1 /*
2  * Copyright (c) 2015 Ingo Schwarze <schwarze@openbsd.org>
3  *
4  * Permission to use, copy, modify, and distribute this software for any
5  * purpose with or without fee is hereby granted, provided that the above
6  * copyright notice and this permission notice appear in all copies.
7  *
8  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
9  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
10  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
11  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
12  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
13  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
14  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
15  *
16  * This fallback implementation is not efficient:
17  * It does the formatting twice.
18  * Short of fiddling with the unknown internals of the system's
19  * printf(3) or completely reimplementing printf(3), i can't think
20  * of another portable solution.
21  */
22 
23 #include <stdarg.h>
24 #include <stdio.h>
25 #include <stdlib.h>
26 
27 int
28 vasprintf(char **ret, const char *format, va_list ap)
29 {
30 	char	 buf[2];
31 	va_list	 ap2;
32 	int	 sz;
33 
34 	va_copy(ap2, ap);
35 	sz = vsnprintf(buf, sizeof(buf), format, ap2);
36 	va_end(ap2);
37 
38 	if (sz != -1 && (*ret = malloc(sz + 1)) != NULL) {
39 		if (vsnprintf(*ret, sz + 1, format, ap) == sz)
40 			return sz;
41 		free(*ret);
42 	}
43 	*ret = NULL;
44 	return -1;
45 }