#!/usr/bin/python

# Eric's first python program :)

import sys #for sys.argv
import fcntl #for fcntl.ioctl
import os #for os.access
import struct # for struct.pack and struct.unpack

print "WARNING: This script may not work for files with holes."

if len(sys.argv) != 2:
	print "Usage: " + sys.argv[0] + " <filename>"
	print "Note: This program uses the FIBMAP ioctl, so you must be root."
	sys.exit(1)

if os.access(sys.argv[1], os.F_OK) == False:
	print "File " + sys.argv[1] + " doesn't exist."
	sys.exit(1)

f = open(sys.argv[1],'r')

fsBlockSize = struct.unpack('i',fcntl.ioctl(f,2,'    '))[0]
numFileBlocks = os.stat(sys.argv[1])[6] / fsBlockSize
if (os.stat(sys.argv[1])[6] % fsBlockSize) != 0:
	numFileBlocks += 1

blockIterator = 0
blockmap = []
for blockIterator in range(numFileBlocks):
	h=struct.pack('i',blockIterator)
	blockmap += struct.unpack('i',fcntl.ioctl(f,1,h))

print "Filesystem block size: " + str(fsBlockSize)
print "Number of filesystem blocks in file: " + str(numFileBlocks)

extentBegin = []
extentEnd = []
extentBegin += [blockmap[0]]
for blockIterator in range(1,len(blockmap)):
	if blockmap[blockIterator]-blockmap[blockIterator-1] == 1:
		blockIterator += 1
		continue
	else:
		extentEnd += [blockmap[blockIterator-1]]
		extentBegin += [blockmap[blockIterator]]
		blockIterator += 1
extentEnd += [blockmap[blockIterator-1]]

for n in range(0,len(extentBegin)):
	print "Contiguous chunk " + str(n) + ": " + str(extentBegin[n]) + " - " + str(extentEnd[n]) + "  (" + str(extentEnd[n] - extentBegin[n]+1) + " blocks)"
sys.exit(0)