validate_filename() and sanitize_filename() pass '.' and '..'

[mkbloke]

In pathvalidate 2.4.1:

>>> pathvalidate.validate_filename(".")
>>> pathvalidate.validate_filename("..")
>>> pathvalidate.sanitize_filename(".")
'.'
>>> pathvalidate.sanitize_filename("..")
'..'

I know that . and .. can be valid in a path, but surely not as filenames on any of the supported platforms?

Thanks.

Edited to add:

My expectation would be that validate_filename() would perhaps raise a ValidationError with a reason of RESERVED_NAME in the two cases above?

Also, if these are considered reserved filenames, shouldn't _ be appended to each, as with, for example: sanitize_filename("con") returns con_?

[blerrgh]

Was this ever resolved? I have the same issue in 2.5.2

It would be great if sanitize_filename("..") (or maybe sanitize_filename("..", check_reserved=True)) returned "_"

[thombashi]

I have considered this previously and concluded that it is difficult to apply replacements unconditionally.
Unlike other reserved words, . and .. can be assumed to be recognized as reserved keywords and used as reserved names in most cases, so I think it is inappropriate to treat them in the same way as other reserved words.
In many cases, users would expect to preserve . and .. as they are, and there is a possibility that the valid file paths are broken if they are replaced.

In the future, another solution may be to add an interface that specifies a callback function to process reserved names.
By customizing this callback function, changing the behavior as you wish will be possible.

[blerrgh]

In many cases, users would expect to preserve . and .. as they are, and there is a possibility that the valid file paths are broken if they are replaced.

I agree that they probably shouldn't be replaced in sanitize_filepath since both . and .. are valid in relative paths. But personally I'm not sure I would expect them to ever be valid via sanitize_filename since you cannot name a file . or ...

I suppose if people are using sanitize_filename to check individual path components then they might want to preserve periods.

[thombashi]

pathvalidate v3.2.0 can do the following:

from pathvalidate import sanitize_filename, ValidationError

def add_trailing_underscore(e: ValidationError) -> str:
    if e.reusable_name:
        return e.reserved_name

    return f"{e.reserved_name}_"

sanitize_filename(".", reserved_name_handler=add_trailing_underscore, additional_reserved_names=["."])

'._'