Path: utzoo!mnetor!uunet!mcvax!unido!sbsvax!greim
From: greim@sbsvax.UUCP (Michael Greim)
Newsgroups: comp.bugs.4bsd
Subject: Re: C-shell expression bug with fix. My fix.
Message-ID: <469@sbsvax.UUCP>
Date: 23 Mar 88 14:36:49 GMT
Organization: Universitaet des Saarlandes, D-6600 Saarbruecken, FRG
Lines: 121
Keywords: csh expression pattern bug

Hi folks,

Sorry that I am a little late with this fix, but our computers got
moved to a new building, so we were rather isolated the last few days.

In <479@sol.warwick.ac.uk> Rob McMahon writes :

>One of our students reported the following bug to me:
>
> 	% if ( abc =~ * ) echo yes
> 	<silence>
> 	% if ( abc =~ ** ) echo yes
> 	yes
> 
> Further investigation gave the following:
> 
> 	% if ( 0 =~ * ) echo yes
> 	yes
> 	% if ( 2 == 2 + ) echo yes
> 	yes
> 	% if ( 2 == + 2 ) echo yes
> 	yes
> 
> The * is being treated as multiply, and the shell doesn't care that it's
> got no operands, it just fills them in with 0.  I've applied the
> following fix, but I'm slightly unsure about it because I may have
<rest deleted>

Well the fix causes some new bugs. I present here my own fix,
which seems to work slightly better. I append a file I used for testing
which demonstrates the use of patterns.

I don't think it should be an error if you tried
	if ( 2 == 2 + ) echo yes
because the manual explicitly says :
	"... Null or missing arguments are considered '0'"
so my fix only fixes the behaviour when dealing with a pattern.


FIX:

*** sh.exp.c.old	Wed Mar 23 14:29:26 1988
--- sh.exp.c	Wed Mar 23 14:27:53 1988
***************
*** 156,164 ****
  #endif
  	if (i = isa(**vp, EQOP)) {
  		(*vp)++;
! 		if (i == EQMATCH || i == NOTEQMATCH)
  			ignore |= NOGLOB;
! 		p2 = exp3(vp, ignore);
  #ifdef EDEBUG
  		etracc("exp2c p2", p2, vp);
  #endif
--- 156,167 ----
  #endif
  	if (i = isa(**vp, EQOP)) {
  		(*vp)++;
! 		if (i == EQMATCH || i == NOTEQMATCH) {
  			ignore |= NOGLOB;
! 			p2 = **vp;
! 			(*vp)++;
! 		} else
! 			p2 = exp3(vp, ignore);
  #ifdef EDEBUG
  		etracc("exp2c p2", p2, vp);
  #endif

TESTS:

if ( abc =~ * ) then
	echo "ok 1"
else
	echo "false 1"
endif
if ( "abc" =~ * ) then
	echo "ok 2"
else
	echo "false 2"
endif
set abc='d b'
if ( "$abc" =~ d\ * ) then
	echo "ok 3"
else
	echo "false 3"
endif
set abc='234 - zzz'
if ( "$abc" =~ [1-9]*\ -\ ??? ) then
	echo "ok 4"
else
	echo "false 4"
endif
set abc='"abc"'
if ( $abc =~ \"*\" ) then
	echo "ok 5"
else
	echo "false 5"
endif
set abc='misty?hallo'
set def='call.me'
if ( $abc =~ *\?* && $def !~ *\?me ) then
	echo "ok 6"
else
	echo "false 6"
endif


Running this file through old csh should produce :
false 1
false 2
ok 3
ok 4
ok 5
misty?hallo: no match

Running cured csh returns for all cases "ok".


Have a nice day,

		Michael