1 files changed, 77 insertions, 0 deletions
diff --git a/lockdev.h b/lockdev.h
new file mode 100644
index 0000000..4467bc2
--- /dev/null
+++ b/lockdev.h
@@ -0,0 +1,77 @@
+#ifndef LOCK_DEV
+#define LOCK_DEV
+
+/*  Copyright 2005,2009 Alain Knaff.
+ *  This file is part of mtools.
+ *
+ *  Mtools 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.
+ *
+ *  Mtools 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 Mtools.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ * Create an advisory lock on the device to prevent concurrent writes.
+ * Uses either lockf, flock, or fcntl locking methods.  See the Makefile
+ * and the Configure files for how to specify the proper method.
+ */
+
+int lock_dev(int fd, int mode, struct device *dev)
+{
+#if (defined(HAVE_FLOCK) && defined (LOCK_EX) && defined(LOCK_NB))
+	/**/
+#else /* FLOCK */
+
+#if (defined(HAVE_LOCKF) && defined(F_TLOCK))
+	/**/
+#else /* LOCKF */
+
+#if (defined(F_SETLK) && defined(F_WRLCK))
+	struct flock flk;
+
+#endif /* FCNTL */
+#endif /* LOCKF */
+#endif /* FLOCK */
+
+	if(IS_NOLOCK(dev))
+		return 0;
+
+#if (defined(HAVE_FLOCK) && defined (LOCK_EX) && defined(LOCK_NB))
+	if (flock(fd, (mode ? LOCK_EX : LOCK_SH)|LOCK_NB) < 0)
+#else /* FLOCK */
+
+#if (defined(HAVE_LOCKF) && defined(F_TLOCK))
+	if (mode && lockf(fd, F_TLOCK, 0) < 0)
+#else /* LOCKF */
+
+#if (defined(F_SETLK) && defined(F_WRLCK))
+	flk.l_type = mode ? F_WRLCK : F_RDLCK;
+	flk.l_whence = 0;
+	flk.l_start = 0L;
+	flk.l_len = 0L;
+
+	if (fcntl(fd, F_SETLK, &flk) < 0)
+#endif /* FCNTL */
+#endif /* LOCKF */
+#endif /* FLOCK */
+	{
+		if(errno == EINVAL
+#ifdef  EOPNOTSUPP 
+		   || errno ==  EOPNOTSUPP
+#endif
+		  )
+			return 0;
+		else
+			return 1;
+	}
+	return 0;
+}
+
+
+#endif