From owner-cvs-all  Sat Mar 16 18:55:56 2002
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Date: Sun, 17 Mar 2002 13:57:24 +1100 (EST)
From: Bruce Evans <bde@zeta.org.au>
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Subject: Re: cvs commit: src/share/man/man4 ng_pptpgre.4
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On Sun, 17 Mar 2002, I wrote:

> That may be, but ispell is not man's best friend:
>
>     $ man ispell
>     Segmentation fault (core dumped)
>
> The bug seems to be in libz.  Upgrading to the previous version of libz
> fixes it.

The following patch (obtained from the upgrade) fixes "man ispell"
(but may break libz).

%%%
Index: infcodes.c
===================================================================
RCS file: /home/ncvs/src/lib/libz/infcodes.c,v
retrieving revision 1.3
diff -u -2 -r1.3 infcodes.c
--- infcodes.c	11 Mar 2002 22:36:26 -0000	1.3
+++ infcodes.c	17 Mar 2002 02:41:53 -0000
@@ -201,5 +201,5 @@
     case COPY:          /* o: copying bytes in window, waiting for space */
       f = q - c->sub.copy.dist;
-      while (f < s->window)             /* modulo window size-"while" instead */
+      if (f < s->window)                /* modulo window size-"while" instead */
         f += s->end - s->window;        /* of "if" handles invalid distances */
       while (c->len)
%%%

The while loop caused some pointer to become invalid.  I think the bug
is really in gcc.  The register hildng 's' seemed to get clobbered to
(s->end - s->window) so 's' was invalid after 1 iteration.  With an
"if" instead of a "while", gcc generates simpler code with line numbers
that are actually correct and without the register clobber.  Compiling
the unpatched version with -O0 also unbreaks "man ispell".

Bruce


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