dump_djgpp.py

#!/usr/bin/python
from sys import argv
from struct import unpack
	
def dump_coff(input_buffer):
	header = dict(zip(['signature', 'bytes_in_last_block', 'blocks_in_file',
	'num_relocs', 'header_paragraphs', 'min_extra_paragraphs',
	'max_extra_paragraphs', 'ss', 'sp', 'checksum', 'ip', 'cs',
	'reloc_table_offset', 'overlay_number'], unpack("<HHHHHHHHHHHHHH", input_buffer[:28])))
	if header['signature'] != 0x5A4D:
		raise RuntimeError("Invalid signature!")
	return input_buffer[header['blocks_in_file'] * 512 - (512 - header['bytes_in_last_block'] if header['bytes_in_last_block'] else 0):]
	
def dump_flat(input_coff, out_file):
	header = dict(zip(['f_magic', 'f_nscns', 'f_timdat', 'f_symptr',
	'f_nsyms', 'f_opthdr', 'f_flags'], unpack("<HHLLLHH", input_coff[:20])))
	if header['f_magic'] != 0x014C:
		raise RuntimeError("Invalid COFF magic!")
	for section in [dict(zip(['s_name', 's_paddr', 's_vaddr', 's_size', 's_scnptr', 's_relptr', 's_lnnoptr', 's_nreloc', 's_nlnno', 's_flags'], unpack("8sLLLLLLHHL",input_coff[begin:end]))) for begin, end in [(20+header['f_opthdr']+(n*40), 60+header['f_opthdr']+(n*40)) for n in range(header['f_nscns'])]]:
		out_file.seek(section['s_paddr'])
		out_file.write(chr(0)*section['s_size'] if section['s_flags'] == 0x80 else input_coff[section['s_scnptr']:section['s_scnptr']+section['s_size']])
if __name__ == '__main__':
	if len(argv) < 3:
		exit(1)
	else:
		try:
			with open(argv[1], 'rb') as file:
				with open(argv[2], 'wb') as flat:
					dump_flat(dump_coff(file.read()), flat)
		except EnvironmentError:
			print("Unable to open file!")