Re: uninitialized variables

[Ralf Wildenhues]

Hi Paul,

* Paul Eggert wrote on Mon, Nov 07, 2005 at 03:07:10AM CET:
> Ralf Wildenhues <address@hidden> writes:
> 
> > +  tmp=
> >    trap 'exit_status=$?; rm -fr "$tmp" && exit $exit_status' 0
> 
> On ancient systems, "" is an alias for ".",

Should this be mentioned in autoconf.texi?  Do you know offhand of such
a system?  I'm trying to evaluate whether I need to audit Libtool for
this.

> so can you please change
> the code to check whether tmp is empty?  Also, we should check that
> $tmp is a directory, for the same reason that AS_TMPDIR does.
> Something like this, perhaps?
> 
> trap '
>   exit_status=$?
>   { test -z "$tmp" || test ! -d "$tmp" || rm -fr "$tmp"; } && exit 
> $exit_status
> ' 0
> 
> This code still has a race condition, as tmpdir might not get cleaned
> up if the script is interrupted between the time the directory is made
> and $tmp is assigned to.  Perhaps that could be in a comment somewhere.

How about this?

        * lib/autoconf/status.m4 (_AC_OUTPUT_MAIN_LOOP): Initialize
        `tmp' to avoid file removal race.

Index: lib/autoconf/status.m4
===================================================================
RCS file: /cvsroot/autoconf/autoconf/lib/autoconf/status.m4,v
retrieving revision 1.77
diff -u -r1.77 status.m4
--- lib/autoconf/status.m4      21 Oct 2005 07:36:32 -0000      1.77
+++ lib/autoconf/status.m4      7 Nov 2005 06:46:44 -0000
@@ -1317,9 +1322,14 @@
 # simply because there is no reason against having it here, and in addition,
 # creating and moving files from /tmp can sometimes cause problems.
 # Hook for its removal unless debugging.
+# Note that there is a small window in which the directory will not be cleaned:
+# after its creation but before its name has been assigned to `$tmp'.
 $debug ||
 {
-  trap 'exit_status=$?; rm -fr "$tmp" && exit $exit_status' 0
+  tmp=
+  trap 'exit_status=$?
+  { test -z "$tmp" || test ! -d "$tmp" || rm -fr "$tmp"; } && exit $exit_status
+' 0
   trap 'AS_EXIT([1])' 1 2 13 15
 }
 dnl The comment above AS_TMPDIR says at most 4 chars are allowed.

> >         * lib/autoconf/general.m4 (_AC_INIT_DEFAULTS): Initialize
> >         ac_clean_files and LIBOBJS.
> 
> That looks good to me; please install.

Done.  Thanks for the review.

Cheers,
Ralf