elf.h

#ifndef _ELF_H_
#define _ELF_H_

#include <stdint.h>

// ELF magic numbers.
#define ELFMAG0   0x7f
#define ELFMAG1   'E'
#define ELFMAG2   'L'
#define ELFMAG3   'F'
#define EI_NIDENT 16

// ELF data types.
typedef uint32_t Elf32_Word;
typedef uint32_t Elf32_Addr;
typedef uint32_t Elf32_Off;
typedef uint32_t Elf32_Sword;
typedef uint16_t Elf32_Half;

// ELF header.
typedef struct {
  uint8_t    e_ident[EI_NIDENT];
  Elf32_Half e_type;
  Elf32_Half e_machine;
  Elf32_Word e_version;
  Elf32_Addr e_entry;
  Elf32_Off  e_phoff;
  Elf32_Off  e_shoff;
  Elf32_Word e_flags;
  Elf32_Half e_ehsize;
  Elf32_Half e_phentsize;
  Elf32_Half e_phnum;
  Elf32_Half e_shentsize;
  Elf32_Half e_shnum;
  Elf32_Half e_shstrndx;
} Elf32_Header;

// e_type values.
#define ET_NONE   0
#define ET_REL    1
#define ET_EXEC   2
#define ET_DYN    3
#define ET_CORE   4
#define ET_LOPROC 0xff0
#define ET_HIPROC 0xfff

// Program header.
typedef struct {
  Elf32_Word p_type;
  Elf32_Off  p_offset;
  Elf32_Addr p_vaddr;
  Elf32_Addr p_paddr;
  Elf32_Word p_filesz;
  Elf32_Word p_memsz;
  Elf32_Word p_flags;
  Elf32_Word p_align;
} Elf32_Phdr;

// p_type values.
#define PT_NULL    0
#define PT_LOAD    1
#define PT_DYNAMIC 2
#define PT_INTERP  3
#define PT_NOTE    4
#define PT_SHLIB   5
#define PT_PHDR    6
#define PT_LOPROC  0x70000000
#define PT_HIPROC  0x7FFFFFFF

// p_flags values.
#define PF_X 1
#define PF_W 2
#define PF_R 4

// Section header.
typedef struct {
  Elf32_Word sh_name;
  Elf32_Word sh_type;
  Elf32_Word sh_flags;
  Elf32_Addr sh_addr;
  Elf32_Off  sh_offset;
  Elf32_Word sh_size;
  Elf32_Word sh_link;
  Elf32_Word sh_info;
  Elf32_Word sh_addralign;
  Elf32_Word sh_entsize;
} Elf32_Shdr;

// sh_type values
#define SHT_NONE     0
#define SHT_PROGBITS 1
#define SHT_SYMTAB   2
#define SHT_STRTAB   3
#define SHT_RELA     4
#define SHT_NOBITS   8
#define SHT_REL      9

// sh_flags values
#define SHF_WRITE     1
#define SHF_ALLOC     2
#define SHF_EXECINSTR 4
#define SHF_INFO_LINK 0x40

// Symbol
typedef struct {
  Elf32_Word    st_name;
  Elf32_Addr    st_value;
  Elf32_Word    st_size;
  unsigned char st_info;
  unsigned char st_other;
  Elf32_Half    st_shndx;
} Elf32_Sym;

// Macros to apply to st_info
#define ELF32_ST_BIND(i)   ((i)>>4)
#define ELF32_ST_TYPE(i)   ((i)&0xf)
#define ELF32_ST_INFO(b,t) (((b)<<4)+((t)&0xf))

// ST_BIND values
#define STB_LOCAL  0
#define STB_GLOBAL 1
#define STB_WEAK   2

// ST_TYPE values
#define STT_NOTYPE  0
#define STT_OBJECT  1
#define STT_FUNC    2
#define STT_SECTION 3
#define STT_FILE    4

// Relocation entry
typedef struct {
  Elf32_Addr r_offset;
  Elf32_Word r_info;
} Elf32_Rel;

// Macros to apply to r_info
#define ELF32_R_SYM(i)    ((i)>>8)
#define ELF32_R_TYPE(i)   ((unsigned char)(i))
#define ELF32_R_INFO(s,t) (((s)<<8)+(unsigned char)(t))

// R_TYPE values
#define R_386_32   1
#define R_386_PC32 2

#endif /* _ELF_H_ */