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functions into one ReadBufferExtended function, that takes the strategy and mode as argument. There's three modes, RBM_NORMAL which is the default used by plain ReadBuffer(), RBM_ZERO, which replaces ZeroOrReadBuffer, and a new mode RBM_ZERO_ON_ERROR, which allows callers to read corrupt pages without throwing an error. The FSM needs the new mode to recover from corrupt pages, which could happend if we crash after extending an FSM file, and the new page is "torn". Add fork number to some error messages in bufmgr.c, that still lacked it.
172 lines
4.4 KiB
C
172 lines
4.4 KiB
C
/*-------------------------------------------------------------------------
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*
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* rawpage.c
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* Functions to extract a raw page as bytea and inspect it
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*
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* Access-method specific inspection functions are in separate files.
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*
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* Copyright (c) 2007-2008, PostgreSQL Global Development Group
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*
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* IDENTIFICATION
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* $PostgreSQL: pgsql/contrib/pageinspect/rawpage.c,v 1.9 2008/10/31 15:04:59 heikki Exp $
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*
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*-------------------------------------------------------------------------
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*/
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#include "postgres.h"
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#include "access/heapam.h"
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#include "access/transam.h"
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#include "catalog/catalog.h"
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#include "catalog/namespace.h"
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#include "catalog/pg_type.h"
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#include "fmgr.h"
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#include "funcapi.h"
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#include "miscadmin.h"
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#include "storage/bufmgr.h"
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#include "utils/builtins.h"
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PG_MODULE_MAGIC;
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Datum get_raw_page(PG_FUNCTION_ARGS);
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Datum page_header(PG_FUNCTION_ARGS);
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/*
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* get_raw_page
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*
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* Returns a copy of a page from shared buffers as a bytea
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*/
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PG_FUNCTION_INFO_V1(get_raw_page);
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Datum
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get_raw_page(PG_FUNCTION_ARGS)
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{
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text *relname = PG_GETARG_TEXT_P(0);
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text *forkname = PG_GETARG_TEXT_P(1);
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uint32 blkno = PG_GETARG_UINT32(2);
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ForkNumber forknum;
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Relation rel;
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RangeVar *relrv;
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bytea *raw_page;
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char *raw_page_data;
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Buffer buf;
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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 functions"))));
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forknum = forkname_to_number(text_to_cstring(forkname));
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relrv = makeRangeVarFromNameList(textToQualifiedNameList(relname));
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rel = relation_openrv(relrv, AccessShareLock);
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/* Check that this relation has storage */
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if (rel->rd_rel->relkind == RELKIND_VIEW)
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ereport(ERROR,
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(errcode(ERRCODE_WRONG_OBJECT_TYPE),
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errmsg("cannot get raw page from view \"%s\"",
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RelationGetRelationName(rel))));
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if (rel->rd_rel->relkind == RELKIND_COMPOSITE_TYPE)
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ereport(ERROR,
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(errcode(ERRCODE_WRONG_OBJECT_TYPE),
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errmsg("cannot get raw page from composite type \"%s\"",
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RelationGetRelationName(rel))));
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if (blkno >= RelationGetNumberOfBlocks(rel))
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elog(ERROR, "block number %u is out of range for relation \"%s\"",
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blkno, RelationGetRelationName(rel));
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/* Initialize buffer to copy to */
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raw_page = (bytea *) palloc(BLCKSZ + VARHDRSZ);
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SET_VARSIZE(raw_page, BLCKSZ + VARHDRSZ);
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raw_page_data = VARDATA(raw_page);
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/* Take a verbatim copy of the page */
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buf = ReadBufferExtended(rel, forknum, blkno, RBM_NORMAL, NULL);
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LockBuffer(buf, BUFFER_LOCK_SHARE);
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memcpy(raw_page_data, BufferGetPage(buf), BLCKSZ);
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LockBuffer(buf, BUFFER_LOCK_UNLOCK);
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ReleaseBuffer(buf);
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relation_close(rel, AccessShareLock);
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PG_RETURN_BYTEA_P(raw_page);
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}
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/*
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* page_header
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*
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* Allows inspection of page header fields of a raw page
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*/
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PG_FUNCTION_INFO_V1(page_header);
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Datum
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page_header(PG_FUNCTION_ARGS)
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{
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bytea *raw_page = PG_GETARG_BYTEA_P(0);
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int raw_page_size;
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TupleDesc tupdesc;
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Datum result;
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HeapTuple tuple;
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Datum values[9];
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bool nulls[9];
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PageHeader page;
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XLogRecPtr lsn;
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char lsnchar[64];
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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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/*
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* Check that enough data was supplied, so that we don't try to access
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* fields outside the supplied buffer.
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*/
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if (raw_page_size < sizeof(PageHeaderData))
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ereport(ERROR,
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(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
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errmsg("input page too small (%d bytes)", raw_page_size)));
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page = (PageHeader) VARDATA(raw_page);
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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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/* Extract information from the page header */
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lsn = PageGetLSN(page);
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snprintf(lsnchar, sizeof(lsnchar), "%X/%X", lsn.xlogid, lsn.xrecoff);
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values[0] = CStringGetTextDatum(lsnchar);
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values[1] = UInt16GetDatum(PageGetTLI(page));
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values[2] = UInt16GetDatum(page->pd_flags);
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values[3] = UInt16GetDatum(page->pd_lower);
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values[4] = UInt16GetDatum(page->pd_upper);
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values[5] = UInt16GetDatum(page->pd_special);
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values[6] = UInt16GetDatum(PageGetPageSize(page));
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values[7] = UInt16GetDatum(PageGetPageLayoutVersion(page));
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values[8] = TransactionIdGetDatum(page->pd_prune_xid);
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/* Build and return the tuple. */
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memset(nulls, 0, sizeof(nulls));
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tuple = heap_form_tuple(tupdesc, values, nulls);
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result = HeapTupleGetDatum(tuple);
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PG_RETURN_DATUM(result);
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}
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