98 lines
3.6 KiB
C++
98 lines
3.6 KiB
C++
//===- MachOLayoutBuilder.h -------------------------------------*- C++ -*-===//
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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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#ifndef LLVM_LIB_OBJCOPY_MACHO_MACHOLAYOUTBUILDER_H
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#define LLVM_LIB_OBJCOPY_MACHO_MACHOLAYOUTBUILDER_H
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#include "MachOObject.h"
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#include "llvm/ObjCopy/MachO/MachOObjcopy.h"
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namespace llvm {
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namespace objcopy {
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namespace macho {
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/// When MachO binaries include a LC_CODE_SIGNATURE load command,
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/// the __LINKEDIT data segment will include a section corresponding
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/// to the LC_CODE_SIGNATURE load command. This section serves as a signature
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/// for the binary. Included in the CodeSignature section is a header followed
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/// by a hash of the binary. If present, the CodeSignature section is the
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/// last component of the binary.
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struct CodeSignatureInfo {
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// NOTE: These values are to be kept in sync with those in
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// LLD's CodeSignatureSection class.
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static constexpr uint32_t Align = 16;
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static constexpr uint8_t BlockSizeShift = 12;
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// The binary is read in blocks of the following size.
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static constexpr size_t BlockSize = (1 << BlockSizeShift); // 4 KiB
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// For each block, a SHA256 hash (256 bits, 32 bytes) is written to
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// the CodeSignature section.
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static constexpr size_t HashSize = 256 / 8;
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static constexpr size_t BlobHeadersSize = llvm::alignTo<8>(
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sizeof(llvm::MachO::CS_SuperBlob) + sizeof(llvm::MachO::CS_BlobIndex));
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// The size of the entire header depends upon the filename the binary is being
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// written to, but the rest of the header is fixed in size.
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static constexpr uint32_t FixedHeadersSize =
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BlobHeadersSize + sizeof(llvm::MachO::CS_CodeDirectory);
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// The offset relative to the start of the binary where
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// the CodeSignature section should begin.
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uint32_t StartOffset;
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// The size of the entire header, output file name size included.
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uint32_t AllHeadersSize;
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// The number of blocks required to hash the binary.
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uint32_t BlockCount;
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StringRef OutputFileName;
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// The size of the entire CodeSignature section, including both the header and
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// hashes.
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uint32_t Size;
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};
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class MachOLayoutBuilder {
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Object &O;
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bool Is64Bit;
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StringRef OutputFileName;
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uint64_t PageSize;
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CodeSignatureInfo CodeSignature;
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// Points to the __LINKEDIT segment if it exists.
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MachO::macho_load_command *LinkEditLoadCommand = nullptr;
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StringTableBuilder StrTableBuilder;
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uint32_t computeSizeOfCmds() const;
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void constructStringTable();
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void updateSymbolIndexes();
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void updateDySymTab(MachO::macho_load_command &MLC);
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uint64_t layoutSegments();
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uint64_t layoutRelocations(uint64_t Offset);
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Error layoutTail(uint64_t Offset);
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static StringTableBuilder::Kind getStringTableBuilderKind(const Object &O,
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bool Is64Bit);
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public:
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MachOLayoutBuilder(Object &O, bool Is64Bit, StringRef OutputFileName,
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uint64_t PageSize)
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: O(O), Is64Bit(Is64Bit), OutputFileName(OutputFileName),
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PageSize(PageSize),
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StrTableBuilder(getStringTableBuilderKind(O, Is64Bit)) {}
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// Recomputes and updates fields in the given object such as file offsets.
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Error layout();
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StringTableBuilder &getStringTableBuilder() { return StrTableBuilder; }
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const CodeSignatureInfo &getCodeSignature() const { return CodeSignature; }
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};
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} // end namespace macho
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} // end namespace objcopy
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} // end namespace llvm
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#endif // LLVM_LIB_OBJCOPY_MACHO_MACHOLAYOUTBUILDER_H
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