lib/openmax.c

#include "apue.h"#include <errno.h>#include <limits.h>#ifdef	OPEN_MAXstatic long	openmax = OPEN_MAX;#elsestatic long	openmax = 0;#endif/* * If OPEN_MAX is indeterminate, we‘re not * guaranteed that this is adequate. */#define	OPEN_MAX_GUESS	256longopen_max(void){	if (openmax == 0) {		/* first time through */		errno = 0;		if ((openmax = sysconf(_SC_OPEN_MAX)) < 0) {			if (errno == 0)				openmax = OPEN_MAX_GUESS;	/* it‘s indeterminate */			else				err_sys("sysconf error for _SC_OPEN_MAX");		}	}	return(openmax);}