From: Collin Funk <collin.funk1@gmail.com>
To: Leah Neukirchen <leah@vuxu.org>, Rich Felker <dalias@libc.org>
Cc: musl@lists.openwall.com
Subject: Re: [musl] getusershell should ignore comments and empty lines.
Date: Thu, 23 May 2024 06:59:42 -0700 [thread overview]
Message-ID: <cca07bee-bbc7-449c-92b5-767d7b56c8e1@gmail.com> (raw)
In-Reply-To: <87pltc63rt.fsf@vuxu.org>
Hi Rich and Leah,
On 5/23/24 6:45 AM, Leah Neukirchen wrote:
>> "A hash mark (``#'') indicates the beginning of a comment;
>> subsequent characters up to the end of the line are not
>> interpreted by the routines which search the file."
>>
>> This isn't very clear whether # is only a comment on the beginning of
>> a line (after potential whitespace?) or whether # appearing in a line
>> with a shell pathname is a comment or part of the pathname. If it's a
>> comment, it's not clear if whitespace before it is part of the shell
>> pathname -- e.g. does "/bin/sh # best shell" define "/bin/sh" or
>> "/bin/sh " as the shell pathname?
>>
>> It sounds like nobody ever thought about whitespace, quoting, or
>> rigorous comment syntax here...
>
> True:
>
> OpenBSD drops the rest of the line with "#" and ignores lines not
> starting with a "/".
>
> glibc drops the rest of the line with "#", elides spaces after the
> entry, and skips everything before the first "/" (quite bold).
I noticed the glibc behavior as well, but I thought the BSDs did it
too. Like this:
'bin/bash' -> '/bash'
which is interesting. :)
I think the general algorithm is read a single line. Find the first
'/' character and then begin at the next character. Then continue
until the end of line or other whitespace character. Perhaps the
others felt that was awkward and changed it, I am not sure.
I think it would be nice to ignore lines starting with '#' though and
empty lines. That should cover 99% of cases. Most distributions,
including Alpine Linux, come with an '/etc/shells' like this:
===================
# Some commentary redirecting to a man page or other documentation.
/bin/sh
/bin/bash
/usr/bin/sh
/usr/bin/bash
===================
I doubt anyone changes it from that simple format.
Collin
next prev parent reply other threads:[~2024-05-23 13:59 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-05-18 3:17 Collin Funk
2024-05-23 13:21 ` Rich Felker
2024-05-23 13:45 ` Leah Neukirchen
2024-05-23 13:59 ` Collin Funk [this message]
2024-05-23 14:47 ` Rich Felker
2024-05-23 15:27 ` Rich Felker
2024-05-25 0:16 ` Collin Funk
2024-06-22 1:06 ` Rich Felker
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=cca07bee-bbc7-449c-92b5-767d7b56c8e1@gmail.com \
--to=collin.funk1@gmail.com \
--cc=dalias@libc.org \
--cc=leah@vuxu.org \
--cc=musl@lists.openwall.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
Code repositories for project(s) associated with this public inbox
https://git.vuxu.org/mirror/musl/
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).