open Library

type elf32_addr     = int32
type elf32_half     = int
type elf32_off      = int32
type elf32_sword    = int32
type elf32_word     = int32
type byte           = int

(** ELF identification *)

type elfclass =
  | ELFCLASSNONE
  | ELFCLASS32
  | ELFCLASS64
  | ELFCLASSUNKNOWN

type elfdata =
  | ELFDATANONE
  | ELFDATA2LSB
  | ELFDATA2MSB
  | ELFDATAUNKNOWN

type ev =
  | EV_NONE
  | EV_CURRENT
  | EV_UNKNOWN

type elf_identification = {
  ei_class:     elfclass;   (* 32/64 bit *)
  ei_data:      elfdata;    (* endianness *)
  ei_version:   ev;         (* ELF header version *)
}

(** ELF header *)

type et =
  | ET_NONE
  | ET_REL
  | ET_EXEC
  | ET_DYN
  | ET_CORE
  | ET_UNKNOWN

type em =
  | EM_NONE
  | EM_M32
  | EM_SPARC
  | EM_386
  | EM_68K
  | EM_88K
  | EM_860
  | EM_MIPS
  | EM_MIPS_RS4_BE
  | EM_PPC
  | EM_UNKNOWN

let shn_UNDEF  = 0
let shn_ABS    = 0xFFF1
let shn_COMMON = 0xFFF2

type elf32_ehdr = {
  e_ident:      elf_identification;     (* Machine-independent data *)
  e_type:       et;                     (* Object file type *)
  e_machine:    em;                     (* Required architecture *)
  e_version:    ev;                     (* Object file version *)
  e_entry:      elf32_addr;             (* Entry point virtual address *)
  e_phoff:      elf32_off;              (* Program header table's offset *)
  e_shoff:      elf32_off;              (* Section header table's offset *)
  e_flags:      Bitstring.bitstring;    (* Processor-specific flags *)
  e_ehsize:     elf32_half;             (* ELF header size *)
  e_phentsize:  elf32_half;             (* Size of a program header's entry *)
  e_phnum:      elf32_half;             (* Number of program header entries *)
  e_shentsize:  elf32_half;             (* Size of a section header's entry *)
  e_shnum:      elf32_half;             (* Number of section header entries *)
  e_shstrndx:   elf32_half;             (* Section name string table index *)
}

(** ELF section header *)

type sht =
  | SHT_NULL
  | SHT_PROGBITS
  | SHT_SYMTAB
  | SHT_STRTAB
  | SHT_RELA
  | SHT_HASH
  | SHT_DYNAMIC
  | SHT_NOTE
  | SHT_NOBITS
  | SHT_REL
  | SHT_SHLIB
  | SHT_DYNSYM
  | SHT_UNKNOWN

type elf32_shdr = {
  sh_name:      string;
  sh_type:      sht;
  sh_flags:     elf32_word;
  sh_addr:      elf32_addr;
  sh_offset:    elf32_off;
  sh_size:      elf32_word;
  sh_link:      elf32_word;
  sh_info:      elf32_word;
  sh_addralign: elf32_word;
  sh_entsize:   elf32_word;
}

let shf_WRITE = 0x1l
let shf_ALLOC = 0x2l
let shf_EXECINSTR = 0x4l

type elf32_st_bind =
  | STB_LOCAL
  | STB_GLOBAL
  | STB_WEAK
  | STB_UNKNOWN

type elf32_st_type =
  | STT_NOTYPE
  | STT_OBJECT
  | STT_FUNC
  | STT_SECTION
  | STT_FILE
  | STT_UNKNOWN

type elf32_sym = {
  st_name:      string;
  st_value:     elf32_addr;
  st_size:      elf32_word;
  st_bind:      elf32_st_bind;
  st_type:      elf32_st_type;
  st_other:     byte;
  st_shndx:     elf32_half;
}

(** ELF program header *)

type p_type =
  | PT_NULL
  | PT_LOAD
  | PT_DYNAMIC
  | PT_INTERP
  | PT_NOTE
  | PT_SHLIB
  | PT_PHDR
  | PT_UNKNOWN

type elf32_phdr = {
  p_type:   p_type      ;
  p_offset: elf32_off   ;
  p_vaddr:  elf32_addr  ;
  p_paddr:  elf32_addr  ;
  p_filesz: elf32_word  ;
  p_memsz:  elf32_word  ;
  p_flags:  bitstring   ;
  p_align:  elf32_word  ;
}

(** ELF *)
type elf = {
  e_bitstring:    bitstring;
  e_hdr:          elf32_ehdr;
  e_shdra:        elf32_shdr array;
  e_phdra:        elf32_phdr array;
  e_symtab:       elf32_sym array;
  e_symtab_sndx:  int; (* to avoid having to find it again when needed *)
  e_syms_by_name: int list StringMap.t; (* faster lookup *)
}