ndet_fcntl.c

操作系统SunOS 4.1.3版本的源码

#ifndef	lint
#ifdef sccs
static	char sccsid[] = "@(#)ndet_fcntl.c 1.1 92/07/30 Copyr 1985 Sun Micro";
#endif
#endif

/*
 * Copyright (c) 1985 by Sun Microsystems, Inc.
 */

/*
 * Ndet_fcntl.c - Notifier's version of fcntl.  Used to detect async
 *		   mode of fds managing.
 */

#include <sunwindow/ntfy.h>
#include <sunwindow/ndet.h>
#include <signal.h>
#include <fcntl.h>

extern int
fcntl(fd, cmd, arg)
	int fd, cmd, arg;
{
	fd_set bit;
	int res;

	/* Set fd bit */
	FD_ZERO(&bit);
	FD_SET(fd, &bit);
	/* If call fails then ignore transition */
	if ((res = notify_fcntl(fd, cmd, arg)) == -1)
		return(res);
	/*
	 * Update non-blocking read and async data ready flags if setting
	 * or querying.  Doing it on querying double checks information.
	 */
	/* System V has its own distinct style of no-delay i/o requested by
	 * FNBIO in addition to the 4.2 FNDELAY.  This code segment
	 * recognizes both and sets the ndet_fndelay_mask.  At this time
	 * (87/2/9) it has not been verified that this is sufficient--perhaps
	 * more discrimination is necessary.  The #ifdef is needed because
	 * the FNBIO symbol has not yet arrived in our include files from 
	 * argon.  The #ifdef can go away when we get the new include files.
	 */
	if (cmd == F_SETFL || cmd == F_GETFL) {
		/* For F_GETFL, res contains flags */
		if (cmd == F_GETFL)
			arg = res;
		NTFY_BEGIN_CRITICAL;
		if (arg & FNDELAY)
			FD_SET(fd, &ndet_fndelay_mask);
#ifdef FNBIO
		else if (arg & FNBIO)
			FD_SET(fd, &ndet_fndelay_mask);
#endif
		else
			FD_CLR(fd, &ndet_fndelay_mask);
		if (arg & FASYNC)
			FD_SET(fd, &ndet_fasync_mask);
		else
			FD_CLR(fd, &ndet_fasync_mask);
		/* Make sure that are catching async related signals now */
		if (ntfy_fd_anyset(&ndet_fasync_mask)) {
			ndet_enable_sig(SIGIO);
			ndet_enable_sig(SIGURG);
		}
		/*
		 * Setting NDET_FD_CHANGE will "fix up" signals being caught
		 * to be the minimum required next time around the
		 * notification loop.
		 */
		ndet_flags |= NDET_FD_CHANGE;
		NTFY_END_CRITICAL;
	}
	return(res);
}