diff options
Diffstat (limited to 'contrib/pageinspect/rawpage.c')
| -rw-r--r-- | contrib/pageinspect/rawpage.c | 164 |
1 files changed, 164 insertions, 0 deletions
diff --git a/contrib/pageinspect/rawpage.c b/contrib/pageinspect/rawpage.c new file mode 100644 index 00000000000..4aba08e7800 --- /dev/null +++ b/contrib/pageinspect/rawpage.c @@ -0,0 +1,164 @@ +/*------------------------------------------------------------------------- + * + * rawpage.c + * Functions to extract a raw page as bytea and inspect it + * + * Access-method specific inspection functions are in separate files. + * + * Copyright (c) 2007, PostgreSQL Global Development Group + * + * IDENTIFICATION + * $PostgreSQL: pgsql/contrib/pageinspect/rawpage.c,v 1.1 2007/05/17 19:11:24 momjian Exp $ + * + *------------------------------------------------------------------------- + */ + +#include "postgres.h" + +#include "fmgr.h" +#include "funcapi.h" +#include "access/heapam.h" +#include "access/transam.h" +#include "catalog/namespace.h" +#include "catalog/pg_type.h" +#include "utils/builtins.h" +#include "miscadmin.h" + +PG_MODULE_MAGIC; + +Datum get_raw_page(PG_FUNCTION_ARGS); +Datum page_header(PG_FUNCTION_ARGS); + +/* + * get_raw_page + * + * Returns a copy of a page from shared buffers as a bytea + */ +PG_FUNCTION_INFO_V1(get_raw_page); + +Datum +get_raw_page(PG_FUNCTION_ARGS) +{ + text *relname = PG_GETARG_TEXT_P(0); + uint32 blkno = PG_GETARG_UINT32(1); + + Relation rel; + RangeVar *relrv; + bytea *raw_page; + char *raw_page_data; + Buffer buf; + + if (!superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + (errmsg("must be superuser to use raw functions")))); + + relrv = makeRangeVarFromNameList(textToQualifiedNameList(relname)); + rel = relation_openrv(relrv, AccessShareLock); + + /* Check that this relation has storage */ + if (rel->rd_rel->relkind == RELKIND_VIEW) + ereport(ERROR, + (errcode(ERRCODE_WRONG_OBJECT_TYPE), + errmsg("cannot get raw page from view \"%s\"", + RelationGetRelationName(rel)))); + if (rel->rd_rel->relkind == RELKIND_COMPOSITE_TYPE) + ereport(ERROR, + (errcode(ERRCODE_WRONG_OBJECT_TYPE), + errmsg("cannot get raw page from composite type \"%s\"", + RelationGetRelationName(rel)))); + + if (blkno >= RelationGetNumberOfBlocks(rel)) + elog(ERROR, "block number %u is out of range for relation \"%s\"", + blkno, RelationGetRelationName(rel)); + + /* Initialize buffer to copy to */ + raw_page = (bytea *) palloc(BLCKSZ + VARHDRSZ); + SET_VARSIZE(raw_page, BLCKSZ + VARHDRSZ); + raw_page_data = VARDATA(raw_page); + + /* Take a verbatim copy of the page */ + + buf = ReadBuffer(rel, blkno); + LockBuffer(buf, BUFFER_LOCK_SHARE); + + memcpy(raw_page_data, BufferGetPage(buf), BLCKSZ); + + LockBuffer(buf, BUFFER_LOCK_UNLOCK); + ReleaseBuffer(buf); + + relation_close(rel, AccessShareLock); + + PG_RETURN_BYTEA_P(raw_page); +} + +/* + * page_header + * + * Allows inspection of page header fields of a raw page + */ + +PG_FUNCTION_INFO_V1(page_header); + +Datum +page_header(PG_FUNCTION_ARGS) +{ + bytea *raw_page = PG_GETARG_BYTEA_P(0); + int raw_page_size; + + TupleDesc tupdesc; + + Datum result; + HeapTuple tuple; + Datum values[8]; + bool nulls[8]; + + PageHeader page; + XLogRecPtr lsn; + char lsnchar[64]; + + if (!superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + (errmsg("must be superuser to use raw page functions")))); + + raw_page_size = VARSIZE(raw_page) - VARHDRSZ; + + /* + * Check that enough data was supplied, so that we don't try to access + * fields outside the supplied buffer. + */ + if(raw_page_size < sizeof(PageHeaderData)) + ereport(ERROR, + (errcode(ERRCODE_INVALID_PARAMETER_VALUE), + errmsg("input page too small (%d bytes)", raw_page_size))); + + page = (PageHeader) VARDATA(raw_page); + + /* Build a tuple descriptor for our result type */ + if (get_call_result_type(fcinfo, NULL, &tupdesc) != TYPEFUNC_COMPOSITE) + elog(ERROR, "return type must be a row type"); + + /* Extract information from the page header */ + + lsn = PageGetLSN(page); + snprintf(lsnchar, sizeof(lsnchar), "%X/%X", lsn.xlogid, lsn.xrecoff); + + values[0] = DirectFunctionCall1(textin, CStringGetDatum(lsnchar)); + values[1] = UInt16GetDatum(PageGetTLI(page)); + values[2] = UInt16GetDatum(page->pd_flags); + values[3] = UInt16GetDatum(page->pd_lower); + values[4] = UInt16GetDatum(page->pd_upper); + values[5] = UInt16GetDatum(page->pd_special); + values[6] = UInt16GetDatum(PageGetPageSize(page)); + values[7] = UInt16GetDatum(PageGetPageLayoutVersion(page)); + + /* Build and return the tuple. */ + + memset(nulls, 0, sizeof(nulls)); + + tuple = heap_form_tuple(tupdesc, values, nulls); + result = HeapTupleGetDatum(tuple); + + PG_RETURN_DATUM(result); +} |