From 677708032c4a4d37cdb2a4bd45726fc260308db7 Mon Sep 17 00:00:00 2001 From: Tom Lane Date: Wed, 12 Nov 2014 15:58:37 -0500 Subject: [PATCH] Explicitly support the case that a plancache's raw_parse_tree is NULL. This only happens if a client issues a Parse message with an empty query string, which is a bit odd; but since it is explicitly called out as legal by our FE/BE protocol spec, we'd probably better continue to allow it. Fix by adding tests everywhere that the raw_parse_tree field is passed to functions that don't or shouldn't accept NULL. Also make it clear in the relevant comments that NULL is an expected case. This reverts commits a73c9dbab0165b3395dfe8a44a7dfd16166963c4 and 2e9650cbcff8c8fb0d9ef807c73a44f241822eee, which fixed specific crash symptoms by hacking things at what now seems to be the wrong end, ie the callee functions. Making the callees allow NULL is superficially more robust, but it's not always true that there is a defensible thing for the callee to do in such cases. The caller has more context and is better able to decide what the empty-query case ought to do. Per followup discussion of bug #11335. Back-patch to 9.2. The code before that is sufficiently different that it would require development of a separate patch, which doesn't seem worthwhile for what is believed to be an essentially cosmetic change. --- src/backend/executor/spi.c | 4 +++- src/backend/parser/analyze.c | 6 +----- src/backend/tcop/postgres.c | 4 +++- src/backend/tcop/utility.c | 5 +---- src/backend/utils/cache/plancache.c | 9 ++++++--- src/include/utils/plancache.h | 2 +- 6 files changed, 15 insertions(+), 15 deletions(-) diff --git a/src/backend/executor/spi.c b/src/backend/executor/spi.c index 7ba1fd9066..cfa4a24686 100644 --- a/src/backend/executor/spi.c +++ b/src/backend/executor/spi.c @@ -2037,7 +2037,9 @@ _SPI_execute_plan(SPIPlanPtr plan, ParamListInfo paramLI, * Parameter datatypes are driven by parserSetup hook if provided, * otherwise we use the fixed parameter list. */ - if (plan->parserSetup != NULL) + if (parsetree == NULL) + stmt_list = NIL; + else if (plan->parserSetup != NULL) { Assert(plan->nargs == 0); stmt_list = pg_analyze_and_rewrite_params(parsetree, diff --git a/src/backend/parser/analyze.c b/src/backend/parser/analyze.c index bd78e94985..cc569eddd5 100644 --- a/src/backend/parser/analyze.c +++ b/src/backend/parser/analyze.c @@ -288,17 +288,13 @@ transformStmt(ParseState *pstate, Node *parseTree) * Returns true if a snapshot must be set before doing parse analysis * on the given raw parse tree. * - * Classification here should match transformStmt(); but we also have to - * allow a NULL input (for Parse/Bind of an empty query string). + * Classification here should match transformStmt(). */ bool analyze_requires_snapshot(Node *parseTree) { bool result; - if (parseTree == NULL) - return false; - switch (nodeTag(parseTree)) { /* diff --git a/src/backend/tcop/postgres.c b/src/backend/tcop/postgres.c index 61f17bf1e9..cc62b2cfe8 100644 --- a/src/backend/tcop/postgres.c +++ b/src/backend/tcop/postgres.c @@ -1546,7 +1546,9 @@ exec_bind_message(StringInfo input_message) * snapshot active till we're done, so that plancache.c doesn't have to * take new ones. */ - if (numParams > 0 || analyze_requires_snapshot(psrc->raw_parse_tree)) + if (numParams > 0 || + (psrc->raw_parse_tree && + analyze_requires_snapshot(psrc->raw_parse_tree))) { PushActiveSnapshot(GetTransactionSnapshot()); snapshot_set = true; diff --git a/src/backend/tcop/utility.c b/src/backend/tcop/utility.c index 422911cde0..58f78ce50d 100644 --- a/src/backend/tcop/utility.c +++ b/src/backend/tcop/utility.c @@ -2485,9 +2485,6 @@ GetCommandLogLevel(Node *parsetree) { LogStmtLevel lev; - if (parsetree == NULL) - return LOGSTMT_ALL; - switch (nodeTag(parsetree)) { /* raw plannable queries */ @@ -2592,7 +2589,7 @@ GetCommandLogLevel(Node *parsetree) /* Look through an EXECUTE to the referenced stmt */ ps = FetchPreparedStatement(stmt->name, false); - if (ps) + if (ps && ps->plansource->raw_parse_tree) lev = GetCommandLogLevel(ps->plansource->raw_parse_tree); else lev = LOGSTMT_ALL; diff --git a/src/backend/utils/cache/plancache.c b/src/backend/utils/cache/plancache.c index 26ef2fa6ff..d85ea1bbd3 100644 --- a/src/backend/utils/cache/plancache.c +++ b/src/backend/utils/cache/plancache.c @@ -141,7 +141,7 @@ InitPlanCache(void) * Once constructed, the cached plan can be made longer-lived, if needed, * by calling SaveCachedPlan. * - * raw_parse_tree: output of raw_parser() + * raw_parse_tree: output of raw_parser(), or NULL if empty query * query_string: original query text * commandTag: compile-time-constant tag for query, or NULL if empty query */ @@ -232,7 +232,7 @@ CreateCachedPlan(Node *raw_parse_tree, * invalidation, so plan use must be completed in the current transaction, * and DDL that might invalidate the querytree_list must be avoided as well. * - * raw_parse_tree: output of raw_parser() + * raw_parse_tree: output of raw_parser(), or NULL if empty query * query_string: original query text * commandTag: compile-time-constant tag for query, or NULL if empty query */ @@ -699,7 +699,9 @@ RevalidateCachedQuery(CachedPlanSource *plansource) * the cache. */ rawtree = copyObject(plansource->raw_parse_tree); - if (plansource->parserSetup != NULL) + if (rawtree == NULL) + tlist = NIL; + else if (plansource->parserSetup != NULL) tlist = pg_analyze_and_rewrite_params(rawtree, plansource->query_string, plansource->parserSetup, @@ -928,6 +930,7 @@ BuildCachedPlan(CachedPlanSource *plansource, List *qlist, */ snapshot_set = false; if (!ActiveSnapshotSet() && + plansource->raw_parse_tree && analyze_requires_snapshot(plansource->raw_parse_tree)) { PushActiveSnapshot(GetTransactionSnapshot()); diff --git a/src/include/utils/plancache.h b/src/include/utils/plancache.h index 56bf4bb7af..2622ceb54b 100644 --- a/src/include/utils/plancache.h +++ b/src/include/utils/plancache.h @@ -76,7 +76,7 @@ typedef struct CachedPlanSource { int magic; /* should equal CACHEDPLANSOURCE_MAGIC */ - Node *raw_parse_tree; /* output of raw_parser() */ + Node *raw_parse_tree; /* output of raw_parser(), or NULL */ const char *query_string; /* source text of query */ const char *commandTag; /* command tag (a constant!), or NULL */ Oid *param_types; /* array of parameter type OIDs, or NULL */