llvm/lib/Object/Decompressor.cpp

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