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1/* $OpenBSD: asprintf.c,v 1.27 2025/08/08 15:58:53 yasuoka Exp $ */
2
3/*
4 * Copyright (c) 1997 Todd C. Miller <millert@openbsd.org>
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#include <stdio.h>
20#include <stdlib.h>
21#include <string.h>
22#include <errno.h>
23#include <stdarg.h>
24#include <unistd.h>
25#include "local.h"
26
27#define INITIAL_SIZE 128
28
29int
30asprintf(char **str, const char *fmt, ...)
31{
32 int ret;
33 va_list ap;
34 FILE f = FILEINIT(__SWR | __SSTR | __SALC);
35 const int pgsz = getpagesize();
36
37 f._bf._base = f._p = malloc(INITIAL_SIZE);
38 if (f._bf._base == NULL)
39 goto err;
40 f._bf._size = f._w = INITIAL_SIZE - 1; /* leave room for the NUL */
41 va_start(ap, fmt);
42 ret = __vfprintf(&f, fmt, ap);
43 va_end(ap);
44 if (ret == -1)
45 goto err;
46 *f._p = '\0';
47 if (ret + 1 > INITIAL_SIZE && ret + 1 < pgsz / 2) {
48 /* midsize allocations can try to conserve memory */
49 unsigned char *_base = recallocarray(f._bf._base,
50 f._bf._size + 1, ret + 1, 1);
51
52 if (_base == NULL)
53 goto err;
54 *str = (char *)_base;
55 } else
56 *str = (char *)f._bf._base;
57 return (ret);
58
59err:
60 free(f._bf._base);
61 f._bf._base = NULL;
62 *str = NULL;
63 errno = ENOMEM;
64 return (-1);
65}
66DEF_WEAK(asprintf);