src/backend/nodes/params.c

   1 /*-------------------------------------------------------------------------
   2  *
   3  * params.c
   4  *        Support for finding the values associated with Param nodes.
   5  *
   6  *
   7  * Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
   8  * Portions Copyright (c) 1994, Regents of the University of California
   9  *
  10  * IDENTIFICATION
  11  *        $PostgreSQL$
  12  *
  13  *-------------------------------------------------------------------------
  14  */
  15
  16 #include "postgres.h"
  17
  18 #include "nodes/params.h"
  19 #include "utils/datum.h"
  20 #include "utils/lsyscache.h"
  21
  22
  23 /*
  24  * Copy a ParamListInfo structure.
  25  *
  26  * The result is allocated in CurrentMemoryContext.
  27  */
  28 ParamListInfo
  29 copyParamList(ParamListInfo from)
  30 {
  31         ParamListInfo retval;
  32         Size            size;
  33         int                     i;
  34
  35         if (from == NULL || from->numParams <= 0)
  36                 return NULL;
  37
  38         /* sizeof(ParamListInfoData) includes the first array element */
  39         size = sizeof(ParamListInfoData) +
  40                 (from->numParams - 1) *sizeof(ParamExternData);
  41
  42         retval = (ParamListInfo) palloc(size);
  43         memcpy(retval, from, size);
  44
  45         /*
  46          * Flat-copy is not good enough for pass-by-ref data values, so make a
  47          * pass over the array to copy those.
  48          */
  49         for (i = 0; i < retval->numParams; i++)
  50         {
  51                 ParamExternData *prm = &retval->params[i];
  52                 int16           typLen;
  53                 bool            typByVal;
  54
  55                 if (prm->isnull || !OidIsValid(prm->ptype))
  56                         continue;
  57                 get_typlenbyval(prm->ptype, &typLen, &typByVal);
  58                 prm->value = datumCopy(prm->value, typByVal, typLen);
  59         }
  60
  61         return retval;
  62 }
  63
  64 /*
  65  * Extract an array of parameter type OIDs from a ParamListInfo.
  66  *
  67  * The result is allocated in CurrentMemoryContext.
  68  */
  69 void
  70 getParamListTypes(ParamListInfo params,
  71                                   Oid **param_types, int *num_params)
  72 {
  73         Oid                *ptypes;
  74         int                     i;
  75
  76         if (params == NULL || params->numParams <= 0)
  77         {
  78                 *param_types = NULL;
  79                 *num_params = 0;
  80                 return;
  81         }
  82
  83         ptypes = (Oid *) palloc(params->numParams * sizeof(Oid));
  84         *param_types = ptypes;
  85         *num_params = params->numParams;
  86
  87         for (i = 0; i < params->numParams; i++)
  88         {
  89                 ParamExternData *prm = &params->params[i];
  90
  91                 ptypes[i] = prm->ptype;
  92         }
  93 }