Create an ISO9660 compliant filename using pycdlib

Question

I'm trying to implement the pycdlib example-creating-new-basic-iso example shown below. About half way down there is a line that reads, iso.add_fp(BytesIO(foostr), len(foostr), '/FOO.;1'). This writes a new file to the ISO that will be names "FOO" in the root directory of the iso. This example works for me.

Building on the example, I'm trying to change the filename inside the iso from "/FOO", to "/FOO.txt" but I keep getting the error, PyCdlibInvalidInput: ISO9660 filenames must consist of characters A-Z, 0-9, and _. How do I write an ISO9660 compliant filename with pycdlib with ".txt" in it?

Example code:

try:
    from cStringIO import StringIO as BytesIO
except ImportError:
    from io import BytesIO

import pycdlib

iso = pycdlib.PyCdlib()
iso.new()

foostr = b'foo\n'
iso.add_fp(BytesIO(foostr), len(foostr), '/FOO.;1')

iso.add_directory('/DIR1')

iso.write('new.iso')
iso.close()

Answer 1

The key here is in the error: PyCdlibInvalidInput: ISO9660 filenames must consist of characters A-Z, 0-9, and _, but there is a more complete [explanation] (https://wiki.osdev.org/ISO_9660#Filenames):

d-characters: A B C D E F G H I J K L M N O P Q R S T U V W X Y Z 0 1 2 3 4 5 6 7 8 9 _

Filenames must use d-character encoding (strD), plus dot and semicolon which have to occur exactly once per filename. Filenames are composed of a File Name, a dot, a File Name Extension, a semicolon; and a version number in decimal digits. The latter two are usually not displayed to the user.

There are three Levels of Interchange defined. Level 1 allows filenames with a File Name length of 8 and an extension length of 3 (like MS-DOS). Levels 2 and 3 allow File Name and File Name Extension to have a combined length of up to 30 characters.

The ECMA-119 Directory Record format can hold composed names of up to 222 characters. This would violate the specs but must nevertheless be handled by a reader of the filesystem.

You can't name the file FOO.txt because lowercase letters aren't included in the d-characters. You need to capitalize the extension in order to be ISO9660-compliant.

iso.add_fp(BytesIO(foostr), len(foostr), '/FOO.TXT;1')

Answer 2

You need to use: UDF format, here it's an example:

try:
    from cStringIO import StringIO as BytesIO
except ImportError:
    from io import BytesIO
import pycdlib
   
iso = pycdlib.PyCdlib()
iso.new(udf='2.60')
foostr = b"This it's a random text\n"
iso.add_fp(BytesIO(foostr), len(foostr), '/FILE_OUT.TXT;1', udf_path='/file_out.txt')
iso.write('new.iso')
iso.close()

source: https://clalancette.github.io/pycdlib/example-creating-udf-iso.html