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XLogReader, walsender and pg_waldump all had their own routines to read data from WAL files to memory, with slightly different approaches according to the particular conditions of each environment. There's a lot of commonality, so we can refactor that into a single routine WALRead in XLogReader, and move the differences to a separate (simpler) callback that just opens the next WAL-segment. This results in a clearer (ahem) code flow. The error reporting needs are covered by filling in a new error-info struct, WALReadError, and it's the caller's responsibility to act on it. The backend has WALReadRaiseError() to do so. We no longer ever need to seek in this interface; switch to using pg_pread(). Author: Antonin Houska, with contributions from Álvaro Herrera Reviewed-by: Michaël Paquier, Kyotaro Horiguchi Discussion: https://postgr.es/m/14984.1554998742@spoje.net
1593 lines
43 KiB
C
1593 lines
43 KiB
C
/*-------------------------------------------------------------------------
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*
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* xlogreader.c
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* Generic XLog reading facility
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*
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* Portions Copyright (c) 2013-2019, PostgreSQL Global Development Group
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*
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* IDENTIFICATION
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* src/backend/access/transam/xlogreader.c
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*
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* NOTES
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* See xlogreader.h for more notes on this facility.
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*
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* This file is compiled as both front-end and backend code, so it
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* may not use ereport, server-defined static variables, etc.
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*-------------------------------------------------------------------------
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*/
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#include "postgres.h"
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#include <unistd.h>
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#include "access/transam.h"
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#include "access/xlog_internal.h"
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#include "access/xlogreader.h"
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#include "access/xlogrecord.h"
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#include "catalog/pg_control.h"
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#include "common/pg_lzcompress.h"
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#include "replication/origin.h"
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#ifndef FRONTEND
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#include "miscadmin.h"
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#include "pgstat.h"
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#include "utils/memutils.h"
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#endif
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static void report_invalid_record(XLogReaderState *state, const char *fmt,...)
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pg_attribute_printf(2, 3);
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static bool allocate_recordbuf(XLogReaderState *state, uint32 reclength);
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static int ReadPageInternal(XLogReaderState *state, XLogRecPtr pageptr,
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int reqLen);
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static void XLogReaderInvalReadState(XLogReaderState *state);
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static bool ValidXLogRecordHeader(XLogReaderState *state, XLogRecPtr RecPtr,
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XLogRecPtr PrevRecPtr, XLogRecord *record, bool randAccess);
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static bool ValidXLogRecord(XLogReaderState *state, XLogRecord *record,
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XLogRecPtr recptr);
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static void ResetDecoder(XLogReaderState *state);
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/* size of the buffer allocated for error message. */
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#define MAX_ERRORMSG_LEN 1000
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/*
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* Construct a string in state->errormsg_buf explaining what's wrong with
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* the current record being read.
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*/
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static void
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report_invalid_record(XLogReaderState *state, const char *fmt,...)
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{
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va_list args;
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fmt = _(fmt);
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va_start(args, fmt);
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vsnprintf(state->errormsg_buf, MAX_ERRORMSG_LEN, fmt, args);
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va_end(args);
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}
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/*
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* Allocate and initialize a new XLogReader.
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*
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* Returns NULL if the xlogreader couldn't be allocated.
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*/
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XLogReaderState *
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XLogReaderAllocate(int wal_segment_size, const char *waldir,
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XLogPageReadCB pagereadfunc, void *private_data)
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{
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XLogReaderState *state;
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state = (XLogReaderState *)
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palloc_extended(sizeof(XLogReaderState),
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MCXT_ALLOC_NO_OOM | MCXT_ALLOC_ZERO);
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if (!state)
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return NULL;
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state->max_block_id = -1;
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/*
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* Permanently allocate readBuf. We do it this way, rather than just
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* making a static array, for two reasons: (1) no need to waste the
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* storage in most instantiations of the backend; (2) a static char array
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* isn't guaranteed to have any particular alignment, whereas
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* palloc_extended() will provide MAXALIGN'd storage.
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*/
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state->readBuf = (char *) palloc_extended(XLOG_BLCKSZ,
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MCXT_ALLOC_NO_OOM);
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if (!state->readBuf)
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{
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pfree(state);
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return NULL;
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}
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/* Initialize segment info. */
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WALOpenSegmentInit(&state->seg, &state->segcxt, wal_segment_size,
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waldir);
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state->read_page = pagereadfunc;
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/* system_identifier initialized to zeroes above */
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state->private_data = private_data;
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/* ReadRecPtr, EndRecPtr and readLen initialized to zeroes above */
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state->errormsg_buf = palloc_extended(MAX_ERRORMSG_LEN + 1,
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MCXT_ALLOC_NO_OOM);
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if (!state->errormsg_buf)
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{
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pfree(state->readBuf);
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pfree(state);
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return NULL;
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}
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state->errormsg_buf[0] = '\0';
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/*
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* Allocate an initial readRecordBuf of minimal size, which can later be
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* enlarged if necessary.
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*/
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if (!allocate_recordbuf(state, 0))
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{
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pfree(state->errormsg_buf);
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pfree(state->readBuf);
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pfree(state);
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return NULL;
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}
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return state;
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}
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void
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XLogReaderFree(XLogReaderState *state)
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{
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int block_id;
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for (block_id = 0; block_id <= XLR_MAX_BLOCK_ID; block_id++)
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{
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if (state->blocks[block_id].data)
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pfree(state->blocks[block_id].data);
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}
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if (state->main_data)
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pfree(state->main_data);
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pfree(state->errormsg_buf);
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if (state->readRecordBuf)
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pfree(state->readRecordBuf);
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pfree(state->readBuf);
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pfree(state);
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}
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/*
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* Allocate readRecordBuf to fit a record of at least the given length.
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* Returns true if successful, false if out of memory.
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*
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* readRecordBufSize is set to the new buffer size.
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*
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* To avoid useless small increases, round its size to a multiple of
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* XLOG_BLCKSZ, and make sure it's at least 5*Max(BLCKSZ, XLOG_BLCKSZ) to start
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* with. (That is enough for all "normal" records, but very large commit or
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* abort records might need more space.)
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*/
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static bool
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allocate_recordbuf(XLogReaderState *state, uint32 reclength)
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{
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uint32 newSize = reclength;
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newSize += XLOG_BLCKSZ - (newSize % XLOG_BLCKSZ);
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newSize = Max(newSize, 5 * Max(BLCKSZ, XLOG_BLCKSZ));
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#ifndef FRONTEND
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/*
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* Note that in much unlucky circumstances, the random data read from a
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* recycled segment can cause this routine to be called with a size
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* causing a hard failure at allocation. For a standby, this would cause
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* the instance to stop suddenly with a hard failure, preventing it to
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* retry fetching WAL from one of its sources which could allow it to move
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* on with replay without a manual restart. If the data comes from a past
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* recycled segment and is still valid, then the allocation may succeed
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* but record checks are going to fail so this would be short-lived. If
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* the allocation fails because of a memory shortage, then this is not a
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* hard failure either per the guarantee given by MCXT_ALLOC_NO_OOM.
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*/
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if (!AllocSizeIsValid(newSize))
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return false;
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#endif
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if (state->readRecordBuf)
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pfree(state->readRecordBuf);
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state->readRecordBuf =
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(char *) palloc_extended(newSize, MCXT_ALLOC_NO_OOM);
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if (state->readRecordBuf == NULL)
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{
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state->readRecordBufSize = 0;
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return false;
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}
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state->readRecordBufSize = newSize;
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return true;
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}
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/*
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* Initialize the passed segment structs.
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*/
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void
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WALOpenSegmentInit(WALOpenSegment *seg, WALSegmentContext *segcxt,
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int segsize, const char *waldir)
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{
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seg->ws_file = -1;
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seg->ws_segno = 0;
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seg->ws_tli = 0;
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segcxt->ws_segsize = segsize;
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if (waldir)
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snprintf(segcxt->ws_dir, MAXPGPATH, "%s", waldir);
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}
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/*
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* Attempt to read an XLOG record.
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*
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* If RecPtr is valid, try to read a record at that position. Otherwise
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* try to read a record just after the last one previously read.
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*
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* If the read_page callback fails to read the requested data, NULL is
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* returned. The callback is expected to have reported the error; errormsg
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* is set to NULL.
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*
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* If the reading fails for some other reason, NULL is also returned, and
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* *errormsg is set to a string with details of the failure.
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*
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* The returned pointer (or *errormsg) points to an internal buffer that's
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* valid until the next call to XLogReadRecord.
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*/
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XLogRecord *
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XLogReadRecord(XLogReaderState *state, XLogRecPtr RecPtr, char **errormsg)
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{
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XLogRecord *record;
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XLogRecPtr targetPagePtr;
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bool randAccess;
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uint32 len,
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total_len;
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uint32 targetRecOff;
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uint32 pageHeaderSize;
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bool gotheader;
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int readOff;
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/*
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* randAccess indicates whether to verify the previous-record pointer of
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* the record we're reading. We only do this if we're reading
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* sequentially, which is what we initially assume.
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*/
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randAccess = false;
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/* reset error state */
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*errormsg = NULL;
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state->errormsg_buf[0] = '\0';
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ResetDecoder(state);
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if (RecPtr == InvalidXLogRecPtr)
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{
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/* No explicit start point; read the record after the one we just read */
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RecPtr = state->EndRecPtr;
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if (state->ReadRecPtr == InvalidXLogRecPtr)
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randAccess = true;
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/*
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* RecPtr is pointing to end+1 of the previous WAL record. If we're
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* at a page boundary, no more records can fit on the current page. We
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* must skip over the page header, but we can't do that until we've
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* read in the page, since the header size is variable.
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*/
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}
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else
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{
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/*
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* Caller supplied a position to start at.
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*
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* In this case, the passed-in record pointer should already be
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* pointing to a valid record starting position.
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*/
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Assert(XRecOffIsValid(RecPtr));
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randAccess = true;
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}
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state->currRecPtr = RecPtr;
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targetPagePtr = RecPtr - (RecPtr % XLOG_BLCKSZ);
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targetRecOff = RecPtr % XLOG_BLCKSZ;
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/*
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* Read the page containing the record into state->readBuf. Request enough
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* byte to cover the whole record header, or at least the part of it that
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* fits on the same page.
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*/
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readOff = ReadPageInternal(state, targetPagePtr,
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Min(targetRecOff + SizeOfXLogRecord, XLOG_BLCKSZ));
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if (readOff < 0)
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goto err;
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/*
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* ReadPageInternal always returns at least the page header, so we can
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* examine it now.
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*/
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pageHeaderSize = XLogPageHeaderSize((XLogPageHeader) state->readBuf);
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if (targetRecOff == 0)
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{
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/*
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* At page start, so skip over page header.
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*/
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RecPtr += pageHeaderSize;
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targetRecOff = pageHeaderSize;
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}
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else if (targetRecOff < pageHeaderSize)
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{
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report_invalid_record(state, "invalid record offset at %X/%X",
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(uint32) (RecPtr >> 32), (uint32) RecPtr);
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goto err;
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}
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if ((((XLogPageHeader) state->readBuf)->xlp_info & XLP_FIRST_IS_CONTRECORD) &&
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targetRecOff == pageHeaderSize)
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{
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report_invalid_record(state, "contrecord is requested by %X/%X",
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(uint32) (RecPtr >> 32), (uint32) RecPtr);
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goto err;
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}
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/* ReadPageInternal has verified the page header */
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Assert(pageHeaderSize <= readOff);
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/*
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* Read the record length.
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*
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* NB: Even though we use an XLogRecord pointer here, the whole record
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* header might not fit on this page. xl_tot_len is the first field of the
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* struct, so it must be on this page (the records are MAXALIGNed), but we
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* cannot access any other fields until we've verified that we got the
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* whole header.
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*/
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record = (XLogRecord *) (state->readBuf + RecPtr % XLOG_BLCKSZ);
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total_len = record->xl_tot_len;
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/*
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* If the whole record header is on this page, validate it immediately.
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* Otherwise do just a basic sanity check on xl_tot_len, and validate the
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* rest of the header after reading it from the next page. The xl_tot_len
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* check is necessary here to ensure that we enter the "Need to reassemble
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* record" code path below; otherwise we might fail to apply
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* ValidXLogRecordHeader at all.
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*/
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if (targetRecOff <= XLOG_BLCKSZ - SizeOfXLogRecord)
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{
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if (!ValidXLogRecordHeader(state, RecPtr, state->ReadRecPtr, record,
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randAccess))
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goto err;
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gotheader = true;
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}
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else
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{
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/* XXX: more validation should be done here */
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if (total_len < SizeOfXLogRecord)
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{
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report_invalid_record(state,
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"invalid record length at %X/%X: wanted %u, got %u",
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(uint32) (RecPtr >> 32), (uint32) RecPtr,
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(uint32) SizeOfXLogRecord, total_len);
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goto err;
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}
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gotheader = false;
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}
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len = XLOG_BLCKSZ - RecPtr % XLOG_BLCKSZ;
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if (total_len > len)
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{
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/* Need to reassemble record */
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char *contdata;
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XLogPageHeader pageHeader;
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char *buffer;
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uint32 gotlen;
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/*
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* Enlarge readRecordBuf as needed.
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*/
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if (total_len > state->readRecordBufSize &&
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!allocate_recordbuf(state, total_len))
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{
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/* We treat this as a "bogus data" condition */
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report_invalid_record(state, "record length %u at %X/%X too long",
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total_len,
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(uint32) (RecPtr >> 32), (uint32) RecPtr);
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goto err;
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}
|
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/* Copy the first fragment of the record from the first page. */
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memcpy(state->readRecordBuf,
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state->readBuf + RecPtr % XLOG_BLCKSZ, len);
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buffer = state->readRecordBuf + len;
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gotlen = len;
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do
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{
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/* Calculate pointer to beginning of next page */
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targetPagePtr += XLOG_BLCKSZ;
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/* Wait for the next page to become available */
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readOff = ReadPageInternal(state, targetPagePtr,
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Min(total_len - gotlen + SizeOfXLogShortPHD,
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XLOG_BLCKSZ));
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|
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if (readOff < 0)
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goto err;
|
|
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Assert(SizeOfXLogShortPHD <= readOff);
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|
|
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/* Check that the continuation on next page looks valid */
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pageHeader = (XLogPageHeader) state->readBuf;
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if (!(pageHeader->xlp_info & XLP_FIRST_IS_CONTRECORD))
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{
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report_invalid_record(state,
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"there is no contrecord flag at %X/%X",
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(uint32) (RecPtr >> 32), (uint32) RecPtr);
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goto err;
|
|
}
|
|
|
|
/*
|
|
* Cross-check that xlp_rem_len agrees with how much of the record
|
|
* we expect there to be left.
|
|
*/
|
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if (pageHeader->xlp_rem_len == 0 ||
|
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total_len != (pageHeader->xlp_rem_len + gotlen))
|
|
{
|
|
report_invalid_record(state,
|
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"invalid contrecord length %u at %X/%X",
|
|
pageHeader->xlp_rem_len,
|
|
(uint32) (RecPtr >> 32), (uint32) RecPtr);
|
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goto err;
|
|
}
|
|
|
|
/* Append the continuation from this page to the buffer */
|
|
pageHeaderSize = XLogPageHeaderSize(pageHeader);
|
|
|
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if (readOff < pageHeaderSize)
|
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readOff = ReadPageInternal(state, targetPagePtr,
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pageHeaderSize);
|
|
|
|
Assert(pageHeaderSize <= readOff);
|
|
|
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contdata = (char *) state->readBuf + pageHeaderSize;
|
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len = XLOG_BLCKSZ - pageHeaderSize;
|
|
if (pageHeader->xlp_rem_len < len)
|
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len = pageHeader->xlp_rem_len;
|
|
|
|
if (readOff < pageHeaderSize + len)
|
|
readOff = ReadPageInternal(state, targetPagePtr,
|
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pageHeaderSize + len);
|
|
|
|
memcpy(buffer, (char *) contdata, len);
|
|
buffer += len;
|
|
gotlen += len;
|
|
|
|
/* If we just reassembled the record header, validate it. */
|
|
if (!gotheader)
|
|
{
|
|
record = (XLogRecord *) state->readRecordBuf;
|
|
if (!ValidXLogRecordHeader(state, RecPtr, state->ReadRecPtr,
|
|
record, randAccess))
|
|
goto err;
|
|
gotheader = true;
|
|
}
|
|
} while (gotlen < total_len);
|
|
|
|
Assert(gotheader);
|
|
|
|
record = (XLogRecord *) state->readRecordBuf;
|
|
if (!ValidXLogRecord(state, record, RecPtr))
|
|
goto err;
|
|
|
|
pageHeaderSize = XLogPageHeaderSize((XLogPageHeader) state->readBuf);
|
|
state->ReadRecPtr = RecPtr;
|
|
state->EndRecPtr = targetPagePtr + pageHeaderSize
|
|
+ MAXALIGN(pageHeader->xlp_rem_len);
|
|
}
|
|
else
|
|
{
|
|
/* Wait for the record data to become available */
|
|
readOff = ReadPageInternal(state, targetPagePtr,
|
|
Min(targetRecOff + total_len, XLOG_BLCKSZ));
|
|
if (readOff < 0)
|
|
goto err;
|
|
|
|
/* Record does not cross a page boundary */
|
|
if (!ValidXLogRecord(state, record, RecPtr))
|
|
goto err;
|
|
|
|
state->EndRecPtr = RecPtr + MAXALIGN(total_len);
|
|
|
|
state->ReadRecPtr = RecPtr;
|
|
}
|
|
|
|
/*
|
|
* Special processing if it's an XLOG SWITCH record
|
|
*/
|
|
if (record->xl_rmid == RM_XLOG_ID &&
|
|
(record->xl_info & ~XLR_INFO_MASK) == XLOG_SWITCH)
|
|
{
|
|
/* Pretend it extends to end of segment */
|
|
state->EndRecPtr += state->segcxt.ws_segsize - 1;
|
|
state->EndRecPtr -= XLogSegmentOffset(state->EndRecPtr, state->segcxt.ws_segsize);
|
|
}
|
|
|
|
if (DecodeXLogRecord(state, record, errormsg))
|
|
return record;
|
|
else
|
|
return NULL;
|
|
|
|
err:
|
|
|
|
/*
|
|
* Invalidate the read state. We might read from a different source after
|
|
* failure.
|
|
*/
|
|
XLogReaderInvalReadState(state);
|
|
|
|
if (state->errormsg_buf[0] != '\0')
|
|
*errormsg = state->errormsg_buf;
|
|
|
|
return NULL;
|
|
}
|
|
|
|
/*
|
|
* Read a single xlog page including at least [pageptr, reqLen] of valid data
|
|
* via the read_page() callback.
|
|
*
|
|
* Returns -1 if the required page cannot be read for some reason; errormsg_buf
|
|
* is set in that case (unless the error occurs in the read_page callback).
|
|
*
|
|
* We fetch the page from a reader-local cache if we know we have the required
|
|
* data and if there hasn't been any error since caching the data.
|
|
*/
|
|
static int
|
|
ReadPageInternal(XLogReaderState *state, XLogRecPtr pageptr, int reqLen)
|
|
{
|
|
int readLen;
|
|
uint32 targetPageOff;
|
|
XLogSegNo targetSegNo;
|
|
XLogPageHeader hdr;
|
|
|
|
Assert((pageptr % XLOG_BLCKSZ) == 0);
|
|
|
|
XLByteToSeg(pageptr, targetSegNo, state->segcxt.ws_segsize);
|
|
targetPageOff = XLogSegmentOffset(pageptr, state->segcxt.ws_segsize);
|
|
|
|
/* check whether we have all the requested data already */
|
|
if (targetSegNo == state->seg.ws_segno &&
|
|
targetPageOff == state->segoff && reqLen <= state->readLen)
|
|
return state->readLen;
|
|
|
|
/*
|
|
* Data is not in our buffer.
|
|
*
|
|
* Every time we actually read the page, even if we looked at parts of it
|
|
* before, we need to do verification as the read_page callback might now
|
|
* be rereading data from a different source.
|
|
*
|
|
* Whenever switching to a new WAL segment, we read the first page of the
|
|
* file and validate its header, even if that's not where the target
|
|
* record is. This is so that we can check the additional identification
|
|
* info that is present in the first page's "long" header.
|
|
*/
|
|
if (targetSegNo != state->seg.ws_segno && targetPageOff != 0)
|
|
{
|
|
XLogRecPtr targetSegmentPtr = pageptr - targetPageOff;
|
|
|
|
readLen = state->read_page(state, targetSegmentPtr, XLOG_BLCKSZ,
|
|
state->currRecPtr,
|
|
state->readBuf);
|
|
if (readLen < 0)
|
|
goto err;
|
|
|
|
/* we can be sure to have enough WAL available, we scrolled back */
|
|
Assert(readLen == XLOG_BLCKSZ);
|
|
|
|
if (!XLogReaderValidatePageHeader(state, targetSegmentPtr,
|
|
state->readBuf))
|
|
goto err;
|
|
}
|
|
|
|
/*
|
|
* First, read the requested data length, but at least a short page header
|
|
* so that we can validate it.
|
|
*/
|
|
readLen = state->read_page(state, pageptr, Max(reqLen, SizeOfXLogShortPHD),
|
|
state->currRecPtr,
|
|
state->readBuf);
|
|
if (readLen < 0)
|
|
goto err;
|
|
|
|
Assert(readLen <= XLOG_BLCKSZ);
|
|
|
|
/* Do we have enough data to check the header length? */
|
|
if (readLen <= SizeOfXLogShortPHD)
|
|
goto err;
|
|
|
|
Assert(readLen >= reqLen);
|
|
|
|
hdr = (XLogPageHeader) state->readBuf;
|
|
|
|
/* still not enough */
|
|
if (readLen < XLogPageHeaderSize(hdr))
|
|
{
|
|
readLen = state->read_page(state, pageptr, XLogPageHeaderSize(hdr),
|
|
state->currRecPtr,
|
|
state->readBuf);
|
|
if (readLen < 0)
|
|
goto err;
|
|
}
|
|
|
|
/*
|
|
* Now that we know we have the full header, validate it.
|
|
*/
|
|
if (!XLogReaderValidatePageHeader(state, pageptr, (char *) hdr))
|
|
goto err;
|
|
|
|
/* update read state information */
|
|
state->seg.ws_segno = targetSegNo;
|
|
state->segoff = targetPageOff;
|
|
state->readLen = readLen;
|
|
|
|
return readLen;
|
|
|
|
err:
|
|
XLogReaderInvalReadState(state);
|
|
return -1;
|
|
}
|
|
|
|
/*
|
|
* Invalidate the xlogreader's read state to force a re-read.
|
|
*/
|
|
static void
|
|
XLogReaderInvalReadState(XLogReaderState *state)
|
|
{
|
|
state->seg.ws_segno = 0;
|
|
state->segoff = 0;
|
|
state->readLen = 0;
|
|
}
|
|
|
|
/*
|
|
* Validate an XLOG record header.
|
|
*
|
|
* This is just a convenience subroutine to avoid duplicated code in
|
|
* XLogReadRecord. It's not intended for use from anywhere else.
|
|
*/
|
|
static bool
|
|
ValidXLogRecordHeader(XLogReaderState *state, XLogRecPtr RecPtr,
|
|
XLogRecPtr PrevRecPtr, XLogRecord *record,
|
|
bool randAccess)
|
|
{
|
|
if (record->xl_tot_len < SizeOfXLogRecord)
|
|
{
|
|
report_invalid_record(state,
|
|
"invalid record length at %X/%X: wanted %u, got %u",
|
|
(uint32) (RecPtr >> 32), (uint32) RecPtr,
|
|
(uint32) SizeOfXLogRecord, record->xl_tot_len);
|
|
return false;
|
|
}
|
|
if (record->xl_rmid > RM_MAX_ID)
|
|
{
|
|
report_invalid_record(state,
|
|
"invalid resource manager ID %u at %X/%X",
|
|
record->xl_rmid, (uint32) (RecPtr >> 32),
|
|
(uint32) RecPtr);
|
|
return false;
|
|
}
|
|
if (randAccess)
|
|
{
|
|
/*
|
|
* We can't exactly verify the prev-link, but surely it should be less
|
|
* than the record's own address.
|
|
*/
|
|
if (!(record->xl_prev < RecPtr))
|
|
{
|
|
report_invalid_record(state,
|
|
"record with incorrect prev-link %X/%X at %X/%X",
|
|
(uint32) (record->xl_prev >> 32),
|
|
(uint32) record->xl_prev,
|
|
(uint32) (RecPtr >> 32), (uint32) RecPtr);
|
|
return false;
|
|
}
|
|
}
|
|
else
|
|
{
|
|
/*
|
|
* Record's prev-link should exactly match our previous location. This
|
|
* check guards against torn WAL pages where a stale but valid-looking
|
|
* WAL record starts on a sector boundary.
|
|
*/
|
|
if (record->xl_prev != PrevRecPtr)
|
|
{
|
|
report_invalid_record(state,
|
|
"record with incorrect prev-link %X/%X at %X/%X",
|
|
(uint32) (record->xl_prev >> 32),
|
|
(uint32) record->xl_prev,
|
|
(uint32) (RecPtr >> 32), (uint32) RecPtr);
|
|
return false;
|
|
}
|
|
}
|
|
|
|
return true;
|
|
}
|
|
|
|
|
|
/*
|
|
* CRC-check an XLOG record. We do not believe the contents of an XLOG
|
|
* record (other than to the minimal extent of computing the amount of
|
|
* data to read in) until we've checked the CRCs.
|
|
*
|
|
* We assume all of the record (that is, xl_tot_len bytes) has been read
|
|
* into memory at *record. Also, ValidXLogRecordHeader() has accepted the
|
|
* record's header, which means in particular that xl_tot_len is at least
|
|
* SizeOfXLogRecord.
|
|
*/
|
|
static bool
|
|
ValidXLogRecord(XLogReaderState *state, XLogRecord *record, XLogRecPtr recptr)
|
|
{
|
|
pg_crc32c crc;
|
|
|
|
/* Calculate the CRC */
|
|
INIT_CRC32C(crc);
|
|
COMP_CRC32C(crc, ((char *) record) + SizeOfXLogRecord, record->xl_tot_len - SizeOfXLogRecord);
|
|
/* include the record header last */
|
|
COMP_CRC32C(crc, (char *) record, offsetof(XLogRecord, xl_crc));
|
|
FIN_CRC32C(crc);
|
|
|
|
if (!EQ_CRC32C(record->xl_crc, crc))
|
|
{
|
|
report_invalid_record(state,
|
|
"incorrect resource manager data checksum in record at %X/%X",
|
|
(uint32) (recptr >> 32), (uint32) recptr);
|
|
return false;
|
|
}
|
|
|
|
return true;
|
|
}
|
|
|
|
/*
|
|
* Validate a page header.
|
|
*
|
|
* Check if 'phdr' is valid as the header of the XLog page at position
|
|
* 'recptr'.
|
|
*/
|
|
bool
|
|
XLogReaderValidatePageHeader(XLogReaderState *state, XLogRecPtr recptr,
|
|
char *phdr)
|
|
{
|
|
XLogRecPtr recaddr;
|
|
XLogSegNo segno;
|
|
int32 offset;
|
|
XLogPageHeader hdr = (XLogPageHeader) phdr;
|
|
|
|
Assert((recptr % XLOG_BLCKSZ) == 0);
|
|
|
|
XLByteToSeg(recptr, segno, state->segcxt.ws_segsize);
|
|
offset = XLogSegmentOffset(recptr, state->segcxt.ws_segsize);
|
|
|
|
XLogSegNoOffsetToRecPtr(segno, offset, state->segcxt.ws_segsize, recaddr);
|
|
|
|
if (hdr->xlp_magic != XLOG_PAGE_MAGIC)
|
|
{
|
|
char fname[MAXFNAMELEN];
|
|
|
|
XLogFileName(fname, state->seg.ws_tli, segno, state->segcxt.ws_segsize);
|
|
|
|
report_invalid_record(state,
|
|
"invalid magic number %04X in log segment %s, offset %u",
|
|
hdr->xlp_magic,
|
|
fname,
|
|
offset);
|
|
return false;
|
|
}
|
|
|
|
if ((hdr->xlp_info & ~XLP_ALL_FLAGS) != 0)
|
|
{
|
|
char fname[MAXFNAMELEN];
|
|
|
|
XLogFileName(fname, state->seg.ws_tli, segno, state->segcxt.ws_segsize);
|
|
|
|
report_invalid_record(state,
|
|
"invalid info bits %04X in log segment %s, offset %u",
|
|
hdr->xlp_info,
|
|
fname,
|
|
offset);
|
|
return false;
|
|
}
|
|
|
|
if (hdr->xlp_info & XLP_LONG_HEADER)
|
|
{
|
|
XLogLongPageHeader longhdr = (XLogLongPageHeader) hdr;
|
|
|
|
if (state->system_identifier &&
|
|
longhdr->xlp_sysid != state->system_identifier)
|
|
{
|
|
report_invalid_record(state,
|
|
"WAL file is from different database system: WAL file database system identifier is %llu, pg_control database system identifier is %llu",
|
|
(unsigned long long) longhdr->xlp_sysid,
|
|
(unsigned long long) state->system_identifier);
|
|
return false;
|
|
}
|
|
else if (longhdr->xlp_seg_size != state->segcxt.ws_segsize)
|
|
{
|
|
report_invalid_record(state,
|
|
"WAL file is from different database system: incorrect segment size in page header");
|
|
return false;
|
|
}
|
|
else if (longhdr->xlp_xlog_blcksz != XLOG_BLCKSZ)
|
|
{
|
|
report_invalid_record(state,
|
|
"WAL file is from different database system: incorrect XLOG_BLCKSZ in page header");
|
|
return false;
|
|
}
|
|
}
|
|
else if (offset == 0)
|
|
{
|
|
char fname[MAXFNAMELEN];
|
|
|
|
XLogFileName(fname, state->seg.ws_tli, segno, state->segcxt.ws_segsize);
|
|
|
|
/* hmm, first page of file doesn't have a long header? */
|
|
report_invalid_record(state,
|
|
"invalid info bits %04X in log segment %s, offset %u",
|
|
hdr->xlp_info,
|
|
fname,
|
|
offset);
|
|
return false;
|
|
}
|
|
|
|
/*
|
|
* Check that the address on the page agrees with what we expected. This
|
|
* check typically fails when an old WAL segment is recycled, and hasn't
|
|
* yet been overwritten with new data yet.
|
|
*/
|
|
if (hdr->xlp_pageaddr != recaddr)
|
|
{
|
|
char fname[MAXFNAMELEN];
|
|
|
|
XLogFileName(fname, state->seg.ws_tli, segno, state->segcxt.ws_segsize);
|
|
|
|
report_invalid_record(state,
|
|
"unexpected pageaddr %X/%X in log segment %s, offset %u",
|
|
(uint32) (hdr->xlp_pageaddr >> 32), (uint32) hdr->xlp_pageaddr,
|
|
fname,
|
|
offset);
|
|
return false;
|
|
}
|
|
|
|
/*
|
|
* Since child timelines are always assigned a TLI greater than their
|
|
* immediate parent's TLI, we should never see TLI go backwards across
|
|
* successive pages of a consistent WAL sequence.
|
|
*
|
|
* Sometimes we re-read a segment that's already been (partially) read. So
|
|
* we only verify TLIs for pages that are later than the last remembered
|
|
* LSN.
|
|
*/
|
|
if (recptr > state->latestPagePtr)
|
|
{
|
|
if (hdr->xlp_tli < state->latestPageTLI)
|
|
{
|
|
char fname[MAXFNAMELEN];
|
|
|
|
XLogFileName(fname, state->seg.ws_tli, segno, state->segcxt.ws_segsize);
|
|
|
|
report_invalid_record(state,
|
|
"out-of-sequence timeline ID %u (after %u) in log segment %s, offset %u",
|
|
hdr->xlp_tli,
|
|
state->latestPageTLI,
|
|
fname,
|
|
offset);
|
|
return false;
|
|
}
|
|
}
|
|
state->latestPagePtr = recptr;
|
|
state->latestPageTLI = hdr->xlp_tli;
|
|
|
|
return true;
|
|
}
|
|
|
|
#ifdef FRONTEND
|
|
/*
|
|
* Functions that are currently not needed in the backend, but are better
|
|
* implemented inside xlogreader.c because of the internal facilities available
|
|
* here.
|
|
*/
|
|
|
|
/*
|
|
* Find the first record with an lsn >= RecPtr.
|
|
*
|
|
* Useful for checking whether RecPtr is a valid xlog address for reading, and
|
|
* to find the first valid address after some address when dumping records for
|
|
* debugging purposes.
|
|
*/
|
|
XLogRecPtr
|
|
XLogFindNextRecord(XLogReaderState *state, XLogRecPtr RecPtr)
|
|
{
|
|
XLogReaderState saved_state = *state;
|
|
XLogRecPtr tmpRecPtr;
|
|
XLogRecPtr found = InvalidXLogRecPtr;
|
|
XLogPageHeader header;
|
|
char *errormsg;
|
|
|
|
Assert(!XLogRecPtrIsInvalid(RecPtr));
|
|
|
|
/*
|
|
* skip over potential continuation data, keeping in mind that it may span
|
|
* multiple pages
|
|
*/
|
|
tmpRecPtr = RecPtr;
|
|
while (true)
|
|
{
|
|
XLogRecPtr targetPagePtr;
|
|
int targetRecOff;
|
|
uint32 pageHeaderSize;
|
|
int readLen;
|
|
|
|
/*
|
|
* Compute targetRecOff. It should typically be equal or greater than
|
|
* short page-header since a valid record can't start anywhere before
|
|
* that, except when caller has explicitly specified the offset that
|
|
* falls somewhere there or when we are skipping multi-page
|
|
* continuation record. It doesn't matter though because
|
|
* ReadPageInternal() is prepared to handle that and will read at
|
|
* least short page-header worth of data
|
|
*/
|
|
targetRecOff = tmpRecPtr % XLOG_BLCKSZ;
|
|
|
|
/* scroll back to page boundary */
|
|
targetPagePtr = tmpRecPtr - targetRecOff;
|
|
|
|
/* Read the page containing the record */
|
|
readLen = ReadPageInternal(state, targetPagePtr, targetRecOff);
|
|
if (readLen < 0)
|
|
goto err;
|
|
|
|
header = (XLogPageHeader) state->readBuf;
|
|
|
|
pageHeaderSize = XLogPageHeaderSize(header);
|
|
|
|
/* make sure we have enough data for the page header */
|
|
readLen = ReadPageInternal(state, targetPagePtr, pageHeaderSize);
|
|
if (readLen < 0)
|
|
goto err;
|
|
|
|
/* skip over potential continuation data */
|
|
if (header->xlp_info & XLP_FIRST_IS_CONTRECORD)
|
|
{
|
|
/*
|
|
* If the length of the remaining continuation data is more than
|
|
* what can fit in this page, the continuation record crosses over
|
|
* this page. Read the next page and try again. xlp_rem_len in the
|
|
* next page header will contain the remaining length of the
|
|
* continuation data
|
|
*
|
|
* Note that record headers are MAXALIGN'ed
|
|
*/
|
|
if (MAXALIGN(header->xlp_rem_len) >= (XLOG_BLCKSZ - pageHeaderSize))
|
|
tmpRecPtr = targetPagePtr + XLOG_BLCKSZ;
|
|
else
|
|
{
|
|
/*
|
|
* The previous continuation record ends in this page. Set
|
|
* tmpRecPtr to point to the first valid record
|
|
*/
|
|
tmpRecPtr = targetPagePtr + pageHeaderSize
|
|
+ MAXALIGN(header->xlp_rem_len);
|
|
break;
|
|
}
|
|
}
|
|
else
|
|
{
|
|
tmpRecPtr = targetPagePtr + pageHeaderSize;
|
|
break;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* we know now that tmpRecPtr is an address pointing to a valid XLogRecord
|
|
* because either we're at the first record after the beginning of a page
|
|
* or we just jumped over the remaining data of a continuation.
|
|
*/
|
|
while (XLogReadRecord(state, tmpRecPtr, &errormsg) != NULL)
|
|
{
|
|
/* continue after the record */
|
|
tmpRecPtr = InvalidXLogRecPtr;
|
|
|
|
/* past the record we've found, break out */
|
|
if (RecPtr <= state->ReadRecPtr)
|
|
{
|
|
found = state->ReadRecPtr;
|
|
goto out;
|
|
}
|
|
}
|
|
|
|
err:
|
|
out:
|
|
/* Reset state to what we had before finding the record */
|
|
state->ReadRecPtr = saved_state.ReadRecPtr;
|
|
state->EndRecPtr = saved_state.EndRecPtr;
|
|
XLogReaderInvalReadState(state);
|
|
|
|
return found;
|
|
}
|
|
|
|
#endif /* FRONTEND */
|
|
|
|
/*
|
|
* Read 'count' bytes into 'buf', starting at location 'startptr', from WAL
|
|
* fetched from timeline 'tli'.
|
|
*
|
|
* 'seg/segcxt' identify the last segment used. 'openSegment' is a callback
|
|
* to open the next segment, if necessary.
|
|
*
|
|
* Returns true if succeeded, false if an error occurs, in which case
|
|
* 'errinfo' receives error details.
|
|
*
|
|
* XXX probably this should be improved to suck data directly from the
|
|
* WAL buffers when possible.
|
|
*/
|
|
bool
|
|
WALRead(char *buf, XLogRecPtr startptr, Size count, TimeLineID tli,
|
|
WALOpenSegment *seg, WALSegmentContext *segcxt,
|
|
WALSegmentOpen openSegment, WALReadError *errinfo)
|
|
{
|
|
char *p;
|
|
XLogRecPtr recptr;
|
|
Size nbytes;
|
|
|
|
p = buf;
|
|
recptr = startptr;
|
|
nbytes = count;
|
|
|
|
while (nbytes > 0)
|
|
{
|
|
uint32 startoff;
|
|
int segbytes;
|
|
int readbytes;
|
|
|
|
startoff = XLogSegmentOffset(recptr, segcxt->ws_segsize);
|
|
|
|
/*
|
|
* If the data we want is not in a segment we have open, close what we
|
|
* have (if anything) and open the next one, using the caller's
|
|
* provided openSegment callback.
|
|
*/
|
|
if (seg->ws_file < 0 ||
|
|
!XLByteInSeg(recptr, seg->ws_segno, segcxt->ws_segsize) ||
|
|
tli != seg->ws_tli)
|
|
{
|
|
XLogSegNo nextSegNo;
|
|
|
|
if (seg->ws_file >= 0)
|
|
close(seg->ws_file);
|
|
|
|
XLByteToSeg(recptr, nextSegNo, segcxt->ws_segsize);
|
|
seg->ws_file = openSegment(nextSegNo, segcxt, &tli);
|
|
|
|
/* Update the current segment info. */
|
|
seg->ws_tli = tli;
|
|
seg->ws_segno = nextSegNo;
|
|
}
|
|
|
|
/* How many bytes are within this segment? */
|
|
if (nbytes > (segcxt->ws_segsize - startoff))
|
|
segbytes = segcxt->ws_segsize - startoff;
|
|
else
|
|
segbytes = nbytes;
|
|
|
|
#ifndef FRONTEND
|
|
pgstat_report_wait_start(WAIT_EVENT_WAL_READ);
|
|
#endif
|
|
|
|
/* Reset errno first; eases reporting non-errno-affecting errors */
|
|
errno = 0;
|
|
readbytes = pg_pread(seg->ws_file, p, segbytes, (off_t) startoff);
|
|
|
|
#ifndef FRONTEND
|
|
pgstat_report_wait_end();
|
|
#endif
|
|
|
|
if (readbytes <= 0)
|
|
{
|
|
errinfo->wre_errno = errno;
|
|
errinfo->wre_req = segbytes;
|
|
errinfo->wre_read = readbytes;
|
|
errinfo->wre_off = startoff;
|
|
errinfo->wre_seg = *seg;
|
|
return false;
|
|
}
|
|
|
|
/* Update state for read */
|
|
recptr += readbytes;
|
|
nbytes -= readbytes;
|
|
p += readbytes;
|
|
}
|
|
|
|
return true;
|
|
}
|
|
|
|
/* ----------------------------------------
|
|
* Functions for decoding the data and block references in a record.
|
|
* ----------------------------------------
|
|
*/
|
|
|
|
/* private function to reset the state between records */
|
|
static void
|
|
ResetDecoder(XLogReaderState *state)
|
|
{
|
|
int block_id;
|
|
|
|
state->decoded_record = NULL;
|
|
|
|
state->main_data_len = 0;
|
|
|
|
for (block_id = 0; block_id <= state->max_block_id; block_id++)
|
|
{
|
|
state->blocks[block_id].in_use = false;
|
|
state->blocks[block_id].has_image = false;
|
|
state->blocks[block_id].has_data = false;
|
|
state->blocks[block_id].apply_image = false;
|
|
}
|
|
state->max_block_id = -1;
|
|
}
|
|
|
|
/*
|
|
* Decode the previously read record.
|
|
*
|
|
* On error, a human-readable error message is returned in *errormsg, and
|
|
* the return value is false.
|
|
*/
|
|
bool
|
|
DecodeXLogRecord(XLogReaderState *state, XLogRecord *record, char **errormsg)
|
|
{
|
|
/*
|
|
* read next _size bytes from record buffer, but check for overrun first.
|
|
*/
|
|
#define COPY_HEADER_FIELD(_dst, _size) \
|
|
do { \
|
|
if (remaining < _size) \
|
|
goto shortdata_err; \
|
|
memcpy(_dst, ptr, _size); \
|
|
ptr += _size; \
|
|
remaining -= _size; \
|
|
} while(0)
|
|
|
|
char *ptr;
|
|
uint32 remaining;
|
|
uint32 datatotal;
|
|
RelFileNode *rnode = NULL;
|
|
uint8 block_id;
|
|
|
|
ResetDecoder(state);
|
|
|
|
state->decoded_record = record;
|
|
state->record_origin = InvalidRepOriginId;
|
|
|
|
ptr = (char *) record;
|
|
ptr += SizeOfXLogRecord;
|
|
remaining = record->xl_tot_len - SizeOfXLogRecord;
|
|
|
|
/* Decode the headers */
|
|
datatotal = 0;
|
|
while (remaining > datatotal)
|
|
{
|
|
COPY_HEADER_FIELD(&block_id, sizeof(uint8));
|
|
|
|
if (block_id == XLR_BLOCK_ID_DATA_SHORT)
|
|
{
|
|
/* XLogRecordDataHeaderShort */
|
|
uint8 main_data_len;
|
|
|
|
COPY_HEADER_FIELD(&main_data_len, sizeof(uint8));
|
|
|
|
state->main_data_len = main_data_len;
|
|
datatotal += main_data_len;
|
|
break; /* by convention, the main data fragment is
|
|
* always last */
|
|
}
|
|
else if (block_id == XLR_BLOCK_ID_DATA_LONG)
|
|
{
|
|
/* XLogRecordDataHeaderLong */
|
|
uint32 main_data_len;
|
|
|
|
COPY_HEADER_FIELD(&main_data_len, sizeof(uint32));
|
|
state->main_data_len = main_data_len;
|
|
datatotal += main_data_len;
|
|
break; /* by convention, the main data fragment is
|
|
* always last */
|
|
}
|
|
else if (block_id == XLR_BLOCK_ID_ORIGIN)
|
|
{
|
|
COPY_HEADER_FIELD(&state->record_origin, sizeof(RepOriginId));
|
|
}
|
|
else if (block_id <= XLR_MAX_BLOCK_ID)
|
|
{
|
|
/* XLogRecordBlockHeader */
|
|
DecodedBkpBlock *blk;
|
|
uint8 fork_flags;
|
|
|
|
if (block_id <= state->max_block_id)
|
|
{
|
|
report_invalid_record(state,
|
|
"out-of-order block_id %u at %X/%X",
|
|
block_id,
|
|
(uint32) (state->ReadRecPtr >> 32),
|
|
(uint32) state->ReadRecPtr);
|
|
goto err;
|
|
}
|
|
state->max_block_id = block_id;
|
|
|
|
blk = &state->blocks[block_id];
|
|
blk->in_use = true;
|
|
blk->apply_image = false;
|
|
|
|
COPY_HEADER_FIELD(&fork_flags, sizeof(uint8));
|
|
blk->forknum = fork_flags & BKPBLOCK_FORK_MASK;
|
|
blk->flags = fork_flags;
|
|
blk->has_image = ((fork_flags & BKPBLOCK_HAS_IMAGE) != 0);
|
|
blk->has_data = ((fork_flags & BKPBLOCK_HAS_DATA) != 0);
|
|
|
|
COPY_HEADER_FIELD(&blk->data_len, sizeof(uint16));
|
|
/* cross-check that the HAS_DATA flag is set iff data_length > 0 */
|
|
if (blk->has_data && blk->data_len == 0)
|
|
{
|
|
report_invalid_record(state,
|
|
"BKPBLOCK_HAS_DATA set, but no data included at %X/%X",
|
|
(uint32) (state->ReadRecPtr >> 32), (uint32) state->ReadRecPtr);
|
|
goto err;
|
|
}
|
|
if (!blk->has_data && blk->data_len != 0)
|
|
{
|
|
report_invalid_record(state,
|
|
"BKPBLOCK_HAS_DATA not set, but data length is %u at %X/%X",
|
|
(unsigned int) blk->data_len,
|
|
(uint32) (state->ReadRecPtr >> 32), (uint32) state->ReadRecPtr);
|
|
goto err;
|
|
}
|
|
datatotal += blk->data_len;
|
|
|
|
if (blk->has_image)
|
|
{
|
|
COPY_HEADER_FIELD(&blk->bimg_len, sizeof(uint16));
|
|
COPY_HEADER_FIELD(&blk->hole_offset, sizeof(uint16));
|
|
COPY_HEADER_FIELD(&blk->bimg_info, sizeof(uint8));
|
|
|
|
blk->apply_image = ((blk->bimg_info & BKPIMAGE_APPLY) != 0);
|
|
|
|
if (blk->bimg_info & BKPIMAGE_IS_COMPRESSED)
|
|
{
|
|
if (blk->bimg_info & BKPIMAGE_HAS_HOLE)
|
|
COPY_HEADER_FIELD(&blk->hole_length, sizeof(uint16));
|
|
else
|
|
blk->hole_length = 0;
|
|
}
|
|
else
|
|
blk->hole_length = BLCKSZ - blk->bimg_len;
|
|
datatotal += blk->bimg_len;
|
|
|
|
/*
|
|
* cross-check that hole_offset > 0, hole_length > 0 and
|
|
* bimg_len < BLCKSZ if the HAS_HOLE flag is set.
|
|
*/
|
|
if ((blk->bimg_info & BKPIMAGE_HAS_HOLE) &&
|
|
(blk->hole_offset == 0 ||
|
|
blk->hole_length == 0 ||
|
|
blk->bimg_len == BLCKSZ))
|
|
{
|
|
report_invalid_record(state,
|
|
"BKPIMAGE_HAS_HOLE set, but hole offset %u length %u block image length %u at %X/%X",
|
|
(unsigned int) blk->hole_offset,
|
|
(unsigned int) blk->hole_length,
|
|
(unsigned int) blk->bimg_len,
|
|
(uint32) (state->ReadRecPtr >> 32), (uint32) state->ReadRecPtr);
|
|
goto err;
|
|
}
|
|
|
|
/*
|
|
* cross-check that hole_offset == 0 and hole_length == 0 if
|
|
* the HAS_HOLE flag is not set.
|
|
*/
|
|
if (!(blk->bimg_info & BKPIMAGE_HAS_HOLE) &&
|
|
(blk->hole_offset != 0 || blk->hole_length != 0))
|
|
{
|
|
report_invalid_record(state,
|
|
"BKPIMAGE_HAS_HOLE not set, but hole offset %u length %u at %X/%X",
|
|
(unsigned int) blk->hole_offset,
|
|
(unsigned int) blk->hole_length,
|
|
(uint32) (state->ReadRecPtr >> 32), (uint32) state->ReadRecPtr);
|
|
goto err;
|
|
}
|
|
|
|
/*
|
|
* cross-check that bimg_len < BLCKSZ if the IS_COMPRESSED
|
|
* flag is set.
|
|
*/
|
|
if ((blk->bimg_info & BKPIMAGE_IS_COMPRESSED) &&
|
|
blk->bimg_len == BLCKSZ)
|
|
{
|
|
report_invalid_record(state,
|
|
"BKPIMAGE_IS_COMPRESSED set, but block image length %u at %X/%X",
|
|
(unsigned int) blk->bimg_len,
|
|
(uint32) (state->ReadRecPtr >> 32), (uint32) state->ReadRecPtr);
|
|
goto err;
|
|
}
|
|
|
|
/*
|
|
* cross-check that bimg_len = BLCKSZ if neither HAS_HOLE nor
|
|
* IS_COMPRESSED flag is set.
|
|
*/
|
|
if (!(blk->bimg_info & BKPIMAGE_HAS_HOLE) &&
|
|
!(blk->bimg_info & BKPIMAGE_IS_COMPRESSED) &&
|
|
blk->bimg_len != BLCKSZ)
|
|
{
|
|
report_invalid_record(state,
|
|
"neither BKPIMAGE_HAS_HOLE nor BKPIMAGE_IS_COMPRESSED set, but block image length is %u at %X/%X",
|
|
(unsigned int) blk->data_len,
|
|
(uint32) (state->ReadRecPtr >> 32), (uint32) state->ReadRecPtr);
|
|
goto err;
|
|
}
|
|
}
|
|
if (!(fork_flags & BKPBLOCK_SAME_REL))
|
|
{
|
|
COPY_HEADER_FIELD(&blk->rnode, sizeof(RelFileNode));
|
|
rnode = &blk->rnode;
|
|
}
|
|
else
|
|
{
|
|
if (rnode == NULL)
|
|
{
|
|
report_invalid_record(state,
|
|
"BKPBLOCK_SAME_REL set but no previous rel at %X/%X",
|
|
(uint32) (state->ReadRecPtr >> 32), (uint32) state->ReadRecPtr);
|
|
goto err;
|
|
}
|
|
|
|
blk->rnode = *rnode;
|
|
}
|
|
COPY_HEADER_FIELD(&blk->blkno, sizeof(BlockNumber));
|
|
}
|
|
else
|
|
{
|
|
report_invalid_record(state,
|
|
"invalid block_id %u at %X/%X",
|
|
block_id,
|
|
(uint32) (state->ReadRecPtr >> 32),
|
|
(uint32) state->ReadRecPtr);
|
|
goto err;
|
|
}
|
|
}
|
|
|
|
if (remaining != datatotal)
|
|
goto shortdata_err;
|
|
|
|
/*
|
|
* Ok, we've parsed the fragment headers, and verified that the total
|
|
* length of the payload in the fragments is equal to the amount of data
|
|
* left. Copy the data of each fragment to a separate buffer.
|
|
*
|
|
* We could just set up pointers into readRecordBuf, but we want to align
|
|
* the data for the convenience of the callers. Backup images are not
|
|
* copied, however; they don't need alignment.
|
|
*/
|
|
|
|
/* block data first */
|
|
for (block_id = 0; block_id <= state->max_block_id; block_id++)
|
|
{
|
|
DecodedBkpBlock *blk = &state->blocks[block_id];
|
|
|
|
if (!blk->in_use)
|
|
continue;
|
|
|
|
Assert(blk->has_image || !blk->apply_image);
|
|
|
|
if (blk->has_image)
|
|
{
|
|
blk->bkp_image = ptr;
|
|
ptr += blk->bimg_len;
|
|
}
|
|
if (blk->has_data)
|
|
{
|
|
if (!blk->data || blk->data_len > blk->data_bufsz)
|
|
{
|
|
if (blk->data)
|
|
pfree(blk->data);
|
|
|
|
/*
|
|
* Force the initial request to be BLCKSZ so that we don't
|
|
* waste time with lots of trips through this stanza as a
|
|
* result of WAL compression.
|
|
*/
|
|
blk->data_bufsz = MAXALIGN(Max(blk->data_len, BLCKSZ));
|
|
blk->data = palloc(blk->data_bufsz);
|
|
}
|
|
memcpy(blk->data, ptr, blk->data_len);
|
|
ptr += blk->data_len;
|
|
}
|
|
}
|
|
|
|
/* and finally, the main data */
|
|
if (state->main_data_len > 0)
|
|
{
|
|
if (!state->main_data || state->main_data_len > state->main_data_bufsz)
|
|
{
|
|
if (state->main_data)
|
|
pfree(state->main_data);
|
|
|
|
/*
|
|
* main_data_bufsz must be MAXALIGN'ed. In many xlog record
|
|
* types, we omit trailing struct padding on-disk to save a few
|
|
* bytes; but compilers may generate accesses to the xlog struct
|
|
* that assume that padding bytes are present. If the palloc
|
|
* request is not large enough to include such padding bytes then
|
|
* we'll get valgrind complaints due to otherwise-harmless fetches
|
|
* of the padding bytes.
|
|
*
|
|
* In addition, force the initial request to be reasonably large
|
|
* so that we don't waste time with lots of trips through this
|
|
* stanza. BLCKSZ / 2 seems like a good compromise choice.
|
|
*/
|
|
state->main_data_bufsz = MAXALIGN(Max(state->main_data_len,
|
|
BLCKSZ / 2));
|
|
state->main_data = palloc(state->main_data_bufsz);
|
|
}
|
|
memcpy(state->main_data, ptr, state->main_data_len);
|
|
ptr += state->main_data_len;
|
|
}
|
|
|
|
return true;
|
|
|
|
shortdata_err:
|
|
report_invalid_record(state,
|
|
"record with invalid length at %X/%X",
|
|
(uint32) (state->ReadRecPtr >> 32), (uint32) state->ReadRecPtr);
|
|
err:
|
|
*errormsg = state->errormsg_buf;
|
|
|
|
return false;
|
|
}
|
|
|
|
/*
|
|
* Returns information about the block that a block reference refers to.
|
|
*
|
|
* If the WAL record contains a block reference with the given ID, *rnode,
|
|
* *forknum, and *blknum are filled in (if not NULL), and returns true.
|
|
* Otherwise returns false.
|
|
*/
|
|
bool
|
|
XLogRecGetBlockTag(XLogReaderState *record, uint8 block_id,
|
|
RelFileNode *rnode, ForkNumber *forknum, BlockNumber *blknum)
|
|
{
|
|
DecodedBkpBlock *bkpb;
|
|
|
|
if (!record->blocks[block_id].in_use)
|
|
return false;
|
|
|
|
bkpb = &record->blocks[block_id];
|
|
if (rnode)
|
|
*rnode = bkpb->rnode;
|
|
if (forknum)
|
|
*forknum = bkpb->forknum;
|
|
if (blknum)
|
|
*blknum = bkpb->blkno;
|
|
return true;
|
|
}
|
|
|
|
/*
|
|
* Returns the data associated with a block reference, or NULL if there is
|
|
* no data (e.g. because a full-page image was taken instead). The returned
|
|
* pointer points to a MAXALIGNed buffer.
|
|
*/
|
|
char *
|
|
XLogRecGetBlockData(XLogReaderState *record, uint8 block_id, Size *len)
|
|
{
|
|
DecodedBkpBlock *bkpb;
|
|
|
|
if (!record->blocks[block_id].in_use)
|
|
return NULL;
|
|
|
|
bkpb = &record->blocks[block_id];
|
|
|
|
if (!bkpb->has_data)
|
|
{
|
|
if (len)
|
|
*len = 0;
|
|
return NULL;
|
|
}
|
|
else
|
|
{
|
|
if (len)
|
|
*len = bkpb->data_len;
|
|
return bkpb->data;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Restore a full-page image from a backup block attached to an XLOG record.
|
|
*
|
|
* Returns the buffer number containing the page.
|
|
*/
|
|
bool
|
|
RestoreBlockImage(XLogReaderState *record, uint8 block_id, char *page)
|
|
{
|
|
DecodedBkpBlock *bkpb;
|
|
char *ptr;
|
|
PGAlignedBlock tmp;
|
|
|
|
if (!record->blocks[block_id].in_use)
|
|
return false;
|
|
if (!record->blocks[block_id].has_image)
|
|
return false;
|
|
|
|
bkpb = &record->blocks[block_id];
|
|
ptr = bkpb->bkp_image;
|
|
|
|
if (bkpb->bimg_info & BKPIMAGE_IS_COMPRESSED)
|
|
{
|
|
/* If a backup block image is compressed, decompress it */
|
|
if (pglz_decompress(ptr, bkpb->bimg_len, tmp.data,
|
|
BLCKSZ - bkpb->hole_length, true) < 0)
|
|
{
|
|
report_invalid_record(record, "invalid compressed image at %X/%X, block %d",
|
|
(uint32) (record->ReadRecPtr >> 32),
|
|
(uint32) record->ReadRecPtr,
|
|
block_id);
|
|
return false;
|
|
}
|
|
ptr = tmp.data;
|
|
}
|
|
|
|
/* generate page, taking into account hole if necessary */
|
|
if (bkpb->hole_length == 0)
|
|
{
|
|
memcpy(page, ptr, BLCKSZ);
|
|
}
|
|
else
|
|
{
|
|
memcpy(page, ptr, bkpb->hole_offset);
|
|
/* must zero-fill the hole */
|
|
MemSet(page + bkpb->hole_offset, 0, bkpb->hole_length);
|
|
memcpy(page + (bkpb->hole_offset + bkpb->hole_length),
|
|
ptr + bkpb->hole_offset,
|
|
BLCKSZ - (bkpb->hole_offset + bkpb->hole_length));
|
|
}
|
|
|
|
return true;
|
|
}
|
|
|
|
#ifndef FRONTEND
|
|
|
|
/*
|
|
* Extract the FullTransactionId from a WAL record.
|
|
*/
|
|
FullTransactionId
|
|
XLogRecGetFullXid(XLogReaderState *record)
|
|
{
|
|
TransactionId xid,
|
|
next_xid;
|
|
uint32 epoch;
|
|
|
|
/*
|
|
* This function is only safe during replay, because it depends on the
|
|
* replay state. See AdvanceNextFullTransactionIdPastXid() for more.
|
|
*/
|
|
Assert(AmStartupProcess() || !IsUnderPostmaster);
|
|
|
|
xid = XLogRecGetXid(record);
|
|
next_xid = XidFromFullTransactionId(ShmemVariableCache->nextFullXid);
|
|
epoch = EpochFromFullTransactionId(ShmemVariableCache->nextFullXid);
|
|
|
|
/*
|
|
* If xid is numerically greater than next_xid, it has to be from the
|
|
* last epoch.
|
|
*/
|
|
if (unlikely(xid > next_xid))
|
|
--epoch;
|
|
|
|
return FullTransactionIdFromEpochAndXid(epoch, xid);
|
|
}
|
|
|
|
#endif
|