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In HEAD only, revert kluge solution for preventing misuse of pg_get_expr().
A data-type-based solution, which is much cleaner and more bulletproof, will follow shortly. It seemed best to make this a separate commit though.
This commit is contained in:
Tom Lane
parent
c89a1198f9
commit
8ab6a6b456
@ -8,18 +8,15 @@
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*
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*
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* IDENTIFICATION
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* $PostgreSQL: pgsql/src/backend/parser/parse_func.c,v 1.226 2010/08/05 21:45:35 tgl Exp $
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* $PostgreSQL: pgsql/src/backend/parser/parse_func.c,v 1.227 2010/09/03 01:26:52 tgl Exp $
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*
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*-------------------------------------------------------------------------
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*/
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#include "postgres.h"
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#include "catalog/pg_attrdef.h"
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#include "catalog/pg_constraint.h"
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#include "catalog/pg_proc.h"
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#include "catalog/pg_type.h"
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#include "funcapi.h"
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#include "miscadmin.h"
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#include "nodes/makefuncs.h"
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#include "nodes/nodeFuncs.h"
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#include "parser/parse_agg.h"
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@ -29,7 +26,6 @@
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#include "parser/parse_target.h"
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#include "parser/parse_type.h"
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#include "utils/builtins.h"
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#include "utils/fmgroids.h"
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#include "utils/lsyscache.h"
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#include "utils/syscache.h"
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@ -511,9 +507,6 @@ ParseFuncOrColumn(ParseState *pstate, List *funcname, List *fargs,
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retval = (Node *) wfunc;
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}
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/* Hack to protect pg_get_expr() against misuse */
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check_pg_get_expr_args(pstate, funcid, fargs);
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return retval;
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}
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@ -1600,107 +1593,3 @@ LookupAggNameTypeNames(List *aggname, List *argtypes, bool noError)
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return oid;
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}
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/*
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* pg_get_expr() is a system function that exposes the expression
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* deparsing functionality in ruleutils.c to users. Very handy, but it was
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* later realized that the functions in ruleutils.c don't check the input
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* rigorously, assuming it to come from system catalogs and to therefore
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* be valid. That makes it easy for a user to crash the backend by passing
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* a maliciously crafted string representation of an expression to
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* pg_get_expr().
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*
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* There's a lot of code in ruleutils.c, so it's not feasible to add
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* water-proof input checking after the fact. Even if we did it once, it
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* would need to be taken into account in any future patches too.
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*
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* Instead, we restrict pg_rule_expr() to only allow input from system
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* catalogs. This is a hack, but it's the most robust and easiest
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* to backpatch way of plugging the vulnerability.
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*
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* This is transparent to the typical usage pattern of
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* "pg_get_expr(systemcolumn, ...)", but will break "pg_get_expr('foo',
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* ...)", even if 'foo' is a valid expression fetched earlier from a
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* system catalog. Hopefully there aren't many clients doing that out there.
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*/
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void
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check_pg_get_expr_args(ParseState *pstate, Oid fnoid, List *args)
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{
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bool allowed = false;
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Node *arg;
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int netlevelsup;
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/* if not being called for pg_get_expr, do nothing */
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if (fnoid != F_PG_GET_EXPR && fnoid != F_PG_GET_EXPR_EXT)
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return;
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/* superusers are allowed to call it anyway (dubious) */
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if (superuser())
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return;
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/*
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* The first argument must be a Var referencing one of the allowed
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* system-catalog columns. It could be a join alias Var, though.
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*/
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Assert(list_length(args) > 1);
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arg = (Node *) linitial(args);
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netlevelsup = 0;
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restart:
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if (IsA(arg, Var))
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{
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Var *var = (Var *) arg;
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RangeTblEntry *rte;
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netlevelsup += var->varlevelsup;
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rte = GetRTEByRangeTablePosn(pstate, var->varno, netlevelsup);
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if (rte->rtekind == RTE_JOIN)
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{
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/* Expand join alias reference */
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if (var->varattno > 0 &&
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var->varattno <= list_length(rte->joinaliasvars))
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{
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arg = (Node *) list_nth(rte->joinaliasvars, var->varattno - 1);
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goto restart;
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}
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}
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else if (rte->rtekind == RTE_RELATION)
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{
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switch (rte->relid)
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{
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case IndexRelationId:
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if (var->varattno == Anum_pg_index_indexprs ||
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var->varattno == Anum_pg_index_indpred)
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allowed = true;
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break;
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case AttrDefaultRelationId:
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if (var->varattno == Anum_pg_attrdef_adbin)
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allowed = true;
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break;
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case ProcedureRelationId:
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if (var->varattno == Anum_pg_proc_proargdefaults)
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allowed = true;
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break;
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case ConstraintRelationId:
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if (var->varattno == Anum_pg_constraint_conbin)
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allowed = true;
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break;
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case TypeRelationId:
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if (var->varattno == Anum_pg_type_typdefaultbin)
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allowed = true;
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break;
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}
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}
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}
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if (!allowed)
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ereport(ERROR,
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(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
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errmsg("argument to pg_get_expr() must come from system catalogs")));
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}
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@ -8,7 +8,7 @@
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*
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*
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* IDENTIFICATION
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* $PostgreSQL: pgsql/src/backend/parser/parse_oper.c,v 1.114 2010/07/29 23:16:33 tgl Exp $
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* $PostgreSQL: pgsql/src/backend/parser/parse_oper.c,v 1.115 2010/09/03 01:26:52 tgl Exp $
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*
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*-------------------------------------------------------------------------
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*/
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@ -869,9 +869,6 @@ make_op(ParseState *pstate, List *opname, Node *ltree, Node *rtree,
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ReleaseSysCache(tup);
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/* Hack to protect pg_get_expr() against misuse */
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check_pg_get_expr_args(pstate, result->opfuncid, args);
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return (Expr *) result;
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}
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@ -1000,9 +997,6 @@ make_scalar_array_op(ParseState *pstate, List *opname,
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ReleaseSysCache(tup);
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/* Hack to protect pg_get_expr() against misuse */
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check_pg_get_expr_args(pstate, result->opfuncid, args);
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return (Expr *) result;
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}
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@ -8,7 +8,7 @@
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*
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*
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* IDENTIFICATION
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* $PostgreSQL: pgsql/src/backend/tcop/fastpath.c,v 1.105 2010/07/06 19:18:57 momjian Exp $
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* $PostgreSQL: pgsql/src/backend/tcop/fastpath.c,v 1.106 2010/09/03 01:26:52 tgl Exp $
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*
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* NOTES
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* This cruft is the server side of PQfn.
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@ -29,7 +29,6 @@
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#include "tcop/fastpath.h"
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#include "tcop/tcopprot.h"
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#include "utils/acl.h"
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#include "utils/fmgroids.h"
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#include "utils/lsyscache.h"
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#include "utils/snapmgr.h"
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#include "utils/syscache.h"
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@ -348,16 +347,6 @@ HandleFunctionRequest(StringInfo msgBuf)
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aclcheck_error(aclresult, ACL_KIND_PROC,
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get_func_name(fid));
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/*
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* Restrict access to pg_get_expr(). This reflects the hack in
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* transformFuncCall() in parse_expr.c, see comments there for an
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* explanation.
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*/
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if ((fid == F_PG_GET_EXPR || fid == F_PG_GET_EXPR_EXT) && !superuser())
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ereport(ERROR,
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(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
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errmsg("argument to pg_get_expr() must come from system catalogs")));
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/*
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* Prepare function call info block and insert arguments.
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*/
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@ -7,7 +7,7 @@
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* Portions Copyright (c) 1996-2010, PostgreSQL Global Development Group
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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* $PostgreSQL: pgsql/src/include/parser/parse_func.h,v 1.69 2010/07/29 23:16:33 tgl Exp $
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* $PostgreSQL: pgsql/src/include/parser/parse_func.h,v 1.70 2010/09/03 01:26:52 tgl Exp $
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*
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*-------------------------------------------------------------------------
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*/
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@ -82,6 +82,4 @@ extern Oid LookupFuncNameTypeNames(List *funcname, List *argtypes,
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extern Oid LookupAggNameTypeNames(List *aggname, List *argtypes,
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bool noError);
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extern void check_pg_get_expr_args(ParseState *pstate, Oid fnoid, List *args);
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#endif /* PARSE_FUNC_H */
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