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
create(StringRef Name,StringRef Data,bool IsLE,bool Is64Bit)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
Decompressor(StringRef Data)28 Decompressor::Decompressor(StringRef Data)
29 : SectionData(Data), DecompressedSize(0) {}
30
consumeCompressedHeader(bool Is64Bit,bool IsLittleEndian)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
decompress(MutableArrayRef<uint8_t> Output)65 Error Decompressor::decompress(MutableArrayRef<uint8_t> Output) {
66 return compression::decompress(CompressionType,
67 arrayRefFromStringRef(SectionData),
68 Output.data(), Output.size());
69 }
70