Home | History | Annotate | Line # | Download | only in compat
flock.c revision 1.5 
      1 /*	$NetBSD: flock.c,v 1.5 2003/10/27 00:12:43 lukem Exp $	*/
      2 
      3 /*-
      4  * Copyright (c) 2001 The NetBSD Foundation, Inc.
      5  * All rights reserved.
      6  *
      7  * This code is derived from software contributed to The NetBSD Foundation
      8  * by Todd Vierling.
      9  *
     10  * Redistribution and use in source and binary forms, with or without
     11  * modification, are permitted provided that the following conditions
     12  * are met:
     13  * 1. Redistributions of source code must retain the above copyright
     14  *    notice, this list of conditions and the following disclaimer.
     15  * 2. Redistributions in binary form must reproduce the above copyright
     16  *    notice, this list of conditions and the following disclaimer in the
     17  *    documentation and/or other materials provided with the distribution.
     18  * 3. All advertising materials mentioning features or use of this software
     19  *    must display the following acknowledgement:
     20  *        This product includes software developed by the NetBSD
     21  *        Foundation, Inc. and its contributors.
     22  * 4. Neither the name of The NetBSD Foundation nor the names of its
     23  *    contributors may be used to endorse or promote products derived
     24  *    from this software without specific prior written permission.
     25  *
     26  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
     27  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
     28  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     29  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
     30  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     31  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     32  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     33  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     34  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     35  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     36  * POSSIBILITY OF SUCH DAMAGE.
     37  */
     38 
     39 /*
     40  * Emulate flock() with fcntl(), where available.
     41  * Otherwise, don't do locking; just pretend success.
     42  */
     43 
     44 #include "nbtool_config.h"
     45 
     46 #if !HAVE_FLOCK
     47 #include <errno.h>
     48 #include <fcntl.h>
     49 
     50 int flock(int fd, int op) {
     51 	int rc = 0;
     52 
     53 #if defined(F_SETLK) && defined(F_SETLKW)
     54 	struct flock fl = {0};
     55 
     56 	switch (op & (LOCK_EX|LOCK_SH|LOCK_UN)) {
     57 	case LOCK_EX:
     58 		fl.l_type = F_WRLCK;
     59 		break;
     60 
     61 	case LOCK_SH:
     62 		fl.l_type = F_RDLCK;
     63 		break;
     64 
     65 	case LOCK_UN:
     66 		fl.l_type = F_UNLCK;
     67 		break;
     68 
     69 	default:
     70 		errno = EINVAL;
     71 		return -1;
     72 	}
     73 
     74 	fl.l_whence = SEEK_SET;
     75 	rc = fcntl(fd, op & LOCK_NB ? F_SETLK : F_SETLKW, &fl);
     76 
     77 	if (rc && (errno == EAGAIN))
     78 		errno = EWOULDBLOCK;
     79 #endif
     80 
     81 	return rc;
     82 }
     83 #endif
     84