Re: regcomp problem with 2.1.3

["H . J . Lu" <hjl at lucon dot org>]

On Mon, May 15, 2000 at 03:34:26PM +0200, Andreas Jaeger wrote:
> 
> Hi all,
> 
> Andreas Hartmann reported a problem with regular expressions in glibc
> 2.1.3.  He's written a small program to show the problem which I just
> polished up a little bit.
> 
> 
> The appended program gives the following error:
> $ ./a.out 
> <13>
> <Invalid preceding regular expression>
> 
> Removing either of the RE_ options results in correct behaviour, but
> the combination of both RE_BACKSLASH_ESCAPE_IN_LISTS and
> RE_CONTEXT_INDEP_ANCHORS leads to an error in regcomp.
> 
> Could somebody please investigate what's wrong here?
> 
> Thanks,
> Andreas
> 
> #include <ctype.h>
> #include <regex.h>
> #include <stdio.h>
> #include <malloc.h>
> 
> int
> main (void)
> {
>   regex_t *preg;
>   int ret;
> 
>   preg = calloc(1, sizeof(regex_t));
> 
>   if((ret = regcomp(preg, "*.ANF", RE_BACKSLASH_ESCAPE_IN_LISTS|RE_CONTEXT_INDEP_ANCHORS)) != 0)
>     {

I am confused. From regex.h:


/* If this bit is set, then ^ and $ are always anchors (outside bracket 
     expressions, of course).
   If this bit is not set, then it depends:
        ^  is an anchor if it is at the beginning of a regular 
           expression or after an open-group or an alternation operator;
        $  is an anchor if it is at the end of a regular expression, or
           before a close-group or an alternation operator.

   This bit could be (re)combined with RE_CONTEXT_INDEP_OPS, because 
   POSIX draft 11.2 says that * etc. in leading positions is undefined.
   We already implemented a previous draft which made those constructs
   invalid, though, so we haven't changed the code back.  */
#define RE_CONTEXT_INDEP_ANCHORS (RE_CHAR_CLASSES << 1)

When you have "*..ANF", you will get undefined hehavior. I have no
idea if there is an incorrect behaviour.


H.J.