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