1 /* GNU Mailutils -- a suite of utilities for electronic mail
2 Copyright (C) 2009-2021 Free Software Foundation, Inc.
3
4 This library is free software; you can redistribute it and/or
5 modify it under the terms of the GNU Lesser General Public
6 License as published by the Free Software Foundation; either
7 version 3 of the License, or (at your option) any later version.
8
9 This library is distributed in the hope that it will be useful,
10 but WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 Lesser General Public License for more details.
13
14 You should have received a copy of the GNU Lesser General
15 Public License along with this library. If not, see
16 <http://www.gnu.org/licenses/>. */
17
18 #if HAVE_CONFIG_H
19 # include <config.h>
20 #endif
21
22 #include <stdlib.h>
23 #include <stdarg.h>
24 #include <stdio.h>
25 #include <errno.h>
26 #include <string.h>
27
28 #include <mailutils/io.h>
29
30 int
mu_vasnprintf(char ** pbuf,size_t * psize,const char * fmt,va_list ap)31 mu_vasnprintf (char **pbuf, size_t *psize, const char *fmt, va_list ap)
32 {
33 char *buf = *pbuf;
34 size_t buflen = *psize;
35 int rc = 0;
36
37 if (!buf)
38 {
39 if (buflen == 0)
40 buflen = 512; /* Initial allocation */
41
42 buf = calloc (1, buflen);
43 if (buf == NULL)
44 return ENOMEM;
45 }
46
47 for (;;)
48 {
49 ssize_t n;
50 va_list aq;
51
52 va_copy(aq, ap);
53 n = vsnprintf (buf, buflen, fmt, aq);
54 va_end(aq);
55
56 if (n < 0 || n >= buflen || !memchr (buf, '\0', n + 1))
57 {
58 char *newbuf;
59 size_t newlen = buflen * 2;
60 if (newlen < buflen)
61 {
62 rc = ENOMEM;
63 break;
64 }
65 newbuf = realloc (buf, newlen);
66 if (newbuf == NULL)
67 {
68 rc = ENOMEM;
69 break;
70 }
71 buflen = newlen;
72 buf = newbuf;
73 }
74 else
75 break;
76 }
77
78 if (rc)
79 {
80 if (!*pbuf)
81 {
82 /* We made first allocation, now free it */
83 free (buf);
84 buf = NULL;
85 buflen = 0;
86 }
87 }
88
89 *pbuf = buf;
90 *psize = buflen;
91 return rc;
92 }
93