usr/src/lib/libbc/libc/compat/common/lockf.c

   1 /*
   2  * CDDL HEADER START
   3  *
   4  * The contents of this file are subject to the terms of the
   5  * Common Development and Distribution License, Version 1.0 only
   6  * (the "License").  You may not use this file except in compliance
   7  * with the License.
   8  *
   9  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
  10  * or http://www.opensolaris.org/os/licensing.
  11  * See the License for the specific language governing permissions
  12  * and limitations under the License.
  13  *
  14  * When distributing Covered Code, include this CDDL HEADER in each
  15  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
  16  * If applicable, add the following below this CDDL HEADER, with the
  17  * fields enclosed by brackets "[]" replaced with your own identifying
  18  * information: Portions Copyright [yyyy] [name of copyright owner]
  19  *
  20  * CDDL HEADER END
  21  */
  22 /*
  23  * Copyright 1989 Sun Microsystems, Inc.  All rights reserved.
  24  * Use is subject to license terms.
  25  */
  26
  27 /*      Copyright (c) 1984 AT&T */
  28 /*        All Rights Reserved   */
  29
  30 #pragma ident   "%Z%%M% %I%     %E% SMI"
  31
  32 #include <fcntl.h>
  33 #include <unistd.h>
  34 #include <errno.h>
  35 #include <sys/syscall.h>
  36
  37 /*
  38  * convert lockf() into fcntl() for SystemV compatibility
  39  */
  40
  41 /* New SVR4 values */
  42 #define SV_GETLK        5
  43 #define SV_SETLK        6
  44 #define SV_SETLKW       7
  45
  46 int
  47 lockf(int fildes, int function, long size)
  48 {
  49         struct flock ld;
  50         int cmd;
  51
  52         cmd = SV_SETLK;         /* assume non-blocking operation */
  53         ld.l_type = F_WRLCK;    /* lockf() only deals with exclusive locks */
  54         ld.l_whence = 1;        /* lock always starts at current position */
  55         if (size < 0) {
  56                 ld.l_start = size;
  57                 ld.l_len = -size;
  58         } else {
  59                 ld.l_start = 0L;
  60                 ld.l_len = size;
  61         }
  62
  63         switch (function) {
  64         case F_TEST:
  65                 if (_syscall(SYS_fcntl, fildes, SV_GETLK, &ld) != -1) {
  66                         if (ld.l_type == F_UNLCK) {
  67                                 ld.l_pid = ld.l_xxx;
  68                                         /* l_pid is the last field in the
  69                                            SVr3 flock structure */
  70                                 return (0);
  71                         } else
  72                                 errno = EACCES;         /* EAGAIN ?? */
  73                 }
  74                 return (-1);
  75
  76         default:
  77                 errno = EINVAL;
  78                 return (-1);
  79
  80                         /* the rest fall thru to the fcntl() at the end */
  81         case F_ULOCK:
  82                 ld.l_type = F_UNLCK;
  83                 break;
  84
  85         case F_LOCK:
  86                 cmd = SV_SETLKW;        /* block, if not available */
  87                 break;
  88
  89         case F_TLOCK:
  90                 break;
  91         }
  92         if (_syscall(SYS_fcntl, fildes, cmd, &ld) == -1) {
  93                 switch (errno) {
  94                 /* this hack is purported to be for /usr/group compatibility */
  95                 case ENOLCK:
  96                         errno = EDEADLK;
  97                 }
  98                 return(-1);
  99         } else {
 100                 ld.l_pid = ld.l_xxx;    /* l_pid is the last field in the
 101                                            SVr3 flock structure */
 102                 return(0);
 103         }
 104 }