On Fri, 29 Sep 2017, Mikulas Patocka wrote:
>
>
> On Thu, 28 Sep 2017, Eduardo A. Bustamante López wrote:
>
> > On Thu, Sep 28, 2017 at 11:44:02AM +0200, Mikulas Patocka wrote:
> > [...]
> > > +++ bash/variables.c
> > > @@ -899,7 +899,7 @@ set_pwd ()
> > > don't find OLDPWD in the environment, or it doesn't name a
> > > directory,
> > > make a dummy invisible variable for OLDPWD, and mark it as
> > > exported. */
> > > temp_var = find_variable ("OLDPWD");
> > > - if (temp_var == 0 || value_cell (temp_var) == 0 || file_isdir
> > > (value_cell (temp_var)) == 0)
> > > + if (temp_var == 0 || value_cell (temp_var) == 0)
> > > {
> > > temp_var = bind_variable ("OLDPWD", (char *)NULL, 0);
> >
> > This patch would revert the change introduced in:
> >
> > http://git.savannah.gnu.org/cgit/bash.git/commit/?h=devel&id=e6f5e0c858b7c0839d346d7d55e56894648c5a33
>
> This patch doesn't revert the above change. It only removes a test if
> $OLDPWD is a directory. With this patch, if $OLDPWD points to a directory,
> there will be no change, and if $OLDPWD points to non-directory, it will
> not be cleared.
>
> > Which was prompted by the following bug report from John Wiersba:
> > https://lists.gnu.org/archive/html/bug-bash/2015-11/msg00115.html
> >
> > Correct me if I'm wrong, but a hanged sshfs mount will cause many more
> > issues, not only with OLDPWD.
>
> Hung mount shouldn't cause problems unless someone is accessing it.
>
> What happened to me - I use the autofs filesystem to automatically mount
> filesystems on various machines. I was on some autofs-mounted directory, I
> moved to the home directory (which is not on autofs) and I typed startx.
> Some times after that I shut down the remote machine that provided the
> autofs mount.
>
> The whole X session started to severely mibehave, starting various
> programs caused hangs, I couldn't even start an xterm with the shell, I
> couldn't even start the chome browser - the reason for the hangs was, that
> the OLDPWD variable pointing to the autofs directory ended up being
> propagated to the Xserver, to the desktop environment and to any program
> that was running within the X session. I caused serious trouble and I
> think it should be fixed.
>
> If I started Xwindow on the non-functioning autofs directory, it would be
> expected that I get hangs. However, I started Xwindow in the home
> directory that has nothing to do with autofs - and I got hangs.
>
> Mikulas
Another problem is that various daemons change the working directory to
"/", so that they don't keep the directory they were started from open -
however they don't clear the $OLDPWD environment variable.
So the $OLDPWD variable in a daemon could contain arbitrary garbage. If
the $OLDPWD variable points to some network directory that is currently
inaccessible, the daemon won't be able to start any bash scripts.
Mikulas
