Re: ksh very slow compared to bash when running ghostscript's ./configure script

[Todd C . Miller]

On Wed, 22 Jul 2020 18:38:42 +0200, Theo Buehler wrote:

> Likely glob. Many glob implementations were found to suffer from
> complexity issues: https://research.swtch.com/glob
>
> The glob(3) in libc was fixed
> https://github.com/openbsd/src/commit/5c36dd0c22429e7b00ed5df80ed1383807532b5
> 9
> but ksh's builtin glog still has the issue.

At the very least we should collapse consecutive stars.  This is a
separate issue from making gmatch() iterative.

 - todd

Index: bin/ksh/misc.c
===================================================================
RCS file: /cvs/src/bin/ksh/misc.c,v
retrieving revision 1.74
diff -u -p -u -r1.74 misc.c
--- bin/ksh/misc.c      7 Jul 2020 10:33:58 -0000       1.74
+++ bin/ksh/misc.c      22 Jul 2020 19:08:20 -0000
@@ -615,6 +615,9 @@ do_gmatch(const unsigned char *s, const 
                        break;
 
                case '*':
+                       /* collapse consecutive stars */
+                       while (ISMAGIC(p[0]) && p[1] == '*')
+                               p += 2;
                        if (p == pe)
                                return 1;
                        s--;