Quick Python script to generate a linux device mapper table from a ddrescue map file, placing errors where ddrescue had bad blocks.

map2dmtable.py

#!/usr/bin/env python

import argparse

parser = argparse.ArgumentParser(description='Create a device mapper table from a ddrescue map file. '
	'Blocks that are marked as bad will be mapped to the error target, while successfully-read '
	'blocks will be passed through to the device. The dm table will be written to stdout so it can '
	'be piped directly into dmsetup.')
parser.add_argument('mapfile', help='The ddrescue map file to convert')
parser.add_argument('device', help='The device containing the image that corresponds to the map file. (typically a loop device)')
args = parser.parse_args()

mapfile = args.mapfile
imagefile = args.device

with open(mapfile) as file:
	statusline = None
	for line in file:
		if line.startswith("#"):
			continue
		
		if not statusline:
			statusline = line
			continue
			
		block = line.split()
		
		start = int(block[0], 0) / 512
		len = int(block[1], 0) / 512
		module = None
		
		if block[2] == '-':
			module = "error"
		elif block[2] == '+':
			module = "linear %s %d" % (imagefile, start)
		else:
			raise ('Unimplemented block status type: "%s"' % (block[2]))
		
		print "%d %d %s" % (start, len, module)