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This reduces unnecessary exposure of other headers through htup.h, which is very widely included by many files. I have chosen to move the function prototypes to the new file as well, because that means htup.h no longer needs to include tupdesc.h. In itself this doesn't have much effect in indirect inclusion of tupdesc.h throughout the tree, because it's also required by execnodes.h; but it's something to explore in the future, and it seemed best to do the htup.h change now while I'm busy with it.
232 lines
6.0 KiB
C
232 lines
6.0 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) 2007-2012, PostgreSQL Global Development Group
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*
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* IDENTIFICATION
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* contrib/pageinspect/rawpage.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 "access/htup_details.h"
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#include "catalog/catalog.h"
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#include "catalog/namespace.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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#include "utils/rel.h"
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PG_MODULE_MAGIC;
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Datum get_raw_page(PG_FUNCTION_ARGS);
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Datum get_raw_page_fork(PG_FUNCTION_ARGS);
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Datum page_header(PG_FUNCTION_ARGS);
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static bytea *get_raw_page_internal(text *relname, ForkNumber forknum,
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BlockNumber blkno);
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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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bytea *raw_page;
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/*
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* We don't normally bother to check the number of arguments to a C
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* function, but here it's needed for safety because early 8.4 beta
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* releases mistakenly redefined get_raw_page() as taking three arguments.
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*/
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if (PG_NARGS() != 2)
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ereport(ERROR,
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(errmsg("wrong number of arguments to get_raw_page()"),
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errhint("Run the updated pageinspect.sql script.")));
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raw_page = get_raw_page_internal(relname, MAIN_FORKNUM, blkno);
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PG_RETURN_BYTEA_P(raw_page);
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}
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/*
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* get_raw_page_fork
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*
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* Same, for any fork
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*/
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PG_FUNCTION_INFO_V1(get_raw_page_fork);
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Datum
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get_raw_page_fork(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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bytea *raw_page;
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ForkNumber forknum;
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forknum = forkname_to_number(text_to_cstring(forkname));
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raw_page = get_raw_page_internal(relname, forknum, blkno);
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PG_RETURN_BYTEA_P(raw_page);
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}
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/*
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* workhorse
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*/
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static bytea *
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get_raw_page_internal(text *relname, ForkNumber forknum, BlockNumber blkno)
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{
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bytea *raw_page;
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RangeVar *relrv;
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Relation rel;
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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 (rel->rd_rel->relkind == RELKIND_FOREIGN_TABLE)
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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 foreign table \"%s\"",
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RelationGetRelationName(rel))));
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/*
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* Reject attempts to read non-local temporary relations; we would be
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* likely to get wrong data since we have no visibility into the owning
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* session's local buffers.
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*/
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if (RELATION_IS_OTHER_TEMP(rel))
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ereport(ERROR,
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(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
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errmsg("cannot access temporary tables of other sessions")));
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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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return 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",
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(uint32) (lsn >> 32), (uint32) lsn);
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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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