user/962: m4 STREQ broken

[ca+openbsd@zardoc.endmail.org]

>Number:         962
>Category:       user
>Synopsis:       STREQ in m4 is seriously broken
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    bugs
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Tue Nov  2 10:00:01 MST 1999
>Last-Modified:
>Originator:     Claus Assmann
>Organization:
endmail.ORG
>Release:        OpenBSD 2.6
>Environment:
	System      : OpenBSD 2.6
	Architecture: OpenBSD.i386
	Machine     : i386
>Description:
	the definition of STREQ in m4/stdd.h is seriously broken!
	it accesses empty strings after their end.

>How-To-Repeat:
	create t.m4 with content:
	ifelse(`', `', `OK',`WRONG')

	then run m4 t.m4

>Fix:
--- stdd.h	Tue Nov  2 08:47:43 1999
+++ /usr/src/usr.bin/m4/stdd.h	Wed Sep 22 14:44:38 1999
@@ -52,7 +52,7 @@
  * STREQ is an optimised strcmp(a,b)==0 
  * STREQN is an optimised strncmp(a,b,n)==0; assumes n > 0 
  */
-#define STREQ(a, b) ((a)[0] == (b)[0] && strcmp((a), (b)) == 0)
+#define STREQ(a, b) ((a)[0] == (b)[0] && strcmp((a)+1, (b)+1) == 0)
 #define STREQN(a, b, n) ((a)[0] == (b)[0] && strncmp((a)+1, (b)+1, (n)-1) == 0)
 
 #define YES 1

>Audit-Trail:
>Unformatted: