#include "apue.h"
#include <limits.h>
#include <sys/resource.h>

#define OPEN_MAX_GUESS	256

long
open_max(void)
{
	long openmax;
	struct rlimit rl;

	if ((openmax = sysconf(_SC_OPEN_MAX)) < 0 ||
	  openmax == LONG_MAX) {
		if (getrlimit(RLIMIT_NOFILE, &rl) < 0)
			err_sys("can't get file limit");
		if (rl.rlim_max == RLIM_INFINITY)
			openmax = OPEN_MAX_GUESS;
		else
			openmax = rl.rlim_max;
	}
	return(openmax);
}