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 viprintf.c */
7
8 #define _DEFAULT_SOURCE
9 #include <stdio.h>
10 #include <stdarg.h>
11 #include <limits.h>
12 #include <errno.h>
13 #include "local.h"
14
15 char *
vasniprintf(char * buf,size_t * lenp,const char * fmt,va_list ap)16 vasniprintf (
17 char *buf,
18 size_t *lenp,
19 const char *fmt,
20 va_list ap)
21 {
22 int ret;
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 ret = svfiprintf ( &f, fmt, ap);
50 if (ret < 0)
51 return NULL;
52 *lenp = ret;
53 *f._p = '\0';
54 return (char *) f._bf._base;
55 }
56
