upstream: add xextendf() to extend a string with a format

(reallocating as necessary). ok aja@ as part of a larger diff

OpenBSD-Commit-ID: 30796b50d330b3e0e201747fe40cdf9aa70a77f9

1 files changed, 3 insertions, 1 deletions

diff --git a/misc.h b/misc.h
index 2221a54c8..4a05db2da 100644
--- a/misc.h
+++ b/misc.h
@@ -1,4 +1,4 @@
-/* $OpenBSD: misc.h,v 1.83 2020/01/23 07:10:22 dtucker Exp $ */
+/* $OpenBSD: misc.h,v 1.84 2020/01/24 23:54:40 djm Exp $ */
 
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
@@ -69,6 +69,8 @@ long	 convtime(const char *);
 char    *tilde_expand_filename(const char *, uid_t);
 char    *percent_expand(const char *, ...) __attribute__((__sentinel__));
 char    *tohex(const void *, size_t);
+void     xextendf(char **s, const char *sep, const char *fmt, ...)
+    __attribute__((__format__ (printf, 3, 4))) __attribute__((__nonnull__ (3)));
 void     sanitise_stdfd(void);
 void     ms_subtract_diff(struct timeval *, int *);
 void     ms_to_timeval(struct timeval *, int);