104 lines
2.9 KiB
C
104 lines
2.9 KiB
C
/*-------------------------------------------------------------------------
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*
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* pg_config.c
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* Expose same output as pg_config except as an SRF
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*
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* Portions Copyright (c) 1996-2016, 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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* IDENTIFICATION
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* src/backend/utils/misc/pg_config.c
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*
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*-------------------------------------------------------------------------
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*/
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#include "postgres.h"
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#include "funcapi.h"
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#include "miscadmin.h"
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#include "catalog/pg_type.h"
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#include "common/config_info.h"
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#include "utils/builtins.h"
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#include "utils/elog.h"
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#include "port.h"
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Datum
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pg_config(PG_FUNCTION_ARGS)
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{
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ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
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Tuplestorestate *tupstore;
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HeapTuple tuple;
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TupleDesc tupdesc;
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AttInMetadata *attinmeta;
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MemoryContext per_query_ctx;
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MemoryContext oldcontext;
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ConfigData *configdata;
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size_t configdata_len;
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char *values[2];
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int i = 0;
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/* check to see if caller supports us returning a tuplestore */
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if (!rsinfo || !(rsinfo->allowedModes & SFRM_Materialize))
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ereport(ERROR,
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(errcode(ERRCODE_SYNTAX_ERROR),
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errmsg("materialize mode required, but it is not "
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"allowed in this context")));
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per_query_ctx = rsinfo->econtext->ecxt_per_query_memory;
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oldcontext = MemoryContextSwitchTo(per_query_ctx);
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/* get the requested return tuple description */
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tupdesc = CreateTupleDescCopy(rsinfo->expectedDesc);
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/*
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* Check to make sure we have a reasonable tuple descriptor
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*/
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if (tupdesc->natts != 2 ||
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tupdesc->attrs[0]->atttypid != TEXTOID ||
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tupdesc->attrs[1]->atttypid != TEXTOID)
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ereport(ERROR,
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(errcode(ERRCODE_SYNTAX_ERROR),
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errmsg("query-specified return tuple and "
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"function return type are not compatible")));
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/* OK to use it */
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attinmeta = TupleDescGetAttInMetadata(tupdesc);
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/* let the caller know we're sending back a tuplestore */
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rsinfo->returnMode = SFRM_Materialize;
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/* initialize our tuplestore */
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tupstore = tuplestore_begin_heap(true, false, work_mem);
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configdata = get_configdata(my_exec_path, &configdata_len);
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for (i = 0; i < configdata_len; i++)
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{
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values[0] = configdata[i].name;
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values[1] = configdata[i].setting;
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tuple = BuildTupleFromCStrings(attinmeta, values);
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tuplestore_puttuple(tupstore, tuple);
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}
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/*
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* no longer need the tuple descriptor reference created by
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* TupleDescGetAttInMetadata()
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*/
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ReleaseTupleDesc(tupdesc);
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tuplestore_donestoring(tupstore);
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rsinfo->setResult = tupstore;
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/*
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* SFRM_Materialize mode expects us to return a NULL Datum. The actual
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* tuples are in our tuplestore and passed back through rsinfo->setResult.
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* rsinfo->setDesc is set to the tuple description that we actually used
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* to build our tuples with, so the caller can verify we did what it was
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* expecting.
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*/
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rsinfo->setDesc = tupdesc;
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MemoryContextSwitchTo(oldcontext);
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return (Datum) 0;
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}
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