=== modified file 'src/log.c'
--- old/src/log.c	2010-03-05 12:51:12 +0000
+++ new/src/log.c	2011-02-25 14:38:19 +0000
@@ -33,6 +33,8 @@
 #include <sys/time.h>
 #include <time.h>
 #include <stdio.h>
+#include <errno.h>
+#include <string.h>
 #include <glib.h>
 
 #include "bubble.h"
@@ -61,6 +63,13 @@
 	g_mkdir_with_parents (dirname, 0700);
 
 	char *filename = g_build_filename (dirname, "notify-osd.log", NULL);
+	char *backup = g_build_filename (dirname, "notify-osd.log.1", NULL);
+
+	/* attempt to back up the log file */
+	if (rename (filename, backup) != 0) {
+		g_warning("failed to back up previous log file: %s", strerror(errno));
+	}
+	g_free(backup);
 
 	logfile = fopen (filename, "w");
 	if (logfile == NULL)