This patch corrects "Edit [erw] filename" errors when "filename" is unrooted.
Under this condition the effective file name becomes the entire tag line. (Button 
3 clicking on an unrooted file name in the tag line also fails, but silently.)

The propsed change to dirname() explicitly sets a terminating null for the
unrooted file name case.

Notes:
Wed Mar 23 13:37:41 EST 2005 rsc
    Thanks for the report.  Your fix only sets the terminating
    NUL in one case of dirname, and even then only if cleanname
    doesn't shorten the name at all: with your fix I believe 
    that if one did Edit e ../edit.c, you'd still end up with
    something like /whatever/edit.ct.c being returned.
    We can't set the NUL in the general case because the
    dirname might not have had space allocated for it.
    
    Instead I fixed cmdname to add the NUL itself, which it
    should have been doing all along.
    
    I didn't understand your comment about button 3 failing.
    I click button 3 on unrooted file names in tags all the time
    and have no problems.  Did you mean it fails after a bogus
    Edit e command?
    
    Russ
    


Reference: /n/sources/patch/applied/acme-look
Date: Wed Mar 23 08:06:27 CET 2005
Reviewed-by: rsc

--- /sys/src/cmd/acme/look.c	Wed Mar 23 08:06:09 2005
+++ /sys/src/cmd/acme/look.c	Wed Mar 23 08:05:55 2005
@@ -423,6 +423,7 @@
 	if(slash < 0)
 		goto Rescue;
 	runemove(b+slash+1, r, n);
+	b[slash+1+n] = '\0';
 	free(r);
 	return cleanrname((Runestr){b, slash+1+n});