lib/roken/flock.c

   1 /*
   2  * Copyright (c) 1995, 1996, 1997 Kungliga Tekniska Högskolan
   3  * (Royal Institute of Technology, Stockholm, Sweden).
   4  * All rights reserved.
   5  *
   6  * Redistribution and use in source and binary forms, with or without
   7  * modification, are permitted provided that the following conditions
   8  * are met:
   9  *
  10  * 1. Redistributions of source code must retain the above copyright
  11  *    notice, this list of conditions and the following disclaimer.
  12  *
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions and the following disclaimer in the
  15  *    documentation and/or other materials provided with the distribution.
  16  *
  17  * 3. Neither the name of the Institute nor the names of its contributors
  18  *    may be used to endorse or promote products derived from this software
  19  *    without specific prior written permission.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
  22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
  25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  31  * SUCH DAMAGE.
  32  */
  33
  34 #ifdef HAVE_CONFIG_H
  35 #include <config.h>
  36 #endif
  37
  38 #ifndef HAVE_FLOCK
  39 RCSID("$Id$");
  40
  41 #include "roken.h"
  42
  43
  44 #define OP_MASK (LOCK_SH | LOCK_EX | LOCK_UN)
  45
  46 int ROKEN_LIB_FUNCTION
  47 flock(int fd, int operation)
  48 {
  49 #if defined(HAVE_FCNTL) && defined(F_SETLK)
  50   struct flock arg;
  51   int code, cmd;
  52
  53   arg.l_whence = SEEK_SET;
  54   arg.l_start = 0;
  55   arg.l_len = 0;                /* means to EOF */
  56
  57   if (operation & LOCK_NB)
  58     cmd = F_SETLK;
  59   else
  60     cmd = F_SETLKW;             /* Blocking */
  61
  62   switch (operation & OP_MASK) {
  63   case LOCK_UN:
  64     arg.l_type = F_UNLCK;
  65     code = fcntl(fd, F_SETLK, &arg);
  66     break;
  67   case LOCK_SH:
  68     arg.l_type = F_RDLCK;
  69     code = fcntl(fd, cmd, &arg);
  70     break;
  71   case LOCK_EX:
  72     arg.l_type = F_WRLCK;
  73     code = fcntl(fd, cmd, &arg);
  74     break;
  75   default:
  76     errno = EINVAL;
  77     code = -1;
  78     break;
  79   }
  80   return code;
  81 #else
  82   return -1;
  83 #endif
  84 }
  85
  86 #endif
  87