Prevent extensions from creating custom GUCs that are GUC_LIST_QUOTE.

tglsfdc · tglsfdc · commit 846b5a525746 · 2018-03-21T20:11:07.000-04:00
Pending some solution for the problems noted in commit 7428699, disallow dynamic creation of GUC_LIST_QUOTE variables. If there are any extensions out there using this feature, they'd not be happy for us to start enforcing this rule in minor releases, so this is a HEAD-only change. The previous commit didn't make things any worse than they already were for such cases. Discussion: https://postgr.es/m/20180111064900.GA51030@paquier.xyz
diff --git a/src/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c
@@ -7606,6 +7606,15 @@ init_custom_variable(const char *name,
 		!process_shared_preload_libraries_in_progress)
 		elog(FATAL, "cannot create PGC_POSTMASTER variables after startup");
 
+	/*
+	 * We can't support custom GUC_LIST_QUOTE variables, because the wrong
+	 * things would happen if such a variable were set or pg_dump'd when the
+	 * defining extension isn't loaded.  Again, treat this as fatal because
+	 * the loadable module may be partly initialized already.
+	 */
+	if (flags & GUC_LIST_QUOTE)
+		elog(FATAL, "extensions cannot define GUC_LIST_QUOTE variables");
+
 	/*
 	 * Before pljava commit 398f3b876ed402bdaec8bc804f29e2be95c75139
 	 * (2015-12-15), two of that module's PGC_USERSET variables facilitated
