compat_vasprintf.c

   1 #include "config.h"
   2
   3 #if HAVE_VASPRINTF
   4
   5 int dummy;
   6
   7 #else
   8
   9 /*      $Id: compat_vasprintf.c,v 1.3 2015/10/06 18:32:19 schwarze Exp $        */
  10 /*
  11  * Copyright (c) 2015 Ingo Schwarze <schwarze@openbsd.org>
  12  *
  13  * Permission to use, copy, modify, and distribute this software for any
  14  * purpose with or without fee is hereby granted, provided that the above
  15  * copyright notice and this permission notice appear in all copies.
  16  *
  17  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
  18  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
  19  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
  20  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  21  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
  22  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
  23  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  24  *
  25  * This fallback implementation is not efficient:
  26  * It does the formatting twice.
  27  * Short of fiddling with the unknown internals of the system's
  28  * printf(3) or completely reimplementing printf(3), i can't think
  29  * of another portable solution.
  30  */
  31
  32 #include <stdarg.h>
  33 #include <stdio.h>
  34 #include <stdlib.h>
  35
  36 int
  37 vasprintf(char **ret, const char *format, va_list ap)
  38 {
  39         char     buf[2];
  40         va_list  ap2;
  41         int      sz;
  42
  43         va_copy(ap2, ap);
  44         sz = vsnprintf(buf, sizeof(buf), format, ap2);
  45         va_end(ap2);
  46
  47         if (sz != -1 && (*ret = malloc(sz + 1)) != NULL) {
  48                 if (vsnprintf(*ret, sz + 1, format, ap) == sz)
  49                         return sz;
  50                 free(*ret);
  51         }
  52         *ret = NULL;
  53         return -1;
  54 }
  55
  56 #endif