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 <stdio.h>
10 #include <stdarg.h>
11 #include <limits.h>
12 #include <errno.h>
13 #include "local.h"
14 
15 char *
asniprintf(char * buf,size_t * lenp,const char * fmt,...)16 asniprintf (char *buf,
17        size_t *lenp,
18        const char *fmt, ...)
19 {
20   int ret;
21   va_list ap;
22   FILE f;
23   size_t len = *lenp;
24 
25   if (buf && len)
26     {
27       /* mark an existing buffer, but allow allocation of larger string */
28       f._flags = __SWR | __SSTR | __SOPT;
29     }
30   else
31     {
32       /* mark a zero-length reallocatable buffer */
33       f._flags = __SWR | __SSTR | __SMBF;
34       len = 0;
35       buf = NULL;
36     }
37   f._flags2 = 0;
38   f._bf._base = f._p = (unsigned char *) buf;
39   /* For now, inherit the 32-bit signed limit of FILE._bf._size.
40      for _size.  */
41   if (len > INT_MAX)
42     {
43       _REENT_ERRNO(ptr) = EOVERFLOW;
44       return NULL;
45     }
46   f._bf._size = f._w = len;
47   f._file = -1;  /* No file. */
48   va_start (ap, fmt);
49   ret = svfiprintf ( &f, fmt, ap);
50   va_end (ap);
51   if (ret < 0)
52     return NULL;
53   *lenp = ret;
54   *f._p = '\0';
55   return (char *) f._bf._base;
56 }
57