Toggle whether the "immutable" flag is set on a file. (Works only on EXT file systems.)

set_immutable_file.py

#!/usr/bin/python2

# Toggle the "immutable" flag on a file. This flag will prevent you from
# removing or rewriting a file, even if you have permissions or or root.

# Usage:
# $0 <filepath> [on|off]
# $0 <dirpath> [on|off]

# If the argument is a file and no second argument (on/off) is given, then 
# the script will read the current ext file flags and toggle the immutable flag.

# If the argument is a directory, the script runs on all of the files in
# the file tree beneath the directory. The operation is set to "on" automatically.

import fcntl
import os
import struct
import sys

# Taken from ext2fs/ext2_fs.h.
EXT2_IMMUTABLE_FL = 0x00000010
if struct.calcsize('P') == 8:
	EXT2_IOC_SETFLAGS = 0x40086602 # This is the 64-bit code
	EXT2_IOC_GETFLAGS = 0x80086601 # This is the 64-bit code
else:
	EXT2_IOC_SETFLAGS = 0x40046602 # this is the 32-bit code
	EXT2_IOC_GETFLAGS = 0x80046601 # This is the 32-bit code

FORCE_ON  = 'on' in sys.argv[1:]
FORCE_OFF = 'off' in sys.argv[1:]
QUIET     = 'q' in sys.argv[1:]

def log(text):
	if not QUIET:
		print(text)

def do_file(fpath):
	fd = os.open(fpath, os.O_RDONLY)
	rec = struct.pack('L', 0)
	x = fcntl.ioctl(fd, EXT2_IOC_GETFLAGS, rec)
	flags = struct.unpack('L',x)[0]
	was_immutable = flags & EXT2_IMMUTABLE_FL

	if FORCE_ON:
		do_immutable = True
	elif FORCE_OFF:
		do_immutable = False
	elif was_immutable:
		do_immutable = False
	else:
		do_immutable = True

	if (FORCE_ON and was_immutable) or (FORCE_OFF and not was_immutable):
		log('skipping %s' % fpath)
	else:
		if do_immutable:
			flags = flags | EXT2_IMMUTABLE_FL
		else:
			flags = flags & ~EXT2_IMMUTABLE_FL
		log('toggling immutable %5s %s' % ('__ON_' if flags & EXT2_IMMUTABLE_FL else '_OFF_', fpath))
		f = struct.pack('i', flags)
		fcntl.ioctl(fd, EXT2_IOC_SETFLAGS, f);

	os.close(fd)

# Traverse file tree beneath this dir and call do_file on all files
def do_dir(dpath):
	if len(sys.argv) == 2:
		global FORCE_ON
		FORCE_ON = True
	for triplet in os.walk(dpath):
		for file in triplet[2]:
			fpath = os.path.join(triplet[0], file)
			if not os.path.islink(fpath):
				do_file(fpath)

if len(sys.argv) < 2:
	sys.stderr.write("Usage:\n%s <file> [on|off]\n%s <dir> [on|off]\n" % (sys.argv[0], sys.argv[0]))
	sys.exit(1)
path = sys.argv[1]
if os.path.isfile(path):
	do_file(path)
elif os.path.isdir(path):
	do_dir(path)