#!/usr/bin/env python
import os, sys

'''
Nuke GPT on any given block device.
Based on original work by lestercheung@gmail.com
   http://blog.gnub.net/2009/03/die-gpt-die.html
'''

def clear_gpt(target):
	'''
	According to http://en.wikipedia.org/wiki/GUID_Partition_Table - GPT
	stores partition data in the first and last 34 LBA blocks. A LBA sector
	is normally 512 bytes.
	'''
	sys.stdout.write("%s nuked: " %target)
	fd = open(target, "w+")
	fd.seek(0)
	fd.write('\0' * 34 * 512)
	sys.stdout.write("[%s] " %"GPT1")
	fd.seek(0, 2) # SEEK_END is 2
	disk_size = fd.tell()
	fd.seek(disk_size - 34*512)
	fd.write('\0' * 34 * 512)
	sys.stdout.write("[%s] " %"GPT2")
	sys.stdout.write("\n")


if __name__ == '__main__':
	args = sys.argv
	if len(args) < 2:
		sys.stderr.write("Use: %s device1-to-nuke-gpt-table [ ... device2-3-4-to-nuke-gpt-table ... ]\n" %args[0])
		sys.exit(1)
	for x in sys.argv[1:]:
		if os.path.exists(x):
			clear_gpt(x)
		else:
			sys.stderr.write("%s: not found\n" %x)