+/* check existing pid file to see whether a daemon is running */
+static int check_pidfile(void)
+{
+ int pid_fd;
+ pid_t pid;
+ char pid_str[16];
+
+ pid_fd = open_pidfile("open", O_RDWR);
+ if (pid_fd < 0)
+ return pid_fd;
+
+ if (read(pid_fd, pid_str, sizeof(pid_str)) <= 0)
+ return -1;
+
+ pid = atoi(pid_str);
+ if (pid <= 0)
+ return -1;
+
+ /* another running process that we can signal COULD be
+ * a competing rrdcached */
+ if (pid != getpid() && kill(pid, 0) == 0)
+ {
+ fprintf(stderr,
+ "FATAL: Another rrdcached daemon is running?? (pid %d)\n", pid);
+ close(pid_fd);
+ return -1;
+ }
+
+ lseek(pid_fd, 0, SEEK_SET);
+ ftruncate(pid_fd, 0);
+
+ fprintf(stderr,
+ "rrdcached: removed stale PID file (no rrdcached on pid %d)\n"
+ "rrdcached: starting normally.\n", pid);
+
+ return pid_fd;
+} /* }}} static int check_pidfile */
+