upstream: add allocating variant of the safe utf8 printer; ok

dtucker as part of a larger diff

OpenBSD-Commit-ID: 037e2965bd50eacc2ffb49889ecae41552744fa0

utf8.c

@@ -1,4 +1,4 @@
-/* $OpenBSD: utf8.c,v 1.9 2020/03/06 18:12:55 markus Exp $ */
+/* $OpenBSD: utf8.c,v 1.10 2020/04/03 02:25:21 djm Exp $ */
 /*
  * Copyright (c) 2016 Ingo Schwarze <schwarze@openbsd.org>
  *
@@ -255,6 +255,20 @@ snmprintf(char *str, size_t sz, int *wp, const char *fmt, ...)
 	return ret;
 }
 
+int
+asmprintf(char **outp, size_t sz, int *wp, const char *fmt, ...)
+{
+	va_list	 ap;
+	int	 ret;
+
+	*outp = NULL;
+	va_start(ap, fmt);
+	ret = vasnmprintf(outp, sz, wp, fmt, ap);
+	va_end(ap);
+
+	return ret;
+}
+
 /*
  * To stay close to the standard interfaces, the following functions
  * return the number of non-NUL bytes written.

utf8.h

@@ -1,4 +1,4 @@
-/* $OpenBSD: utf8.h,v 1.1 2016/05/25 23:48:45 schwarze Exp $ */
+/* $OpenBSD: utf8.h,v 1.2 2020/04/03 02:25:21 djm Exp $ */
 /*
  * Copyright (c) 2016 Ingo Schwarze <schwarze@openbsd.org>
  *
@@ -22,4 +22,6 @@ int	 fmprintf(FILE *, const char *, ...)
 int	 vfmprintf(FILE *, const char *, va_list);
 int	 snmprintf(char *, size_t, int *, const char *, ...)
 	     __attribute__((format(printf, 4, 5)));
+int	 asmprintf(char **, size_t, int *, const char *, ...)
+	     __attribute__((format(printf, 4, 5)));
 void	 msetlocale(void);