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/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this file,
* You can obtain one at http://mozilla.org/MPL/2.0/. */
#ifndef Elfxx_h
#define Elfxx_h
#include "Utils.h"
/**
* Android system headers have two different elf.h file. The one under linux/
* is the most complete on older Android API versions without unified headers.
*/
#if defined(ANDROID) && __ANDROID_API__ < 21 && !defined(__ANDROID_API_L__)
# include <linux/elf.h>
#else
# include <elf.h>
#endif
#include <endian.h>
#if defined(__ARM_EABI__) && !defined(PT_ARM_EXIDX)
# define PT_ARM_EXIDX 0x70000001
#endif
/**
* Generic ELF macros for the target system
*/
#ifdef __LP64__
# define Elf_(type) Elf64_##type
# define ELFCLASS ELFCLASS64
# define ELF_R_TYPE ELF64_R_TYPE
# define ELF_R_SYM ELF64_R_SYM
# ifndef ELF_ST_BIND
# define ELF_ST_BIND ELF64_ST_BIND
# endif
#else
# define Elf_(type) Elf32_##type
# define ELFCLASS ELFCLASS32
# define ELF_R_TYPE ELF32_R_TYPE
# define ELF_R_SYM ELF32_R_SYM
# ifndef ELF_ST_BIND
# define ELF_ST_BIND ELF32_ST_BIND
# endif
#endif
#ifndef __BYTE_ORDER
# error Cannot find endianness
#endif
#if __BYTE_ORDER == __LITTLE_ENDIAN
# define ELFDATA ELFDATA2LSB
#elif __BYTE_ORDER == __BIG_ENDIAN
# define ELFDATA ELFDATA2MSB
#endif
#ifdef __linux__
# define ELFOSABI ELFOSABI_LINUX
# ifdef EI_ABIVERSION
# define ELFABIVERSION 0
# endif
#else
# error Unknown ELF OSABI
#endif
#if defined(__i386__)
# define ELFMACHINE EM_386
// Doing this way probably doesn't scale to other architectures
# define R_ABS R_386_32
# define R_GLOB_DAT R_386_GLOB_DAT
# define R_JMP_SLOT R_386_JMP_SLOT
# define R_RELATIVE R_386_RELATIVE
# define RELOC(n) DT_REL##n
# define UNSUPPORTED_RELOC(n) DT_RELA##n
# define STR_RELOC(n) "DT_REL" # n
# define Reloc Rel
#elif defined(__x86_64__)
# define ELFMACHINE EM_X86_64
# define R_ABS R_X86_64_64
# define R_GLOB_DAT R_X86_64_GLOB_DAT
# define R_JMP_SLOT R_X86_64_JUMP_SLOT
# define R_RELATIVE R_X86_64_RELATIVE
# define RELOC(n) DT_RELA##n
# define UNSUPPORTED_RELOC(n) DT_REL##n
# define STR_RELOC(n) "DT_RELA" # n
# define Reloc Rela
#elif defined(__arm__)
# define ELFMACHINE EM_ARM
# ifndef R_ARM_ABS32
# define R_ARM_ABS32 2
# endif
# ifndef R_ARM_GLOB_DAT
# define R_ARM_GLOB_DAT 21
# endif
# ifndef R_ARM_JUMP_SLOT
# define R_ARM_JUMP_SLOT 22
# endif
# ifndef R_ARM_RELATIVE
# define R_ARM_RELATIVE 23
# endif
# define R_ABS R_ARM_ABS32
# define R_GLOB_DAT R_ARM_GLOB_DAT
# define R_JMP_SLOT R_ARM_JUMP_SLOT
# define R_RELATIVE R_ARM_RELATIVE
# define RELOC(n) DT_REL##n
# define UNSUPPORTED_RELOC(n) DT_RELA##n
# define STR_RELOC(n) "DT_REL" # n
# define Reloc Rel
#elif defined(__aarch64__)
# define ELFMACHINE EM_AARCH64
# define R_ABS R_AARCH64_ABS64
# define R_GLOB_DAT R_AARCH64_GLOB_DAT
# define R_JMP_SLOT R_AARCH64_JUMP_SLOT
# define R_RELATIVE R_AARCH64_RELATIVE
# define RELOC(n) DT_RELA##n
# define UNSUPPORTED_RELOC(n) DT_REL##n
# define STR_RELOC(n) "DT_RELA" # n
# define Reloc Rela
#else
# error Unknown ELF machine type
#endif
/**
* Android system headers don't have all definitions
*/
#ifndef STN_UNDEF
# define STN_UNDEF 0
#endif
#ifndef DT_INIT_ARRAY
# define DT_INIT_ARRAY 25
#endif
#ifndef DT_FINI_ARRAY
# define DT_FINI_ARRAY 26
#endif
#ifndef DT_INIT_ARRAYSZ
# define DT_INIT_ARRAYSZ 27
#endif
#ifndef DT_FINI_ARRAYSZ
# define DT_FINI_ARRAYSZ 28
#endif
#ifndef DT_RELACOUNT
# define DT_RELACOUNT 0x6ffffff9
#endif
#ifndef DT_RELCOUNT
# define DT_RELCOUNT 0x6ffffffa
#endif
#ifndef DT_VERSYM
# define DT_VERSYM 0x6ffffff0
#endif
#ifndef DT_VERDEF
# define DT_VERDEF 0x6ffffffc
#endif
#ifndef DT_VERDEFNUM
# define DT_VERDEFNUM 0x6ffffffd
#endif
#ifndef DT_VERNEED
# define DT_VERNEED 0x6ffffffe
#endif
#ifndef DT_VERNEEDNUM
# define DT_VERNEEDNUM 0x6fffffff
#endif
#ifndef DT_FLAGS_1
# define DT_FLAGS_1 0x6ffffffb
#endif
#ifndef DT_FLAGS
# define DT_FLAGS 30
#endif
#ifndef DF_SYMBOLIC
# define DF_SYMBOLIC 0x00000002
#endif
#ifndef DF_TEXTREL
# define DF_TEXTREL 0x00000004
#endif
namespace Elf {
/**
* Define a few basic Elf Types
*/
typedef Elf_(Phdr) Phdr;
typedef Elf_(Dyn) Dyn;
typedef Elf_(Sym) Sym;
typedef Elf_(Addr) Addr;
typedef Elf_(Word) Word;
typedef Elf_(Half) Half;
/**
* Helper class around the standard Elf header struct
*/
struct Ehdr : public Elf_(Ehdr) {
/**
* Equivalent to reinterpret_cast<const Ehdr *>(buf), but additionally
* checking that this is indeed an Elf header and that the Elf type
* corresponds to that of the system
*/
static const Ehdr* validate(const void* buf);
};
/**
* Elf String table
*/
class Strtab : public UnsizedArray<const char> {
public:
/**
* Returns the string at the given index in the table
*/
const char* GetStringAt(off_t index) const {
return &UnsizedArray<const char>::operator[](index);
}
};
/**
* Helper class around Elf relocation.
*/
struct Rel : public Elf_(Rel) {
/**
* Returns the addend for the relocation, which is the value stored
* at r_offset.
*/
Addr GetAddend(void* base) const {
return *(reinterpret_cast<const Addr*>(reinterpret_cast<const char*>(base) +
r_offset));
}
};
/**
* Helper class around Elf relocation with addend.
*/
struct Rela : public Elf_(Rela) {
/**
* Returns the addend for the relocation.
*/
Addr GetAddend(void* base) const { return r_addend; }
};
} /* namespace Elf */
#endif /* Elfxx_h */