Re: BUG #15120: use of getcwd(3)/chdir(2) during path resolution (exec.c)

>>>>> "Tom" == Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> writes:

Tom> ... I find that quite an unacceptable answer. We need to resolve
Tom> the symlink correctly, or we risk malfunctioning later, for the
Tom> reasons recited in the comment for find_my_exec().

On systems with openat(), would it not be possible to resolve symlinks
without ever needing chdir?

Tom> I think your example of "sudo /usr/bin/pg_ctl" is pretty
Tom> artificial; who'd bother spelling that out?

Not necessarily exactly like that, but we do occasionally get this issue
coming up on the IRC channel.

Tom> While I've not thought about it very hard, it might be possible to
Tom> rewrite find_my_exec() and resolve_symlinks() "from the ground up"
Tom> so that they don't do getcwd() except in cases where there's
Tom> really no alternative, such as the executable having been invoked
Tom> using a relative path.

I think getcwd is avoidable even then, if openat() etc. are available.

--
Andrew (irc:RhodiumToad)