Quelle  pg_parameter_acl.c

/*-------------------------------------------------------------------------
 *
 * pg_parameter_acl.c
 *   routines to support manipulation of the pg_parameter_acl relation
 *
 * Portions Copyright (c) 1996-2025, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 *
 * IDENTIFICATION
 *   src/backend/catalog/pg_parameter_acl.c
 *
 *-------------------------------------------------------------------------
 */
#include "postgres.h"

#include "access/table.h"
#include "catalog/catalog.h"
#include "catalog/indexing.h"
#include "catalog/pg_parameter_acl.h"
#include "utils/builtins.h"
#include "utils/guc.h"
#include "utils/rel.h"
#include "utils/syscache.h"


/*
 * ParameterAclLookup - Given a configuration parameter name,
 * look up the associated configuration parameter ACL's OID.
 *
 * If missing_ok is false, throw an error if ACL entry not found.  If
 * true, just return InvalidOid.
 */
Oid
ParameterAclLookup(const char *parameter, bool missing_ok)
{
 Oid   oid;
 char    *parname;

 /* Convert name to the form it should have in pg_parameter_acl... */
 parname = convert_GUC_name_for_parameter_acl(parameter);

 /* ... and look it up */
 oid = GetSysCacheOid1(PARAMETERACLNAME, Anum_pg_parameter_acl_oid,
        PointerGetDatum(cstring_to_text(parname)));

 if (!OidIsValid(oid) && !missing_ok)
  ereport(ERROR,
    (errcode(ERRCODE_UNDEFINED_OBJECT),
     errmsg("parameter ACL \"%s\" does not exist", parameter)));

 pfree(parname);

 return oid;
}

/*
 * ParameterAclCreate
 *
 * Add a new tuple to pg_parameter_acl.
 *
 * parameter: the parameter name to create an entry for.
 * Caller should have verified that there's no such entry already.
 *
 * Returns the new entry's OID.
 */
Oid
ParameterAclCreate(const char *parameter)
{
 Oid   parameterId;
 char    *parname;
 Relation rel;
 TupleDesc tupDesc;
 HeapTuple tuple;
 Datum  values[Natts_pg_parameter_acl] = {0};
 bool  nulls[Natts_pg_parameter_acl] = {0};

 /*
  * To prevent cluttering pg_parameter_acl with useless entries, insist
  * that the name be valid.
 */
 check_GUC_name_for_parameter_acl(parameter);

 /* Convert name to the form it should have in pg_parameter_acl. */
 parname = convert_GUC_name_for_parameter_acl(parameter);

 /*
  * Create and insert a new record containing a null ACL.
  *
  * We don't take a strong enough lock to prevent concurrent insertions,
  * relying instead on the unique index.
 */
 rel = table_open(ParameterAclRelationId, RowExclusiveLock);
 tupDesc = RelationGetDescr(rel);
 parameterId = GetNewOidWithIndex(rel,
          ParameterAclOidIndexId,
          Anum_pg_parameter_acl_oid);
 values[Anum_pg_parameter_acl_oid - 1] = ObjectIdGetDatum(parameterId);
 values[Anum_pg_parameter_acl_parname - 1] =
  PointerGetDatum(cstring_to_text(parname));
 nulls[Anum_pg_parameter_acl_paracl - 1] = true;
 tuple = heap_form_tuple(tupDesc, values, nulls);
 CatalogTupleInsert(rel, tuple);

 /* Close pg_parameter_acl, but keep lock till commit. */
 heap_freetuple(tuple);
 table_close(rel, NoLock);

 return parameterId;
}