sysdeps/unix/sysv/linux/i386/lockf64.c

   1 /* Copyright (C) 1994-2014 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3
   4    The GNU C Library is free software; you can redistribute it and/or
   5    modify it under the terms of the GNU Lesser General Public
   6    License as published by the Free Software Foundation; either
   7    version 2.1 of the License, or (at your option) any later version.
   8
   9    The GNU C Library is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12    Lesser General Public License for more details.
  13
  14    You should have received a copy of the GNU Lesser General Public
  15    License along with the GNU C Library; if not, see
  16    <http://www.gnu.org/licenses/>.  */
  17
  18 #include <sys/types.h>
  19 #include <unistd.h>
  20 #include <fcntl.h>
  21 #include <errno.h>
  22 #include <string.h>
  23 #include <sysdep.h>
  24
  25 /* lockf is a simplified interface to fcntl's locking facilities.  */
  26
  27 int
  28 lockf64 (int fd, int cmd, off64_t len64)
  29 {
  30   struct flock64 fl64;
  31   int cmd64;
  32
  33   memset ((char *) &fl64, '\0', sizeof (fl64));
  34   fl64.l_whence = SEEK_CUR;
  35   fl64.l_start = 0;
  36   fl64.l_len = len64;
  37
  38   switch (cmd)
  39     {
  40     case F_TEST:
  41       /* Test the lock: return 0 if FD is unlocked or locked by this process;
  42          return -1, set errno to EACCES, if another process holds the lock.  */
  43       fl64.l_type = F_RDLCK;
  44       if (INLINE_SYSCALL (fcntl64, 3, fd, F_GETLK64, &fl64) < 0)
  45         return -1;
  46       if (fl64.l_type == F_UNLCK || fl64.l_pid == __getpid ())
  47         return 0;
  48       __set_errno (EACCES);
  49       return -1;
  50     case F_ULOCK:
  51       fl64.l_type = F_UNLCK;
  52       cmd64 = F_SETLK64;
  53       break;
  54     case F_LOCK:
  55       fl64.l_type = F_WRLCK;
  56       cmd64 = F_SETLKW64;
  57       break;
  58     case F_TLOCK:
  59       fl64.l_type = F_WRLCK;
  60       cmd64 = F_SETLK64;
  61       break;
  62
  63     default:
  64       __set_errno (EINVAL);
  65       return -1;
  66     }
  67   return INLINE_SYSCALL (fcntl64, 3, fd, cmd64, &fl64);
  68 }