+/**
+ * imagetool_get_source_date() - Get timestamp for build output.
+ *
+ * Gets a timestamp for embedding it in a build output. If set
+ * SOURCE_DATE_EPOCH is used. Else the given fallback value is returned. Prints
+ * an error message if SOURCE_DATE_EPOCH contains an invalid value and returns
+ * 0.
+ *
+ * @cmdname: command name
+ * @fallback: timestamp to use if SOURCE_DATE_EPOCH isn't set
+ * @return timestamp based on SOURCE_DATE_EPOCH
+ */
+time_t imagetool_get_source_date(
+ const char *cmdname,
+ time_t fallback);
+