Re: $ORIGIN (was: Re: make: ensure ${.MAKE} works)

[David Holland <dholland-tech%netbsd.org@localhost>]

On Wed, Apr 28, 2010 at 02:57:47PM -0400, der Mouse wrote:
 >>> To wit: as far as I can tell, having been wading around in that code
 >>> recently, the only problem with what we have is that if the path
 >>> sent back by namei isn't absolute it needs a getcwd() stuck on the
 >>> front of it.
 > 
 >>> Is it reasonable to just do that?
 > 
 > I don't think so.  It would be a regression in that it would break
 > things in no-path-up-to-/ situations; it also would either fail or
 > expose paths that shouldn't be accessible in path-to-/-isn't-readable
 > situations.

Does anyone know how other implementations of $ORIGIN deal with these
cases?

For the time being, even if we just provide a relative path when
getcwd fails it'd still be more functional than the current situation.

 > > Why not get the kernel to keep a reference to the vnode of the
 > > directory that contained the process image?
 > 
 > > Then use some flag to open() (or similar) to open a file relative to
 > > that vnode?

Someone already invented $ORIGIN with absolute paths and we ought to
support that, especially since we already have a half-baked
implementation.

I've often thought something like this (keeping the directory) would
be a decent approach but it's not clear how to set it up, or e.g. what
ought to be done if the executable is moved or other such cases.

 > Hacking on namei() just to get an absolute path in $(.MAKE)? 

It's not just make; see for example PR 42420.

-- 
David A. Holland
dholland%netbsd.org@localhost