pg_dump: Fix handling of ALTER DEFAULT PRIVILEGES

In commit 23f34fa, we changed how ACLs were handled to use the new
pg_init_privs catalog and to dump out the ACL commands as REVOKE+GRANT
combinations instead of trying to REVOKE all rights always and then
GRANT back just the ones which were in place.

Unfortunately, the DEFAULT PRIVILEGES system didn't quite get the
correct treatment with this change and ended up (incorrectly) only
including positive GRANTs instead of both the REVOKEs and GRANTs
necessary to preserve the correct privileges.

There are only a couple cases where such REVOKEs are possible because,
generally speaking, there's few rights which exist on objects by
default to be revoked.

Examples of REVOKEs which weren't being correctly preserved are when
privileges are REVOKE'd from the creator/owner, like so:

ALTER DEFAULT PRIVILEGES
  FOR ROLE myrole
  REVOKE SELECT ON TABLES FROM myrole;

or when other default privileges are being revoked, such as EXECUTE
rights granted to public for functions:

ALTER DEFAULT PRIVILEGES
  FOR ROLE myrole
  REVOKE EXECUTE ON FUNCTIONS FROM PUBLIC;

Fix this by correctly working out what the correct REVOKE statements are
(if any) and dump them out, just as we do for everything else.

Noticed while developing additional regression tests for pg_dump, which
will be landing shortly.

Back-patch to 9.6 where the bug was introduced.

src/bin/pg_dump/dumputils.c

@@ -364,11 +364,12 @@ buildACLCommands(const char *name, const char *subname,
  */
 bool
 buildDefaultACLCommands(const char *type, const char *nspname,
-						const char *acls, const char *owner,
+						const char *acls, const char *racls,
+						const char *initacls, const char *initracls,
+						const char *owner,
 						int remoteVersion,
 						PQExpBuffer sql)
 {
-	bool		result;
 	PQExpBuffer prefix;
 
 	prefix = createPQExpBuffer();
@@ -384,14 +385,22 @@ buildDefaultACLCommands(const char *type, const char *nspname,
 	if (nspname)
 		appendPQExpBuffer(prefix, "IN SCHEMA %s ", fmtId(nspname));
 
-	result = buildACLCommands("", NULL,
-							  type, acls, "", owner,
-							  prefix->data, remoteVersion,
-							  sql);
+	if (strlen(initacls) != 0 || strlen(initracls) != 0)
+	{
+		appendPQExpBuffer(sql, "SELECT pg_catalog.binary_upgrade_set_record_init_privs(true);\n");
+		if (!buildACLCommands("", NULL, type, initacls, initracls, owner,
+							  prefix->data, remoteVersion, sql))
+			return false;
+		appendPQExpBuffer(sql, "SELECT pg_catalog.binary_upgrade_set_record_init_privs(false);\n");
+	}
+
+	if (!buildACLCommands("", NULL, type, acls, racls, owner,
+						  prefix->data, remoteVersion, sql))
+		return false;
 
 	destroyPQExpBuffer(prefix);
 
-	return result;
+	return true;
 }
 
 /*

src/bin/pg_dump/dumputils.h

@@ -41,7 +41,9 @@ extern bool buildACLCommands(const char *name, const char *subname,
 				 const char *owner, const char *prefix, int remoteVersion,
 				 PQExpBuffer sql);
 extern bool buildDefaultACLCommands(const char *type, const char *nspname,
-						const char *acls, const char *owner,
+						const char *acls, const char *racls,
+						const char *initacls, const char *initracls,
+						const char *owner,
 						int remoteVersion,
 						PQExpBuffer sql);
 extern void buildShSecLabelQuery(PGconn *conn, const char *catalog_name,

src/bin/pg_dump/pg_dump.c

@@ -8683,6 +8683,9 @@ getDefaultACLs(Archive *fout, int *numDefaultACLs)
 	int			i_defaclnamespace;
 	int			i_defaclobjtype;
 	int			i_defaclacl;
+	int			i_rdefaclacl;
+	int			i_initdefaclacl;
+	int			i_initrdefaclacl;
 	int			i,
 				ntups;
 
@@ -8697,13 +8700,50 @@ getDefaultACLs(Archive *fout, int *numDefaultACLs)
 	/* Make sure we are in proper schema */
 	selectSourceSchema(fout, "pg_catalog");
 
-	appendPQExpBuffer(query, "SELECT oid, tableoid, "
-					  "(%s defaclrole) AS defaclrole, "
-					  "defaclnamespace, "
-					  "defaclobjtype, "
-					  "defaclacl "
-					  "FROM pg_default_acl",
-					  username_subquery);
+	if (fout->remoteVersion >= 90600)
+	{
+		PQExpBuffer acl_subquery = createPQExpBuffer();
+		PQExpBuffer racl_subquery = createPQExpBuffer();
+		PQExpBuffer initacl_subquery = createPQExpBuffer();
+		PQExpBuffer initracl_subquery = createPQExpBuffer();
+
+		buildACLQueries(acl_subquery, racl_subquery, initacl_subquery,
+						initracl_subquery, "defaclacl", "defaclrole",
+						"CASE WHEN defaclobjtype = 'S' THEN 's' ELSE defaclobjtype END::\"char\"",
+						dopt->binary_upgrade);
+
+		appendPQExpBuffer(query, "SELECT d.oid, d.tableoid, "
+						  "(%s d.defaclrole) AS defaclrole, "
+						  "d.defaclnamespace, "
+						  "d.defaclobjtype, "
+						  "%s AS defaclacl, "
+						  "%s AS rdefaclacl, "
+						  "%s AS initdefaclacl, "
+						  "%s AS initrdefaclacl "
+						  "FROM pg_default_acl d "
+						  "LEFT JOIN pg_init_privs pip ON "
+						  "(d.oid = pip.objoid "
+						  "AND pip.classoid = 'pg_default_acl'::regclass "
+						  "AND pip.objsubid = 0) ",
+						  username_subquery,
+						  acl_subquery->data,
+						  racl_subquery->data,
+						  initacl_subquery->data,
+						  initracl_subquery->data);
+	}
+	else
+	{
+		appendPQExpBuffer(query, "SELECT oid, tableoid, "
+						  "(%s defaclrole) AS defaclrole, "
+						  "defaclnamespace, "
+						  "defaclobjtype, "
+						  "defaclacl, "
+						  "NULL AS rdefaclacl, "
+						  "NULL AS initdefaclacl, "
+						  "NULL AS initrdefaclacl "
+						  "FROM pg_default_acl",
+						  username_subquery);
+	}
 
 	res = ExecuteSqlQuery(fout, query->data, PGRES_TUPLES_OK);
 
@@ -8718,6 +8758,9 @@ getDefaultACLs(Archive *fout, int *numDefaultACLs)
 	i_defaclnamespace = PQfnumber(res, "defaclnamespace");
 	i_defaclobjtype = PQfnumber(res, "defaclobjtype");
 	i_defaclacl = PQfnumber(res, "defaclacl");
+	i_rdefaclacl = PQfnumber(res, "rdefaclacl");
+	i_initdefaclacl = PQfnumber(res, "initdefaclacl");
+	i_initrdefaclacl = PQfnumber(res, "initrdefaclacl");
 
 	for (i = 0; i < ntups; i++)
 	{
@@ -8738,6 +8781,9 @@ getDefaultACLs(Archive *fout, int *numDefaultACLs)
 		daclinfo[i].defaclrole = pg_strdup(PQgetvalue(res, i, i_defaclrole));
 		daclinfo[i].defaclobjtype = *(PQgetvalue(res, i, i_defaclobjtype));
 		daclinfo[i].defaclacl = pg_strdup(PQgetvalue(res, i, i_defaclacl));
+		daclinfo[i].rdefaclacl = pg_strdup(PQgetvalue(res, i, i_rdefaclacl));
+		daclinfo[i].initdefaclacl = pg_strdup(PQgetvalue(res, i, i_initdefaclacl));
+		daclinfo[i].initrdefaclacl = pg_strdup(PQgetvalue(res, i, i_initrdefaclacl));
 
 		/* Decide whether we want to dump it */
 		selectDumpableDefaultACL(&(daclinfo[i]), dopt);
@@ -14038,6 +14084,9 @@ dumpDefaultACL(Archive *fout, DefaultACLInfo *daclinfo)
 								 daclinfo->dobj.namespace != NULL ?
 								 daclinfo->dobj.namespace->dobj.name : NULL,
 								 daclinfo->defaclacl,
+								 daclinfo->rdefaclacl,
+								 daclinfo->initdefaclacl,
+								 daclinfo->initrdefaclacl,
 								 daclinfo->defaclrole,
 								 fout->remoteVersion,
 								 q))

src/bin/pg_dump/pg_dump.h

@@ -539,6 +539,9 @@ typedef struct _defaultACLInfo
 	char	   *defaclrole;
 	char		defaclobjtype;
 	char	   *defaclacl;
+	char	   *rdefaclacl;
+	char	   *initdefaclacl;
+	char	   *initrdefaclacl;
 } DefaultACLInfo;
 
 typedef struct _blobInfo