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Message-ID: <5726D80C.2000006@landley.net>
Date: Sun, 1 May 2016 23:31:08 -0500
From: Rob Landley <rob@...dley.net>
To: Rich Felker <dalias@...c.org>
Cc: j-core@...ts.j-core.org, musl@...ts.openwall.com
Subject: Re: [J-core] updated cross-compiler build system
On 05/01/2016 09:58 PM, Rich Felker wrote:
>>> The dep was wrong, but the quoting was intentional, albeit untested.
In bash you can ${blah:-defaultvalue}, but make is crazy.
>>> The idea was to make broken symlinks that would then ENOENT out if the
>>> caller does not want to provide these libs (i.e. wants to use the
>>> system ones). But apparently symlink(2) fails with ENOENT in this
>>> case, so I need a new solution...
>>
>> I don't understand? Your _destination_ must exist. Your source can more
>> or less be an arbitrary string.
>
> Except the empty string. Linux's symlink(2) fails with ENOENT when the
> source is a zero-length string. I'm skeptical whether this behavior is
> conforming.
Looks like it was introduced in Linux 0.99.7 back in 1993. In my
one-big-repository going back to 0.0.1 it's commit a2a2a154ed6 and the
comment is:
+ * POSIX.1 2.4: an empty pathname is invalid (ENOENT).
Posix says:
http://pubs.opengroup.org/onlinepubs/9699919799/functions/symlink.html
[ENOENT]
A component of the path prefix of path2 does not name an existing file
or path2 is an empty string.
And this would be also ENOENTing for path1 _and_ path2, but I'm pretty
sure that if Linux has had a historical behavior for 23 years and nobody
cared to correct it, Posix is what's wrong.
NetBSD wasn't sure what to do a few years ago:
https://mail-index.netbsd.org/tech-kern/2013/11/01/msg015865.html
MacOS fsck considers zero length symlinks to be an error in HFS:
https://www.reddit.com/r/applehelp/comments/25h4by/2009_macbook_pro_failing_to_start/
Rob
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