#!/usr/bin/env python
# Copyright 2020 The Chromium Authors
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.
# maketoc inserts a table of contents (TOC) into an icns file if one does not
# exist, or verifies it if it is present. The icns files produced by makeicns
# do not contain TOCs. This script will add them.
#
# TOCs are not required, but are produced by recent icns-writing tools like
# icnsutil.
import struct
import sys
def _interpret_header(header):
assert len(header) == 8
(magic, length) = struct.unpack('>4sI', header)
assert length >= len(header)
return (magic, length)
def _read_header(file):
return _interpret_header(file.read(8))
def _write_header(file, magic, length):
header = struct.pack('>4sI', magic, length)
file.write(header)
def make_toc(path):
file = open(path, 'r+b')
(file_magic, file_length) = _read_header(file)
assert file_magic == b'icns'
read_length = file.tell()
chunk_list = []
chunk_dict = {}
for chunk_header in iter(lambda: file.read(8), b''):
(chunk_magic, chunk_length) = _interpret_header(chunk_header)
assert chunk_magic not in chunk_dict
chunk_list.append(chunk_magic)
chunk_dict[chunk_magic] = chunk_length
read_length += chunk_length
file.seek(chunk_length - 8, 1)
assert read_length == file_length
if b'TOC ' in chunk_dict:
# TOC exists, verify it.
assert chunk_list[0] == b'TOC '
toc_length = chunk_dict[b'TOC ']
assert toc_length % 8 == 0
chunk_count = (toc_length - 8) // 8
assert chunk_count == len(chunk_list) - 1
# The TOC just duplicates each chunk's header in sequence except for
# its own.
file.seek(16)
for i in range(0, chunk_count):
(chunk_magic, chunk_length) = _read_header(file)
assert chunk_magic == chunk_list[i + 1]
assert chunk_length == chunk_dict[chunk_magic]
else:
# TOC is not present, create it.
# Update the file header with the new length.
toc_length = 8 + len(chunk_list) * 8
file_length += toc_length
file.seek(0)
_write_header(file, b'icns', file_length)
after_file_header = file.tell()
remainder = file.read()
file.seek(after_file_header)
# The TOC just duplicates each chunk's header in sequence except for
# its own.
_write_header(file, b'TOC ', toc_length)
for chunk_magic in chunk_list:
_write_header(file, chunk_magic, chunk_dict[chunk_magic])
file.write(remainder)
assert file_length == file.tell()
file.close()
def main(args):
for path in args:
print(path)
make_toc(path)
return 0
if __name__ == '__main__':
sys.exit(main(sys.argv[1:]))
Codebase Browser
chromium