Line data    Source code

       1             : /*-------------------------------------------------------------------------
       2             :  *
       3             :  * pg_config.c
       4             :  *      Expose same output as pg_config except as an SRF
       5             :  *
       6             :  * Portions Copyright (c) 1996-2017, PostgreSQL Global Development Group
       7             :  * Portions Copyright (c) 1994, Regents of the University of California
       8             :  *
       9             :  * IDENTIFICATION
      10             :  *    src/backend/utils/misc/pg_config.c
      11             :  *
      12             :  *-------------------------------------------------------------------------
      13             :  */
      14             : 
      15             : #include "postgres.h"
      16             : 
      17             : #include "funcapi.h"
      18             : #include "miscadmin.h"
      19             : #include "catalog/pg_type.h"
      20             : #include "common/config_info.h"
      21             : #include "utils/builtins.h"
      22             : #include "utils/elog.h"
      23             : #include "port.h"
      24             : 
      25             : Datum
      26           1 : pg_config(PG_FUNCTION_ARGS)
      27             : {
      28           1 :     ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
      29             :     Tuplestorestate *tupstore;
      30             :     HeapTuple   tuple;
      31             :     TupleDesc   tupdesc;
      32             :     AttInMetadata *attinmeta;
      33             :     MemoryContext per_query_ctx;
      34             :     MemoryContext oldcontext;
      35             :     ConfigData *configdata;
      36             :     size_t      configdata_len;
      37             :     char       *values[2];
      38           1 :     int         i = 0;
      39             : 
      40             :     /* check to see if caller supports us returning a tuplestore */
      41           1 :     if (!rsinfo || !(rsinfo->allowedModes & SFRM_Materialize))
      42           0 :         ereport(ERROR,
      43             :                 (errcode(ERRCODE_SYNTAX_ERROR),
      44             :                  errmsg("materialize mode required, but it is not "
      45             :                         "allowed in this context")));
      46             : 
      47           1 :     per_query_ctx = rsinfo->econtext->ecxt_per_query_memory;
      48           1 :     oldcontext = MemoryContextSwitchTo(per_query_ctx);
      49             : 
      50             :     /* get the requested return tuple description */
      51           1 :     tupdesc = CreateTupleDescCopy(rsinfo->expectedDesc);
      52             : 
      53             :     /*
      54             :      * Check to make sure we have a reasonable tuple descriptor
      55             :      */
      56           2 :     if (tupdesc->natts != 2 ||
      57           2 :         TupleDescAttr(tupdesc, 0)->atttypid != TEXTOID ||
      58           1 :         TupleDescAttr(tupdesc, 1)->atttypid != TEXTOID)
      59           0 :         ereport(ERROR,
      60             :                 (errcode(ERRCODE_SYNTAX_ERROR),
      61             :                  errmsg("query-specified return tuple and "
      62             :                         "function return type are not compatible")));
      63             : 
      64             :     /* OK to use it */
      65           1 :     attinmeta = TupleDescGetAttInMetadata(tupdesc);
      66             : 
      67             :     /* let the caller know we're sending back a tuplestore */
      68           1 :     rsinfo->returnMode = SFRM_Materialize;
      69             : 
      70             :     /* initialize our tuplestore */
      71           1 :     tupstore = tuplestore_begin_heap(true, false, work_mem);
      72             : 
      73           1 :     configdata = get_configdata(my_exec_path, &configdata_len);
      74          24 :     for (i = 0; i < configdata_len; i++)
      75             :     {
      76          23 :         values[0] = configdata[i].name;
      77          23 :         values[1] = configdata[i].setting;
      78             : 
      79          23 :         tuple = BuildTupleFromCStrings(attinmeta, values);
      80          23 :         tuplestore_puttuple(tupstore, tuple);
      81             :     }
      82             : 
      83             :     /*
      84             :      * no longer need the tuple descriptor reference created by
      85             :      * TupleDescGetAttInMetadata()
      86             :      */
      87           1 :     ReleaseTupleDesc(tupdesc);
      88             : 
      89             :     tuplestore_donestoring(tupstore);
      90           1 :     rsinfo->setResult = tupstore;
      91             : 
      92             :     /*
      93             :      * SFRM_Materialize mode expects us to return a NULL Datum. The actual
      94             :      * tuples are in our tuplestore and passed back through rsinfo->setResult.
      95             :      * rsinfo->setDesc is set to the tuple description that we actually used
      96             :      * to build our tuples with, so the caller can verify we did what it was
      97             :      * expecting.
      98             :      */
      99           1 :     rsinfo->setDesc = tupdesc;
     100           1 :     MemoryContextSwitchTo(oldcontext);
     101             : 
     102           1 :     return (Datum) 0;
     103             : }