99 lines
3.2 KiB
C++
99 lines
3.2 KiB
C++
//===-- Decompressor.cpp --------------------------------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/Object/Decompressor.h"
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#include "llvm/BinaryFormat/ELF.h"
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#include "llvm/Object/ELFObjectFile.h"
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#include "llvm/Support/Compression.h"
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#include "llvm/Support/DataExtractor.h"
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#include "llvm/Support/Endian.h"
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using namespace llvm;
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using namespace llvm::support::endian;
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using namespace object;
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Expected<Decompressor> Decompressor::create(StringRef Name, StringRef Data,
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bool IsLE, bool Is64Bit) {
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if (!zlib::isAvailable())
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return createError("zlib is not available");
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Decompressor D(Data);
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Error Err = isGnuStyle(Name) ? D.consumeCompressedGnuHeader()
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: D.consumeCompressedZLibHeader(Is64Bit, IsLE);
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if (Err)
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return std::move(Err);
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return D;
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}
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Decompressor::Decompressor(StringRef Data)
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: SectionData(Data), DecompressedSize(0) {}
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Error Decompressor::consumeCompressedGnuHeader() {
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if (!SectionData.startswith("ZLIB"))
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return createError("corrupted compressed section header");
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SectionData = SectionData.substr(4);
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// Consume uncompressed section size (big-endian 8 bytes).
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if (SectionData.size() < 8)
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return createError("corrupted uncompressed section size");
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DecompressedSize = read64be(SectionData.data());
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SectionData = SectionData.substr(8);
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return Error::success();
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}
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Error Decompressor::consumeCompressedZLibHeader(bool Is64Bit,
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bool IsLittleEndian) {
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using namespace ELF;
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uint64_t HdrSize = Is64Bit ? sizeof(Elf64_Chdr) : sizeof(Elf32_Chdr);
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if (SectionData.size() < HdrSize)
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return createError("corrupted compressed section header");
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DataExtractor Extractor(SectionData, IsLittleEndian, 0);
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uint64_t Offset = 0;
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if (Extractor.getUnsigned(&Offset, Is64Bit ? sizeof(Elf64_Word)
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: sizeof(Elf32_Word)) !=
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ELFCOMPRESS_ZLIB)
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return createError("unsupported compression type");
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// Skip Elf64_Chdr::ch_reserved field.
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if (Is64Bit)
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Offset += sizeof(Elf64_Word);
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DecompressedSize = Extractor.getUnsigned(
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&Offset, Is64Bit ? sizeof(Elf64_Xword) : sizeof(Elf32_Word));
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SectionData = SectionData.substr(HdrSize);
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return Error::success();
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}
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bool Decompressor::isGnuStyle(StringRef Name) {
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return Name.startswith(".zdebug");
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}
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bool Decompressor::isCompressed(const object::SectionRef &Section) {
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if (Section.isCompressed())
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return true;
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Expected<StringRef> SecNameOrErr = Section.getName();
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if (SecNameOrErr)
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return isGnuStyle(*SecNameOrErr);
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consumeError(SecNameOrErr.takeError());
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return false;
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}
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bool Decompressor::isCompressedELFSection(uint64_t Flags, StringRef Name) {
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return (Flags & ELF::SHF_COMPRESSED) || isGnuStyle(Name);
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}
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Error Decompressor::decompress(MutableArrayRef<char> Buffer) {
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size_t Size = Buffer.size();
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return zlib::uncompress(SectionData, Buffer.data(), Size);
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}
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