From 07a3af0ff81d8ac6d2e787e13ca10de36313aa51 Mon Sep 17 00:00:00 2001 From: Tom Lane Date: Mon, 17 Sep 2018 13:16:32 -0400 Subject: [PATCH] Fix parsetree representation of XMLTABLE(XMLNAMESPACES(DEFAULT ...)). The original coding for XMLTABLE thought it could represent a default namespace by a T_String Value node with a null string pointer. That's not okay, though; in particular outfuncs.c/readfuncs.c are not on board with such a representation, meaning you'll get a null pointer crash if you try to store a view or rule containing this construct. To fix, change the parsetree representation so that we have a NULL list element, instead of a bogus Value node. This isn't really a functional limitation since default XML namespaces aren't yet implemented in the executor; you'd just get "DEFAULT namespace is not supported" anyway. But crashes are not nice, so back-patch to v10 where this syntax was added. Ordinarily we'd consider a parsetree representation change to be un-backpatchable; but since existing releases would crash on the way to storing such constructs, there can't be any existing views/rules to be incompatible with. Per report from Andrey Lepikhov. Discussion: https://postgr.es/m/3690074f-abd2-56a9-144a-aa5545d7a291@postgrespro.ru --- src/backend/executor/nodeTableFuncscan.c | 6 +++++- src/backend/parser/parse_clause.c | 15 ++++++++------- src/backend/utils/adt/ruleutils.c | 6 +++--- src/include/nodes/execnodes.h | 4 ++-- src/include/nodes/primnodes.h | 7 +++++-- 5 files changed, 23 insertions(+), 15 deletions(-) diff --git a/src/backend/executor/nodeTableFuncscan.c b/src/backend/executor/nodeTableFuncscan.c index abbf0e4d445..a9fd3fda6be 100644 --- a/src/backend/executor/nodeTableFuncscan.c +++ b/src/backend/executor/nodeTableFuncscan.c @@ -364,8 +364,9 @@ tfuncInitialize(TableFuncScanState *tstate, ExprContext *econtext, Datum doc) forboth(lc1, tstate->ns_uris, lc2, tstate->ns_names) { ExprState *expr = (ExprState *) lfirst(lc1); - char *ns_name = strVal(lfirst(lc2)); + Value *ns_node = (Value *) lfirst(lc2); char *ns_uri; + char *ns_name; value = ExecEvalExpr((ExprState *) expr, econtext, &isnull); if (isnull) @@ -374,6 +375,9 @@ tfuncInitialize(TableFuncScanState *tstate, ExprContext *econtext, Datum doc) errmsg("namespace URI must not be null"))); ns_uri = TextDatumGetCString(value); + /* DEFAULT is passed down to SetNamespace as NULL */ + ns_name = ns_node ? strVal(ns_node) : NULL; + routine->SetNamespace(tstate, ns_name, ns_uri); } diff --git a/src/backend/parser/parse_clause.c b/src/backend/parser/parse_clause.c index cfd4b91897f..d6b93f55dfd 100644 --- a/src/backend/parser/parse_clause.c +++ b/src/backend/parser/parse_clause.c @@ -779,7 +779,7 @@ transformRangeTableFunc(ParseState *pstate, RangeTableFunc *rtf) /* undef ordinality column number */ tf->ordinalitycol = -1; - + /* Process column specs */ names = palloc(sizeof(char *) * list_length(rtf->columns)); colno = 0; @@ -900,15 +900,15 @@ transformRangeTableFunc(ParseState *pstate, RangeTableFunc *rtf) { foreach(lc2, ns_names) { - char *name = strVal(lfirst(lc2)); + Value *ns_node = (Value *) lfirst(lc2); - if (name == NULL) + if (ns_node == NULL) continue; - if (strcmp(name, r->name) == 0) + if (strcmp(strVal(ns_node), r->name) == 0) ereport(ERROR, (errcode(ERRCODE_SYNTAX_ERROR), errmsg("namespace name \"%s\" is not unique", - name), + r->name), parser_errposition(pstate, r->location))); } } @@ -922,8 +922,9 @@ transformRangeTableFunc(ParseState *pstate, RangeTableFunc *rtf) default_ns_seen = true; } - /* Note the string may be NULL */ - ns_names = lappend(ns_names, makeString(r->name)); + /* We represent DEFAULT by a null pointer */ + ns_names = lappend(ns_names, + r->name ? makeString(r->name) : NULL); } tf->ns_uris = ns_uris; diff --git a/src/backend/utils/adt/ruleutils.c b/src/backend/utils/adt/ruleutils.c index 4c2408d6551..eecd64e4b57 100644 --- a/src/backend/utils/adt/ruleutils.c +++ b/src/backend/utils/adt/ruleutils.c @@ -9739,17 +9739,17 @@ get_tablefunc(TableFunc *tf, deparse_context *context, bool showimplicit) forboth(lc1, tf->ns_uris, lc2, tf->ns_names) { Node *expr = (Node *) lfirst(lc1); - char *name = strVal(lfirst(lc2)); + Value *ns_node = (Value *) lfirst(lc2); if (!first) appendStringInfoString(buf, ", "); else first = false; - if (name != NULL) + if (ns_node != NULL) { get_rule_expr(expr, context, showimplicit); - appendStringInfo(buf, " AS %s", name); + appendStringInfo(buf, " AS %s", strVal(ns_node)); } else { diff --git a/src/include/nodes/execnodes.h b/src/include/nodes/execnodes.h index c830f141b16..687d7cd2f41 100644 --- a/src/include/nodes/execnodes.h +++ b/src/include/nodes/execnodes.h @@ -1573,8 +1573,8 @@ typedef struct TableFuncScanState ExprState *rowexpr; /* state for row-generating expression */ List *colexprs; /* state for column-generating expression */ List *coldefexprs; /* state for column default expressions */ - List *ns_names; /* list of str nodes with namespace names */ - List *ns_uris; /* list of states of namespace uri exprs */ + List *ns_names; /* same as TableFunc.ns_names */ + List *ns_uris; /* list of states of namespace URI exprs */ Bitmapset *notnulls; /* nullability flag for each output column */ void *opaque; /* table builder private space */ const struct TableFuncRoutine *routine; /* table builder methods */ diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h index 1b4b0d75afa..40f6eb03d24 100644 --- a/src/include/nodes/primnodes.h +++ b/src/include/nodes/primnodes.h @@ -75,12 +75,15 @@ typedef struct RangeVar /* * TableFunc - node for a table function, such as XMLTABLE. + * + * Entries in the ns_names list are either string Value nodes containing + * literal namespace names, or NULL pointers to represent DEFAULT. */ typedef struct TableFunc { NodeTag type; - List *ns_uris; /* list of namespace uri */ - List *ns_names; /* list of namespace names */ + List *ns_uris; /* list of namespace URI expressions */ + List *ns_names; /* list of namespace names or NULL */ Node *docexpr; /* input document expression */ Node *rowexpr; /* row filter expression */ List *colnames; /* column names (list of String) */