update-license-header.py

#!/usr/bin/env python
# -*- coding: utf-8
#
# Copyright 2005-2017 The Mumble Developers. All rights reserved.
# Use of this source code is governed by a BSD-style license
# that can be found in the LICENSE file at the root of the
# Mumble source tree or at <https://www.mumble.info/LICENSE>.

from __future__ import (unicode_literals, print_function, division)

import os

def licenseHeader():
	s = ''
	with open('LICENSE.header', 'r') as f:
		s = f.read()
	return s

def splitLicenseHeader():
	hdr = licenseHeader()
	splat = hdr.split(b'\n')[0:-1]
	out = []
	for line in splat:
		fixedLine = line.replace(b'// ', b'', 1)
		out.append(fixedLine)
	return out

def fileHasLicenseHeader(fn):
	f = open(fn, 'r')
	buf = f.read(4096)

	splitHeaderLines = splitLicenseHeader()

	if not splitHeaderLines[0].startswith(b'Copyright'):
		raise Exception('Expected LICENSE.header to start with "Copyright".')

	if not b'Copyright' in buf:
		return False

	for line in splitHeaderLines[1:]:
		if not line in buf:
			return False

	return True

def updateLicenseHeader(fn):
	hdr = licenseHeader()
	splitHdr = splitLicenseHeader()

	# Read the original file
	with open(fn, 'rb') as f:
		buf = f.read()

	# Figure out which comment style
	# the file uses. Also, try to figure
	# out if it uses Unix-style line endings,
	# or Windows-style line endings.
	lastLine = splitHdr[-1]
	lastLineIndex = buf.find(b' ' + lastLine)
	if lastLineIndex < 0:
		raise Exception('bad file')

	commentToken = b''
	idx = lastLineIndex
	while idx >= 0:
		idx -= 1
		if buf[idx] == '\n':
			break
		commentToken = buf[idx] + commentToken

	newline = '\n'
	if buf[idx-1] == '\r':
		newline = '\r\n'

	# Construct the new header
	newHeader = b''
	for line in splitHdr:
		newHeader += commentToken + b' ' + line + newline

	# Now, find the beginning of the license
	# header in the file.
	needle = commentToken + b' Copyright'

	idx = lastLineIndex
	while idx >= 0:
		checkBuf = buf[idx:idx+len(needle)]
		if checkBuf == needle:
			break
		idx -= 1
	if idx == -1:
		raise Exception('could not find beginning of license header in {0}'.format(fn))
	headerBeginIndex = idx

	# OK, we have the beginning.
	# Now, find the full length of the
	# existing header. (Inlcuding
	# newline characters.)
	idx = lastLineIndex
	while True:
		if buf[idx] == '\n' or buf[idx] == '\r':
			break
		idx += 1

	headerLength = byteAfterHeaderIdx = idx - 1 + len(newline) + 1

	# OK, let's re-write the file.
	with open(fn, 'wb') as nf:
		if headerBeginIndex > 0:
			nf.write(buf[0:headerBeginIndex])
		nf.write(newHeader)
		nf.write(buf[byteAfterHeaderIdx:])

def main():
	target = '.'
	for root, dirs, files in os.walk(target):
		for fn in files:
			absFn = os.path.join(root, fn)
			# Skip git
			if os.path.join(target, '.git', '') in absFn:
				continue
			# Skip LICENSE.header
			if absFn == os.path.join(target, 'LICENSE.header'):
				continue
			hasHeader = fileHasLicenseHeader(absFn)
			if hasHeader:
				updateLicenseHeader(absFn)
				print('Updated license header in file at {0}'.format(absFn))

if __name__ == '__main__':
	main()