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rsync/connection.c

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+/*
+ * Support the max connections option.
+ *
+ * Copyright (C) 1998 Andrew Tridgell
+ *
+ * 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, visit the http://fsf.org website.
+ */
+
+#include "rsync.h"
+
+/* A simple routine to do connection counting.  This returns 1 on success
+ * and 0 on failure, with errno also being set if the open() failed (errno
+ * will be 0 if the lock request failed). */
+int claim_connection(char *fname, int max_connections)
+{
+	int fd, i;
+
+	if (max_connections == 0)
+		return 1;
+
+	if ((fd = open(fname, O_RDWR|O_CREAT, 0600)) < 0)
+		return 0;
+
+	/* Find a free spot. */
+	for (i = 0; i < max_connections; i++) {
+		if (lock_range(fd, i*4, 4))
+			return 1;
+	}
+
+	close(fd);
+
+	/* A lock failure needs to return an errno of 0. */
+	errno = 0;
+	return 0;
+}