#!/usr/bin/env python
# Verify that a mkisofs image has been burnt correctly to CD, automatically
# ignoring errors within the padding at the end of the image.
# Adam Sampson <ats@offog.org>

import sys, os, progress

if len(sys.argv) != 3:
	print >>sys.stderr, "Usage: verify-iso ISO DEVICE"
	sys.exit(1)

block = 4096

fi = open(sys.argv[1])
size = os.fstat(fi.fileno()).st_size
prog = progress.Progress(size, sys.argv[1])
fo = open(sys.argv[2])

start = 0
fi.seek(start)
fo.seek(start)
done = start

while done < size:
	n = block
	if n > (size - done):
		n = size - done
	di = fi.read(n)
	fault = "end of disc"
	try:
		do = fo.read(n)
	except IOError:
		do = ""
		fault = "read error"
	if len(do) < n:
		prog.close()
		pos = size + len(do)
		if (size - pos) < (300 * 1024):
			# It appears Linux's CD devices won't read the end of
			# the disc correctly -- so mkisofs pads its images by
			# 300KiB to get around it. Ignore read errors within
			# that pad.
			print >>sys.stderr, "Ignored %s within 300KiB pad" % (fault,)
			break
		else:
			print >>sys.stderr, "Unexpected %s at %d of %d" % (fault, pos, size)
			sys.exit(1)
	if di != do:
		prog.close()
		print >>sys.stderr, "Files differ between %d and %d" % (done, done + n)
		i = 0
		while i < n:
			b = 16
			if (n - i) < b:
				b = n - i
			def fmt(d):
				s = "%10d: " % (size + i,)
				for j in range(b):
					s += " %02d" % (ord(d[i + j]),)
				return s
			print >>sys.stderr, "ISO:  " + fmt(di)
			print >>sys.stderr, "Disc: " + fmt(do)
			i += b
		sys.exit(1)
	done += len(di)
	prog.update(done)
fi.close()
fo.close()
prog.close()

sys.exit(0)