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brin_page_type() and brin_metapage_info() did not enforce being called by superuser, like other pageinspect functions that take bytea do. Since they don't verify the passed page thoroughly, it is possible to use them to read the server memory with a carefully crafted bytea value, up to a file kilobytes from where the input bytea is located. Have them throw errors if called by a non-superuser. Report and initial patch: Andreas Seltenreich Security: CVE-2016-3065
410 lines
10 KiB
C
410 lines
10 KiB
C
/*
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* brinfuncs.c
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* Functions to investigate BRIN indexes
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*
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* Copyright (c) 2014-2016, PostgreSQL Global Development Group
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*
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* IDENTIFICATION
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* contrib/pageinspect/brinfuncs.c
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*/
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#include "postgres.h"
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#include "access/htup_details.h"
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#include "access/brin.h"
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#include "access/brin_internal.h"
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#include "access/brin_page.h"
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#include "access/brin_revmap.h"
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#include "access/brin_tuple.h"
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#include "catalog/index.h"
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#include "catalog/pg_type.h"
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#include "funcapi.h"
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#include "lib/stringinfo.h"
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#include "utils/array.h"
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#include "utils/builtins.h"
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#include "utils/lsyscache.h"
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#include "utils/rel.h"
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#include "miscadmin.h"
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PG_FUNCTION_INFO_V1(brin_page_type);
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PG_FUNCTION_INFO_V1(brin_page_items);
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PG_FUNCTION_INFO_V1(brin_metapage_info);
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PG_FUNCTION_INFO_V1(brin_revmap_data);
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typedef struct brin_column_state
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{
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int nstored;
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FmgrInfo outputFn[FLEXIBLE_ARRAY_MEMBER];
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} brin_column_state;
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static Page verify_brin_page(bytea *raw_page, uint16 type,
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const char *strtype);
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Datum
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brin_page_type(PG_FUNCTION_ARGS)
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{
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bytea *raw_page = PG_GETARG_BYTEA_P(0);
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Page page = VARDATA(raw_page);
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int raw_page_size;
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char *type;
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if (!superuser())
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ereport(ERROR,
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(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
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(errmsg("must be superuser to use raw page functions"))));
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raw_page_size = VARSIZE(raw_page) - VARHDRSZ;
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if (raw_page_size != BLCKSZ)
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ereport(ERROR,
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(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
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errmsg("input page too small"),
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errdetail("Expected size %d, got %d",
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BLCKSZ, raw_page_size)));
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switch (BrinPageType(page))
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{
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case BRIN_PAGETYPE_META:
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type = "meta";
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break;
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case BRIN_PAGETYPE_REVMAP:
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type = "revmap";
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break;
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case BRIN_PAGETYPE_REGULAR:
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type = "regular";
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break;
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default:
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type = psprintf("unknown (%02x)", BrinPageType(page));
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break;
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}
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PG_RETURN_TEXT_P(cstring_to_text(type));
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}
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/*
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* Verify that the given bytea contains a BRIN page of the indicated page
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* type, or die in the attempt. A pointer to the page is returned.
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*/
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static Page
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verify_brin_page(bytea *raw_page, uint16 type, const char *strtype)
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{
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Page page;
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int raw_page_size;
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raw_page_size = VARSIZE(raw_page) - VARHDRSZ;
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if (raw_page_size != BLCKSZ)
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ereport(ERROR,
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(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
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errmsg("input page too small"),
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errdetail("Expected size %d, got %d",
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BLCKSZ, raw_page_size)));
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page = VARDATA(raw_page);
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/* verify the special space says this page is what we want */
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if (BrinPageType(page) != type)
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ereport(ERROR,
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(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
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errmsg("page is not a BRIN page of type \"%s\"", strtype),
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errdetail("Expected special type %08x, got %08x.",
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type, BrinPageType(page))));
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return page;
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}
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/*
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* Extract all item values from a BRIN index page
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*
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* Usage: SELECT * FROM brin_page_items(get_raw_page('idx', 1), 'idx'::regclass);
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*/
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Datum
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brin_page_items(PG_FUNCTION_ARGS)
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{
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bytea *raw_page = PG_GETARG_BYTEA_P(0);
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Oid indexRelid = PG_GETARG_OID(1);
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ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
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TupleDesc tupdesc;
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MemoryContext oldcontext;
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Tuplestorestate *tupstore;
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Relation indexRel;
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brin_column_state **columns;
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BrinDesc *bdesc;
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BrinMemTuple *dtup;
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Page page;
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OffsetNumber offset;
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AttrNumber attno;
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bool unusedItem;
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if (!superuser())
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ereport(ERROR,
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(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
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(errmsg("must be superuser to use raw page functions"))));
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/* check to see if caller supports us returning a tuplestore */
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if (rsinfo == NULL || !IsA(rsinfo, ReturnSetInfo))
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ereport(ERROR,
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(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
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errmsg("set-valued function called in context that cannot accept a set")));
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if (!(rsinfo->allowedModes & SFRM_Materialize) ||
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rsinfo->expectedDesc == NULL)
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ereport(ERROR,
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(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
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errmsg("materialize mode required, but it is not allowed in this context")));
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/* Build a tuple descriptor for our result type */
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if (get_call_result_type(fcinfo, NULL, &tupdesc) != TYPEFUNC_COMPOSITE)
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elog(ERROR, "return type must be a row type");
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/* Build tuplestore to hold the result rows */
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oldcontext = MemoryContextSwitchTo(rsinfo->econtext->ecxt_per_query_memory);
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tupstore = tuplestore_begin_heap(true, false, work_mem);
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rsinfo->returnMode = SFRM_Materialize;
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rsinfo->setResult = tupstore;
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rsinfo->setDesc = tupdesc;
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MemoryContextSwitchTo(oldcontext);
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indexRel = index_open(indexRelid, AccessShareLock);
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bdesc = brin_build_desc(indexRel);
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/* minimally verify the page we got */
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page = verify_brin_page(raw_page, BRIN_PAGETYPE_REGULAR, "regular");
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/*
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* Initialize output functions for all indexed datatypes; simplifies
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* calling them later.
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*/
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columns = palloc(sizeof(brin_column_state *) * RelationGetDescr(indexRel)->natts);
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for (attno = 1; attno <= bdesc->bd_tupdesc->natts; attno++)
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{
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Oid output;
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bool isVarlena;
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BrinOpcInfo *opcinfo;
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int i;
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brin_column_state *column;
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opcinfo = bdesc->bd_info[attno - 1];
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column = palloc(offsetof(brin_column_state, outputFn) +
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sizeof(FmgrInfo) * opcinfo->oi_nstored);
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column->nstored = opcinfo->oi_nstored;
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for (i = 0; i < opcinfo->oi_nstored; i++)
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{
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getTypeOutputInfo(opcinfo->oi_typcache[i]->type_id, &output, &isVarlena);
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fmgr_info(output, &column->outputFn[i]);
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}
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columns[attno - 1] = column;
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}
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offset = FirstOffsetNumber;
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unusedItem = false;
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dtup = NULL;
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for (;;)
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{
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Datum values[7];
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bool nulls[7];
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/*
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* This loop is called once for every attribute of every tuple in the
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* page. At the start of a tuple, we get a NULL dtup; that's our
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* signal for obtaining and decoding the next one. If that's not the
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* case, we output the next attribute.
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*/
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if (dtup == NULL)
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{
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ItemId itemId;
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/* verify item status: if there's no data, we can't decode */
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itemId = PageGetItemId(page, offset);
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if (ItemIdIsUsed(itemId))
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{
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dtup = brin_deform_tuple(bdesc,
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(BrinTuple *) PageGetItem(page, itemId));
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attno = 1;
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unusedItem = false;
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}
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else
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unusedItem = true;
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}
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else
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attno++;
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MemSet(nulls, 0, sizeof(nulls));
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if (unusedItem)
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{
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values[0] = UInt16GetDatum(offset);
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nulls[1] = true;
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nulls[2] = true;
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nulls[3] = true;
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nulls[4] = true;
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nulls[5] = true;
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nulls[6] = true;
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}
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else
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{
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int att = attno - 1;
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values[0] = UInt16GetDatum(offset);
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values[1] = UInt32GetDatum(dtup->bt_blkno);
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values[2] = UInt16GetDatum(attno);
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values[3] = BoolGetDatum(dtup->bt_columns[att].bv_allnulls);
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values[4] = BoolGetDatum(dtup->bt_columns[att].bv_hasnulls);
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values[5] = BoolGetDatum(dtup->bt_placeholder);
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if (!dtup->bt_columns[att].bv_allnulls)
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{
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BrinValues *bvalues = &dtup->bt_columns[att];
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StringInfoData s;
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bool first;
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int i;
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initStringInfo(&s);
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appendStringInfoChar(&s, '{');
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first = true;
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for (i = 0; i < columns[att]->nstored; i++)
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{
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char *val;
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if (!first)
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appendStringInfoString(&s, " .. ");
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first = false;
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val = OutputFunctionCall(&columns[att]->outputFn[i],
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bvalues->bv_values[i]);
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appendStringInfoString(&s, val);
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pfree(val);
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}
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appendStringInfoChar(&s, '}');
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values[6] = CStringGetTextDatum(s.data);
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pfree(s.data);
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}
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else
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{
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nulls[6] = true;
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}
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}
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tuplestore_putvalues(tupstore, tupdesc, values, nulls);
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/*
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* If the item was unused, jump straight to the next one; otherwise,
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* the only cleanup needed here is to set our signal to go to the next
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* tuple in the following iteration, by freeing the current one.
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*/
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if (unusedItem)
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offset = OffsetNumberNext(offset);
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else if (attno >= bdesc->bd_tupdesc->natts)
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{
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pfree(dtup);
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dtup = NULL;
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offset = OffsetNumberNext(offset);
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}
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/*
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* If we're beyond the end of the page, we're done.
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*/
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if (offset > PageGetMaxOffsetNumber(page))
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break;
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}
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/* clean up and return the tuplestore */
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brin_free_desc(bdesc);
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tuplestore_donestoring(tupstore);
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index_close(indexRel, AccessShareLock);
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return (Datum) 0;
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}
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Datum
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brin_metapage_info(PG_FUNCTION_ARGS)
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{
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bytea *raw_page = PG_GETARG_BYTEA_P(0);
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Page page;
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BrinMetaPageData *meta;
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TupleDesc tupdesc;
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Datum values[4];
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bool nulls[4];
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HeapTuple htup;
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if (!superuser())
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ereport(ERROR,
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(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
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(errmsg("must be superuser to use raw page functions"))));
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page = verify_brin_page(raw_page, BRIN_PAGETYPE_META, "metapage");
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/* Build a tuple descriptor for our result type */
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if (get_call_result_type(fcinfo, NULL, &tupdesc) != TYPEFUNC_COMPOSITE)
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elog(ERROR, "return type must be a row type");
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tupdesc = BlessTupleDesc(tupdesc);
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/* Extract values from the metapage */
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meta = (BrinMetaPageData *) PageGetContents(page);
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MemSet(nulls, 0, sizeof(nulls));
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values[0] = CStringGetTextDatum(psprintf("0x%08X", meta->brinMagic));
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values[1] = Int32GetDatum(meta->brinVersion);
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values[2] = Int32GetDatum(meta->pagesPerRange);
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values[3] = Int64GetDatum(meta->lastRevmapPage);
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htup = heap_form_tuple(tupdesc, values, nulls);
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PG_RETURN_DATUM(HeapTupleGetDatum(htup));
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}
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/*
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* Return the TID array stored in a BRIN revmap page
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*/
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Datum
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brin_revmap_data(PG_FUNCTION_ARGS)
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{
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struct
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{
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ItemPointerData *tids;
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int idx;
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} *state;
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FuncCallContext *fctx;
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if (!superuser())
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ereport(ERROR,
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(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
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(errmsg("must be superuser to use raw page functions"))));
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if (SRF_IS_FIRSTCALL())
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{
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bytea *raw_page = PG_GETARG_BYTEA_P(0);
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MemoryContext mctx;
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Page page;
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/* minimally verify the page we got */
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page = verify_brin_page(raw_page, BRIN_PAGETYPE_REVMAP, "revmap");
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/* create a function context for cross-call persistence */
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fctx = SRF_FIRSTCALL_INIT();
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/* switch to memory context appropriate for multiple function calls */
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mctx = MemoryContextSwitchTo(fctx->multi_call_memory_ctx);
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state = palloc(sizeof(*state));
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state->tids = ((RevmapContents *) PageGetContents(page))->rm_tids;
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state->idx = 0;
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fctx->user_fctx = state;
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MemoryContextSwitchTo(mctx);
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}
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fctx = SRF_PERCALL_SETUP();
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state = fctx->user_fctx;
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if (state->idx < REVMAP_PAGE_MAXITEMS)
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SRF_RETURN_NEXT(fctx, PointerGetDatum(&state->tids[state->idx++]));
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SRF_RETURN_DONE(fctx);
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}
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