-/* Sets program_name based on 'argv0'. Should be called at the beginning of
- * main(), as "set_program_name(argv[0]);". */
-void set_program_name(const char *argv0)
+/* Many OVS functions return an int which is one of:
+ * - 0: no error yet
+ * - >0: errno value
+ * - EOF: end of file (not necessarily an error; depends on the function called)
+ *
+ * Returns the appropriate human-readable string. The caller must copy the
+ * string if it wants to hold onto it, as the storage may be overwritten on
+ * subsequent function calls.
+ */
+const char *
+ovs_retval_to_string(int retval)
+{
+ static char unknown[48];
+
+ if (!retval) {
+ return "";
+ }
+ if (retval > 0) {
+ return strerror(retval);
+ }
+ if (retval == EOF) {
+ return "End of file";
+ }
+ snprintf(unknown, sizeof unknown, "***unknown return value: %d***", retval);
+ return unknown;
+}
+
+/* Sets global "program_name" and "program_version" variables. Should
+ * be called at the beginning of main() with "argv[0]" as the argument
+ * to 'argv0'.
+ *
+ * The 'date' and 'time' arguments should likely be called with
+ * "__DATE__" and "__TIME__" to use the time the binary was built.
+ * Alternatively, the "set_program_name" macro may be called to do this
+ * automatically.
+ */
+void
+set_program_name__(const char *argv0, const char *date, const char *time)