#!/bin/env python2
import os, sys
import struct

# This program parses criu magic.h file and produces
# magic.py with all *_MAGIC constants except RAW and V1.
def main(argv):
	if len(argv) != 3:
		print("Usage: magic-gen.py path/to/image.h path/to/magic.py")
		exit(1)

	magic_c_header = argv[1]
	magic_py = argv[2]

	out = open(magic_py, 'w+')

	# all_magic is used to parse constructions like:
	# #define PAGEMAP_MAGIC		0x56084025
	# #define SHMEM_PAGEMAP_MAGIC	PAGEMAP_MAGIC
	all_magic = {}
	# and magic is used to store only unique magic.
	magic = {}

	f = open(magic_c_header, 'r')
	for line in f:
		split = line.split()

		if len(split) < 3:
			continue

		if not '#define' in split[0]:
			continue

		key = split[1]
		value = split[2]

		if value in all_magic:
			value = all_magic[value]
		else:
			magic[key] = value

		all_magic[key] = value

	out.write('#Autogenerated. Do not edit!\n')
	out.write('by_name = {}\n')
	out.write('by_val = {}\n')
	for k,v in list(magic.items()):
		# We don't need RAW or V1 magic, because
		# they can't be used to identify images.
		if v == '0x0' or v == '1' or k == '0x0' or v == '1':
			continue
		if k.endswith("_MAGIC"):
			# Just cutting _MAGIC suffix
			k = k[:-6]
		v = int(v, 16)
		out.write("by_name['"+ k +"'] = "+ str(v) +"\n")
		out.write("by_val["+ str(v) +"] = '"+ k +"'\n")
	f.close()
	out.close()

if __name__ == "__main__":
	main(sys.argv)
