struct elf {
   struct {
      u8 ei_magic[4] | matches('\x7fELF') str;

      enum {
         CLASS_32 = 1,
         CLASS_64
      } u8 ei_class;

      enum {
         ENDIANESS_LE = 1,
         ENDIANESS_BE
      } u8 ei_data;

      u8 ei_version;

      enum {
         OSABI_SYSTEM_V,
         OSABI_HP_UX,
         OSABI_NETBSD,
         OSABI_LINUX,
         OSABI_GNU_HURD,
         OSABI_SOLARIS,
         OSABI_AIX,
         OSABI_IRIX,
         OSABI_FREEBSD,
         OSABI_TRU64,
         OSABI_NOVELL_MODESTO,
         OSABI_OPENBSD,
         OSABI_OPENVMS,
         OSABI_NONSTOP_KERNEL,
         OSABI_AROS,
         OSABI_FENIX_OS,
         OSABI_CLOUD_ABI
      } u8 ei_osabi;

      u8 ei_abi_version;
      u8 ei_pad[7] nul;
   } e_ident;

   struct program_header {
      enum {
         PT_NULL,
         PT_LOAD,
         PT_DYNAMIC,
         PT_INTERP,
         PT_NOTE,
         PT_SHLIB,
         PT_PHDR,
         PT_LOOS,
         PT_HIOS,
         PT_LOPROC,
         PT_HIPROC
      } u32 p_type;

      select (e_ident.ei_class) {
         header.CLASS_32)
            struct {
               u32 p_offset hex;
               u32 p_vaddr hex;
               u32 p_paddr hex;
               u32 p_filesz;
               u32 p_memsz;
               u32 p_flags hex;
               u32 p_align;
            } elf32;
         header.CLASS_64)
            struct {
               u32 p_flags hex;
               u64 p_offset hex;
               u64 p_vaddr hex;
               u64 p_paddr hex;
               u64 p_filesz;
               u64 p_memsz;
               u64 p_align;
            } elf64;
      } arch;
   };

   struct section_header {
      enum sh_flags {
         SHF_WRITE = 0x1,
         SHF_ALLOC = 0x2,
         SHF_EXECINSTR = 0x4,
         SHF_MERGE = 0x10,
         SHF_STRINGS = 0x20,
         SHF_INFO_LINK = 0x40,
         SHF_LINK_ORDER = 0x80,
         SHF_OS_NONCONFORMING = 0x100,
         SHF_GROUP = 0x200,
         SHF_TLS = 0x400,
         SHF_MASKOS = 0x0ff00000,
         SHF_MASKPROC = 0xf0000000,
         SHF_ORDERED = 0x40000000,
         SHF_EXCLUDE = 0x80000000
      };

      select (e_ident.ei_class) {
         header.CLASS_32)
            struct {
               u32 sh_name hex;

               enum sh_type {
                  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_INIT_ARRAY,
                  SHT_FINI_ARRAY,
                  SHT_PREINIT_ARRAY,
                  SHT_GROUP,
                  SHT_SYMTAB_INDEX,
                  SHT_NUM,
                  SHT_LOOS = 0x60000000
               } u32 sh_type;

               enum sh_flags u32 sh_flags;
               u32 sh_addr hex;
               u32 sh_offset hex;
               u32 sh_size;
               u32 sh_link;
               u32 sh_info;
               u32 sh_addralign;
               u32 sh_entsize;
            } elf32;
         header.CLASS_64)
            struct {
               enum sh_flags u64 sh_flags;
               u64 sh_addr hex;
               u64 sh_offset hex;
               u64 sh_size;
               u64 sh_addralign;
               u64 sh_entsize;
            } elf64;
      } arch;
   };

   struct body {
      enum {
         ET_NONE,
         ET_REL,
         ET_EXEC,
         ET_DYN,
         ET_CORE,
         ET_LOOS = 0xfe00,
         ET_HIOS = 0xfeff,
         ET_LOPROC = 0xff00,
         ET_HIPROC = 0xffff
      } u16 e_type hex;

      enum {
         MACHINE_NONE,
         MACHINE_SPARC = 0x02,
         MACHINE_X86 = 0x03,
         MACHINE_MIPS = 0x08,
         MACHINE_POWERPC = 0x14,
         MACHINE_S390 = 0x16,
         MACHINE_ARM = 0x28,
         MACHINE_SUPERH = 0x2A,
         MACHINE_IA_64 = 0x32,
         MACHINE_X86_64 = 0x3E,
         MACHINE_AARCH64 = 0xB7,
         MACHINE_RISCV = 0xF3
      } u16 e_machine hex;

      u32 e_version;

      select (e_ident.ei_class) {
         header.CLASS_32)
            struct {
               u32 e_entry hex;
               u32 e_phoff;
               u32 e_shoff;
            } elf32;
         header.CLASS_64)
            struct {
               u64 e_entry hex;
               u64 e_phoff;
               u64 e_shoff;
            } elf64;
      } arch;

      u32 e_flags hex;
      u16 e_ehsz;
      u16 e_phentsize;
      u16 e_phnum;
      u16 e_shentsize;
      u16 e_shnum;
      u16 e_shstrndx;

      // TODO: need to handle offsets
      struct program_header e_ph[e_phnum:e_phentsize];
      struct section_header e_sh[e_shnum:e_shentsize];
   };

   select (e_ident.ei_class) {
      e_ident.ENDIANESS_LE) struct body le | endianess('le');
      e_ident.ENDIANESS_BE) struct body be | endianess('be');
   } body;
};