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ccac3a0229
Mark destination buffer in zlib::compress and zlib::decompress as fully initialized. When building LLVM with system zlib and MemorySanitizer instrumentation, MSan does not observe memory writes in zlib code and erroneously considers zlib output buffers as uninitialized, resulting in false use-of-uninitialized memory reports. This change helps MSan understand the state of that memory and prevents such reports. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@222763 91177308-0d34-0410-b5e6-96231b3b80d8
99 lines
3.7 KiB
C++
99 lines
3.7 KiB
C++
//===--- Compression.cpp - Compression implementation ---------------------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file implements compression functions.
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/Support/Compression.h"
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#include "llvm/ADT/StringRef.h"
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#include "llvm/Config/config.h"
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#include "llvm/Support/Compiler.h"
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#include "llvm/Support/ErrorHandling.h"
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#if LLVM_ENABLE_ZLIB == 1 && HAVE_ZLIB_H
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#include <zlib.h>
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#endif
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using namespace llvm;
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#if LLVM_ENABLE_ZLIB == 1 && HAVE_LIBZ
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static int encodeZlibCompressionLevel(zlib::CompressionLevel Level) {
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switch (Level) {
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case zlib::NoCompression: return 0;
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case zlib::BestSpeedCompression: return 1;
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case zlib::DefaultCompression: return Z_DEFAULT_COMPRESSION;
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case zlib::BestSizeCompression: return 9;
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}
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llvm_unreachable("Invalid zlib::CompressionLevel!");
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}
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static zlib::Status encodeZlibReturnValue(int ReturnValue) {
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switch (ReturnValue) {
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case Z_OK: return zlib::StatusOK;
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case Z_MEM_ERROR: return zlib::StatusOutOfMemory;
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case Z_BUF_ERROR: return zlib::StatusBufferTooShort;
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case Z_STREAM_ERROR: return zlib::StatusInvalidArg;
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case Z_DATA_ERROR: return zlib::StatusInvalidData;
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default: llvm_unreachable("unknown zlib return status!");
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}
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}
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bool zlib::isAvailable() { return true; }
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zlib::Status zlib::compress(StringRef InputBuffer,
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SmallVectorImpl<char> &CompressedBuffer,
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CompressionLevel Level) {
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unsigned long CompressedSize = ::compressBound(InputBuffer.size());
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CompressedBuffer.resize(CompressedSize);
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int CLevel = encodeZlibCompressionLevel(Level);
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Status Res = encodeZlibReturnValue(::compress2(
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(Bytef *)CompressedBuffer.data(), &CompressedSize,
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(const Bytef *)InputBuffer.data(), InputBuffer.size(), CLevel));
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// Tell MemorySanitizer that zlib output buffer is fully initialized.
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// This avoids a false report when running LLVM with uninstrumented ZLib.
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__msan_unpoison(CompressedBuffer.data(), CompressedSize);
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CompressedBuffer.resize(CompressedSize);
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return Res;
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}
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zlib::Status zlib::uncompress(StringRef InputBuffer,
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SmallVectorImpl<char> &UncompressedBuffer,
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size_t UncompressedSize) {
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UncompressedBuffer.resize(UncompressedSize);
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Status Res = encodeZlibReturnValue(::uncompress(
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(Bytef *)UncompressedBuffer.data(), (uLongf *)&UncompressedSize,
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(const Bytef *)InputBuffer.data(), InputBuffer.size()));
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// Tell MemorySanitizer that zlib output buffer is fully initialized.
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// This avoids a false report when running LLVM with uninstrumented ZLib.
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__msan_unpoison(UncompressedBuffer.data(), UncompressedSize);
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UncompressedBuffer.resize(UncompressedSize);
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return Res;
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}
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uint32_t zlib::crc32(StringRef Buffer) {
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return ::crc32(0, (const Bytef *)Buffer.data(), Buffer.size());
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}
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#else
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bool zlib::isAvailable() { return false; }
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zlib::Status zlib::compress(StringRef InputBuffer,
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SmallVectorImpl<char> &CompressedBuffer,
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CompressionLevel Level) {
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return zlib::StatusUnsupported;
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}
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zlib::Status zlib::uncompress(StringRef InputBuffer,
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SmallVectorImpl<char> &UncompressedBuffer,
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size_t UncompressedSize) {
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return zlib::StatusUnsupported;
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}
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uint32_t zlib::crc32(StringRef Buffer) {
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llvm_unreachable("zlib::crc32 is unavailable");
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}
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#endif
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