From 761a5688b179d46091e7314458571c5fc537084a Mon Sep 17 00:00:00 2001 From: Tom Lane Date: Wed, 19 Feb 2020 14:44:58 -0500 Subject: [PATCH] Fix confusion about event trigger vs. plain function in plpgsql. The function hash table keys made by compute_function_hashkey() failed to distinguish event-trigger call context from regular call context. This meant that once we'd successfully made a hash entry for an event trigger (either by validation, or by normal use as an event trigger), an attempt to call the trigger function as a plain function would find this hash entry and thereby bypass the you-can't-do-that check in do_compile(). Thus we'd attempt to execute the function, leading to strange errors or even crashes, depending on function contents and server version. To fix, add an isEventTrigger field to PLpgSQL_func_hashkey, paralleling the longstanding infrastructure for regular triggers. This fits into what had been pad space, so there's no risk of an ABI break, even assuming that any third-party code is looking at these hash keys. (I considered replacing isTrigger with a PLpgSQL_trigtype enum field, but felt that that carried some API/ABI risk. Maybe we should change it in HEAD though.) Per bug #16266 from Alexander Lakhin. This has been broken since event triggers were invented, so back-patch to all supported branches. Discussion: https://postgr.es/m/16266-fcd7f838e97ba5d4@postgresql.org --- src/pl/plpgsql/src/pl_comp.c | 15 +++++++++++---- src/pl/plpgsql/src/plpgsql.h | 5 +++-- src/test/regress/expected/event_trigger.out | 4 ++++ src/test/regress/sql/event_trigger.sql | 3 +++ 4 files changed, 21 insertions(+), 6 deletions(-) diff --git a/src/pl/plpgsql/src/pl_comp.c b/src/pl/plpgsql/src/pl_comp.c index 66bf9f1211..4f6b36b145 100644 --- a/src/pl/plpgsql/src/pl_comp.c +++ b/src/pl/plpgsql/src/pl_comp.c @@ -2418,12 +2418,19 @@ compute_function_hashkey(FunctionCallInfo fcinfo, /* get call context */ hashkey->isTrigger = CALLED_AS_TRIGGER(fcinfo); + hashkey->isEventTrigger = CALLED_AS_EVENT_TRIGGER(fcinfo); /* - * if trigger, get its OID. In validation mode we do not know what - * relation or transition table names are intended to be used, so we leave - * trigOid zero; the hash entry built in this case will never really be - * used. + * If DML trigger, include trigger's OID in the hash, so that each trigger + * usage gets a different hash entry, allowing for e.g. different relation + * rowtypes or transition table names. In validation mode we do not know + * what relation or transition table names are intended to be used, so we + * leave trigOid zero; the hash entry built in this case will never be + * used for any actual calls. + * + * We don't currently need to distinguish different event trigger usages + * in the same way, since the special parameter variables don't vary in + * type in that case. */ if (hashkey->isTrigger && !forValidator) { diff --git a/src/pl/plpgsql/src/plpgsql.h b/src/pl/plpgsql/src/plpgsql.h index b599f67fc5..69df3306fd 100644 --- a/src/pl/plpgsql/src/plpgsql.h +++ b/src/pl/plpgsql/src/plpgsql.h @@ -939,7 +939,8 @@ typedef struct PLpgSQL_func_hashkey { Oid funcOid; - bool isTrigger; /* true if called as a trigger */ + bool isTrigger; /* true if called as a DML trigger */ + bool isEventTrigger; /* true if called as an event trigger */ /* be careful that pad bytes in this struct get zeroed! */ @@ -947,7 +948,7 @@ typedef struct PLpgSQL_func_hashkey * For a trigger function, the OID of the trigger is part of the hash key * --- we want to compile the trigger function separately for each trigger * it is used with, in case the rowtype or transition table names are - * different. Zero if not called as a trigger. + * different. Zero if not called as a DML trigger. */ Oid trigOid; diff --git a/src/test/regress/expected/event_trigger.out b/src/test/regress/expected/event_trigger.out index 788be86b33..bdd0ffcdaf 100644 --- a/src/test/regress/expected/event_trigger.out +++ b/src/test/regress/expected/event_trigger.out @@ -9,6 +9,10 @@ BEGIN RAISE NOTICE 'test_event_trigger: % %', tg_event, tg_tag; END $$ language plpgsql; +-- should fail, can't call it as a plain function +SELECT test_event_trigger(); +ERROR: trigger functions can only be called as triggers +CONTEXT: compilation of PL/pgSQL function "test_event_trigger" near line 1 -- should fail, event triggers cannot have declared arguments create function test_event_trigger_arg(name text) returns event_trigger as $$ BEGIN RETURN 1; END $$ language plpgsql; diff --git a/src/test/regress/sql/event_trigger.sql b/src/test/regress/sql/event_trigger.sql index 346168673d..18b2a267cb 100644 --- a/src/test/regress/sql/event_trigger.sql +++ b/src/test/regress/sql/event_trigger.sql @@ -10,6 +10,9 @@ BEGIN END $$ language plpgsql; +-- should fail, can't call it as a plain function +SELECT test_event_trigger(); + -- should fail, event triggers cannot have declared arguments create function test_event_trigger_arg(name text) returns event_trigger as $$ BEGIN RETURN 1; END $$ language plpgsql;