[mpol@charybda.icm.edu.pl: Bug#306346: zsh: replacement seems broken in prompt]

[mpol@charybda.icm.edu.pl: Bug#306346: zsh: replacement seems broken in prompt]

[Clint Adams]

This is with 21170.

----- Forwarded message from Michal Politowski <mpol@charybda.icm.edu.pl> -----

Date: Tue, 26 Apr 2005 00:01:18 +0200
From: Michal Politowski <mpol@charybda.icm.edu.pl>
To: Debian Bug Tracking System <submit@bugs.debian.org>
Subject: Bug#306346: zsh: replacement seems broken in prompt

4.2.5-4 didn't show this behaviour, so maybe it's the newest patch.
${${foo}/?*/replacement} puts replacement in the prompt even when foo is empty
${foo/?*/replacement} works as expected.

On the command line, echo ${...} works as expected for both expressions,
printing nothing when foo is the empty string.

----- End forwarded message -----

Re: [mpol@charybda.icm.edu.pl: Bug#306346: zsh: replacement seems broken in prompt]

[Bart Schaefer]

On Apr 25,  9:37pm, Clint Adams wrote:
} Subject: [mpol@charybda.icm.edu.pl: Bug#306346: zsh: replacement seems bro
}
} This is with 21170.
} 
} ----- Forwarded message from Michal Politowski <mpol@charybda.icm.edu.pl> -----
} 
} ${${foo}/?*/replacement} puts replacement in the prompt even when foo is empty

Hrm.  This seems to be strictly a promptsubst thing, because

schaefer<505> echo ${${foo}/?*/replacement}

schaefer<506> RPS1='${${foo}/?*/replacement}'
schaefer<507> setopt promptsubst                       ${${foo}/?*/replacement}
schaefer<508>                                                       replacement

Ah, here's an easier way to reproduce it:

schaefer<510> echo "${${foo}/?*/replacement}"
replacement

So it's a quoting thing.

According to GDB, both before and after 21170 the inner ${foo} is
resulting in "\233\0" (which is a Nularg).  After 21170, however, the
comparison against ?* matches this as one character.

The problem is here at line 2344:

2344                        if (pattrylen(p, t, s + l - t, umlen, ioff)) {

And it seems that this is the answer to the question in pattern.c:

    /* inherited from domatch, but why, exactly? */
    if (*string == Nularg)
	string++;

This is precisely the case we're encountering here; it changes the value
of unmetalen within pattryrefs() in a way that we're not changing it
when precomputing it in igetmatch().

What I don't know, though, is whether the Nularg test should be copied
into both igetmatch() and down to by the ztrsub() call in pattryrefs(),
or whether it should simply be

    /* inherited from domatch, but why, exactly? */
    if (*string == Nularg)
	string++, unmetalen--;

Re: [mpol@charybda.icm.edu.pl: Bug#306346: zsh: replacement seems broken in prompt]

[Peter Stephenson]

Bart Schaefer wrote:
> What I don't know, though, is whether the Nularg test should be copied
> into both igetmatch() and down to by the ztrsub() call in pattryrefs(),
> or whether it should simply be
> 
>     /* inherited from domatch, but why, exactly? */
>     if (*string == Nularg)
> 	string++, unmetalen--;

I'd be inclined to keep it local and use this fix.  (This can end up
with unmetalen being -2, but that doesn't matter.)  Here's a test, too.

Index: Src/pattern.c
===================================================================
RCS file: /cvsroot/zsh/zsh/Src/pattern.c,v
retrieving revision 1.25
diff -u -r1.25 pattern.c
--- Src/pattern.c	24 Apr 2005 00:38:15 -0000	1.25
+++ Src/pattern.c	26 Apr 2005 09:40:40 -0000
@@ -1552,8 +1552,10 @@
 	*nump = 0;
     }
     /* inherited from domatch, but why, exactly? */
-    if (*string == Nularg)
+    if (*string == Nularg) {
 	string++;
+	unmetalen--;
+    }
 
     if (stringlen < 0)
 	stringlen = strlen(string);
Index: Test/D04parameter.ztst
===================================================================
RCS file: /cvsroot/zsh/zsh/Test/D04parameter.ztst,v
retrieving revision 1.9
diff -u -r1.9 D04parameter.ztst
--- Test/D04parameter.ztst	21 May 2003 16:21:01 -0000	1.9
+++ Test/D04parameter.ztst	26 Apr 2005 09:40:40 -0000
@@ -599,3 +599,8 @@
 >said
 >i
 >willJOYCE
+
+  foo=
+  print "${${foo}/?*/replacement}"
+0:Quoted zero-length strings are handled properly
+>

-- 
Peter Stephenson <pws@csr.com>                  Software Engineer
CSR PLC, Churchill House, Cambridge Business Park, Cowley Road
Cambridge, CB4 0WZ, UK                          Tel: +44 (0)1223 692070


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Re: [mpol@charybda.icm.edu.pl: Bug#306346: zsh: replacement seems broken in prompt]

[Bart Schaefer]

On Apr 26, 10:44am, Peter Stephenson wrote:
} Subject: Re: [mpol@charybda.icm.edu.pl: Bug#306346: zsh: replacement seems
}
} > or whether it should simply be
} > 
} >     /* inherited from domatch, but why, exactly? */
} 
} I'd be inclined to keep it local and use this fix.

Maybe we should update the comment as well?

-- 
Bart Schaefer                                 Brass Lantern Enterprises
http://www.well.com/user/barts              http://www.brasslantern.com

Zsh: http://www.zsh.org | PHPerl Project: http://phperl.sourceforge.net