1 /* Copyright (C) 2007, 2008 Eric Blake
2 * Permission to use, copy, modify, and distribute this software
3 * is freely granted, provided that this notice is preserved.
4 */
5 /* This code was derived from asprintf.c */
6 /* doc in siprintf.c */
7
8 #define _DEFAULT_SOURCE
9 #include <_ansi.h>
10 #include <stdio.h>
11 #include <stdarg.h>
12 #include <limits.h>
13 #include <errno.h>
14 #include "local.h"
15
16 char *
asniprintf(char * buf,size_t * lenp,const char * fmt,...)17 asniprintf (char *buf,
18 size_t *lenp,
19 const char *fmt, ...)
20 {
21 int ret;
22 va_list ap;
23 FILE f;
24 size_t len = *lenp;
25
26 if (buf && len)
27 {
28 /* mark an existing buffer, but allow allocation of larger string */
29 f._flags = __SWR | __SSTR | __SOPT;
30 }
31 else
32 {
33 /* mark a zero-length reallocatable buffer */
34 f._flags = __SWR | __SSTR | __SMBF;
35 len = 0;
36 buf = NULL;
37 }
38 f._flags2 = 0;
39 f._bf._base = f._p = (unsigned char *) buf;
40 /* For now, inherit the 32-bit signed limit of FILE._bf._size.
41 for _size. */
42 if (len > INT_MAX)
43 {
44 _REENT_ERRNO(ptr) = EOVERFLOW;
45 return NULL;
46 }
47 f._bf._size = f._w = len;
48 f._file = -1; /* No file. */
49 va_start (ap, fmt);
50 ret = svfiprintf ( &f, fmt, ap);
51 va_end (ap);
52 if (ret < 0)
53 return NULL;
54 *lenp = ret;
55 *f._p = '\0';
56 return (char *) f._bf._base;
57 }
58
