; vim: set ft=nasm:

%include "linkscr.inc"

[section .header]

%include "elf.inc"

%ifndef PT_INTERP_VAL
%define PT_INTERP_VAL "/lib/ld-linux.so.2"
%endif

global _EHDR
_EHDR:
ehdr:
    ; e_ident
    db 0x7F, "ELF"
    db EI_CLASS, EI_DATA, EI_VERSION, EI_OSABI
    db EI_OSABIVERSION
    times 7 db 0       ; EI_PAD, ld.so is a busta and won't let us use our leet
                       ; group tags for padding bytes :(
    dw ELF_TYPE        ; e_type: 2 = executable
    dw ELF_MACHINE     ; e_machine: 3 = x86
    dd EI_VERSION      ; e_version
    dd _smol_start     ; e_entry
    dd (phdr - ehdr)   ; e_phoff
    dd 0               ; e_shoff
    dd 0               ; e_flags
    dw (phdr - ehdr)   ; e_ehsize
    dw (phdr.load - phdr.dynamic) ; e_phentsize
%ifdef USE_NX
%error "USE_NX not supported yet on i386 ('GOT' still needs RWX, and alignment has to be fixed)"
%else
global _PHDR
_PHDR:
phdr:
%endif
%ifdef USE_INTERP
phdr.interp:
    dd PT_INTERP          ; {e_phnum: 2, e_shentsize: 0}, p_type
    dd (interp - ehdr)    ; {e_shnum: <junk>, e_shstrnd: <junk>}, p_offset
    dd interp, interp     ; p_vaddr, p_paddr
    dd (interp.end-interp); p_filesz
    dd (interp.end-interp); p_memsz
    dd 0,0                ; p_flags, p_align
%endif
phdr.dynamic:
    dd PT_DYNAMIC          ; {e_phnum: 2, e_shentsize: 0}, p_type
    dd (dynamic - ehdr)    ; {e_shnum: <junk>, e_shstrnd: <junk>}, p_offset
    dd  dynamic, 0         ; p_vaddr, p_paddr
    dd (dynamic.end - dynamic) ; p_filesz
    dd (dynamic.end - dynamic) ; p_memsz
    dd 0, 0                ; p_flags, p_align
%ifndef USE_NX
phdr.load:
    dd PT_LOAD          ; p_type: 1 = PT_LOAD
    dd 0                ; p_offset
    dd ehdr, 0          ; p_vaddr, p_paddr
    ;; use memsize twice here, linux doesn't care and it compresses better
    ; actually, linux doesn't care, but the hardware does >__>
    dd _smol_total_filesize ; p_filesz
    dd _smol_total_memsize ; p_memsz
    dd (PHDR_R | PHDR_W | PHDR_X) ; p_flags
    dd 0x1000           ; p_align
%else
    ; TODO
%endif
phdr.end:

%ifdef USE_INTERP
[section .rodata.interp]
global _INTERP
_INTERP:
interp:
    db PT_INTERP_VAL,0
interp.end:
%endif

[section .rodata.dynamic]
global _DYNAMIC
_DYNAMIC:
dynamic:
dynamic.strtab:
    dd DT_STRTAB ; d_tag
    dd _strtab   ; d_un.d_ptr
dynamic.symtab:
    ; this is required to be present or ld.so will crash, but it can be bogus
    dd DT_SYMTAB ; d_tag: 6 = DT_SYMTAB
    dd 0         ; d_un.d_ptr
%ifdef USE_DT_DEBUG
dynamic.debug:
    dd DT_DEBUG
_DEBUG:
    dd 0
%endif