params.c

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/*-------------------------------------------------------------------------
 *
 * params.c
 *    Support for finding the values associated with Param nodes.
 *
 *
 * Portions Copyright (c) 1996-2013, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 * IDENTIFICATION
 *    src/backend/nodes/params.c
 *
 *-------------------------------------------------------------------------
 */

#include "postgres.h"

#include "nodes/params.h"
#include "utils/datum.h"
#include "utils/lsyscache.h"


/*
 * Copy a ParamListInfo structure.
 *
 * The result is allocated in CurrentMemoryContext.
 *
 * Note: the intent of this function is to make a static, self-contained
 * set of parameter values.  If dynamic parameter hooks are present, we
 * intentionally do not copy them into the result.  Rather, we forcibly
 * instantiate all available parameter values and copy the datum values.
 */
ParamListInfo
copyParamList(ParamListInfo from)
{
    ParamListInfo retval;
    Size        size;
    int         i;

    if (from == NULL || from->numParams <= 0)
        return NULL;

    /* sizeof(ParamListInfoData) includes the first array element */
    size = sizeof(ParamListInfoData) +
        (from->numParams - 1) * sizeof(ParamExternData);

    retval = (ParamListInfo) palloc(size);
    retval->paramFetch = NULL;
    retval->paramFetchArg = NULL;
    retval->parserSetup = NULL;
    retval->parserSetupArg = NULL;
    retval->numParams = from->numParams;

    for (i = 0; i < from->numParams; i++)
    {
        ParamExternData *oprm = &from->params[i];
        ParamExternData *nprm = &retval->params[i];
        int16       typLen;
        bool        typByVal;

        /* give hook a chance in case parameter is dynamic */
        if (!OidIsValid(oprm->ptype) && from->paramFetch != NULL)
            (*from->paramFetch) (from, i + 1);

        /* flat-copy the parameter info */
        *nprm = *oprm;

        /* need datumCopy in case it's a pass-by-reference datatype */
        if (nprm->isnull || !OidIsValid(nprm->ptype))
            continue;
        get_typlenbyval(nprm->ptype, &typLen, &typByVal);
        nprm->value = datumCopy(nprm->value, typByVal, typLen);
    }

    return retval;
}