scripts: add magic-gen.py

This script is needed to generate python module from
include/magic.h file, that contains dicts with magic
numbers that we put into our criu *.img files.
Signed-off-by: Ruslan Kuprieiev <kupruser@gmail.com>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

scripts/magic-gen.py

+#!/bin/env python
+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 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)