Appimage chdir'ing so relative paths doesn't work

[Dirk Hohndel]

On Thu, Jan 12, 2017 at 09:49:18PM -0800, Dirk Hohndel wrote:
> On Tue, Jan 10, 2017 at 07:17:06PM +0100, probono wrote:
> > 2017-01-08 19:30 GMT+01:00 Dirk Hohndel <dirk at hohndel.org>:
> > >> On Jan 8, 2017, at 09:38, Anton Lundin <glance at acc.umu.se> wrote:
> > >> Hi.
> > >>
> > >> I was about to test some stuff with the appimage-build and noted:
> > >>
> > >> strace -e chdir,open ./Subsurface-4.6-Beta-2-x86_64.AppImage testdata/ostc4.xml |& grep -E 'ostc|chdir'
> > >> chdir("/tmp/.mount_xyn3Tx")             = 0
> > >> chdir("usr")                            = 0
> > >> open("testdata/ostc4.xml", O_RDONLY) = -1 ENOENT (No such file or directory)
> > >>
> > >>
> > >> The chdir'ing might make sense in some case, but in this case it really
> > >> doesn't.
> > >
> > > I think it needs to chdir in order to find its libraries, but I haven't looked
> > > at this in enough detail.
> > 
> > The chdir is required only in cases in which binaries are not
> > relocatable at runtime (i.e., "/usr" is hardcoded at compile time, for
> > example for loading resources). If this is not the case (e.g., in the
> > case of Subsurface), then we should get away without chdir'ing.
> 
> I've played around with this for a bit and it's actually quite a bit more
> complicated than that. All the paths in AppRun.c are currently relative
> paths - so this needs a bit of work that goes beyond "just don't do that
> chdir".

OK, that took a LOT longer than I expected, but over lunch I finally think
I made it work...

Anton, can you try the latest AppImage from downloads/daily? That should
now avoid the chdir and work with relative paths as well.

/D