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220db7ccd8
strings. This patch introduces four support functions cstring_to_text, cstring_to_text_with_len, text_to_cstring, and text_to_cstring_buffer, and two macros CStringGetTextDatum and TextDatumGetCString. A number of existing macros that provided variants on these themes were removed. Most of the places that need to make such conversions now require just one function or macro call, in place of the multiple notational layers that used to be needed. There are no longer any direct calls of textout or textin, and we got most of the places that were using handmade conversions via memcpy (there may be a few still lurking, though). This commit doesn't make any serious effort to eliminate transient memory leaks caused by detoasting toasted text objects before they reach text_to_cstring. We changed PG_GETARG_TEXT_P to PG_GETARG_TEXT_PP in a few places where it was easy, but much more could be done. Brendan Jurd and Tom Lane
166 lines
4.2 KiB
C
166 lines
4.2 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 1.5 2008/03/25 22:42:41 tgl 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 "fmgr.h"
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#include "funcapi.h"
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#include "access/heapam.h"
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#include "access/transam.h"
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#include "catalog/namespace.h"
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#include "catalog/pg_type.h"
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#include "utils/builtins.h"
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#include "miscadmin.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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uint32 blkno = PG_GETARG_UINT32(1);
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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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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 = ReadBuffer(rel, blkno);
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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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