2 * (C) Copyright 2012 Red Hat Inc.
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License as published by
6 * the Free Software Foundation; either version 2 of the License, or
7 * (at your option) any later version.
9 * This program 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
12 * GNU General Public License for more details.
14 * You should have received a copy of the GNU General Public License
15 * along with this program; if not, write to the Free Software
16 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
27 #include <caml/memory.h>
28 #include <caml/mlvalues.h>
29 #include <caml/fail.h>
31 /* flock_exclusive_nonblocking : file_descr -> unit
33 * The reason we need this function is that OCaml only gives us access
34 * to the 'fcntl'-style of locking. These locks are not preserved
35 * over fork(2) (WTF POSIX?) making them pretty much useless.
36 * Therefore use BSD-style flock instead.
39 whenjobs_flock_exclusive_nonblocking (value fdv)
43 /* file_descr is opaque, but on un*x-like platforms it's an integer */
44 int fd = Int_val (fdv);
46 if (flock (fd, LOCK_EX|LOCK_NB) == -1)
47 caml_failwith (strerror (errno));
49 CAMLreturn (Val_unit);