contrib/mdocml/compat_vasprintf.c

0 #include "config.h"
3 #if HAVE_VASPRINTF
5 int dummy;
7 #else
9 /*	$Id: compat_vasprintf.c,v 1.3 2015/10/06 18:32:19 schwarze Exp $	*/
11  * Copyright (c) 2015 Ingo Schwarze <schwarze@openbsd.org>
13  * Permission to use, copy, modify, and distribute this software for any
14  * purpose with or without fee is hereby granted, provided that the above
15  * copyright notice and this permission notice appear in all copies.
17  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
18  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
19  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
20  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
21  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
22  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
23  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
25  * This fallback implementation is not efficient:
26  * It does the formatting twice.
27  * Short of fiddling with the unknown internals of the system's
28  * printf(3) or completely reimplementing printf(3), i can't think
29  * of another portable solution.
32 #include <stdarg.h>
33 #include <stdio.h>
34 #include <stdlib.h>
36 int
37 vasprintf(char **ret, const char *format, va_list ap)
39 	char	 buf[2];
40 	va_list	 ap2;
41 	int	 sz;
43 	va_copy(ap2, ap);
44 	sz = vsnprintf(buf, sizeof(buf), format, ap2);
45 	va_end(ap2);
47 	if (sz != -1 && (*ret = malloc(sz + 1)) != NULL) {
48 		if (vsnprintf(*ret, sz + 1, format, ap) == sz)
49 			return sz;
50 		free(*ret);
52 	*ret = NULL;
53 	return -1;
56 #endif