Extend object access hook framework to support arguments, and DROP.

This allows loadable modules to get control at drop time, perhaps for the
purpose of performing additional security checks or to log the event.
The initial purpose of this code is to support sepgsql, but other
applications should be possible as well.

KaiGai Kohei, reviewed by me.

src/backend/catalog/dependency.c

@@ -20,6 +20,7 @@
 #include "catalog/heap.h"
 #include "catalog/index.h"
 #include "catalog/namespace.h"
+#include "catalog/objectaccess.h"
 #include "catalog/pg_amop.h"
 #include "catalog/pg_amproc.h"
 #include "catalog/pg_attrdef.h"
@@ -991,6 +992,15 @@ deleteOneObject(const ObjectAddress *object, Relation depRel, int flags)
 	SysScanDesc scan;
 	HeapTuple	tup;
 
+	/* DROP hook of the objects being removed */
+	if (object_access_hook)
+	{
+		ObjectAccessDrop	drop_arg;
+		drop_arg.dropflags = flags;
+		InvokeObjectAccessHook(OAT_DROP, object->classId, object->objectId,
+							   object->objectSubId, &drop_arg);
+	}
+
 	/*
 	 * First remove any pg_depend records that link from this object to
 	 * others.	(Any records linking to this object should be gone already.)

src/backend/catalog/heap.c

@@ -1286,7 +1286,8 @@ heap_create_with_catalog(const char *relname,
 	}
 
 	/* Post creation hook for new relation */
-	InvokeObjectAccessHook(OAT_POST_CREATE, RelationRelationId, relid, 0);
+	InvokeObjectAccessHook(OAT_POST_CREATE,
+						   RelationRelationId, relid, 0, NULL);
 
 	/*
 	 * Store any supplied constraints and defaults.

src/backend/catalog/pg_collation.c

@@ -136,7 +136,7 @@ CollationCreate(const char *collname, Oid collnamespace,
 
 	/* Post creation hook for new collation */
 	InvokeObjectAccessHook(OAT_POST_CREATE,
-						   CollationRelationId, oid, 0);
+						   CollationRelationId, oid, 0, NULL);
 
 	heap_freetuple(tup);
 	heap_close(rel, RowExclusiveLock);

src/backend/catalog/pg_constraint.c

@@ -366,7 +366,8 @@ CreateConstraintEntry(const char *constraintName,
 	}
 
 	/* Post creation hook for new constraint */
-	InvokeObjectAccessHook(OAT_POST_CREATE, ConstraintRelationId, conOid, 0);
+	InvokeObjectAccessHook(OAT_POST_CREATE,
+						   ConstraintRelationId, conOid, 0, NULL);
 
 	return conOid;
 }

src/backend/catalog/pg_conversion.c

@@ -134,8 +134,8 @@ ConversionCreate(const char *conname, Oid connamespace,
 	recordDependencyOnCurrentExtension(&myself, false);
 
 	/* Post creation hook for new conversion */
-	InvokeObjectAccessHook(OAT_POST_CREATE,
-						   ConversionRelationId, HeapTupleGetOid(tup), 0);
+	InvokeObjectAccessHook(OAT_POST_CREATE, ConversionRelationId,
+						   HeapTupleGetOid(tup), 0, NULL);
 
 	heap_freetuple(tup);
 	heap_close(rel, RowExclusiveLock);

src/backend/catalog/pg_namespace.c

@@ -95,7 +95,8 @@ NamespaceCreate(const char *nspName, Oid ownerId, bool isTemp)
 		recordDependencyOnCurrentExtension(&myself, false);
 
 	/* Post creation hook for new schema */
-	InvokeObjectAccessHook(OAT_POST_CREATE, NamespaceRelationId, nspoid, 0);
+	InvokeObjectAccessHook(OAT_POST_CREATE,
+						   NamespaceRelationId, nspoid, 0, NULL);
 
 	return nspoid;
 }

src/backend/catalog/pg_operator.c

@@ -275,7 +275,7 @@ OperatorShellMake(const char *operatorName,
 
 	/* Post creation hook for new shell operator */
 	InvokeObjectAccessHook(OAT_POST_CREATE,
-						   OperatorRelationId, operatorObjectId, 0);
+						   OperatorRelationId, operatorObjectId, 0, NULL);
 
 	/*
 	 * Make sure the tuple is visible for subsequent lookups/updates.
@@ -544,7 +544,7 @@ OperatorCreate(const char *operatorName,
 
 	/* Post creation hook for new operator */
 	InvokeObjectAccessHook(OAT_POST_CREATE,
-						   OperatorRelationId, operatorObjectId, 0);
+						   OperatorRelationId, operatorObjectId, 0, NULL);
 
 	heap_close(pg_operator_desc, RowExclusiveLock);
 

src/backend/catalog/pg_proc.c

@@ -655,7 +655,8 @@ ProcedureCreate(const char *procedureName,
 	heap_freetuple(tup);
 
 	/* Post creation hook for new function */
-	InvokeObjectAccessHook(OAT_POST_CREATE, ProcedureRelationId, retval, 0);
+	InvokeObjectAccessHook(OAT_POST_CREATE,
+						   ProcedureRelationId, retval, 0, NULL);
 
 	heap_close(rel, RowExclusiveLock);
 

src/backend/catalog/pg_type.c

@@ -162,7 +162,8 @@ TypeShellMake(const char *typeName, Oid typeNamespace, Oid ownerId)
 								 false);
 
 	/* Post creation hook for new shell type */
-	InvokeObjectAccessHook(OAT_POST_CREATE, TypeRelationId, typoid, 0);
+	InvokeObjectAccessHook(OAT_POST_CREATE,
+						   TypeRelationId, typoid, 0, NULL);
 
 	/*
 	 * clean up and return the type-oid
@@ -474,7 +475,8 @@ TypeCreate(Oid newTypeOid,
 								 rebuildDeps);
 
 	/* Post creation hook for new type */
-	InvokeObjectAccessHook(OAT_POST_CREATE, TypeRelationId, typeObjectId, 0);
+	InvokeObjectAccessHook(OAT_POST_CREATE,
+						   TypeRelationId, typeObjectId, 0, NULL);
 
 	/*
 	 * finish up

src/backend/commands/dbcommands.c

@@ -515,7 +515,8 @@ createdb(const CreatedbStmt *stmt)
 	copyTemplateDependencies(src_dboid, dboid);
 
 	/* Post creation hook for new database */
-	InvokeObjectAccessHook(OAT_POST_CREATE, DatabaseRelationId, dboid, 0);
+	InvokeObjectAccessHook(OAT_POST_CREATE,
+						   DatabaseRelationId, dboid, 0, NULL);
 
 	/*
 	 * Force a checkpoint before starting the copy. This will force dirty
@@ -777,6 +778,15 @@ dropdb(const char *dbname, bool missing_ok)
 		aclcheck_error(ACLCHECK_NOT_OWNER, ACL_KIND_DATABASE,
 					   dbname);
 
+	/* DROP hook for the database being removed */
+	if (object_access_hook)
+	{
+		ObjectAccessDrop    drop_arg;
+		memset(&drop_arg, 0, sizeof(ObjectAccessDrop));
+		InvokeObjectAccessHook(OAT_DROP,
+							   DatabaseRelationId, db_id, 0, &drop_arg);
+	}
+
 	/*
 	 * Disallow dropping a DB that is marked istemplate.  This is just to
 	 * prevent people from accidentally dropping template0 or template1; they

src/backend/commands/extension.c

@@ -1558,7 +1558,7 @@ InsertExtensionTuple(const char *extName, Oid extOwner,
 	}
 	/* Post creation hook for new extension */
 	InvokeObjectAccessHook(OAT_POST_CREATE,
-						   ExtensionRelationId, extensionOid, 0);
+						   ExtensionRelationId, extensionOid, 0, NULL);
 
 	return extensionOid;
 }

src/backend/commands/foreigncmds.c

@@ -666,7 +666,7 @@ CreateForeignDataWrapper(CreateFdwStmt *stmt)
 
 	/* Post creation hook for new foreign data wrapper */
 	InvokeObjectAccessHook(OAT_POST_CREATE,
-						   ForeignDataWrapperRelationId, fdwId, 0);
+						   ForeignDataWrapperRelationId, fdwId, 0, NULL);
 
 	heap_close(rel, RowExclusiveLock);
 }
@@ -962,7 +962,8 @@ CreateForeignServer(CreateForeignServerStmt *stmt)
 	recordDependencyOnCurrentExtension(&myself, false);
 
 	/* Post creation hook for new foreign server */
-	InvokeObjectAccessHook(OAT_POST_CREATE, ForeignServerRelationId, srvId, 0);
+	InvokeObjectAccessHook(OAT_POST_CREATE,
+						   ForeignServerRelationId, srvId, 0, NULL);
 
 	heap_close(rel, RowExclusiveLock);
 }
@@ -1202,7 +1203,8 @@ CreateUserMapping(CreateUserMappingStmt *stmt)
 	recordDependencyOnCurrentExtension(&myself, false);
 
 	/* Post creation hook for new user mapping */
-	InvokeObjectAccessHook(OAT_POST_CREATE, UserMappingRelationId, umId, 0);
+	InvokeObjectAccessHook(OAT_POST_CREATE,
+						   UserMappingRelationId, umId, 0, NULL);
 
 	heap_close(rel, RowExclusiveLock);
 }

src/backend/commands/functioncmds.c

@@ -1759,7 +1759,8 @@ CreateCast(CreateCastStmt *stmt)
 	recordDependencyOnCurrentExtension(&myself, false);
 
 	/* Post creation hook for new cast */
-	InvokeObjectAccessHook(OAT_POST_CREATE, CastRelationId, castid, 0);
+	InvokeObjectAccessHook(OAT_POST_CREATE,
+						   CastRelationId, castid, 0, NULL);
 
 	heap_freetuple(tuple);
 

src/backend/commands/opclasscmds.c

@@ -314,7 +314,7 @@ CreateOpFamily(char *amname, char *opfname, Oid namespaceoid, Oid amoid)
 
 	/* Post creation hook for new operator family */
 	InvokeObjectAccessHook(OAT_POST_CREATE,
-						   OperatorFamilyRelationId, opfamilyoid, 0);
+						   OperatorFamilyRelationId, opfamilyoid, 0, NULL);
 
 	heap_close(rel, RowExclusiveLock);
 
@@ -717,7 +717,7 @@ DefineOpClass(CreateOpClassStmt *stmt)
 
 	/* Post creation hook for new operator class */
 	InvokeObjectAccessHook(OAT_POST_CREATE,
-						   OperatorClassRelationId, opclassoid, 0);
+						   OperatorClassRelationId, opclassoid, 0, NULL);
 
 	heap_close(rel, RowExclusiveLock);
 }

src/backend/commands/proclang.c

@@ -428,7 +428,7 @@ create_proc_lang(const char *languageName, bool replace,
 
 	/* Post creation hook for new procedural language */
 	InvokeObjectAccessHook(OAT_POST_CREATE,
-						   LanguageRelationId, myself.objectId, 0);
+						   LanguageRelationId, myself.objectId, 0, NULL);
 
 	heap_close(rel, RowExclusiveLock);
 }

src/backend/commands/tablecmds.c

@@ -4382,7 +4382,7 @@ ATExecAddColumn(List **wqueue, AlteredTableInfo *tab, Relation rel,
 
 	/* Post creation hook for new attribute */
 	InvokeObjectAccessHook(OAT_POST_CREATE,
-						   RelationRelationId, myrelid, newattnum);
+						   RelationRelationId, myrelid, newattnum, NULL);
 
 	heap_close(pgclass, RowExclusiveLock);
 

src/backend/commands/tablespace.c

@@ -330,7 +330,7 @@ CreateTableSpace(CreateTableSpaceStmt *stmt)
 
 	/* Post creation hook for new tablespace */
 	InvokeObjectAccessHook(OAT_POST_CREATE,
-						   TableSpaceRelationId, tablespaceoid, 0);
+						   TableSpaceRelationId, tablespaceoid, 0, NULL);
 
 	create_tablespace_directories(location, tablespaceoid);
 
@@ -434,6 +434,15 @@ DropTableSpace(DropTableSpaceStmt *stmt)
 		aclcheck_error(ACLCHECK_NO_PRIV, ACL_KIND_TABLESPACE,
 					   tablespacename);
 
+	/* DROP hook for the tablespace being removed */
+	if (object_access_hook)
+	{
+		ObjectAccessDrop    drop_arg;
+		memset(&drop_arg, 0, sizeof(ObjectAccessDrop));
+		InvokeObjectAccessHook(OAT_DROP, TableSpaceRelationId,
+							   tablespaceoid, 0, &drop_arg);
+	}
+
 	/*
 	 * Remove the pg_tablespace tuple (this will roll back if we fail below)
 	 */

src/backend/commands/trigger.c

@@ -756,7 +756,7 @@ CreateTrigger(CreateTrigStmt *stmt, const char *queryString,
 
 	/* Post creation hook for new trigger */
 	InvokeObjectAccessHook(OAT_POST_CREATE,
-						   TriggerRelationId, trigoid, 0);
+						   TriggerRelationId, trigoid, 0, NULL);
 
 	/* Keep lock on target rel until end of xact */
 	heap_close(rel, NoLock);

src/backend/commands/tsearchcmds.c

@@ -271,7 +271,8 @@ DefineTSParser(List *names, List *parameters)
 	makeParserDependencies(tup);
 
 	/* Post creation hook for new text search parser */
-	InvokeObjectAccessHook(OAT_POST_CREATE, TSParserRelationId, prsOid, 0);
+	InvokeObjectAccessHook(OAT_POST_CREATE,
+						   TSParserRelationId, prsOid, 0, NULL);
 
 	heap_freetuple(tup);
 
@@ -565,7 +566,7 @@ DefineTSDictionary(List *names, List *parameters)
 
 	/* Post creation hook for new text search dictionary */
 	InvokeObjectAccessHook(OAT_POST_CREATE,
-						   TSDictionaryRelationId, dictOid, 0);
+						   TSDictionaryRelationId, dictOid, 0, NULL);
 
 	heap_freetuple(tup);
 
@@ -1036,7 +1037,8 @@ DefineTSTemplate(List *names, List *parameters)
 	makeTSTemplateDependencies(tup);
 
 	/* Post creation hook for new text search template */
-	InvokeObjectAccessHook(OAT_POST_CREATE, TSTemplateRelationId, dictOid, 0);
+	InvokeObjectAccessHook(OAT_POST_CREATE,
+						   TSTemplateRelationId, dictOid, 0, NULL);
 
 	heap_freetuple(tup);
 
@@ -1419,7 +1421,8 @@ DefineTSConfiguration(List *names, List *parameters)
 	makeConfigurationDependencies(tup, false, mapRel);
 
 	/* Post creation hook for new text search configuration */
-	InvokeObjectAccessHook(OAT_POST_CREATE, TSConfigRelationId, cfgOid, 0);
+	InvokeObjectAccessHook(OAT_POST_CREATE,
+						   TSConfigRelationId, cfgOid, 0, NULL);
 
 	heap_freetuple(tup);
 

src/backend/commands/user.c

@@ -425,7 +425,8 @@ CreateRole(CreateRoleStmt *stmt)
 				GetUserId(), false);
 
 	/* Post creation hook for new role */
-	InvokeObjectAccessHook(OAT_POST_CREATE, AuthIdRelationId, roleid, 0);
+	InvokeObjectAccessHook(OAT_POST_CREATE,
+						   AuthIdRelationId, roleid, 0, NULL);
 
 	/*
 	 * Close pg_authid, but keep lock till commit.
@@ -932,6 +933,15 @@ DropRole(DropRoleStmt *stmt)
 					(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
 					 errmsg("must be superuser to drop superusers")));
 
+		/* DROP hook for the role being removed */
+		if (object_access_hook)
+		{
+			ObjectAccessDrop	drop_arg;
+			memset(&drop_arg, 0, sizeof(ObjectAccessDrop));
+			InvokeObjectAccessHook(OAT_DROP,
+								   AuthIdRelationId, roleid, 0, &drop_arg);
+		}
+
 		/*
 		 * Lock the role, so nobody can add dependencies to her while we drop
 		 * her.  We keep the lock until the end of transaction.

src/backend/rewrite/rewriteDefine.c

@@ -178,7 +178,7 @@ InsertRule(char *rulname,
 
 	/* Post creation hook for new rule */
 	InvokeObjectAccessHook(OAT_POST_CREATE,
-						   RewriteRelationId, rewriteObjectId, 0);
+						   RewriteRelationId, rewriteObjectId, 0, NULL);
 
 	heap_close(pg_rewrite_desc, RowExclusiveLock);
 

src/backend/storage/large_object/inv_api.c

@@ -217,7 +217,7 @@ inv_create(Oid lobjId)
 
 	/* Post creation hook for new large object */
 	InvokeObjectAccessHook(OAT_POST_CREATE,
-						   LargeObjectRelationId, lobjId_new, 0);
+						   LargeObjectRelationId, lobjId_new, 0, NULL);
 
 	/*
 	 * Advance command counter to make new tuple visible to later operations.

src/include/catalog/objectaccess.h

@@ -19,28 +19,45 @@
  * Typically, this is done after inserting the primary catalog records and
  * associated dependencies.
  *
+ * OAT_DROP should be invoked just before deletion of objects; typically
+ * deleteOneObject(). Its arguments are packed within ObjectAccessDrop.
+ *
  * Other types may be added in the future.
  */
 typedef enum ObjectAccessType
 {
 	OAT_POST_CREATE,
+	OAT_DROP,
 } ObjectAccessType;
 
 /*
- * Hook, and a macro to invoke it.
+ * Arguments of OAT_DROP event
  */
+typedef struct
+{
+	/*
+	 * Flags to inform extensions the context of this deletion.
+	 * Also see PERFORM_DELETION_* in dependency.h
+	 */
+	int		dropflags;
+} ObjectAccessDrop;
 
+/*
+ * Hook, and a macro to invoke it.
+ */
 typedef void (*object_access_hook_type) (ObjectAccessType access,
 													 Oid classId,
 													 Oid objectId,
-													 int subId);
+													 int subId,
+													 void *arg);
 
 extern PGDLLIMPORT object_access_hook_type object_access_hook;
 
-#define InvokeObjectAccessHook(access,classId,objectId,subId)			\
-	do {																\
-		if (object_access_hook)											\
-			(*object_access_hook)((access),(classId),(objectId),(subId)); \
+#define InvokeObjectAccessHook(access,classId,objectId,subId,arg)	\
+	do {															\
+		if (object_access_hook)										\
+			(*object_access_hook)((access),(classId),				\
+								  (objectId),(subId),(arg));		\
 	} while(0)
 
 #endif   /* OBJECTACCESS_H */