRef InputBuffer, char *UncompressedBuffer, 
                       size_t &UncompressedSize) { 
  int Res = 
      ::uncompress((Bytef *)UncompressedBuffer, (uLongf *)&UncompressedSize, 
                   (const Bytef *)InputBuffer.data(), InputBuffer.size()); 
  // Tell MemorySanitizer that zlib output buffer is fully initialized. 
  // This avoids a false report when running LLVM with uninstrumented ZLib. 
  __msan_unpoison(UncompressedBuffer, UncompressedSize); 
  return Res ? createError(convertZlibCodeToString(Res)) : Error::success(); 
} 
 
Error zlib::uncompress(StringRef InputBuffer, 
                       SmallVectorImpl<char> &UncompressedBuffer, 
                       size_t UncompressedSize) { 
  UncompressedBuffer.reserve(UncompressedSize); 
  Error E = 
      uncompress(InputBuffer, UncompressedBuffer.data(), UncompressedSize); 
  UncompressedBuffer.set_size(UncompressedSize); 
  return E; 
} 
 
uint32_t zlib::crc32(StringRef Buffer) { 
  return ::crc32(0, (const Bytef *)Buffer.data(), Buffer.size()); 
} 
 
#else 
bool zlib::isAvailable() { return false; } 
Error zlib::compress(StringRef InputBuffer, 
                     SmallVectorImpl<char> &CompressedBuffer, int Level) { 
  llvm_unreachable("zlib::compress is unavailable"); 
} 
Error zlib::uncompress(StringRef InputBuffer, char *UncompressedBuffer, 
                       size_t &UncompressedSize) { 
  llvm_unreachable("zlib::uncompress is unavailable"); 
} 
Error zlib::uncompress(StringRef InputBuffer, 
                       SmallVectorImpl<char> &UncompressedBuffer, 
                       size_t UncompressedSize) { 
  llvm_unreachable("zlib::uncompress is unavailable"); 
} 
uint32_t zlib::crc32(StringRef Buffer) { 
  llvm_unreachable("zlib::crc32 is unavailable"); 
} 
#endif