1 //===-- Decompressor.cpp --------------------------------------------------===// 2 // 3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4 // See https://llvm.org/LICENSE.txt for license information. 5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6 // 7 //===----------------------------------------------------------------------===// 8 9 #include "llvm/Object/Decompressor.h" 10 #include "llvm/BinaryFormat/ELF.h" 11 #include "llvm/Object/ObjectFile.h" 12 #include "llvm/Support/Compression.h" 13 #include "llvm/Support/DataExtractor.h" 14 #include "llvm/Support/Endian.h" 15 16 using namespace llvm; 17 using namespace llvm::support::endian; 18 using namespace object; 19 20 Expected<Decompressor> Decompressor::create(StringRef Name, StringRef Data, 21 bool IsLE, bool Is64Bit) { 22 Decompressor D(Data); 23 if (Error Err = D.consumeCompressedHeader(Is64Bit, IsLE)) 24 return std::move(Err); 25 return D; 26 } 27 28 Decompressor::Decompressor(StringRef Data) 29 : SectionData(Data), DecompressedSize(0) {} 30 31 Error Decompressor::consumeCompressedHeader(bool Is64Bit, bool IsLittleEndian) { 32 using namespace ELF; 33 uint64_t HdrSize = Is64Bit ? sizeof(Elf64_Chdr) : sizeof(Elf32_Chdr); 34 if (SectionData.size() < HdrSize) 35 return createError("corrupted compressed section header"); 36 37 DataExtractor Extractor(SectionData, IsLittleEndian, 0); 38 uint64_t Offset = 0; 39 auto ChType = Extractor.getUnsigned(&Offset, Is64Bit ? sizeof(Elf64_Word) 40 : sizeof(Elf32_Word)); 41 switch (ChType) { 42 case ELFCOMPRESS_ZLIB: 43 CompressionType = DebugCompressionType::Zlib; 44 break; 45 case ELFCOMPRESS_ZSTD: 46 CompressionType = DebugCompressionType::Zstd; 47 break; 48 default: 49 return createError("unsupported compression type (" + Twine(ChType) + ")"); 50 } 51 if (const char *Reason = llvm::compression::getReasonIfUnsupported( 52 compression::formatFor(CompressionType))) 53 return createError(Reason); 54 55 // Skip Elf64_Chdr::ch_reserved field. 56 if (Is64Bit) 57 Offset += sizeof(Elf64_Word); 58 59 DecompressedSize = Extractor.getUnsigned( 60 &Offset, Is64Bit ? sizeof(Elf64_Xword) : sizeof(Elf32_Word)); 61 SectionData = SectionData.substr(HdrSize); 62 return Error::success(); 63 } 64 65 Error Decompressor::decompress(MutableArrayRef<uint8_t> Output) { 66 return compression::decompress(CompressionType, 67 arrayRefFromStringRef(SectionData), 68 Output.data(), Output.size()); 69 } 70