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/*
* $Id: snprintf.c 5148 2007-05-08 15:40:16Z 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;
}
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