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// Copyright 2018 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include <stddef.h>
#include <stdint.h>
#include <vector>
#include "base/numerics/safe_conversions.h"
#include "base/optional.h"
#include "components/zucchini/address_translator.h"
#include "components/zucchini/buffer_view.h"
#include "components/zucchini/image_utils.h"
#include "components/zucchini/type_elf.h"
namespace zucchini {
// Section dimensions for ELF files, to store relevant dimensions data from
// Elf32_Shdr and Elf64_Shdr, while reducing code duplication from templates.
struct SectionDimensionsElf {
SectionDimensionsElf() = default;
template <class Elf_Shdr>
explicit SectionDimensionsElf(const Elf_Shdr& section)
: region(BufferRegion{base::checked_cast<size_t>(section.sh_offset),
entry_size(base::checked_cast<offset_t>(section.sh_entsize)) {}
friend bool operator<(const SectionDimensionsElf& a,
const SectionDimensionsElf& b) {
return a.region.offset < b.region.offset;
friend bool operator<(offset_t offset, const SectionDimensionsElf& section) {
return offset < section.region.offset;
BufferRegion region;
offset_t entry_size; // Varies across REL / RELA sections.
// A Generator to visit all reloc structs located in [|lo|, |hi|) (excluding
// truncated strct at |lo| but inlcuding truncated struct at |hi|), and emit
// valid References with |rel_type|. This implements a nested loop unrolled into
// a generator: the outer loop has |cur_section_dimensions_| visiting
// |reloc_section_dims| (sorted by |region.offset|), and the inner loop has
// |cursor_| visiting successive reloc structs within |cur_section_dimensions_|.
class RelocReaderElf : public ReferenceReader {
ConstBufferView image,
Bitness bitness,
const std::vector<SectionDimensionsElf>& reloc_section_dimensions,
uint32_t rel_type,
offset_t lo,
offset_t hi,
const AddressTranslator& translator);
~RelocReaderElf() override;
// If |rel| contains |r_offset| for |rel_type_|, return the RVA. Otherwise
// return |kInvalidRva|. These also handle Elf*_Rela, by using the fact that
// Elf*_Rel is a prefix of Elf*_Rela.
rva_t GetRelocationTarget(elf::Elf32_Rel rel) const;
rva_t GetRelocationTarget(elf::Elf64_Rel rel) const;
// ReferenceReader:
base::Optional<Reference> GetNext() override;
const ConstBufferView image_;
const Bitness bitness_;
const uint32_t rel_type_;
const std::vector<SectionDimensionsElf>& reloc_section_dimensions_;
std::vector<SectionDimensionsElf>::const_iterator cur_section_dimensions_;
offset_t hi_;
offset_t cursor_;
AddressTranslator::RvaToOffsetCache target_rva_to_offset_;
class RelocWriterElf : public ReferenceWriter {
RelocWriterElf(MutableBufferView image,
Bitness bitness,
const AddressTranslator& translator);
~RelocWriterElf() override;
// ReferenceWriter:
void PutNext(Reference ref) override;
MutableBufferView image_;
const Bitness bitness_;
AddressTranslator::OffsetToRvaCache target_offset_to_rva_;
} // namespace zucchini