===================================================================
RCS file: /cvsrepo/anoncvs/cvs/src/usr.bin/ssh/misc.c,v
retrieving revision 1.144
retrieving revision 1.145
diff -u -r1.144 -r1.145
--- src/usr.bin/ssh/misc.c	2020/01/23 07:10:22	1.144
+++ src/usr.bin/ssh/misc.c	2020/01/24 23:54:40	1.145
@@ -1,4 +1,4 @@
-/* $OpenBSD: misc.c,v 1.144 2020/01/23 07:10:22 dtucker Exp $ */
+/* $OpenBSD: misc.c,v 1.145 2020/01/24 23:54:40 djm Exp $ */
 /*
  * Copyright (c) 2000 Markus Friedl.  All rights reserved.
  * Copyright (c) 2005,2006 Damien Miller.  All rights reserved.
@@ -1201,6 +1201,33 @@
 	}
 	return (r);
 }
+
+/*
+ * Extend string *sp by the specified format. If *sp is not NULL (or empty),
+ * then the separator 'sep' will be prepended before the formatted arguments.
+ * Extended strings are heap allocated.
+ */
+void
+xextendf(char **sp, const char *sep, const char *fmt, ...)
+{
+	va_list ap;
+	char *tmp1, *tmp2;
+
+	va_start(ap, fmt);
+	xvasprintf(&tmp1, fmt, ap);
+	va_end(ap);
+
+	if (*sp == NULL || **sp == '\0') {
+		free(*sp);
+		*sp = tmp1;
+		return;
+	}
+	xasprintf(&tmp2, "%s%s%s", *sp, sep == NULL ? "" : sep, tmp1);
+	free(tmp1);
+	free(*sp);
+	*sp = tmp2;
+}
+
 
 u_int64_t
 get_u64(const void *vp)