/*
 * $Id: snprintf.c 4003 2005-10-25 21:31:08Z ajc $
 *
 * Replacements for snprintf() and vsnprintf()
 *
 * modified from Sten Gunterberg's BUGTRAQ post of 22 Jul 1997
 * --nathan bryant <nathan@designtrust.com>
 *
 * Use it only if you have the "spare" cycles needed to effectively
 * do every snprintf operation twice! Why is that? Because everything
 * is first vfprintf()'d to /dev/null to determine the number of bytes.
 * Perhaps a bit slow for demanding applications on slow machines,
 * no problem for a fast machine with some spare cycles.
 *
 * You don't have a /dev/null? Every Linux contains one for free!
 *
 * Because the format string is never even looked at, all current and
 * possible future printf-conversions should be handled just fine.
 *
 * Written July 1997 by Sten Gunterberg (gunterberg@ergon.ch)
 */

#include <stdio.h>
#include <stdlib.h>
#include <stdarg.h>
#include <string.h>

static int
needed (const char *fmt, va_list argp)
{
  static FILE *sink = NULL;

  /* ok, there's a small race here that could result in the sink being
   * opened more than once if we're threaded, but I'd rather ignore it than
   * spend cycles synchronizing :-) */

  if (sink == NULL)
    {
      if ((sink = fopen("/dev/null", "w")) == NULL)
	{
	  perror("/dev/null");
	  exit(1);
	}
    }

  return vfprintf(sink, fmt, argp);
}

int
vsnprintf (char *buf, size_t max, const char *fmt, va_list argp)
{
  char *p;
  int size;

  if ((p = malloc(needed(fmt, argp) + 1)) == NULL)
    {
      fprintf(stderr, "vsnprintf: malloc failed, aborting\n");
      abort();
    }

  if ((size = vsprintf(p, fmt, argp)) >= max)
    size = -1;

  strncpy(buf, p, max);
  buf[max - 1] = 0;
  free(p);
  return size;
}

int
snprintf (char *buf, size_t max, const char *fmt, ...)
{
  va_list argp;
  int bytes;

  va_start(argp, fmt);
  bytes = vsnprintf(buf, max, fmt, argp);
  va_end(argp);

  return bytes;
}
