Path: utzoo!mnetor!uunet!husc6!rutgers!ucla-cs!zen!ucbvax!OKEEFFE.BERKELEY.EDU!bostic
From: bostic@OKEEFFE.BERKELEY.EDU (Keith Bostic)
Newsgroups: comp.bugs.2bsd
Subject: V1.21 (strncat is broken)
Message-ID: <8801062002.AA15696@okeeffe.Berkeley.EDU>
Date: 6 Jan 88 20:02:27 GMT
Sender: daemon@ucbvax.BERKELEY.EDU
Lines: 35

Subject: strncat is broken
Index: lib/libc/pdp/gen/strncat.s 2.10BSD

Description:
	strncat(3) doesn't truncate strings correctly.

Repeat-By:
	The following program demonstrates the bug.

	#include <stdio.h>
	#include <strings.h>
	main()
	{
		char *s = "This is a long string, but we'll truncate it at the comma";
		s[21] = '\0';
		printf("%s\n", s);
		strncat(s, "Arragh!!", 7);
		printf("%s\n", s);
	}

Fix:
	Apply the following patch.

*** strncat.s.orig	Wed Jan  6 11:41:24 1988
--- strncat.s	Wed Jan  6 11:41:34 1988
***************
*** 36,41 ****
--- 36,42 ----
  	movb	(r2)+,(r1)+	/ copy s2 to the end of s1 stopping at the
  	beq	3f		/   end of s2 or when n runs out ...
  	sob	r0,2b
+ 	clrb	(r1)
  3:
  	mov	(sp)+,r2	/ restore r2
  4: