Re: [boost] Is "+" safe for file names?

From: Beman Dawes (bdawes_at_[hidden])
Date: 2008-07-01 13:57:15

David Abrahams wrote:
> Daryle Walker wrote:
>> On Jun 27, 2008, at 12:17 PM, Beman Dawes wrote:
>>
>>> Rene Rivera wrote:
>>>> Just noticed this directory name:
>>>>   libs/filesystem/test/vc++.boost.filesystem
>>>> Is "+" safe to use across file systems?
>>> No, not in general.
>>>
>>>> Hm, actually I'm fairly sure more than one "." is not safe. For
>>>> example in the MVS systems?
>>> IIRC, there are several legacy file systems that don't support
>>> multiple periods.
>>>
>>> I'll change the offending name.  It was one I use internally, and
>>> decided to add to SVN without reconsidering the naming.
>> So, should we add a rule about non-ISO9660 names to our file-checking
>> program, and maybe the subversion pre-commit hook (as Dave said)?
>>
> 
> I vote yes

We need to decide what our standard is first. ISO-9660:1999 limits:

* Allowable characters characters are uppercase A-Z, 0-9, and 
underscore. Popular operating systems extend these to at least lowercase 
letters, but usually allow more punctuation characters.

* File names shall not include spaces.

* File names shall not start or end with the dot character.

* File names shall not have more than one dot.

* Directory names shall not use dots at all.

If we allow lowercase letters, and add a restriction that the first 
character has to be a letter or number, but otherwise stick with 
ISO-9660:1999, 1.35.0 would have 773 violations. See 
http://mysite.verizon.net/beman/temp.html

If we also allow '-', that would cut the violations to 130. See 
http://mysite.verizon.net/beman/temp1.html

Note that a-z, A-Z, 0-9, dot, hyphen, and underscore correspond to the 
POSIX portable file name requirements. So that seems to be a natural 
cut-off point for the allowable characters.

Do we also want to drop the "File names shall not have more than one 
dot" and/or "Directory names shall not use dots at all" requirements?

Have we have ever had a complaint about multiple dots in file or 
directory names?

--Beman