xref: /openbsd-src/lib/libc/stdio/asprintf.c (revision 298116df5b000b61a69743d21c92035418df8900)
1 /*	$OpenBSD: asprintf.c,v 1.13 2005/05/28 00:54:50 millert Exp $	*/
2 
3 /*
4  * Copyright (c) 1997 Todd C. Miller <Todd.Miller@courtesan.com>
5  *
6  * Permission to use, copy, modify, and distribute this software for any
7  * purpose with or without fee is hereby granted, provided that the above
8  * copyright notice and this permission notice appear in all copies.
9  *
10  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
11  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
12  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
13  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
14  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
15  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
16  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
17  */
18 
19 #if defined(LIBC_SCCS) && !defined(lint)
20 static char rcsid[] = "$OpenBSD: asprintf.c,v 1.13 2005/05/28 00:54:50 millert Exp $";
21 #endif /* LIBC_SCCS and not lint */
22 
23 #include <stdio.h>
24 #include <stdlib.h>
25 #include <errno.h>
26 #include <stdarg.h>
27 #include "local.h"
28 
29 int
30 asprintf(char **str, const char *fmt, ...)
31 {
32 	int ret;
33 	va_list ap;
34 	FILE f;
35 	struct __sfileext fext;
36 	unsigned char *_base;
37 
38 	_FILEEXT_SETUP(&f, &fext);
39 	f._file = -1;
40 	f._flags = __SWR | __SSTR | __SALC;
41 	f._bf._base = f._p = (unsigned char *)malloc(128);
42 	if (f._bf._base == NULL)
43 		goto err;
44 	f._bf._size = f._w = 127;		/* Leave room for the NUL */
45 	va_start(ap, fmt);
46 	ret = vfprintf(&f, fmt, ap);
47 	va_end(ap);
48 	if (ret == -1)
49 		goto err;
50 	*f._p = '\0';
51 	_base = realloc(f._bf._base, ret + 1);
52 	if (_base == NULL)
53 		goto err;
54 	*str = (char *)_base;
55 	return (ret);
56 
57 err:
58 	if (f._bf._base) {
59 		free(f._bf._base);
60 		f._bf._base = NULL;
61 	}
62 	*str = NULL;
63 	errno = ENOMEM;
64 	return (-1);
65 }
66