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      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 
    122