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* Copyright (C) 2012 The Android Open Source Project
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* See the License for the specific language governing permissions and
* limitations under the License.
#include <map>
#include <vector>
#include <llvm/Support/ELF.h>
#include "base/unix_file/fd_file.h"
#include "globals.h"
#include "mem_map.h"
#include "os.h"
#include "UniquePtr.h"
namespace art {
// Used for compile time and runtime for ElfFile access. Because of
// the need for use at runtime, cannot directly use LLVM classes such as
// ELFObjectFile.
class ElfFile {
static ElfFile* Open(File* file, bool writable, bool program_header_only);
// Load segments into memory based on PT_LOAD program headers
File& GetFile() const {
return *file_;
byte* Begin() {
return map_->Begin();
byte* End() {
return map_->End();
size_t Size() const {
return map_->Size();
::llvm::ELF::Elf32_Ehdr& GetHeader();
::llvm::ELF::Elf32_Word GetProgramHeaderNum();
::llvm::ELF::Elf32_Phdr& GetProgramHeader(::llvm::ELF::Elf32_Word);
::llvm::ELF::Elf32_Phdr* FindProgamHeaderByType(::llvm::ELF::Elf32_Word type);
::llvm::ELF::Elf32_Word GetSectionHeaderNum();
::llvm::ELF::Elf32_Shdr& GetSectionHeader(::llvm::ELF::Elf32_Word);
::llvm::ELF::Elf32_Shdr* FindSectionByType(::llvm::ELF::Elf32_Word type);
::llvm::ELF::Elf32_Shdr& GetSectionNameStringSection();
// Find .dynsym using .hash for more efficient lookup than FindSymbolAddress.
byte* FindDynamicSymbolAddress(const std::string& symbol_name);
static bool IsSymbolSectionType(::llvm::ELF::Elf32_Word section_type);
::llvm::ELF::Elf32_Word GetSymbolNum(::llvm::ELF::Elf32_Shdr&);
::llvm::ELF::Elf32_Sym& GetSymbol(::llvm::ELF::Elf32_Word section_type, ::llvm::ELF::Elf32_Word i);
// Find symbol in specified table, returning NULL if it is not found.
// If build_map is true, builds a map to speed repeated access. The
// map does not included untyped symbol values (aka STT_NOTYPE)
// since they can contain duplicates. If build_map is false, the map
// will be used if it was already created. Typically build_map
// should be set unless only a small number of symbols will be
// looked up.
::llvm::ELF::Elf32_Sym* FindSymbolByName(::llvm::ELF::Elf32_Word section_type,
const std::string& symbol_name,
bool build_map);
// Find address of symbol in specified table, returning 0 if it is
// not found. See FindSymbolByName for an explanation of build_map.
::llvm::ELF::Elf32_Addr FindSymbolAddress(::llvm::ELF::Elf32_Word section_type,
const std::string& symbol_name,
bool build_map);
// Lookup a string given string section and offset. Returns NULL for
// special 0 offset.
const char* GetString(::llvm::ELF::Elf32_Shdr&, ::llvm::ELF::Elf32_Word);
// Lookup a string by section type. Returns NULL for special 0 offset.
const char* GetString(::llvm::ELF::Elf32_Word section_type, ::llvm::ELF::Elf32_Word);
::llvm::ELF::Elf32_Word GetDynamicNum();
::llvm::ELF::Elf32_Dyn& GetDynamic(::llvm::ELF::Elf32_Word);
::llvm::ELF::Elf32_Word FindDynamicValueByType(::llvm::ELF::Elf32_Sword type);
::llvm::ELF::Elf32_Word GetRelNum(::llvm::ELF::Elf32_Shdr&);
::llvm::ELF::Elf32_Rel& GetRel(::llvm::ELF::Elf32_Shdr&, ::llvm::ELF::Elf32_Word);
::llvm::ELF::Elf32_Word GetRelaNum(::llvm::ELF::Elf32_Shdr&);
::llvm::ELF::Elf32_Rela& GetRela(::llvm::ELF::Elf32_Shdr&, ::llvm::ELF::Elf32_Word);
// Returns the expected size when the file is loaded at runtime
size_t GetLoadedSize();
// Load segments into memory based on PT_LOAD program headers
bool Load();
bool Setup(File* file, bool writable, bool program_header_only);
bool SetMap(MemMap* map);
byte* GetProgramHeadersStart();
byte* GetSectionHeadersStart();
::llvm::ELF::Elf32_Phdr& GetDynamicProgramHeader();
::llvm::ELF::Elf32_Dyn* GetDynamicSectionStart();
::llvm::ELF::Elf32_Sym* GetSymbolSectionStart(::llvm::ELF::Elf32_Word section_type);
const char* GetStringSectionStart(::llvm::ELF::Elf32_Word section_type);
::llvm::ELF::Elf32_Rel* GetRelSectionStart(::llvm::ELF::Elf32_Shdr&);
::llvm::ELF::Elf32_Rela* GetRelaSectionStart(::llvm::ELF::Elf32_Shdr&);
::llvm::ELF::Elf32_Word* GetHashSectionStart();
::llvm::ELF::Elf32_Word GetHashBucketNum();
::llvm::ELF::Elf32_Word GetHashChainNum();
::llvm::ELF::Elf32_Word GetHashBucket(size_t i);
::llvm::ELF::Elf32_Word GetHashChain(size_t i);
typedef std::map<std::string, ::llvm::ELF::Elf32_Sym*> SymbolTable;
SymbolTable** GetSymbolTable(::llvm::ELF::Elf32_Word section_type);
File* file_;
bool writable_;
bool program_header_only_;
// ELF header mapping. If program_header_only_ is false, will actually point to the entire elf file.
UniquePtr<MemMap> map_;
::llvm::ELF::Elf32_Ehdr* header_;
std::vector<MemMap*> segments_;
// Pointer to start of first PT_LOAD program segment after Load() when program_header_only_ is true.
byte* base_address_;
// The program header should always available but use GetProgramHeadersStart() to be sure.
byte* program_headers_start_;
// Conditionally available values. Use accessors to ensure they exist if they are required.
byte* section_headers_start_;
::llvm::ELF::Elf32_Phdr* dynamic_program_header_;
::llvm::ELF::Elf32_Dyn* dynamic_section_start_;
::llvm::ELF::Elf32_Sym* symtab_section_start_;
::llvm::ELF::Elf32_Sym* dynsym_section_start_;
const char* strtab_section_start_;
const char* dynstr_section_start_;
::llvm::ELF::Elf32_Word* hash_section_start_;
SymbolTable* symtab_symbol_table_;
SymbolTable* dynsym_symbol_table_;
} // namespace art
#endif // ART_SRC_ELF_FILE_H_