From: Tom Lane Date: Tue, 29 Nov 2011 00:12:17 +0000 (-0500) Subject: Disallow deletion of CurrentExtensionObject while running extension script. X-Git-Tag: REL9_2_BETA1~759 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=871dd024a6adf7766702b1cdacfb02bd8002d2bb;p=thirdparty%2Fpostgresql.git Disallow deletion of CurrentExtensionObject while running extension script. While the deletion in itself wouldn't break things, any further creation of objects in the script would result in dangling pg_depend entries being added by recordDependencyOnCurrentExtension(). An example from Phil Sorber convinced me that this is just barely likely enough to be worth expending a couple lines of code to defend against. The resulting error message might be confusing, but it's better than leaving corrupted catalog contents for the user to deal with. --- diff --git a/src/backend/commands/extension.c b/src/backend/commands/extension.c index c334ca9cf8c..7192c458e75 100644 --- a/src/backend/commands/extension.c +++ b/src/backend/commands/extension.c @@ -1577,6 +1577,23 @@ RemoveExtensionById(Oid extId) HeapTuple tuple; ScanKeyData entry[1]; + /* + * Disallow deletion of any extension that's currently open for insertion; + * else subsequent executions of recordDependencyOnCurrentExtension() + * could create dangling pg_depend records that refer to a no-longer-valid + * pg_extension OID. This is needed not so much because we think people + * might write "DROP EXTENSION foo" in foo's own script files, as because + * errors in dependency management in extension script files could give + * rise to cases where an extension is dropped as a result of recursing + * from some contained object. Because of that, we must test for the case + * here, not at some higher level of the DROP EXTENSION command. + */ + if (extId == CurrentExtensionObject) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE), + errmsg("cannot drop extension \"%s\" because it is being modified", + get_extension_name(extId)))); + rel = heap_open(ExtensionRelationId, RowExclusiveLock); ScanKeyInit(&entry[0],