Re: gawk long lines bug?

[dslate]

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Subject: Re: gawk long lines bug?

I applied Paul's mod to re.c (in gawk-3.1.0.tar.gz), and it does seem to
fix my test case.

Thanks,

-- Dave Slate


> > From: Aharon Robbins <address@hidden>
> > Date: Sun, 17 Feb 2002 15:09:18 +0200
> > 
> > The problem is that the regex routines return -2 indicating that they
> > couldn't allocate enough memory to handle the long string
> 
> That -2 doesn't mean that they couldn't allocate enough memory; it
> means that they merely went over a heuristic limit designed to prevent
> them from allocating too much memory on the C stack.  This heuristic
> doesn't apply to gawk, since it compiles with REGEX_MALLOC.
> 
> This is clearly a bug in regex.c, but there's an easy workaround:
> raise that heuristic limit to be as high as possible.  That way, you
> won't run into this silly limit until much later.
> 
> The following patch causes 'gawk' to work correctly on that test case,
> without any error.
> 
> 2002-02-17  Paul Eggert  <address@hidden>
> 
>       * re.c (resetup): Try to avoid silly limitation of regex.c by
>       setting re_max_failures to the largest reasonable value.
> 
> ===================================================================
> RCS file: re.c,v
> retrieving revision 3.1.0.1
> retrieving revision 3.1.0.2
> diff -pu -r3.1.0.1 -r3.1.0.2
> --- re.c      2002/02/18 05:45:27     3.1.0.1
> +++ re.c      2002/02/18 06:58:40     3.1.0.2
> @@ -245,6 +245,18 @@ re_update(NODE *t)
>  void
>  resetup()
>  {
> +     /*
> +      * Set RE_MAX_FAILURES to the largest reasonable value,
> +      * to avoid spurious "not enough memory" messages.
> +      * The '80' is computed as follows:
> +      * regex.c's MAX_FAILURE_ITEMS is at most 20.
> +      * regex.c computes 2 * MAX_FAILURE_ITEMS, giving us 40.
> +      * re_max_failures is signed, not unsigned, for another factor of 2,
> +      * giving us 80.
> +      */
> +     extern int re_max_failures;
> +     re_max_failures = ((unsigned) -1) / 80;
> +
>       if (do_posix)
>               syn = RE_SYNTAX_POSIX_AWK;      /* strict POSIX re's */
>       else if (do_traditional)