#include <stdio.h>
#include <unistd.h>
#include <assert.h>
#include <fcntl.h>
#include <a.out.h>

typedef struct
{
  FILHDR file_header;
  PEAOUTHDR file_optional_header;
  SCNHDR section_header[32];
} exe_header_t;

static exe_header_t *
read_exe_header (int fd, exe_header_t * exe_header_buffer)
{
  int i;
  int ret;

  assert (exe_header_buffer != 0);

  ret = lseek (fd, 0L, SEEK_SET);
  assert (ret != -1);

  ret =
    read (fd, &exe_header_buffer->file_header,
	  sizeof (exe_header_buffer->file_header));
  assert (ret == sizeof (exe_header_buffer->file_header));

  assert (exe_header_buffer->file_header.e_magic == 0x5a4d);
  assert (exe_header_buffer->file_header.nt_signature == 0x4550);
#ifdef __x86_64__
  assert (exe_header_buffer->file_header.f_magic == 0x8664);
#else
  assert (exe_header_buffer->file_header.f_magic == 0x014c);
#endif
  assert (exe_header_buffer->file_header.f_nscns > 0);
  assert (exe_header_buffer->file_header.f_nscns <=
	  sizeof (exe_header_buffer->section_header) /
	  sizeof (exe_header_buffer->section_header[0]));
  assert (exe_header_buffer->file_header.f_opthdr > 0);

  ret =
    read (fd, &exe_header_buffer->file_optional_header,
	  sizeof (exe_header_buffer->file_optional_header));
  assert (ret == sizeof (exe_header_buffer->file_optional_header));

#ifdef __x86_64__
  assert (exe_header_buffer->file_optional_header.magic == 0x020b);
#else
  assert (exe_header_buffer->file_optional_header.magic == 0x010b);
#endif
  for (i = 0; i < exe_header_buffer->file_header.f_nscns; ++i)
    {
      ret =
	read (fd, &exe_header_buffer->section_header[i],
	      sizeof (exe_header_buffer->section_header[i]));
      assert (ret == sizeof (exe_header_buffer->section_header[i]));
    }

  return (exe_header_buffer);
}

int
main ()
{
  int fd;
  exe_header_t exe_header_buffer;

  printf ("Type PEAOUTHDR has size %u bytes.\n", sizeof (PEAOUTHDR));
  fd = open ("/bin/ls.exe", O_RDONLY);
  assert (fd >= 0);
  read_exe_header (fd, &exe_header_buffer);
}