oc_objdump.ml

(** OCaml implementation of objdump for object files. Supports ELF, Mach-O, and
    PE formats. Should be equivalent to objdump --section-headers <binaries> *)

let print_macho_summary file (header : Object.Macho.header) =
  let open Object in
  Printf.printf "\n%s:\tfile format mach-o %s\n\n" file
    (Macho.cpu_type_to_string header.cpu_type)

let print_pe_summary file (pe_obj : Object.Pe.pe_object) =
  let open Object in
  let format_str = if Pe.is_64bit pe_obj then "coff-x86-64" else "coff-i386" in
  Printf.printf "\n%s:\tfile format %s\n\n" file format_str

let print_macho_sections file =
  let open Printf in
  let open Object in
  let buffer = Buffer.parse file in
  let header, commands = Macho.read buffer in
  print_macho_summary file header;
  printf "Sections:\n";
  printf "%3s %-13s %-8s %-16s %s\n" "Idx" "Name" "Size" "VMA" "Type";

  let section_index = ref 0 in
  let print_section (_segment : Macho.segment) (section : Macho.section) =
    let section_type =
      if section.sec_segname = "__TEXT" then "TEXT" else "DATA"
    in
    printf "%3i %-13s %08Lx %016Lx %s\n" !section_index section.sec_sectname
      (Unsigned.UInt64.to_int64 section.sec_size)
      (Unsigned.UInt64.to_int64 section.sec_addr)
      section_type;
    incr section_index
  in

  let process_segment = function
    | Macho.LC_SEGMENT_64 segment | Macho.LC_SEGMENT_32 segment ->
        let (lazy segment) = segment in
        Array.iter (print_section segment) segment.Macho.seg_sections
    | _ -> ()
  in

  List.iter process_segment commands

let print_pe_sections file =
  let open Printf in
  let open Object in
  let buffer = Buffer.parse file in
  let pe_obj = Pe.read buffer in
  print_pe_summary file pe_obj;
  printf "Sections:\n";
  printf "%3s %-13s %-8s %-16s %s\n" "Idx" "Name" "Size" "VMA" "Type";

  let sections = pe_obj.Pe.section_headers in
  let image_base =
    match pe_obj.optional_header with
    | Some opt -> opt.image_base
    | None -> Unsigned.UInt64.zero
  in

  Array.iteri
    (fun i section ->
      (* Get section name *)
      let name = section.Pe.name in
      let clean_name =
        if String.length name = 0 then sprintf ".sec%d" i else name
      in

      (* Use virtual_size if size_of_raw_data is 0 (like for .bss) *)
      let size =
        let raw_size = Unsigned.UInt32.to_int64 section.Pe.size_of_raw_data in
        if raw_size = 0L then Unsigned.UInt32.to_int64 section.Pe.virtual_size
        else raw_size
      in

      (* Calculate proper VMA by adding image_base to virtual_address *)
      let vma =
        Unsigned.UInt64.add image_base
          (Unsigned.UInt64.of_int
             (Unsigned.UInt32.to_int section.Pe.virtual_address))
      in
      let vma_int64 = Unsigned.UInt64.to_int64 vma in

      let section_type =
        Pe.section_characteristics_to_type_string section.Pe.characteristics
      in

      printf "%3i %-13s %08Lx %016Lx %s\n" i clean_name size vma_int64
        section_type)
    sections

let print_section_headers file =
  let open Object in
  let buffer = Buffer.parse file in
  if Pe.is_pe buffer then print_pe_sections file
  else
    try
      (* Try to read as Mach-O *)
      let _ = Macho.read buffer in
      print_macho_sections file
    with _ -> Printf.printf "Error: Unsupported file format for %s\n" file

let run section_headers files () =
  match section_headers with
  | true -> List.iter print_section_headers files
  | false ->
      Printf.printf
        "Section headers flag required please call with `-h` or \
         `--section-headers`.\n";
      exit 2

open Cmdliner

let section_headers =
  (* Documentation string *)
  let doc = "Display summaries of the headers for each section." in
  (* Add both -h and --section-headers options *)
  let info = Arg.(info [ "h"; "section-headers" ] ~doc) in
  Arg.value (Arg.flag info)

let files =
  let doc = "Object FILEs to read." in
  Arg.(non_empty & pos_all file [] & info [] ~docv:"FILE" ~doc)

let section_headers_t = Term.(const run $ section_headers $ files $ const ())

let cmd =
  let doc = "OCaml object file dumper." in
  let info = Cmd.info "objdump" ~doc in
  Cmd.v info section_headers_t

let () = exit @@ Cmd.eval ~catch:true cmd