--- a
+++ b/src/__bw_lock_file__.cc
@@ -0,0 +1,54 @@
+// Copyright (C) 2009 Olaf Till <olaf.till@uni-jena.de>
+
+// This program is free software; you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation; either version 3 of the License, or
+// (at your option) any later version.
+
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with this program; if not, write to the Free Software
+// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+
+#include <octave/oct.h>
+
+#include <unistd.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <errno.h>
+
+DEFUN_DLD (__bw_lock_file__, args, , "Open the file named in arg and put an advisory write lock on it.\n\
+Internal function of parallel package, function may change.\n") {
+
+  octave_value retval;
+
+  int fd, ret;
+  struct flock fl;
+
+  while ((fd = open (args(0).char_matrix_value().row_as_string(0).c_str(),
+		  O_WRONLY | O_CREAT, S_IRUSR | S_IWUSR)) < 0 &&
+	 errno == EINTR);
+  if (fd < 0) {
+    error ("lock_file: error opening file");
+    return retval;
+  }
+
+  fl.l_type = F_WRLCK;
+  fl.l_whence = SEEK_SET;
+  fl.l_start = 0;
+  fl.l_len = 0;
+
+  while ((ret = fcntl (fd, F_SETLKW, &fl)) < 0 && errno == EINTR);
+  if (ret < 0) {
+    error ("lock_file: error locking file");
+    return retval;
+  }
+
+  return octave_value (fd);
+
+}