In pg_dump, include pg_catalog and extension ACLs, if changed

Now that all of the infrastructure exists, add in the ability to
dump out the ACLs of the objects inside of pg_catalog or the ACLs
for objects which are members of extensions, but only if they have
been changed from their original values.

The original values are tracked in pg_init_privs.  When pg_dump'ing
9.6-and-above databases, we will dump out the ACLs for all objects
in pg_catalog and the ACLs for all extension members, where the ACL
has been changed from the original value which was set during either
initdb or CREATE EXTENSION.

This should not change dumps against pre-9.6 databases.

Reviews by Alexander Korotkov, Jose Luis Tallon

doc/src/sgml/extend.sgml

@@ -338,6 +338,27 @@
     data; see below.)
    </para>
 
+   <para>
+    The extension script may set privileges on objects which are part of the
+    extension via <command>GRANT</command> and <command>REVOKE</command>
+    statements.  The final set of privileges for each object (if any are set)
+    will be stored in the
+    <link linkend="catalog-pg-init-privs"><structname>pg_init_privs</structname></link>
+    system catalog.  When <application>pg_dump</> is used, the
+    <command>CREATE EXTENSION</> command will be included in the dump, followed
+    by the set of <command>GRANT</command> and <command>REVOKE</command>
+    statements necessary to set the privileges on the objects to what they were
+    at the time the dump was taken.
+   </para>
+
+   <para>
+    <productname>PostgreSQL</> does not currently support extension scripts
+    issuing <command>CREATE POLICY</command> or <command>SECURITY LABEL</command>
+    statements.  These are expected to be set after the extension has been
+    created.  All RLS policies and security labels on extension objects will be
+    included in dumps created by <application>pg_dump</>.
+   </para>
+
    <para>
     The extension mechanism also has provisions for packaging modification
     scripts that adjust the definitions of the SQL objects contained in an

src/backend/catalog/aclchk.c

@@ -22,6 +22,7 @@
 #include "access/htup_details.h"
 #include "access/sysattr.h"
 #include "access/xact.h"
+#include "catalog/binary_upgrade.h"
 #include "catalog/catalog.h"
 #include "catalog/dependency.h"
 #include "catalog/indexing.h"
@@ -85,6 +86,12 @@ typedef struct
 	DropBehavior behavior;
 } InternalDefaultACL;
 
+/*
+ * When performing a binary-upgrade, pg_dump will call a function to set
+ * this variable to let us know that we need to populate the pg_init_privs
+ * table for the GRANT/REVOKE commands while this variable is set to true.
+ */
+bool		binary_upgrade_record_init_privs = false;
 
 static void ExecGrantStmt_oids(InternalGrant *istmt);
 static void ExecGrant_Relation(InternalGrant *grantStmt);
@@ -5237,7 +5244,15 @@ recordExtensionInitPriv(Oid objoid, Oid classoid, int objsubid, Acl *new_acl)
 	HeapTuple	tuple;
 	HeapTuple	oldtuple;
 
-	if (!creating_extension)
+	/*
+	 * Generally, we only record the initial privileges when an extension is
+	 * being created, but because we don't actually use CREATE EXTENSION
+	 * during binary upgrades with pg_upgrade, there is a variable to let us
+	 * know that the GRANT and REVOKE statements being issued, while this
+	 * variable is true, are for the initial privileges of the extension
+	 * object and therefore we need to record them.
+	 */
+	if (!creating_extension && !binary_upgrade_record_init_privs)
 		return;
 
 	relation = heap_open(InitPrivsRelationId, RowExclusiveLock);

src/backend/utils/adt/pg_upgrade_support.c

@@ -29,6 +29,7 @@ Datum		binary_upgrade_set_next_toast_pg_class_oid(PG_FUNCTION_ARGS);
 Datum		binary_upgrade_set_next_pg_enum_oid(PG_FUNCTION_ARGS);
 Datum		binary_upgrade_set_next_pg_authid_oid(PG_FUNCTION_ARGS);
 Datum		binary_upgrade_create_empty_extension(PG_FUNCTION_ARGS);
+Datum		binary_upgrade_set_record_init_privs(PG_FUNCTION_ARGS);
 
 
 #define CHECK_IS_BINARY_UPGRADE									\
@@ -193,3 +194,14 @@ binary_upgrade_create_empty_extension(PG_FUNCTION_ARGS)
 
 	PG_RETURN_VOID();
 }
+
+Datum
+binary_upgrade_set_record_init_privs(PG_FUNCTION_ARGS)
+{
+	bool		record_init_privs = PG_GETARG_BOOL(0);
+
+	CHECK_IS_BINARY_UPGRADE;
+	binary_upgrade_record_init_privs = record_init_privs;
+
+	PG_RETURN_VOID();
+}

src/bin/initdb/initdb.c

@@ -2002,7 +2002,11 @@ setup_privileges(FILE *cmdfd)
 	char	  **priv_lines;
 	static char *privileges_setup[] = {
 		"UPDATE pg_class "
-		"  SET relacl = E'{\"=r/\\\\\"$POSTGRES_SUPERUSERNAME\\\\\"\"}' "
+		"  SET relacl = (SELECT array_agg(a.acl) FROM "
+		" (SELECT E'=r/\"$POSTGRES_SUPERUSERNAME\"' as acl "
+		"  UNION SELECT unnest(pg_catalog.acldefault("
+		"    CASE WHEN relkind = 'S' THEN 's' ELSE 'r' END::\"char\",10::oid))"
+		" ) as a) "
 		"  WHERE relkind IN ('r', 'v', 'm', 'S') AND relacl IS NULL;\n\n",
 		"GRANT USAGE ON SCHEMA pg_catalog TO PUBLIC;\n\n",
 		"GRANT CREATE, USAGE ON SCHEMA public TO PUBLIC;\n\n",