From 92eb952610a47e72b227f82fa5b443acef185daa Mon Sep 17 00:00:00 2001
From: Theo de Raadt <deraadt@cvs.openbsd.org>
Date: Tue, 7 Jul 1998 07:12:54 +0000
Subject: per XPG, gethostname() with a short buffer returns truncated data -
 not ENOMEM. As permitted, make the truncated buffer be NUL terminated. make
 getdomainname() match.

---
 sys/kern/kern_sysctl.c | 50 +++++++++++++++++++++++++++++++++++++++++++-------
 1 file changed, 43 insertions(+), 7 deletions(-)

(limited to 'sys/kern/kern_sysctl.c')

diff --git a/sys/kern/kern_sysctl.c b/sys/kern/kern_sysctl.c
index c0d0316cfa7..bf8ec43273d 100644
--- a/sys/kern/kern_sysctl.c
+++ b/sys/kern/kern_sysctl.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: kern_sysctl.c,v 1.25 1998/06/02 06:10:28 deraadt Exp $	*/
+/*	$OpenBSD: kern_sysctl.c,v 1.26 1998/07/07 07:12:40 deraadt Exp $	*/
 /*	$NetBSD: kern_sysctl.c,v 1.17 1996/05/20 17:49:05 mrg Exp $	*/
 
 /*-
@@ -246,13 +246,13 @@ kern_sysctl(name, namelen, oldp, oldlenp, newp, newlen, p)
 		securelevel = level;
 		return (0);
 	case KERN_HOSTNAME:
-		error = sysctl_string(oldp, oldlenp, newp, newlen,
+		error = sysctl_tstring(oldp, oldlenp, newp, newlen,
 		    hostname, sizeof(hostname));
 		if (newp && !error)
 			hostnamelen = newlen;
 		return (error);
 	case KERN_DOMAINNAME:
-		error = sysctl_string(oldp, oldlenp, newp, newlen,
+		error = sysctl_tstring(oldp, oldlenp, newp, newlen,
 		    domainname, sizeof(domainname));
 		if (newp && !error)
 			domainnamelen = newlen;
@@ -478,17 +478,53 @@ sysctl_string(oldp, oldlenp, newp, newlen, str, maxlen)
 	size_t newlen;
 	char *str;
 	int maxlen;
+{
+	return sysctl__string(oldp, oldlenp, newp, newlen, str, maxlen, 0);
+}
+
+int
+sysctl_tstring(oldp, oldlenp, newp, newlen, str, maxlen)
+	void *oldp;
+	size_t *oldlenp;
+	void *newp;
+	size_t newlen;
+	char *str;
+	int maxlen;
+{
+	return sysctl__string(oldp, oldlenp, newp, newlen, str, maxlen, 1);
+}
+
+int
+sysctl__string(oldp, oldlenp, newp, newlen, str, maxlen, trunc)
+	void *oldp;
+	size_t *oldlenp;
+	void *newp;
+	size_t newlen;
+	char *str;
+	int maxlen;
+	int trunc;
 {
 	int len, error = 0;
+	char c;
 
 	len = strlen(str) + 1;
-	if (oldp && *oldlenp < len)
-		return (ENOMEM);
+	if (oldp && *oldlenp < len) {
+		if (trunc == 0 || *oldlenp == 0)
+			return (ENOMEM);
+	}
 	if (newp && newlen >= maxlen)
 		return (EINVAL);
 	if (oldp) {
-		*oldlenp = len;
-		error = copyout(str, oldp, len);
+		if (trunc && *oldlenp < len) {
+			/* XXX save & zap NUL terminator while copying */
+			c = str[*oldlenp-1];
+			str[*oldlenp-1] = '\0';
+			error = copyout(str, oldp, *oldlenp);
+			str[*oldlenp-1] = c;
+		} else {
+			*oldlenp = len;
+			error = copyout(str, oldp, len);
+		}
 	}
 	if (error == 0 && newp) {
 		error = copyin(newp, str, newlen);
-- 
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