Path: utzoo!mnetor!uunet!mcvax!ukc!warwick!cudcv
From: cudcv@daisy.warwick.ac.uk (Rob McMahon)
Newsgroups: comp.bugs.4bsd
Subject: C-Shell expression bug with fix
Message-ID: <479@sol.warwick.ac.uk>
Date: 13 Mar 88 19:11:09 GMT
Reply-To: cudcv@cu.warwick.ac.uk (Rob McMahon)
Organization: Computing Services, Warwick University, UK
Lines: 68

<munch>

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
broken something---that check for an operator and return("") looks very
deliberate, what did they have in mind ?  In particular "if ( x == - y )"
now breaks, it has to be "if ( x == 0 - y )", but then it seems these
only worked by accident anyway, and surely "if ( x = * y )" should be a
syntax error ?  Any comments ?

Here's the fix:

RCS file: sh.exp.c,v
retrieving revision 1.1
diff -c -r1.1 sh.exp.c
*** /tmp/,RCSt1a05867	Sun Mar 13 19:06:09 1988
--- sh.exp.c	Sun Mar 13 18:50:36 1988
***************
*** 419,426 ****
  #endif
  		return (putn(egetn(value("status")) == 0));
  	}
  	if (isa(**vp, ANYOP))
! 		return ("");
  	cp = *(*vp)++;
  	if (*cp == '-' && any(cp[1], "erwxfdzo")) {
  		struct stat stb;
--- 419,436 ----
  #endif
  		return (putn(egetn(value("status")) == 0));
  	}
+ 	/*
+ 	 * if we're looking for a pattern the globbing chars count as strings,
+ 	 * not operators.
+ 	 */
+ 	if ((ignore&NOGLOB) && (***vp == '[' || ***vp == '*'))
+ 		return (savestr(*(*vp)++));
+ 	/*
+ 	 * if we've got an operator now, then we haven't got an operand
+ 	 * for it.
+ 	 */
  	if (isa(**vp, ANYOP))
! 		bferr("Expression syntax");
  	cp = *(*vp)++;
  	if (*cp == '-' && any(cp[1], "erwxfdzo")) {
  		struct stat stb;

-- 
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Rob McMahon, Computing Services, Warwick University, Coventry CV4 7AL, England