Add %e modifier for GError clever printing.

src/libutil/printf.c

@@ -339,6 +339,7 @@ rspamd_vprintf_common (rspamd_printf_append_func func,
 	guint width, sign, hex, humanize, bytes, frac_width, i;
 	rspamd_fstring_t *v;
 	GString *gs;
+	GError *err;
 	gboolean bv;
 
 	while (*fmt) {
@@ -462,6 +463,24 @@ rspamd_vprintf_common (rspamd_printf_append_func func,
 
 				continue;
 
+			case 'e':
+				err = va_arg (args, GError *);
+
+				if (err) {
+					p = err->message;
+
+					if (p == NULL) {
+						p = "(NULL)";
+					}
+				}
+				else {
+					p = "unknown error";
+				}
+
+				slen = strlen (p);
+				RSPAMD_PRINTF_APPEND (p, slen);
+				break;
+
 			case 's':
 				p = va_arg (args, gchar *);
 				if (p == NULL) {

src/libutil/printf.h

@@ -52,6 +52,7 @@
  *	%Z						    '\0'
  *	%N						    '\n'
  *	%c						    gchar
+ *	%e                          GError *
  *	%%						    %
  *
  */