Re: question about hardcoded binary paths (swapon / mkswap)

[Mike Frysinger <vapier@gentoo.org>]

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On 01 Apr 2015 22:06, Ruediger Meier wrote:
> On Wednesday 01 April 2015, Mike Frysinger wrote:
> > On 01 Apr 2015 18:17, Ruediger Meier wrote:
> > > On Wednesday 01 April 2015, Isaac Dunham wrote:
> > > > On Wed, Apr 01, 2015 at 01:42:56PM +0200, Ruediger Meier wrote:
> > > > > I wonder about some hardcoded binary paths.
> > > > >
> > > > > Example swapon.c:
> > > > >
> > > > > #define PATH_MKSWAP    "/sbin/mkswap"
> > > > >
> > > > > There are a two problems.
> > > > > 1. It's wrong. We should use $sbindir from configure.
> > > > > 2. When called from our test-suite it will use a wrong (or
> > > > >    non-existend, broken) binary. This happens in test
> > > > > swapon/fixpgsz.
> > > > >
> > > > > The question is how to fix this.
> > > > >
> > > > > I would prefer to use "mkwsap" from the same directory like
> > > > > swapon or to simply execvp "mkswap" from PATH. But don't know
> > > > > if we want this. If we really want to keep a hardcoded sbindir
> > > > > then we would need "#ifdef TEST_PROGRAM".
> > > > >
> > > > > Any comments?
> > > >
> > > > The approach that seems obvious to me (assuming you want to keep
> > > > the hardcoded path) is:
> > > > -add -DSBINDIR="$sbindir" to CFLAGS
> > >
> > > Yes, this would be easy. But my preferred logic would be like this
> > >
> > > If "swapon" was called from PATH then just take mkswap from PATH
> > > too. If "/whatever/path/swapon" was called then look for mkswap in
> > > the same path.
> > >
> > > Maybe both cases also with or without fallback $sbindir, /sbin or
> > > $PATH.
> > >
> > > I guess we should agree how somthing like this should be handeled
> > > in general. "eject" is also using hardcoded "/bin/umount".
> >
> > seems like $PATH should always be used.  if you broke $PATH, well
> > that's your fualt ... tools shouldn't generally be expected to work
> > in the fact of hostile environments like this.
> > -mike
> 
> I'd also like to use PATH (at least as fallback).
> 
> The only special thing here is IMO that mkswap and swapon belong to the 
> same project. Should we try to use the right one per default?
> 
> Example:
> UL is installed below /usr/local
> PATH="/usr/local/sbin:/sbin"
> 
> Explicitly invoking the (old) globally installed /sbin/swapon should use 
> the old /sbin/mkswap too or the new /usr/local/sbin/mkswap from PATH? 
> 
> Another point:
> If "/sbin" is not in PATH should "sudo /sbin/swapon" find /sbin/mkswap 
> or not?

imo it should just use the $PATH and be done.  sudo will set up a sane path for 
you which includes /sbin.
-mike

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