LCOV - code coverage report
Current view: top level - src/bin/pg_rewind - xlogreader.c (source / functions) Hit Total Coverage
Test: PostgreSQL 16beta1 Lines: 378 736 51.4 %
Date: 2023-06-02 19:12:20 Functions: 19 28 67.9 %
Legend: Lines: hit not hit

          Line data    Source code
       1             : /*-------------------------------------------------------------------------
       2             :  *
       3             :  * xlogreader.c
       4             :  *      Generic XLog reading facility
       5             :  *
       6             :  * Portions Copyright (c) 2013-2023, PostgreSQL Global Development Group
       7             :  *
       8             :  * IDENTIFICATION
       9             :  *      src/backend/access/transam/xlogreader.c
      10             :  *
      11             :  * NOTES
      12             :  *      See xlogreader.h for more notes on this facility.
      13             :  *
      14             :  *      This file is compiled as both front-end and backend code, so it
      15             :  *      may not use ereport, server-defined static variables, etc.
      16             :  *-------------------------------------------------------------------------
      17             :  */
      18             : #include "postgres.h"
      19             : 
      20             : #include <unistd.h>
      21             : #ifdef USE_LZ4
      22             : #include <lz4.h>
      23             : #endif
      24             : #ifdef USE_ZSTD
      25             : #include <zstd.h>
      26             : #endif
      27             : 
      28             : #include "access/transam.h"
      29             : #include "access/xlog_internal.h"
      30             : #include "access/xlogreader.h"
      31             : #include "access/xlogrecord.h"
      32             : #include "catalog/pg_control.h"
      33             : #include "common/pg_lzcompress.h"
      34             : #include "replication/origin.h"
      35             : 
      36             : #ifndef FRONTEND
      37             : #include "miscadmin.h"
      38             : #include "pgstat.h"
      39             : #include "utils/memutils.h"
      40             : #else
      41             : #include "common/logging.h"
      42             : #endif
      43             : 
      44             : static void report_invalid_record(XLogReaderState *state, const char *fmt,...)
      45             :             pg_attribute_printf(2, 3);
      46             : static bool allocate_recordbuf(XLogReaderState *state, uint32 reclength);
      47             : static int  ReadPageInternal(XLogReaderState *state, XLogRecPtr pageptr,
      48             :                              int reqLen);
      49             : static void XLogReaderInvalReadState(XLogReaderState *state);
      50             : static XLogPageReadResult XLogDecodeNextRecord(XLogReaderState *state, bool nonblocking);
      51             : static bool ValidXLogRecordHeader(XLogReaderState *state, XLogRecPtr RecPtr,
      52             :                                   XLogRecPtr PrevRecPtr, XLogRecord *record, bool randAccess);
      53             : static bool ValidXLogRecord(XLogReaderState *state, XLogRecord *record,
      54             :                             XLogRecPtr recptr);
      55             : static void ResetDecoder(XLogReaderState *state);
      56             : static void WALOpenSegmentInit(WALOpenSegment *seg, WALSegmentContext *segcxt,
      57             :                                int segsize, const char *waldir);
      58             : 
      59             : /* size of the buffer allocated for error message. */
      60             : #define MAX_ERRORMSG_LEN 1000
      61             : 
      62             : /*
      63             :  * Default size; large enough that typical users of XLogReader won't often need
      64             :  * to use the 'oversized' memory allocation code path.
      65             :  */
      66             : #define DEFAULT_DECODE_BUFFER_SIZE (64 * 1024)
      67             : 
      68             : /*
      69             :  * Construct a string in state->errormsg_buf explaining what's wrong with
      70             :  * the current record being read.
      71             :  */
      72             : static void
      73           0 : report_invalid_record(XLogReaderState *state, const char *fmt,...)
      74             : {
      75             :     va_list     args;
      76             : 
      77           0 :     fmt = _(fmt);
      78             : 
      79           0 :     va_start(args, fmt);
      80           0 :     vsnprintf(state->errormsg_buf, MAX_ERRORMSG_LEN, fmt, args);
      81           0 :     va_end(args);
      82             : 
      83           0 :     state->errormsg_deferred = true;
      84           0 : }
      85             : 
      86             : /*
      87             :  * Set the size of the decoding buffer.  A pointer to a caller supplied memory
      88             :  * region may also be passed in, in which case non-oversized records will be
      89             :  * decoded there.
      90             :  */
      91             : void
      92           0 : XLogReaderSetDecodeBuffer(XLogReaderState *state, void *buffer, size_t size)
      93             : {
      94             :     Assert(state->decode_buffer == NULL);
      95             : 
      96           0 :     state->decode_buffer = buffer;
      97           0 :     state->decode_buffer_size = size;
      98           0 :     state->decode_buffer_tail = buffer;
      99           0 :     state->decode_buffer_head = buffer;
     100           0 : }
     101             : 
     102             : /*
     103             :  * Allocate and initialize a new XLogReader.
     104             :  *
     105             :  * Returns NULL if the xlogreader couldn't be allocated.
     106             :  */
     107             : XLogReaderState *
     108          78 : XLogReaderAllocate(int wal_segment_size, const char *waldir,
     109             :                    XLogReaderRoutine *routine, void *private_data)
     110             : {
     111             :     XLogReaderState *state;
     112             : 
     113             :     state = (XLogReaderState *)
     114          78 :         palloc_extended(sizeof(XLogReaderState),
     115             :                         MCXT_ALLOC_NO_OOM | MCXT_ALLOC_ZERO);
     116          78 :     if (!state)
     117           0 :         return NULL;
     118             : 
     119             :     /* initialize caller-provided support functions */
     120          78 :     state->routine = *routine;
     121             : 
     122             :     /*
     123             :      * Permanently allocate readBuf.  We do it this way, rather than just
     124             :      * making a static array, for two reasons: (1) no need to waste the
     125             :      * storage in most instantiations of the backend; (2) a static char array
     126             :      * isn't guaranteed to have any particular alignment, whereas
     127             :      * palloc_extended() will provide MAXALIGN'd storage.
     128             :      */
     129          78 :     state->readBuf = (char *) palloc_extended(XLOG_BLCKSZ,
     130             :                                               MCXT_ALLOC_NO_OOM);
     131          78 :     if (!state->readBuf)
     132             :     {
     133           0 :         pfree(state);
     134           0 :         return NULL;
     135             :     }
     136             : 
     137             :     /* Initialize segment info. */
     138          78 :     WALOpenSegmentInit(&state->seg, &state->segcxt, wal_segment_size,
     139             :                        waldir);
     140             : 
     141             :     /* system_identifier initialized to zeroes above */
     142          78 :     state->private_data = private_data;
     143             :     /* ReadRecPtr, EndRecPtr and readLen initialized to zeroes above */
     144          78 :     state->errormsg_buf = palloc_extended(MAX_ERRORMSG_LEN + 1,
     145             :                                           MCXT_ALLOC_NO_OOM);
     146          78 :     if (!state->errormsg_buf)
     147             :     {
     148           0 :         pfree(state->readBuf);
     149           0 :         pfree(state);
     150           0 :         return NULL;
     151             :     }
     152          78 :     state->errormsg_buf[0] = '\0';
     153             : 
     154             :     /*
     155             :      * Allocate an initial readRecordBuf of minimal size, which can later be
     156             :      * enlarged if necessary.
     157             :      */
     158          78 :     if (!allocate_recordbuf(state, 0))
     159             :     {
     160           0 :         pfree(state->errormsg_buf);
     161           0 :         pfree(state->readBuf);
     162           0 :         pfree(state);
     163           0 :         return NULL;
     164             :     }
     165             : 
     166          78 :     return state;
     167             : }
     168             : 
     169             : void
     170          78 : XLogReaderFree(XLogReaderState *state)
     171             : {
     172          78 :     if (state->seg.ws_file != -1)
     173           0 :         state->routine.segment_close(state);
     174             : 
     175          78 :     if (state->decode_buffer && state->free_decode_buffer)
     176          78 :         pfree(state->decode_buffer);
     177             : 
     178          78 :     pfree(state->errormsg_buf);
     179          78 :     if (state->readRecordBuf)
     180          78 :         pfree(state->readRecordBuf);
     181          78 :     pfree(state->readBuf);
     182          78 :     pfree(state);
     183          78 : }
     184             : 
     185             : /*
     186             :  * Allocate readRecordBuf to fit a record of at least the given length.
     187             :  * Returns true if successful, false if out of memory.
     188             :  *
     189             :  * readRecordBufSize is set to the new buffer size.
     190             :  *
     191             :  * To avoid useless small increases, round its size to a multiple of
     192             :  * XLOG_BLCKSZ, and make sure it's at least 5*Max(BLCKSZ, XLOG_BLCKSZ) to start
     193             :  * with.  (That is enough for all "normal" records, but very large commit or
     194             :  * abort records might need more space.)
     195             :  */
     196             : static bool
     197          78 : allocate_recordbuf(XLogReaderState *state, uint32 reclength)
     198             : {
     199          78 :     uint32      newSize = reclength;
     200             : 
     201          78 :     newSize += XLOG_BLCKSZ - (newSize % XLOG_BLCKSZ);
     202          78 :     newSize = Max(newSize, 5 * Max(BLCKSZ, XLOG_BLCKSZ));
     203             : 
     204             : #ifndef FRONTEND
     205             : 
     206             :     /*
     207             :      * Note that in much unlucky circumstances, the random data read from a
     208             :      * recycled segment can cause this routine to be called with a size
     209             :      * causing a hard failure at allocation.  For a standby, this would cause
     210             :      * the instance to stop suddenly with a hard failure, preventing it to
     211             :      * retry fetching WAL from one of its sources which could allow it to move
     212             :      * on with replay without a manual restart. If the data comes from a past
     213             :      * recycled segment and is still valid, then the allocation may succeed
     214             :      * but record checks are going to fail so this would be short-lived.  If
     215             :      * the allocation fails because of a memory shortage, then this is not a
     216             :      * hard failure either per the guarantee given by MCXT_ALLOC_NO_OOM.
     217             :      */
     218             :     if (!AllocSizeIsValid(newSize))
     219             :         return false;
     220             : 
     221             : #endif
     222             : 
     223          78 :     if (state->readRecordBuf)
     224           0 :         pfree(state->readRecordBuf);
     225          78 :     state->readRecordBuf =
     226          78 :         (char *) palloc_extended(newSize, MCXT_ALLOC_NO_OOM);
     227          78 :     if (state->readRecordBuf == NULL)
     228             :     {
     229           0 :         state->readRecordBufSize = 0;
     230           0 :         return false;
     231             :     }
     232          78 :     state->readRecordBufSize = newSize;
     233          78 :     return true;
     234             : }
     235             : 
     236             : /*
     237             :  * Initialize the passed segment structs.
     238             :  */
     239             : static void
     240          78 : WALOpenSegmentInit(WALOpenSegment *seg, WALSegmentContext *segcxt,
     241             :                    int segsize, const char *waldir)
     242             : {
     243          78 :     seg->ws_file = -1;
     244          78 :     seg->ws_segno = 0;
     245          78 :     seg->ws_tli = 0;
     246             : 
     247          78 :     segcxt->ws_segsize = segsize;
     248          78 :     if (waldir)
     249          78 :         snprintf(segcxt->ws_dir, MAXPGPATH, "%s", waldir);
     250          78 : }
     251             : 
     252             : /*
     253             :  * Begin reading WAL at 'RecPtr'.
     254             :  *
     255             :  * 'RecPtr' should point to the beginning of a valid WAL record.  Pointing at
     256             :  * the beginning of a page is also OK, if there is a new record right after
     257             :  * the page header, i.e. not a continuation.
     258             :  *
     259             :  * This does not make any attempt to read the WAL yet, and hence cannot fail.
     260             :  * If the starting address is not correct, the first call to XLogReadRecord()
     261             :  * will error out.
     262             :  */
     263             : void
     264        5156 : XLogBeginRead(XLogReaderState *state, XLogRecPtr RecPtr)
     265             : {
     266             :     Assert(!XLogRecPtrIsInvalid(RecPtr));
     267             : 
     268        5156 :     ResetDecoder(state);
     269             : 
     270             :     /* Begin at the passed-in record pointer. */
     271        5156 :     state->EndRecPtr = RecPtr;
     272        5156 :     state->NextRecPtr = RecPtr;
     273        5156 :     state->ReadRecPtr = InvalidXLogRecPtr;
     274        5156 :     state->DecodeRecPtr = InvalidXLogRecPtr;
     275        5156 : }
     276             : 
     277             : /*
     278             :  * Release the last record that was returned by XLogNextRecord(), if any, to
     279             :  * free up space.  Returns the LSN past the end of the record.
     280             :  */
     281             : XLogRecPtr
     282      356756 : XLogReleasePreviousRecord(XLogReaderState *state)
     283             : {
     284             :     DecodedXLogRecord *record;
     285             :     XLogRecPtr  next_lsn;
     286             : 
     287      356756 :     if (!state->record)
     288      183534 :         return InvalidXLogRecPtr;
     289             : 
     290             :     /*
     291             :      * Remove it from the decoded record queue.  It must be the oldest item
     292             :      * decoded, decode_queue_head.
     293             :      */
     294      173222 :     record = state->record;
     295      173222 :     next_lsn = record->next_lsn;
     296             :     Assert(record == state->decode_queue_head);
     297      173222 :     state->record = NULL;
     298      173222 :     state->decode_queue_head = record->next;
     299             : 
     300             :     /* It might also be the newest item decoded, decode_queue_tail. */
     301      173222 :     if (state->decode_queue_tail == record)
     302      173222 :         state->decode_queue_tail = NULL;
     303             : 
     304             :     /* Release the space. */
     305      173222 :     if (unlikely(record->oversized))
     306             :     {
     307             :         /* It's not in the decode buffer, so free it to release space. */
     308           0 :         pfree(record);
     309             :     }
     310             :     else
     311             :     {
     312             :         /* It must be the head (oldest) record in the decode buffer. */
     313             :         Assert(state->decode_buffer_head == (char *) record);
     314             : 
     315             :         /*
     316             :          * We need to update head to point to the next record that is in the
     317             :          * decode buffer, if any, being careful to skip oversized ones
     318             :          * (they're not in the decode buffer).
     319             :          */
     320      173222 :         record = record->next;
     321      173222 :         while (unlikely(record && record->oversized))
     322           0 :             record = record->next;
     323             : 
     324      173222 :         if (record)
     325             :         {
     326             :             /* Adjust head to release space up to the next record. */
     327           0 :             state->decode_buffer_head = (char *) record;
     328             :         }
     329             :         else
     330             :         {
     331             :             /*
     332             :              * Otherwise we might as well just reset head and tail to the
     333             :              * start of the buffer space, because we're empty.  This means
     334             :              * we'll keep overwriting the same piece of memory if we're not
     335             :              * doing any prefetching.
     336             :              */
     337      173222 :             state->decode_buffer_head = state->decode_buffer;
     338      173222 :             state->decode_buffer_tail = state->decode_buffer;
     339             :         }
     340             :     }
     341             : 
     342      173222 :     return next_lsn;
     343             : }
     344             : 
     345             : /*
     346             :  * Attempt to read an XLOG record.
     347             :  *
     348             :  * XLogBeginRead() or XLogFindNextRecord() and then XLogReadAhead() must be
     349             :  * called before the first call to XLogNextRecord().  This functions returns
     350             :  * records and errors that were put into an internal queue by XLogReadAhead().
     351             :  *
     352             :  * On success, a record is returned.
     353             :  *
     354             :  * The returned record (or *errormsg) points to an internal buffer that's
     355             :  * valid until the next call to XLogNextRecord.
     356             :  */
     357             : DecodedXLogRecord *
     358      178378 : XLogNextRecord(XLogReaderState *state, char **errormsg)
     359             : {
     360             :     /* Release the last record returned by XLogNextRecord(). */
     361      178378 :     XLogReleasePreviousRecord(state);
     362             : 
     363      178378 :     if (state->decode_queue_head == NULL)
     364             :     {
     365           0 :         *errormsg = NULL;
     366           0 :         if (state->errormsg_deferred)
     367             :         {
     368           0 :             if (state->errormsg_buf[0] != '\0')
     369           0 :                 *errormsg = state->errormsg_buf;
     370           0 :             state->errormsg_deferred = false;
     371             :         }
     372             : 
     373             :         /*
     374             :          * state->EndRecPtr is expected to have been set by the last call to
     375             :          * XLogBeginRead() or XLogNextRecord(), and is the location of the
     376             :          * error.
     377             :          */
     378             :         Assert(!XLogRecPtrIsInvalid(state->EndRecPtr));
     379             : 
     380           0 :         return NULL;
     381             :     }
     382             : 
     383             :     /*
     384             :      * Record this as the most recent record returned, so that we'll release
     385             :      * it next time.  This also exposes it to the traditional
     386             :      * XLogRecXXX(xlogreader) macros, which work with the decoder rather than
     387             :      * the record for historical reasons.
     388             :      */
     389      178378 :     state->record = state->decode_queue_head;
     390             : 
     391             :     /*
     392             :      * Update the pointers to the beginning and one-past-the-end of this
     393             :      * record, again for the benefit of historical code that expected the
     394             :      * decoder to track this rather than accessing these fields of the record
     395             :      * itself.
     396             :      */
     397      178378 :     state->ReadRecPtr = state->record->lsn;
     398      178378 :     state->EndRecPtr = state->record->next_lsn;
     399             : 
     400      178378 :     *errormsg = NULL;
     401             : 
     402      178378 :     return state->record;
     403             : }
     404             : 
     405             : /*
     406             :  * Attempt to read an XLOG record.
     407             :  *
     408             :  * XLogBeginRead() or XLogFindNextRecord() must be called before the first call
     409             :  * to XLogReadRecord().
     410             :  *
     411             :  * If the page_read callback fails to read the requested data, NULL is
     412             :  * returned.  The callback is expected to have reported the error; errormsg
     413             :  * is set to NULL.
     414             :  *
     415             :  * If the reading fails for some other reason, NULL is also returned, and
     416             :  * *errormsg is set to a string with details of the failure.
     417             :  *
     418             :  * The returned pointer (or *errormsg) points to an internal buffer that's
     419             :  * valid until the next call to XLogReadRecord.
     420             :  */
     421             : XLogRecord *
     422      178378 : XLogReadRecord(XLogReaderState *state, char **errormsg)
     423             : {
     424             :     DecodedXLogRecord *decoded;
     425             : 
     426             :     /*
     427             :      * Release last returned record, if there is one.  We need to do this so
     428             :      * that we can check for empty decode queue accurately.
     429             :      */
     430      178378 :     XLogReleasePreviousRecord(state);
     431             : 
     432             :     /*
     433             :      * Call XLogReadAhead() in blocking mode to make sure there is something
     434             :      * in the queue, though we don't use the result.
     435             :      */
     436      178378 :     if (!XLogReaderHasQueuedRecordOrError(state))
     437      178378 :         XLogReadAhead(state, false /* nonblocking */ );
     438             : 
     439             :     /* Consume the head record or error. */
     440      178378 :     decoded = XLogNextRecord(state, errormsg);
     441      178378 :     if (decoded)
     442             :     {
     443             :         /*
     444             :          * This function returns a pointer to the record's header, not the
     445             :          * actual decoded record.  The caller will access the decoded record
     446             :          * through the XLogRecGetXXX() macros, which reach the decoded
     447             :          * recorded as xlogreader->record.
     448             :          */
     449             :         Assert(state->record == decoded);
     450      178378 :         return &decoded->header;
     451             :     }
     452             : 
     453           0 :     return NULL;
     454             : }
     455             : 
     456             : /*
     457             :  * Allocate space for a decoded record.  The only member of the returned
     458             :  * object that is initialized is the 'oversized' flag, indicating that the
     459             :  * decoded record wouldn't fit in the decode buffer and must eventually be
     460             :  * freed explicitly.
     461             :  *
     462             :  * The caller is responsible for adjusting decode_buffer_tail with the real
     463             :  * size after successfully decoding a record into this space.  This way, if
     464             :  * decoding fails, then there is nothing to undo unless the 'oversized' flag
     465             :  * was set and pfree() must be called.
     466             :  *
     467             :  * Return NULL if there is no space in the decode buffer and allow_oversized
     468             :  * is false, or if memory allocation fails for an oversized buffer.
     469             :  */
     470             : static DecodedXLogRecord *
     471      178378 : XLogReadRecordAlloc(XLogReaderState *state, size_t xl_tot_len, bool allow_oversized)
     472             : {
     473      178378 :     size_t      required_space = DecodeXLogRecordRequiredSpace(xl_tot_len);
     474      178378 :     DecodedXLogRecord *decoded = NULL;
     475             : 
     476             :     /* Allocate a circular decode buffer if we don't have one already. */
     477      178378 :     if (unlikely(state->decode_buffer == NULL))
     478             :     {
     479          78 :         if (state->decode_buffer_size == 0)
     480          78 :             state->decode_buffer_size = DEFAULT_DECODE_BUFFER_SIZE;
     481          78 :         state->decode_buffer = palloc(state->decode_buffer_size);
     482          78 :         state->decode_buffer_head = state->decode_buffer;
     483          78 :         state->decode_buffer_tail = state->decode_buffer;
     484          78 :         state->free_decode_buffer = true;
     485             :     }
     486             : 
     487             :     /* Try to allocate space in the circular decode buffer. */
     488      178378 :     if (state->decode_buffer_tail >= state->decode_buffer_head)
     489             :     {
     490             :         /* Empty, or tail is to the right of head. */
     491      178378 :         if (state->decode_buffer_tail + required_space <=
     492      178378 :             state->decode_buffer + state->decode_buffer_size)
     493             :         {
     494             :             /* There is space between tail and end. */
     495      178378 :             decoded = (DecodedXLogRecord *) state->decode_buffer_tail;
     496      178378 :             decoded->oversized = false;
     497      178378 :             return decoded;
     498             :         }
     499           0 :         else if (state->decode_buffer + required_space <
     500           0 :                  state->decode_buffer_head)
     501             :         {
     502             :             /* There is space between start and head. */
     503           0 :             decoded = (DecodedXLogRecord *) state->decode_buffer;
     504           0 :             decoded->oversized = false;
     505           0 :             return decoded;
     506             :         }
     507             :     }
     508             :     else
     509             :     {
     510             :         /* Tail is to the left of head. */
     511           0 :         if (state->decode_buffer_tail + required_space <
     512           0 :             state->decode_buffer_head)
     513             :         {
     514             :             /* There is space between tail and head. */
     515           0 :             decoded = (DecodedXLogRecord *) state->decode_buffer_tail;
     516           0 :             decoded->oversized = false;
     517           0 :             return decoded;
     518             :         }
     519             :     }
     520             : 
     521             :     /* Not enough space in the decode buffer.  Are we allowed to allocate? */
     522           0 :     if (allow_oversized)
     523             :     {
     524           0 :         decoded = palloc_extended(required_space, MCXT_ALLOC_NO_OOM);
     525           0 :         if (decoded == NULL)
     526           0 :             return NULL;
     527           0 :         decoded->oversized = true;
     528           0 :         return decoded;
     529             :     }
     530             : 
     531           0 :     return NULL;
     532             : }
     533             : 
     534             : static XLogPageReadResult
     535      178378 : XLogDecodeNextRecord(XLogReaderState *state, bool nonblocking)
     536             : {
     537             :     XLogRecPtr  RecPtr;
     538             :     XLogRecord *record;
     539             :     XLogRecPtr  targetPagePtr;
     540             :     bool        randAccess;
     541             :     uint32      len,
     542             :                 total_len;
     543             :     uint32      targetRecOff;
     544             :     uint32      pageHeaderSize;
     545             :     bool        assembled;
     546             :     bool        gotheader;
     547             :     int         readOff;
     548             :     DecodedXLogRecord *decoded;
     549             :     char       *errormsg;       /* not used */
     550             : 
     551             :     /*
     552             :      * randAccess indicates whether to verify the previous-record pointer of
     553             :      * the record we're reading.  We only do this if we're reading
     554             :      * sequentially, which is what we initially assume.
     555             :      */
     556      178378 :     randAccess = false;
     557             : 
     558             :     /* reset error state */
     559      178378 :     state->errormsg_buf[0] = '\0';
     560      178378 :     decoded = NULL;
     561             : 
     562      178378 :     state->abortedRecPtr = InvalidXLogRecPtr;
     563      178378 :     state->missingContrecPtr = InvalidXLogRecPtr;
     564             : 
     565      178378 :     RecPtr = state->NextRecPtr;
     566             : 
     567      178378 :     if (state->DecodeRecPtr != InvalidXLogRecPtr)
     568             :     {
     569             :         /* read the record after the one we just read */
     570             : 
     571             :         /*
     572             :          * NextRecPtr is pointing to end+1 of the previous WAL record.  If
     573             :          * we're at a page boundary, no more records can fit on the current
     574             :          * page. We must skip over the page header, but we can't do that until
     575             :          * we've read in the page, since the header size is variable.
     576             :          */
     577             :     }
     578             :     else
     579             :     {
     580             :         /*
     581             :          * Caller supplied a position to start at.
     582             :          *
     583             :          * In this case, NextRecPtr should already be pointing either to a
     584             :          * valid record starting position or alternatively to the beginning of
     585             :          * a page. See the header comments for XLogBeginRead.
     586             :          */
     587             :         Assert(RecPtr % XLOG_BLCKSZ == 0 || XRecOffIsValid(RecPtr));
     588        5156 :         randAccess = true;
     589             :     }
     590             : 
     591      178378 : restart:
     592      178378 :     state->nonblocking = nonblocking;
     593      178378 :     state->currRecPtr = RecPtr;
     594      178378 :     assembled = false;
     595             : 
     596      178378 :     targetPagePtr = RecPtr - (RecPtr % XLOG_BLCKSZ);
     597      178378 :     targetRecOff = RecPtr % XLOG_BLCKSZ;
     598             : 
     599             :     /*
     600             :      * Read the page containing the record into state->readBuf. Request enough
     601             :      * byte to cover the whole record header, or at least the part of it that
     602             :      * fits on the same page.
     603             :      */
     604      178378 :     readOff = ReadPageInternal(state, targetPagePtr,
     605      178378 :                                Min(targetRecOff + SizeOfXLogRecord, XLOG_BLCKSZ));
     606      178378 :     if (readOff == XLREAD_WOULDBLOCK)
     607           0 :         return XLREAD_WOULDBLOCK;
     608      178378 :     else if (readOff < 0)
     609           0 :         goto err;
     610             : 
     611             :     /*
     612             :      * ReadPageInternal always returns at least the page header, so we can
     613             :      * examine it now.
     614             :      */
     615      178378 :     pageHeaderSize = XLogPageHeaderSize((XLogPageHeader) state->readBuf);
     616      178378 :     if (targetRecOff == 0)
     617             :     {
     618             :         /*
     619             :          * At page start, so skip over page header.
     620             :          */
     621         172 :         RecPtr += pageHeaderSize;
     622         172 :         targetRecOff = pageHeaderSize;
     623             :     }
     624      178206 :     else if (targetRecOff < pageHeaderSize)
     625             :     {
     626           0 :         report_invalid_record(state, "invalid record offset at %X/%X: expected at least %u, got %u",
     627           0 :                               LSN_FORMAT_ARGS(RecPtr),
     628             :                               pageHeaderSize, targetRecOff);
     629           0 :         goto err;
     630             :     }
     631             : 
     632      178378 :     if ((((XLogPageHeader) state->readBuf)->xlp_info & XLP_FIRST_IS_CONTRECORD) &&
     633             :         targetRecOff == pageHeaderSize)
     634             :     {
     635           0 :         report_invalid_record(state, "contrecord is requested by %X/%X",
     636           0 :                               LSN_FORMAT_ARGS(RecPtr));
     637           0 :         goto err;
     638             :     }
     639             : 
     640             :     /* ReadPageInternal has verified the page header */
     641             :     Assert(pageHeaderSize <= readOff);
     642             : 
     643             :     /*
     644             :      * Read the record length.
     645             :      *
     646             :      * NB: Even though we use an XLogRecord pointer here, the whole record
     647             :      * header might not fit on this page. xl_tot_len is the first field of the
     648             :      * struct, so it must be on this page (the records are MAXALIGNed), but we
     649             :      * cannot access any other fields until we've verified that we got the
     650             :      * whole header.
     651             :      */
     652      178378 :     record = (XLogRecord *) (state->readBuf + RecPtr % XLOG_BLCKSZ);
     653      178378 :     total_len = record->xl_tot_len;
     654             : 
     655             :     /*
     656             :      * If the whole record header is on this page, validate it immediately.
     657             :      * Otherwise do just a basic sanity check on xl_tot_len, and validate the
     658             :      * rest of the header after reading it from the next page.  The xl_tot_len
     659             :      * check is necessary here to ensure that we enter the "Need to reassemble
     660             :      * record" code path below; otherwise we might fail to apply
     661             :      * ValidXLogRecordHeader at all.
     662             :      */
     663      178378 :     if (targetRecOff <= XLOG_BLCKSZ - SizeOfXLogRecord)
     664             :     {
     665      178050 :         if (!ValidXLogRecordHeader(state, RecPtr, state->DecodeRecPtr, record,
     666             :                                    randAccess))
     667           0 :             goto err;
     668      178050 :         gotheader = true;
     669             :     }
     670             :     else
     671             :     {
     672             :         /* XXX: more validation should be done here */
     673         328 :         if (total_len < SizeOfXLogRecord)
     674             :         {
     675           0 :             report_invalid_record(state,
     676             :                                   "invalid record length at %X/%X: expected at least %u, got %u",
     677           0 :                                   LSN_FORMAT_ARGS(RecPtr),
     678             :                                   (uint32) SizeOfXLogRecord, total_len);
     679           0 :             goto err;
     680             :         }
     681         328 :         gotheader = false;
     682             :     }
     683             : 
     684             :     /*
     685             :      * Find space to decode this record.  Don't allow oversized allocation if
     686             :      * the caller requested nonblocking.  Otherwise, we *have* to try to
     687             :      * decode the record now because the caller has nothing else to do, so
     688             :      * allow an oversized record to be palloc'd if that turns out to be
     689             :      * necessary.
     690             :      */
     691      178378 :     decoded = XLogReadRecordAlloc(state,
     692             :                                   total_len,
     693      178378 :                                   !nonblocking /* allow_oversized */ );
     694      178378 :     if (decoded == NULL)
     695             :     {
     696             :         /*
     697             :          * There is no space in the decode buffer.  The caller should help
     698             :          * with that problem by consuming some records.
     699             :          */
     700           0 :         if (nonblocking)
     701           0 :             return XLREAD_WOULDBLOCK;
     702             : 
     703             :         /* We failed to allocate memory for an oversized record. */
     704           0 :         report_invalid_record(state,
     705             :                               "out of memory while trying to decode a record of length %u", total_len);
     706           0 :         goto err;
     707             :     }
     708             : 
     709      178378 :     len = XLOG_BLCKSZ - RecPtr % XLOG_BLCKSZ;
     710      178378 :     if (total_len > len)
     711             :     {
     712             :         /* Need to reassemble record */
     713             :         char       *contdata;
     714             :         XLogPageHeader pageHeader;
     715             :         char       *buffer;
     716             :         uint32      gotlen;
     717             : 
     718        8528 :         assembled = true;
     719             : 
     720             :         /*
     721             :          * Enlarge readRecordBuf as needed.
     722             :          */
     723        8528 :         if (total_len > state->readRecordBufSize &&
     724           0 :             !allocate_recordbuf(state, total_len))
     725             :         {
     726             :             /* We treat this as a "bogus data" condition */
     727           0 :             report_invalid_record(state, "record length %u at %X/%X too long",
     728           0 :                                   total_len, LSN_FORMAT_ARGS(RecPtr));
     729           0 :             goto err;
     730             :         }
     731             : 
     732             :         /* Copy the first fragment of the record from the first page. */
     733        8528 :         memcpy(state->readRecordBuf,
     734        8528 :                state->readBuf + RecPtr % XLOG_BLCKSZ, len);
     735        8528 :         buffer = state->readRecordBuf + len;
     736        8528 :         gotlen = len;
     737             : 
     738             :         do
     739             :         {
     740             :             /* Calculate pointer to beginning of next page */
     741        8536 :             targetPagePtr += XLOG_BLCKSZ;
     742             : 
     743             :             /* Wait for the next page to become available */
     744        8536 :             readOff = ReadPageInternal(state, targetPagePtr,
     745        8536 :                                        Min(total_len - gotlen + SizeOfXLogShortPHD,
     746             :                                            XLOG_BLCKSZ));
     747             : 
     748        8536 :             if (readOff == XLREAD_WOULDBLOCK)
     749           0 :                 return XLREAD_WOULDBLOCK;
     750        8536 :             else if (readOff < 0)
     751           0 :                 goto err;
     752             : 
     753             :             Assert(SizeOfXLogShortPHD <= readOff);
     754             : 
     755        8536 :             pageHeader = (XLogPageHeader) state->readBuf;
     756             : 
     757             :             /*
     758             :              * If we were expecting a continuation record and got an
     759             :              * "overwrite contrecord" flag, that means the continuation record
     760             :              * was overwritten with a different record.  Restart the read by
     761             :              * assuming the address to read is the location where we found
     762             :              * this flag; but keep track of the LSN of the record we were
     763             :              * reading, for later verification.
     764             :              */
     765        8536 :             if (pageHeader->xlp_info & XLP_FIRST_IS_OVERWRITE_CONTRECORD)
     766             :             {
     767           0 :                 state->overwrittenRecPtr = RecPtr;
     768           0 :                 RecPtr = targetPagePtr;
     769           0 :                 goto restart;
     770             :             }
     771             : 
     772             :             /* Check that the continuation on next page looks valid */
     773        8536 :             if (!(pageHeader->xlp_info & XLP_FIRST_IS_CONTRECORD))
     774             :             {
     775           0 :                 report_invalid_record(state,
     776             :                                       "there is no contrecord flag at %X/%X",
     777           0 :                                       LSN_FORMAT_ARGS(RecPtr));
     778           0 :                 goto err;
     779             :             }
     780             : 
     781             :             /*
     782             :              * Cross-check that xlp_rem_len agrees with how much of the record
     783             :              * we expect there to be left.
     784             :              */
     785        8536 :             if (pageHeader->xlp_rem_len == 0 ||
     786        8536 :                 total_len != (pageHeader->xlp_rem_len + gotlen))
     787             :             {
     788           0 :                 report_invalid_record(state,
     789             :                                       "invalid contrecord length %u (expected %lld) at %X/%X",
     790             :                                       pageHeader->xlp_rem_len,
     791           0 :                                       ((long long) total_len) - gotlen,
     792           0 :                                       LSN_FORMAT_ARGS(RecPtr));
     793           0 :                 goto err;
     794             :             }
     795             : 
     796             :             /* Append the continuation from this page to the buffer */
     797        8536 :             pageHeaderSize = XLogPageHeaderSize(pageHeader);
     798             : 
     799        8536 :             if (readOff < pageHeaderSize)
     800           0 :                 readOff = ReadPageInternal(state, targetPagePtr,
     801             :                                            pageHeaderSize);
     802             : 
     803             :             Assert(pageHeaderSize <= readOff);
     804             : 
     805        8536 :             contdata = (char *) state->readBuf + pageHeaderSize;
     806        8536 :             len = XLOG_BLCKSZ - pageHeaderSize;
     807        8536 :             if (pageHeader->xlp_rem_len < len)
     808        8528 :                 len = pageHeader->xlp_rem_len;
     809             : 
     810        8536 :             if (readOff < pageHeaderSize + len)
     811           0 :                 readOff = ReadPageInternal(state, targetPagePtr,
     812           0 :                                            pageHeaderSize + len);
     813             : 
     814        8536 :             memcpy(buffer, (char *) contdata, len);
     815        8536 :             buffer += len;
     816        8536 :             gotlen += len;
     817             : 
     818             :             /* If we just reassembled the record header, validate it. */
     819        8536 :             if (!gotheader)
     820             :             {
     821         328 :                 record = (XLogRecord *) state->readRecordBuf;
     822         328 :                 if (!ValidXLogRecordHeader(state, RecPtr, state->DecodeRecPtr,
     823             :                                            record, randAccess))
     824           0 :                     goto err;
     825         328 :                 gotheader = true;
     826             :             }
     827        8536 :         } while (gotlen < total_len);
     828             : 
     829             :         Assert(gotheader);
     830             : 
     831        8528 :         record = (XLogRecord *) state->readRecordBuf;
     832        8528 :         if (!ValidXLogRecord(state, record, RecPtr))
     833           0 :             goto err;
     834             : 
     835        8528 :         pageHeaderSize = XLogPageHeaderSize((XLogPageHeader) state->readBuf);
     836        8528 :         state->DecodeRecPtr = RecPtr;
     837        8528 :         state->NextRecPtr = targetPagePtr + pageHeaderSize
     838        8528 :             + MAXALIGN(pageHeader->xlp_rem_len);
     839             :     }
     840             :     else
     841             :     {
     842             :         /* Wait for the record data to become available */
     843      169850 :         readOff = ReadPageInternal(state, targetPagePtr,
     844      169850 :                                    Min(targetRecOff + total_len, XLOG_BLCKSZ));
     845      169850 :         if (readOff == XLREAD_WOULDBLOCK)
     846           0 :             return XLREAD_WOULDBLOCK;
     847      169850 :         else if (readOff < 0)
     848           0 :             goto err;
     849             : 
     850             :         /* Record does not cross a page boundary */
     851      169850 :         if (!ValidXLogRecord(state, record, RecPtr))
     852           0 :             goto err;
     853             : 
     854      169850 :         state->NextRecPtr = RecPtr + MAXALIGN(total_len);
     855             : 
     856      169850 :         state->DecodeRecPtr = RecPtr;
     857             :     }
     858             : 
     859             :     /*
     860             :      * Special processing if it's an XLOG SWITCH record
     861             :      */
     862      178378 :     if (record->xl_rmid == RM_XLOG_ID &&
     863       11952 :         (record->xl_info & ~XLR_INFO_MASK) == XLOG_SWITCH)
     864             :     {
     865             :         /* Pretend it extends to end of segment */
     866          16 :         state->NextRecPtr += state->segcxt.ws_segsize - 1;
     867          16 :         state->NextRecPtr -= XLogSegmentOffset(state->NextRecPtr, state->segcxt.ws_segsize);
     868             :     }
     869             : 
     870      178378 :     if (DecodeXLogRecord(state, decoded, record, RecPtr, &errormsg))
     871             :     {
     872             :         /* Record the location of the next record. */
     873      178378 :         decoded->next_lsn = state->NextRecPtr;
     874             : 
     875             :         /*
     876             :          * If it's in the decode buffer, mark the decode buffer space as
     877             :          * occupied.
     878             :          */
     879      178378 :         if (!decoded->oversized)
     880             :         {
     881             :             /* The new decode buffer head must be MAXALIGNed. */
     882             :             Assert(decoded->size == MAXALIGN(decoded->size));
     883      178378 :             if ((char *) decoded == state->decode_buffer)
     884      178378 :                 state->decode_buffer_tail = state->decode_buffer + decoded->size;
     885             :             else
     886           0 :                 state->decode_buffer_tail += decoded->size;
     887             :         }
     888             : 
     889             :         /* Insert it into the queue of decoded records. */
     890             :         Assert(state->decode_queue_tail != decoded);
     891      178378 :         if (state->decode_queue_tail)
     892           0 :             state->decode_queue_tail->next = decoded;
     893      178378 :         state->decode_queue_tail = decoded;
     894      178378 :         if (!state->decode_queue_head)
     895      178378 :             state->decode_queue_head = decoded;
     896      178378 :         return XLREAD_SUCCESS;
     897             :     }
     898             :     else
     899           0 :         return XLREAD_FAIL;
     900             : 
     901           0 : err:
     902           0 :     if (assembled)
     903             :     {
     904             :         /*
     905             :          * We get here when a record that spans multiple pages needs to be
     906             :          * assembled, but something went wrong -- perhaps a contrecord piece
     907             :          * was lost.  If caller is WAL replay, it will know where the aborted
     908             :          * record was and where to direct followup WAL to be written, marking
     909             :          * the next piece with XLP_FIRST_IS_OVERWRITE_CONTRECORD, which will
     910             :          * in turn signal downstream WAL consumers that the broken WAL record
     911             :          * is to be ignored.
     912             :          */
     913           0 :         state->abortedRecPtr = RecPtr;
     914           0 :         state->missingContrecPtr = targetPagePtr;
     915             : 
     916             :         /*
     917             :          * If we got here without reporting an error, report one now so that
     918             :          * XLogPrefetcherReadRecord() doesn't bring us back a second time and
     919             :          * clobber the above state.  Otherwise, the existing error takes
     920             :          * precedence.
     921             :          */
     922           0 :         if (!state->errormsg_buf[0])
     923           0 :             report_invalid_record(state,
     924             :                                   "missing contrecord at %X/%X",
     925           0 :                                   LSN_FORMAT_ARGS(RecPtr));
     926             :     }
     927             : 
     928           0 :     if (decoded && decoded->oversized)
     929           0 :         pfree(decoded);
     930             : 
     931             :     /*
     932             :      * Invalidate the read state. We might read from a different source after
     933             :      * failure.
     934             :      */
     935           0 :     XLogReaderInvalReadState(state);
     936             : 
     937             :     /*
     938             :      * If an error was written to errmsg_buf, it'll be returned to the caller
     939             :      * of XLogReadRecord() after all successfully decoded records from the
     940             :      * read queue.
     941             :      */
     942             : 
     943           0 :     return XLREAD_FAIL;
     944             : }
     945             : 
     946             : /*
     947             :  * Try to decode the next available record, and return it.  The record will
     948             :  * also be returned to XLogNextRecord(), which must be called to 'consume'
     949             :  * each record.
     950             :  *
     951             :  * If nonblocking is true, may return NULL due to lack of data or WAL decoding
     952             :  * space.
     953             :  */
     954             : DecodedXLogRecord *
     955      178378 : XLogReadAhead(XLogReaderState *state, bool nonblocking)
     956             : {
     957             :     XLogPageReadResult result;
     958             : 
     959      178378 :     if (state->errormsg_deferred)
     960           0 :         return NULL;
     961             : 
     962      178378 :     result = XLogDecodeNextRecord(state, nonblocking);
     963      178378 :     if (result == XLREAD_SUCCESS)
     964             :     {
     965             :         Assert(state->decode_queue_tail != NULL);
     966      178378 :         return state->decode_queue_tail;
     967             :     }
     968             : 
     969           0 :     return NULL;
     970             : }
     971             : 
     972             : /*
     973             :  * Read a single xlog page including at least [pageptr, reqLen] of valid data
     974             :  * via the page_read() callback.
     975             :  *
     976             :  * Returns XLREAD_FAIL if the required page cannot be read for some
     977             :  * reason; errormsg_buf is set in that case (unless the error occurs in the
     978             :  * page_read callback).
     979             :  *
     980             :  * Returns XLREAD_WOULDBLOCK if the requested data can't be read without
     981             :  * waiting.  This can be returned only if the installed page_read callback
     982             :  * respects the state->nonblocking flag, and cannot read the requested data
     983             :  * immediately.
     984             :  *
     985             :  * We fetch the page from a reader-local cache if we know we have the required
     986             :  * data and if there hasn't been any error since caching the data.
     987             :  */
     988             : static int
     989      356764 : ReadPageInternal(XLogReaderState *state, XLogRecPtr pageptr, int reqLen)
     990             : {
     991             :     int         readLen;
     992             :     uint32      targetPageOff;
     993             :     XLogSegNo   targetSegNo;
     994             :     XLogPageHeader hdr;
     995             : 
     996             :     Assert((pageptr % XLOG_BLCKSZ) == 0);
     997             : 
     998      356764 :     XLByteToSeg(pageptr, targetSegNo, state->segcxt.ws_segsize);
     999      356764 :     targetPageOff = XLogSegmentOffset(pageptr, state->segcxt.ws_segsize);
    1000             : 
    1001             :     /* check whether we have all the requested data already */
    1002      356764 :     if (targetSegNo == state->seg.ws_segno &&
    1003      356670 :         targetPageOff == state->segoff && reqLen <= state->readLen)
    1004      345450 :         return state->readLen;
    1005             : 
    1006             :     /*
    1007             :      * Invalidate contents of internal buffer before read attempt.  Just set
    1008             :      * the length to 0, rather than a full XLogReaderInvalReadState(), so we
    1009             :      * don't forget the segment we last successfully read.
    1010             :      */
    1011       11314 :     state->readLen = 0;
    1012             : 
    1013             :     /*
    1014             :      * Data is not in our buffer.
    1015             :      *
    1016             :      * Every time we actually read the segment, even if we looked at parts of
    1017             :      * it before, we need to do verification as the page_read callback might
    1018             :      * now be rereading data from a different source.
    1019             :      *
    1020             :      * Whenever switching to a new WAL segment, we read the first page of the
    1021             :      * file and validate its header, even if that's not where the target
    1022             :      * record is.  This is so that we can check the additional identification
    1023             :      * info that is present in the first page's "long" header.
    1024             :      */
    1025       11314 :     if (targetSegNo != state->seg.ws_segno && targetPageOff != 0)
    1026             :     {
    1027          36 :         XLogRecPtr  targetSegmentPtr = pageptr - targetPageOff;
    1028             : 
    1029          36 :         readLen = state->routine.page_read(state, targetSegmentPtr, XLOG_BLCKSZ,
    1030             :                                            state->currRecPtr,
    1031             :                                            state->readBuf);
    1032          36 :         if (readLen == XLREAD_WOULDBLOCK)
    1033           0 :             return XLREAD_WOULDBLOCK;
    1034          36 :         else if (readLen < 0)
    1035           0 :             goto err;
    1036             : 
    1037             :         /* we can be sure to have enough WAL available, we scrolled back */
    1038             :         Assert(readLen == XLOG_BLCKSZ);
    1039             : 
    1040          36 :         if (!XLogReaderValidatePageHeader(state, targetSegmentPtr,
    1041             :                                           state->readBuf))
    1042           0 :             goto err;
    1043             :     }
    1044             : 
    1045             :     /*
    1046             :      * First, read the requested data length, but at least a short page header
    1047             :      * so that we can validate it.
    1048             :      */
    1049       11314 :     readLen = state->routine.page_read(state, pageptr, Max(reqLen, SizeOfXLogShortPHD),
    1050             :                                        state->currRecPtr,
    1051             :                                        state->readBuf);
    1052       11314 :     if (readLen == XLREAD_WOULDBLOCK)
    1053           0 :         return XLREAD_WOULDBLOCK;
    1054       11314 :     else if (readLen < 0)
    1055           0 :         goto err;
    1056             : 
    1057             :     Assert(readLen <= XLOG_BLCKSZ);
    1058             : 
    1059             :     /* Do we have enough data to check the header length? */
    1060       11314 :     if (readLen <= SizeOfXLogShortPHD)
    1061           0 :         goto err;
    1062             : 
    1063             :     Assert(readLen >= reqLen);
    1064             : 
    1065       11314 :     hdr = (XLogPageHeader) state->readBuf;
    1066             : 
    1067             :     /* still not enough */
    1068       11314 :     if (readLen < XLogPageHeaderSize(hdr))
    1069             :     {
    1070           0 :         readLen = state->routine.page_read(state, pageptr, XLogPageHeaderSize(hdr),
    1071             :                                            state->currRecPtr,
    1072             :                                            state->readBuf);
    1073           0 :         if (readLen == XLREAD_WOULDBLOCK)
    1074           0 :             return XLREAD_WOULDBLOCK;
    1075           0 :         else if (readLen < 0)
    1076           0 :             goto err;
    1077             :     }
    1078             : 
    1079             :     /*
    1080             :      * Now that we know we have the full header, validate it.
    1081             :      */
    1082       11314 :     if (!XLogReaderValidatePageHeader(state, pageptr, (char *) hdr))
    1083           0 :         goto err;
    1084             : 
    1085             :     /* update read state information */
    1086       11314 :     state->seg.ws_segno = targetSegNo;
    1087       11314 :     state->segoff = targetPageOff;
    1088       11314 :     state->readLen = readLen;
    1089             : 
    1090       11314 :     return readLen;
    1091             : 
    1092           0 : err:
    1093           0 :     XLogReaderInvalReadState(state);
    1094             : 
    1095           0 :     return XLREAD_FAIL;
    1096             : }
    1097             : 
    1098             : /*
    1099             :  * Invalidate the xlogreader's read state to force a re-read.
    1100             :  */
    1101             : static void
    1102           0 : XLogReaderInvalReadState(XLogReaderState *state)
    1103             : {
    1104           0 :     state->seg.ws_segno = 0;
    1105           0 :     state->segoff = 0;
    1106           0 :     state->readLen = 0;
    1107           0 : }
    1108             : 
    1109             : /*
    1110             :  * Validate an XLOG record header.
    1111             :  *
    1112             :  * This is just a convenience subroutine to avoid duplicated code in
    1113             :  * XLogReadRecord.  It's not intended for use from anywhere else.
    1114             :  */
    1115             : static bool
    1116      178378 : ValidXLogRecordHeader(XLogReaderState *state, XLogRecPtr RecPtr,
    1117             :                       XLogRecPtr PrevRecPtr, XLogRecord *record,
    1118             :                       bool randAccess)
    1119             : {
    1120      178378 :     if (record->xl_tot_len < SizeOfXLogRecord)
    1121             :     {
    1122           0 :         report_invalid_record(state,
    1123             :                               "invalid record length at %X/%X: expected at least %u, got %u",
    1124           0 :                               LSN_FORMAT_ARGS(RecPtr),
    1125             :                               (uint32) SizeOfXLogRecord, record->xl_tot_len);
    1126           0 :         return false;
    1127             :     }
    1128      178378 :     if (!RmgrIdIsValid(record->xl_rmid))
    1129             :     {
    1130           0 :         report_invalid_record(state,
    1131             :                               "invalid resource manager ID %u at %X/%X",
    1132           0 :                               record->xl_rmid, LSN_FORMAT_ARGS(RecPtr));
    1133           0 :         return false;
    1134             :     }
    1135      178378 :     if (randAccess)
    1136             :     {
    1137             :         /*
    1138             :          * We can't exactly verify the prev-link, but surely it should be less
    1139             :          * than the record's own address.
    1140             :          */
    1141        5156 :         if (!(record->xl_prev < RecPtr))
    1142             :         {
    1143           0 :             report_invalid_record(state,
    1144             :                                   "record with incorrect prev-link %X/%X at %X/%X",
    1145           0 :                                   LSN_FORMAT_ARGS(record->xl_prev),
    1146           0 :                                   LSN_FORMAT_ARGS(RecPtr));
    1147           0 :             return false;
    1148             :         }
    1149             :     }
    1150             :     else
    1151             :     {
    1152             :         /*
    1153             :          * Record's prev-link should exactly match our previous location. This
    1154             :          * check guards against torn WAL pages where a stale but valid-looking
    1155             :          * WAL record starts on a sector boundary.
    1156             :          */
    1157      173222 :         if (record->xl_prev != PrevRecPtr)
    1158             :         {
    1159           0 :             report_invalid_record(state,
    1160             :                                   "record with incorrect prev-link %X/%X at %X/%X",
    1161           0 :                                   LSN_FORMAT_ARGS(record->xl_prev),
    1162           0 :                                   LSN_FORMAT_ARGS(RecPtr));
    1163           0 :             return false;
    1164             :         }
    1165             :     }
    1166             : 
    1167      178378 :     return true;
    1168             : }
    1169             : 
    1170             : 
    1171             : /*
    1172             :  * CRC-check an XLOG record.  We do not believe the contents of an XLOG
    1173             :  * record (other than to the minimal extent of computing the amount of
    1174             :  * data to read in) until we've checked the CRCs.
    1175             :  *
    1176             :  * We assume all of the record (that is, xl_tot_len bytes) has been read
    1177             :  * into memory at *record.  Also, ValidXLogRecordHeader() has accepted the
    1178             :  * record's header, which means in particular that xl_tot_len is at least
    1179             :  * SizeOfXLogRecord.
    1180             :  */
    1181             : static bool
    1182      178378 : ValidXLogRecord(XLogReaderState *state, XLogRecord *record, XLogRecPtr recptr)
    1183             : {
    1184             :     pg_crc32c   crc;
    1185             : 
    1186             :     /* Calculate the CRC */
    1187      178378 :     INIT_CRC32C(crc);
    1188      178378 :     COMP_CRC32C(crc, ((char *) record) + SizeOfXLogRecord, record->xl_tot_len - SizeOfXLogRecord);
    1189             :     /* include the record header last */
    1190      178378 :     COMP_CRC32C(crc, (char *) record, offsetof(XLogRecord, xl_crc));
    1191      178378 :     FIN_CRC32C(crc);
    1192             : 
    1193      178378 :     if (!EQ_CRC32C(record->xl_crc, crc))
    1194             :     {
    1195           0 :         report_invalid_record(state,
    1196             :                               "incorrect resource manager data checksum in record at %X/%X",
    1197           0 :                               LSN_FORMAT_ARGS(recptr));
    1198           0 :         return false;
    1199             :     }
    1200             : 
    1201      178378 :     return true;
    1202             : }
    1203             : 
    1204             : /*
    1205             :  * Validate a page header.
    1206             :  *
    1207             :  * Check if 'phdr' is valid as the header of the XLog page at position
    1208             :  * 'recptr'.
    1209             :  */
    1210             : bool
    1211       11350 : XLogReaderValidatePageHeader(XLogReaderState *state, XLogRecPtr recptr,
    1212             :                              char *phdr)
    1213             : {
    1214             :     XLogSegNo   segno;
    1215             :     int32       offset;
    1216       11350 :     XLogPageHeader hdr = (XLogPageHeader) phdr;
    1217             : 
    1218             :     Assert((recptr % XLOG_BLCKSZ) == 0);
    1219             : 
    1220       11350 :     XLByteToSeg(recptr, segno, state->segcxt.ws_segsize);
    1221       11350 :     offset = XLogSegmentOffset(recptr, state->segcxt.ws_segsize);
    1222             : 
    1223       11350 :     if (hdr->xlp_magic != XLOG_PAGE_MAGIC)
    1224             :     {
    1225             :         char        fname[MAXFNAMELEN];
    1226             : 
    1227           0 :         XLogFileName(fname, state->seg.ws_tli, segno, state->segcxt.ws_segsize);
    1228             : 
    1229           0 :         report_invalid_record(state,
    1230             :                               "invalid magic number %04X in WAL segment %s, LSN %X/%X, offset %u",
    1231           0 :                               hdr->xlp_magic,
    1232             :                               fname,
    1233           0 :                               LSN_FORMAT_ARGS(recptr),
    1234             :                               offset);
    1235           0 :         return false;
    1236             :     }
    1237             : 
    1238       11350 :     if ((hdr->xlp_info & ~XLP_ALL_FLAGS) != 0)
    1239             :     {
    1240             :         char        fname[MAXFNAMELEN];
    1241             : 
    1242           0 :         XLogFileName(fname, state->seg.ws_tli, segno, state->segcxt.ws_segsize);
    1243             : 
    1244           0 :         report_invalid_record(state,
    1245             :                               "invalid info bits %04X in WAL segment %s, LSN %X/%X, offset %u",
    1246           0 :                               hdr->xlp_info,
    1247             :                               fname,
    1248           0 :                               LSN_FORMAT_ARGS(recptr),
    1249             :                               offset);
    1250           0 :         return false;
    1251             :     }
    1252             : 
    1253       11350 :     if (hdr->xlp_info & XLP_LONG_HEADER)
    1254             :     {
    1255         106 :         XLogLongPageHeader longhdr = (XLogLongPageHeader) hdr;
    1256             : 
    1257         106 :         if (state->system_identifier &&
    1258           0 :             longhdr->xlp_sysid != state->system_identifier)
    1259             :         {
    1260           0 :             report_invalid_record(state,
    1261             :                                   "WAL file is from different database system: WAL file database system identifier is %llu, pg_control database system identifier is %llu",
    1262           0 :                                   (unsigned long long) longhdr->xlp_sysid,
    1263           0 :                                   (unsigned long long) state->system_identifier);
    1264           0 :             return false;
    1265             :         }
    1266         106 :         else if (longhdr->xlp_seg_size != state->segcxt.ws_segsize)
    1267             :         {
    1268           0 :             report_invalid_record(state,
    1269             :                                   "WAL file is from different database system: incorrect segment size in page header");
    1270           0 :             return false;
    1271             :         }
    1272         106 :         else if (longhdr->xlp_xlog_blcksz != XLOG_BLCKSZ)
    1273             :         {
    1274           0 :             report_invalid_record(state,
    1275             :                                   "WAL file is from different database system: incorrect XLOG_BLCKSZ in page header");
    1276           0 :             return false;
    1277             :         }
    1278             :     }
    1279       11244 :     else if (offset == 0)
    1280             :     {
    1281             :         char        fname[MAXFNAMELEN];
    1282             : 
    1283           0 :         XLogFileName(fname, state->seg.ws_tli, segno, state->segcxt.ws_segsize);
    1284             : 
    1285             :         /* hmm, first page of file doesn't have a long header? */
    1286           0 :         report_invalid_record(state,
    1287             :                               "invalid info bits %04X in WAL segment %s, LSN %X/%X, offset %u",
    1288           0 :                               hdr->xlp_info,
    1289             :                               fname,
    1290           0 :                               LSN_FORMAT_ARGS(recptr),
    1291             :                               offset);
    1292           0 :         return false;
    1293             :     }
    1294             : 
    1295             :     /*
    1296             :      * Check that the address on the page agrees with what we expected. This
    1297             :      * check typically fails when an old WAL segment is recycled, and hasn't
    1298             :      * yet been overwritten with new data yet.
    1299             :      */
    1300       11350 :     if (hdr->xlp_pageaddr != recptr)
    1301             :     {
    1302             :         char        fname[MAXFNAMELEN];
    1303             : 
    1304           0 :         XLogFileName(fname, state->seg.ws_tli, segno, state->segcxt.ws_segsize);
    1305             : 
    1306           0 :         report_invalid_record(state,
    1307             :                               "unexpected pageaddr %X/%X in WAL segment %s, LSN %X/%X, offset %u",
    1308           0 :                               LSN_FORMAT_ARGS(hdr->xlp_pageaddr),
    1309             :                               fname,
    1310           0 :                               LSN_FORMAT_ARGS(recptr),
    1311             :                               offset);
    1312           0 :         return false;
    1313             :     }
    1314             : 
    1315             :     /*
    1316             :      * Since child timelines are always assigned a TLI greater than their
    1317             :      * immediate parent's TLI, we should never see TLI go backwards across
    1318             :      * successive pages of a consistent WAL sequence.
    1319             :      *
    1320             :      * Sometimes we re-read a segment that's already been (partially) read. So
    1321             :      * we only verify TLIs for pages that are later than the last remembered
    1322             :      * LSN.
    1323             :      */
    1324       11350 :     if (recptr > state->latestPagePtr)
    1325             :     {
    1326        8822 :         if (hdr->xlp_tli < state->latestPageTLI)
    1327             :         {
    1328             :             char        fname[MAXFNAMELEN];
    1329             : 
    1330           0 :             XLogFileName(fname, state->seg.ws_tli, segno, state->segcxt.ws_segsize);
    1331             : 
    1332           0 :             report_invalid_record(state,
    1333             :                                   "out-of-sequence timeline ID %u (after %u) in WAL segment %s, LSN %X/%X, offset %u",
    1334             :                                   hdr->xlp_tli,
    1335             :                                   state->latestPageTLI,
    1336             :                                   fname,
    1337           0 :                                   LSN_FORMAT_ARGS(recptr),
    1338             :                                   offset);
    1339           0 :             return false;
    1340             :         }
    1341             :     }
    1342       11350 :     state->latestPagePtr = recptr;
    1343       11350 :     state->latestPageTLI = hdr->xlp_tli;
    1344             : 
    1345       11350 :     return true;
    1346             : }
    1347             : 
    1348             : /*
    1349             :  * Forget about an error produced by XLogReaderValidatePageHeader().
    1350             :  */
    1351             : void
    1352           0 : XLogReaderResetError(XLogReaderState *state)
    1353             : {
    1354           0 :     state->errormsg_buf[0] = '\0';
    1355           0 :     state->errormsg_deferred = false;
    1356           0 : }
    1357             : 
    1358             : /*
    1359             :  * Find the first record with an lsn >= RecPtr.
    1360             :  *
    1361             :  * This is different from XLogBeginRead() in that RecPtr doesn't need to point
    1362             :  * to a valid record boundary.  Useful for checking whether RecPtr is a valid
    1363             :  * xlog address for reading, and to find the first valid address after some
    1364             :  * address when dumping records for debugging purposes.
    1365             :  *
    1366             :  * This positions the reader, like XLogBeginRead(), so that the next call to
    1367             :  * XLogReadRecord() will read the next valid record.
    1368             :  */
    1369             : XLogRecPtr
    1370           0 : XLogFindNextRecord(XLogReaderState *state, XLogRecPtr RecPtr)
    1371             : {
    1372             :     XLogRecPtr  tmpRecPtr;
    1373           0 :     XLogRecPtr  found = InvalidXLogRecPtr;
    1374             :     XLogPageHeader header;
    1375             :     char       *errormsg;
    1376             : 
    1377             :     Assert(!XLogRecPtrIsInvalid(RecPtr));
    1378             : 
    1379             :     /* Make sure ReadPageInternal() can't return XLREAD_WOULDBLOCK. */
    1380           0 :     state->nonblocking = false;
    1381             : 
    1382             :     /*
    1383             :      * skip over potential continuation data, keeping in mind that it may span
    1384             :      * multiple pages
    1385             :      */
    1386           0 :     tmpRecPtr = RecPtr;
    1387             :     while (true)
    1388           0 :     {
    1389             :         XLogRecPtr  targetPagePtr;
    1390             :         int         targetRecOff;
    1391             :         uint32      pageHeaderSize;
    1392             :         int         readLen;
    1393             : 
    1394             :         /*
    1395             :          * Compute targetRecOff. It should typically be equal or greater than
    1396             :          * short page-header since a valid record can't start anywhere before
    1397             :          * that, except when caller has explicitly specified the offset that
    1398             :          * falls somewhere there or when we are skipping multi-page
    1399             :          * continuation record. It doesn't matter though because
    1400             :          * ReadPageInternal() is prepared to handle that and will read at
    1401             :          * least short page-header worth of data
    1402             :          */
    1403           0 :         targetRecOff = tmpRecPtr % XLOG_BLCKSZ;
    1404             : 
    1405             :         /* scroll back to page boundary */
    1406           0 :         targetPagePtr = tmpRecPtr - targetRecOff;
    1407             : 
    1408             :         /* Read the page containing the record */
    1409           0 :         readLen = ReadPageInternal(state, targetPagePtr, targetRecOff);
    1410           0 :         if (readLen < 0)
    1411           0 :             goto err;
    1412             : 
    1413           0 :         header = (XLogPageHeader) state->readBuf;
    1414             : 
    1415           0 :         pageHeaderSize = XLogPageHeaderSize(header);
    1416             : 
    1417             :         /* make sure we have enough data for the page header */
    1418           0 :         readLen = ReadPageInternal(state, targetPagePtr, pageHeaderSize);
    1419           0 :         if (readLen < 0)
    1420           0 :             goto err;
    1421             : 
    1422             :         /* skip over potential continuation data */
    1423           0 :         if (header->xlp_info & XLP_FIRST_IS_CONTRECORD)
    1424             :         {
    1425             :             /*
    1426             :              * If the length of the remaining continuation data is more than
    1427             :              * what can fit in this page, the continuation record crosses over
    1428             :              * this page. Read the next page and try again. xlp_rem_len in the
    1429             :              * next page header will contain the remaining length of the
    1430             :              * continuation data
    1431             :              *
    1432             :              * Note that record headers are MAXALIGN'ed
    1433             :              */
    1434           0 :             if (MAXALIGN(header->xlp_rem_len) >= (XLOG_BLCKSZ - pageHeaderSize))
    1435           0 :                 tmpRecPtr = targetPagePtr + XLOG_BLCKSZ;
    1436             :             else
    1437             :             {
    1438             :                 /*
    1439             :                  * The previous continuation record ends in this page. Set
    1440             :                  * tmpRecPtr to point to the first valid record
    1441             :                  */
    1442           0 :                 tmpRecPtr = targetPagePtr + pageHeaderSize
    1443           0 :                     + MAXALIGN(header->xlp_rem_len);
    1444           0 :                 break;
    1445             :             }
    1446             :         }
    1447             :         else
    1448             :         {
    1449           0 :             tmpRecPtr = targetPagePtr + pageHeaderSize;
    1450           0 :             break;
    1451             :         }
    1452             :     }
    1453             : 
    1454             :     /*
    1455             :      * we know now that tmpRecPtr is an address pointing to a valid XLogRecord
    1456             :      * because either we're at the first record after the beginning of a page
    1457             :      * or we just jumped over the remaining data of a continuation.
    1458             :      */
    1459           0 :     XLogBeginRead(state, tmpRecPtr);
    1460           0 :     while (XLogReadRecord(state, &errormsg) != NULL)
    1461             :     {
    1462             :         /* past the record we've found, break out */
    1463           0 :         if (RecPtr <= state->ReadRecPtr)
    1464             :         {
    1465             :             /* Rewind the reader to the beginning of the last record. */
    1466           0 :             found = state->ReadRecPtr;
    1467           0 :             XLogBeginRead(state, found);
    1468           0 :             return found;
    1469             :         }
    1470             :     }
    1471             : 
    1472           0 : err:
    1473           0 :     XLogReaderInvalReadState(state);
    1474             : 
    1475           0 :     return InvalidXLogRecPtr;
    1476             : }
    1477             : 
    1478             : /*
    1479             :  * Helper function to ease writing of XLogReaderRoutine->page_read callbacks.
    1480             :  * If this function is used, caller must supply a segment_open callback in
    1481             :  * 'state', as that is used here.
    1482             :  *
    1483             :  * Read 'count' bytes into 'buf', starting at location 'startptr', from WAL
    1484             :  * fetched from timeline 'tli'.
    1485             :  *
    1486             :  * Returns true if succeeded, false if an error occurs, in which case
    1487             :  * 'errinfo' receives error details.
    1488             :  *
    1489             :  * XXX probably this should be improved to suck data directly from the
    1490             :  * WAL buffers when possible.
    1491             :  */
    1492             : bool
    1493           0 : WALRead(XLogReaderState *state,
    1494             :         char *buf, XLogRecPtr startptr, Size count, TimeLineID tli,
    1495             :         WALReadError *errinfo)
    1496             : {
    1497             :     char       *p;
    1498             :     XLogRecPtr  recptr;
    1499             :     Size        nbytes;
    1500             : 
    1501           0 :     p = buf;
    1502           0 :     recptr = startptr;
    1503           0 :     nbytes = count;
    1504             : 
    1505           0 :     while (nbytes > 0)
    1506             :     {
    1507             :         uint32      startoff;
    1508             :         int         segbytes;
    1509             :         int         readbytes;
    1510             : 
    1511           0 :         startoff = XLogSegmentOffset(recptr, state->segcxt.ws_segsize);
    1512             : 
    1513             :         /*
    1514             :          * If the data we want is not in a segment we have open, close what we
    1515             :          * have (if anything) and open the next one, using the caller's
    1516             :          * provided segment_open callback.
    1517             :          */
    1518           0 :         if (state->seg.ws_file < 0 ||
    1519           0 :             !XLByteInSeg(recptr, state->seg.ws_segno, state->segcxt.ws_segsize) ||
    1520           0 :             tli != state->seg.ws_tli)
    1521             :         {
    1522             :             XLogSegNo   nextSegNo;
    1523             : 
    1524           0 :             if (state->seg.ws_file >= 0)
    1525           0 :                 state->routine.segment_close(state);
    1526             : 
    1527           0 :             XLByteToSeg(recptr, nextSegNo, state->segcxt.ws_segsize);
    1528           0 :             state->routine.segment_open(state, nextSegNo, &tli);
    1529             : 
    1530             :             /* This shouldn't happen -- indicates a bug in segment_open */
    1531             :             Assert(state->seg.ws_file >= 0);
    1532             : 
    1533             :             /* Update the current segment info. */
    1534           0 :             state->seg.ws_tli = tli;
    1535           0 :             state->seg.ws_segno = nextSegNo;
    1536             :         }
    1537             : 
    1538             :         /* How many bytes are within this segment? */
    1539           0 :         if (nbytes > (state->segcxt.ws_segsize - startoff))
    1540           0 :             segbytes = state->segcxt.ws_segsize - startoff;
    1541             :         else
    1542           0 :             segbytes = nbytes;
    1543             : 
    1544             : #ifndef FRONTEND
    1545             :         pgstat_report_wait_start(WAIT_EVENT_WAL_READ);
    1546             : #endif
    1547             : 
    1548             :         /* Reset errno first; eases reporting non-errno-affecting errors */
    1549           0 :         errno = 0;
    1550           0 :         readbytes = pg_pread(state->seg.ws_file, p, segbytes, (off_t) startoff);
    1551             : 
    1552             : #ifndef FRONTEND
    1553             :         pgstat_report_wait_end();
    1554             : #endif
    1555             : 
    1556           0 :         if (readbytes <= 0)
    1557             :         {
    1558           0 :             errinfo->wre_errno = errno;
    1559           0 :             errinfo->wre_req = segbytes;
    1560           0 :             errinfo->wre_read = readbytes;
    1561           0 :             errinfo->wre_off = startoff;
    1562           0 :             errinfo->wre_seg = state->seg;
    1563           0 :             return false;
    1564             :         }
    1565             : 
    1566             :         /* Update state for read */
    1567           0 :         recptr += readbytes;
    1568           0 :         nbytes -= readbytes;
    1569           0 :         p += readbytes;
    1570             :     }
    1571             : 
    1572           0 :     return true;
    1573             : }
    1574             : 
    1575             : /* ----------------------------------------
    1576             :  * Functions for decoding the data and block references in a record.
    1577             :  * ----------------------------------------
    1578             :  */
    1579             : 
    1580             : /*
    1581             :  * Private function to reset the state, forgetting all decoded records, if we
    1582             :  * are asked to move to a new read position.
    1583             :  */
    1584             : static void
    1585        5156 : ResetDecoder(XLogReaderState *state)
    1586             : {
    1587             :     DecodedXLogRecord *r;
    1588             : 
    1589             :     /* Reset the decoded record queue, freeing any oversized records. */
    1590       10234 :     while ((r = state->decode_queue_head) != NULL)
    1591             :     {
    1592        5078 :         state->decode_queue_head = r->next;
    1593        5078 :         if (r->oversized)
    1594           0 :             pfree(r);
    1595             :     }
    1596        5156 :     state->decode_queue_tail = NULL;
    1597        5156 :     state->decode_queue_head = NULL;
    1598        5156 :     state->record = NULL;
    1599             : 
    1600             :     /* Reset the decode buffer to empty. */
    1601        5156 :     state->decode_buffer_tail = state->decode_buffer;
    1602        5156 :     state->decode_buffer_head = state->decode_buffer;
    1603             : 
    1604             :     /* Clear error state. */
    1605        5156 :     state->errormsg_buf[0] = '\0';
    1606        5156 :     state->errormsg_deferred = false;
    1607        5156 : }
    1608             : 
    1609             : /*
    1610             :  * Compute the maximum possible amount of padding that could be required to
    1611             :  * decode a record, given xl_tot_len from the record's header.  This is the
    1612             :  * amount of output buffer space that we need to decode a record, though we
    1613             :  * might not finish up using it all.
    1614             :  *
    1615             :  * This computation is pessimistic and assumes the maximum possible number of
    1616             :  * blocks, due to lack of better information.
    1617             :  */
    1618             : size_t
    1619      178378 : DecodeXLogRecordRequiredSpace(size_t xl_tot_len)
    1620             : {
    1621      178378 :     size_t      size = 0;
    1622             : 
    1623             :     /* Account for the fixed size part of the decoded record struct. */
    1624      178378 :     size += offsetof(DecodedXLogRecord, blocks[0]);
    1625             :     /* Account for the flexible blocks array of maximum possible size. */
    1626      178378 :     size += sizeof(DecodedBkpBlock) * (XLR_MAX_BLOCK_ID + 1);
    1627             :     /* Account for all the raw main and block data. */
    1628      178378 :     size += xl_tot_len;
    1629             :     /* We might insert padding before main_data. */
    1630      178378 :     size += (MAXIMUM_ALIGNOF - 1);
    1631             :     /* We might insert padding before each block's data. */
    1632      178378 :     size += (MAXIMUM_ALIGNOF - 1) * (XLR_MAX_BLOCK_ID + 1);
    1633             :     /* We might insert padding at the end. */
    1634      178378 :     size += (MAXIMUM_ALIGNOF - 1);
    1635             : 
    1636      178378 :     return size;
    1637             : }
    1638             : 
    1639             : /*
    1640             :  * Decode a record.  "decoded" must point to a MAXALIGNed memory area that has
    1641             :  * space for at least DecodeXLogRecordRequiredSpace(record) bytes.  On
    1642             :  * success, decoded->size contains the actual space occupied by the decoded
    1643             :  * record, which may turn out to be less.
    1644             :  *
    1645             :  * Only decoded->oversized member must be initialized already, and will not be
    1646             :  * modified.  Other members will be initialized as required.
    1647             :  *
    1648             :  * On error, a human-readable error message is returned in *errormsg, and
    1649             :  * the return value is false.
    1650             :  */
    1651             : bool
    1652      178378 : DecodeXLogRecord(XLogReaderState *state,
    1653             :                  DecodedXLogRecord *decoded,
    1654             :                  XLogRecord *record,
    1655             :                  XLogRecPtr lsn,
    1656             :                  char **errormsg)
    1657             : {
    1658             :     /*
    1659             :      * read next _size bytes from record buffer, but check for overrun first.
    1660             :      */
    1661             : #define COPY_HEADER_FIELD(_dst, _size)          \
    1662             :     do {                                        \
    1663             :         if (remaining < _size)                   \
    1664             :             goto shortdata_err;                 \
    1665             :         memcpy(_dst, ptr, _size);               \
    1666             :         ptr += _size;                           \
    1667             :         remaining -= _size;                     \
    1668             :     } while(0)
    1669             : 
    1670             :     char       *ptr;
    1671             :     char       *out;
    1672             :     uint32      remaining;
    1673             :     uint32      datatotal;
    1674      178378 :     RelFileLocator *rlocator = NULL;
    1675             :     uint8       block_id;
    1676             : 
    1677      178378 :     decoded->header = *record;
    1678      178378 :     decoded->lsn = lsn;
    1679      178378 :     decoded->next = NULL;
    1680      178378 :     decoded->record_origin = InvalidRepOriginId;
    1681      178378 :     decoded->toplevel_xid = InvalidTransactionId;
    1682      178378 :     decoded->main_data = NULL;
    1683      178378 :     decoded->main_data_len = 0;
    1684      178378 :     decoded->max_block_id = -1;
    1685      178378 :     ptr = (char *) record;
    1686      178378 :     ptr += SizeOfXLogRecord;
    1687      178378 :     remaining = record->xl_tot_len - SizeOfXLogRecord;
    1688             : 
    1689             :     /* Decode the headers */
    1690      178378 :     datatotal = 0;
    1691      353534 :     while (remaining > datatotal)
    1692             :     {
    1693      341728 :         COPY_HEADER_FIELD(&block_id, sizeof(uint8));
    1694             : 
    1695      341728 :         if (block_id == XLR_BLOCK_ID_DATA_SHORT)
    1696             :         {
    1697             :             /* XLogRecordDataHeaderShort */
    1698             :             uint8       main_data_len;
    1699             : 
    1700      166540 :             COPY_HEADER_FIELD(&main_data_len, sizeof(uint8));
    1701             : 
    1702      166540 :             decoded->main_data_len = main_data_len;
    1703      166540 :             datatotal += main_data_len;
    1704      166540 :             break;              /* by convention, the main data fragment is
    1705             :                                  * always last */
    1706             :         }
    1707      175188 :         else if (block_id == XLR_BLOCK_ID_DATA_LONG)
    1708             :         {
    1709             :             /* XLogRecordDataHeaderLong */
    1710             :             uint32      main_data_len;
    1711             : 
    1712          32 :             COPY_HEADER_FIELD(&main_data_len, sizeof(uint32));
    1713          32 :             decoded->main_data_len = main_data_len;
    1714          32 :             datatotal += main_data_len;
    1715          32 :             break;              /* by convention, the main data fragment is
    1716             :                                  * always last */
    1717             :         }
    1718      175156 :         else if (block_id == XLR_BLOCK_ID_ORIGIN)
    1719             :         {
    1720           0 :             COPY_HEADER_FIELD(&decoded->record_origin, sizeof(RepOriginId));
    1721             :         }
    1722      175156 :         else if (block_id == XLR_BLOCK_ID_TOPLEVEL_XID)
    1723             :         {
    1724           0 :             COPY_HEADER_FIELD(&decoded->toplevel_xid, sizeof(TransactionId));
    1725             :         }
    1726      175156 :         else if (block_id <= XLR_MAX_BLOCK_ID)
    1727             :         {
    1728             :             /* XLogRecordBlockHeader */
    1729             :             DecodedBkpBlock *blk;
    1730             :             uint8       fork_flags;
    1731             : 
    1732             :             /* mark any intervening block IDs as not in use */
    1733      175156 :             for (int i = decoded->max_block_id + 1; i < block_id; ++i)
    1734           0 :                 decoded->blocks[i].in_use = false;
    1735             : 
    1736      175156 :             if (block_id <= decoded->max_block_id)
    1737             :             {
    1738           0 :                 report_invalid_record(state,
    1739             :                                       "out-of-order block_id %u at %X/%X",
    1740             :                                       block_id,
    1741           0 :                                       LSN_FORMAT_ARGS(state->ReadRecPtr));
    1742           0 :                 goto err;
    1743             :             }
    1744      175156 :             decoded->max_block_id = block_id;
    1745             : 
    1746      175156 :             blk = &decoded->blocks[block_id];
    1747      175156 :             blk->in_use = true;
    1748      175156 :             blk->apply_image = false;
    1749             : 
    1750      175156 :             COPY_HEADER_FIELD(&fork_flags, sizeof(uint8));
    1751      175156 :             blk->forknum = fork_flags & BKPBLOCK_FORK_MASK;
    1752      175156 :             blk->flags = fork_flags;
    1753      175156 :             blk->has_image = ((fork_flags & BKPBLOCK_HAS_IMAGE) != 0);
    1754      175156 :             blk->has_data = ((fork_flags & BKPBLOCK_HAS_DATA) != 0);
    1755             : 
    1756      175156 :             blk->prefetch_buffer = InvalidBuffer;
    1757             : 
    1758      175156 :             COPY_HEADER_FIELD(&blk->data_len, sizeof(uint16));
    1759             :             /* cross-check that the HAS_DATA flag is set iff data_length > 0 */
    1760      175156 :             if (blk->has_data && blk->data_len == 0)
    1761             :             {
    1762           0 :                 report_invalid_record(state,
    1763             :                                       "BKPBLOCK_HAS_DATA set, but no data included at %X/%X",
    1764           0 :                                       LSN_FORMAT_ARGS(state->ReadRecPtr));
    1765           0 :                 goto err;
    1766             :             }
    1767      175156 :             if (!blk->has_data && blk->data_len != 0)
    1768             :             {
    1769           0 :                 report_invalid_record(state,
    1770             :                                       "BKPBLOCK_HAS_DATA not set, but data length is %u at %X/%X",
    1771           0 :                                       (unsigned int) blk->data_len,
    1772           0 :                                       LSN_FORMAT_ARGS(state->ReadRecPtr));
    1773           0 :                 goto err;
    1774             :             }
    1775      175156 :             datatotal += blk->data_len;
    1776             : 
    1777      175156 :             if (blk->has_image)
    1778             :             {
    1779       11888 :                 COPY_HEADER_FIELD(&blk->bimg_len, sizeof(uint16));
    1780       11888 :                 COPY_HEADER_FIELD(&blk->hole_offset, sizeof(uint16));
    1781       11888 :                 COPY_HEADER_FIELD(&blk->bimg_info, sizeof(uint8));
    1782             : 
    1783       11888 :                 blk->apply_image = ((blk->bimg_info & BKPIMAGE_APPLY) != 0);
    1784             : 
    1785       11888 :                 if (BKPIMAGE_COMPRESSED(blk->bimg_info))
    1786             :                 {
    1787           0 :                     if (blk->bimg_info & BKPIMAGE_HAS_HOLE)
    1788           0 :                         COPY_HEADER_FIELD(&blk->hole_length, sizeof(uint16));
    1789             :                     else
    1790           0 :                         blk->hole_length = 0;
    1791             :                 }
    1792             :                 else
    1793       11888 :                     blk->hole_length = BLCKSZ - blk->bimg_len;
    1794       11888 :                 datatotal += blk->bimg_len;
    1795             : 
    1796             :                 /*
    1797             :                  * cross-check that hole_offset > 0, hole_length > 0 and
    1798             :                  * bimg_len < BLCKSZ if the HAS_HOLE flag is set.
    1799             :                  */
    1800       11888 :                 if ((blk->bimg_info & BKPIMAGE_HAS_HOLE) &&
    1801       11816 :                     (blk->hole_offset == 0 ||
    1802       11816 :                      blk->hole_length == 0 ||
    1803       11816 :                      blk->bimg_len == BLCKSZ))
    1804             :                 {
    1805           0 :                     report_invalid_record(state,
    1806             :                                           "BKPIMAGE_HAS_HOLE set, but hole offset %u length %u block image length %u at %X/%X",
    1807           0 :                                           (unsigned int) blk->hole_offset,
    1808           0 :                                           (unsigned int) blk->hole_length,
    1809           0 :                                           (unsigned int) blk->bimg_len,
    1810           0 :                                           LSN_FORMAT_ARGS(state->ReadRecPtr));
    1811           0 :                     goto err;
    1812             :                 }
    1813             : 
    1814             :                 /*
    1815             :                  * cross-check that hole_offset == 0 and hole_length == 0 if
    1816             :                  * the HAS_HOLE flag is not set.
    1817             :                  */
    1818       11888 :                 if (!(blk->bimg_info & BKPIMAGE_HAS_HOLE) &&
    1819          72 :                     (blk->hole_offset != 0 || blk->hole_length != 0))
    1820             :                 {
    1821           0 :                     report_invalid_record(state,
    1822             :                                           "BKPIMAGE_HAS_HOLE not set, but hole offset %u length %u at %X/%X",
    1823           0 :                                           (unsigned int) blk->hole_offset,
    1824           0 :                                           (unsigned int) blk->hole_length,
    1825           0 :                                           LSN_FORMAT_ARGS(state->ReadRecPtr));
    1826           0 :                     goto err;
    1827             :                 }
    1828             : 
    1829             :                 /*
    1830             :                  * Cross-check that bimg_len < BLCKSZ if it is compressed.
    1831             :                  */
    1832       11888 :                 if (BKPIMAGE_COMPRESSED(blk->bimg_info) &&
    1833           0 :                     blk->bimg_len == BLCKSZ)
    1834             :                 {
    1835           0 :                     report_invalid_record(state,
    1836             :                                           "BKPIMAGE_COMPRESSED set, but block image length %u at %X/%X",
    1837           0 :                                           (unsigned int) blk->bimg_len,
    1838           0 :                                           LSN_FORMAT_ARGS(state->ReadRecPtr));
    1839           0 :                     goto err;
    1840             :                 }
    1841             : 
    1842             :                 /*
    1843             :                  * cross-check that bimg_len = BLCKSZ if neither HAS_HOLE is
    1844             :                  * set nor COMPRESSED().
    1845             :                  */
    1846       11888 :                 if (!(blk->bimg_info & BKPIMAGE_HAS_HOLE) &&
    1847          72 :                     !BKPIMAGE_COMPRESSED(blk->bimg_info) &&
    1848          72 :                     blk->bimg_len != BLCKSZ)
    1849             :                 {
    1850           0 :                     report_invalid_record(state,
    1851             :                                           "neither BKPIMAGE_HAS_HOLE nor BKPIMAGE_COMPRESSED set, but block image length is %u at %X/%X",
    1852           0 :                                           (unsigned int) blk->data_len,
    1853           0 :                                           LSN_FORMAT_ARGS(state->ReadRecPtr));
    1854           0 :                     goto err;
    1855             :                 }
    1856             :             }
    1857      175156 :             if (!(fork_flags & BKPBLOCK_SAME_REL))
    1858             :             {
    1859      174484 :                 COPY_HEADER_FIELD(&blk->rlocator, sizeof(RelFileLocator));
    1860      174484 :                 rlocator = &blk->rlocator;
    1861             :             }
    1862             :             else
    1863             :             {
    1864         672 :                 if (rlocator == NULL)
    1865             :                 {
    1866           0 :                     report_invalid_record(state,
    1867             :                                           "BKPBLOCK_SAME_REL set but no previous rel at %X/%X",
    1868           0 :                                           LSN_FORMAT_ARGS(state->ReadRecPtr));
    1869           0 :                     goto err;
    1870             :                 }
    1871             : 
    1872         672 :                 blk->rlocator = *rlocator;
    1873             :             }
    1874      175156 :             COPY_HEADER_FIELD(&blk->blkno, sizeof(BlockNumber));
    1875             :         }
    1876             :         else
    1877             :         {
    1878           0 :             report_invalid_record(state,
    1879             :                                   "invalid block_id %u at %X/%X",
    1880           0 :                                   block_id, LSN_FORMAT_ARGS(state->ReadRecPtr));
    1881           0 :             goto err;
    1882             :         }
    1883             :     }
    1884             : 
    1885      178378 :     if (remaining != datatotal)
    1886           0 :         goto shortdata_err;
    1887             : 
    1888             :     /*
    1889             :      * Ok, we've parsed the fragment headers, and verified that the total
    1890             :      * length of the payload in the fragments is equal to the amount of data
    1891             :      * left.  Copy the data of each fragment to contiguous space after the
    1892             :      * blocks array, inserting alignment padding before the data fragments so
    1893             :      * they can be cast to struct pointers by REDO routines.
    1894             :      */
    1895      178378 :     out = ((char *) decoded) +
    1896      178378 :         offsetof(DecodedXLogRecord, blocks) +
    1897      178378 :         sizeof(decoded->blocks[0]) * (decoded->max_block_id + 1);
    1898             : 
    1899             :     /* block data first */
    1900      353534 :     for (block_id = 0; block_id <= decoded->max_block_id; block_id++)
    1901             :     {
    1902      175156 :         DecodedBkpBlock *blk = &decoded->blocks[block_id];
    1903             : 
    1904      175156 :         if (!blk->in_use)
    1905           0 :             continue;
    1906             : 
    1907             :         Assert(blk->has_image || !blk->apply_image);
    1908             : 
    1909      175156 :         if (blk->has_image)
    1910             :         {
    1911             :             /* no need to align image */
    1912       11888 :             blk->bkp_image = out;
    1913       11888 :             memcpy(out, ptr, blk->bimg_len);
    1914       11888 :             ptr += blk->bimg_len;
    1915       11888 :             out += blk->bimg_len;
    1916             :         }
    1917      175156 :         if (blk->has_data)
    1918             :         {
    1919       81780 :             out = (char *) MAXALIGN(out);
    1920       81780 :             blk->data = out;
    1921       81780 :             memcpy(blk->data, ptr, blk->data_len);
    1922       81780 :             ptr += blk->data_len;
    1923       81780 :             out += blk->data_len;
    1924             :         }
    1925             :     }
    1926             : 
    1927             :     /* and finally, the main data */
    1928      178378 :     if (decoded->main_data_len > 0)
    1929             :     {
    1930      166572 :         out = (char *) MAXALIGN(out);
    1931      166572 :         decoded->main_data = out;
    1932      166572 :         memcpy(decoded->main_data, ptr, decoded->main_data_len);
    1933      166572 :         ptr += decoded->main_data_len;
    1934      166572 :         out += decoded->main_data_len;
    1935             :     }
    1936             : 
    1937             :     /* Report the actual size we used. */
    1938      178378 :     decoded->size = MAXALIGN(out - (char *) decoded);
    1939             :     Assert(DecodeXLogRecordRequiredSpace(record->xl_tot_len) >=
    1940             :            decoded->size);
    1941             : 
    1942      178378 :     return true;
    1943             : 
    1944           0 : shortdata_err:
    1945           0 :     report_invalid_record(state,
    1946             :                           "record with invalid length at %X/%X",
    1947           0 :                           LSN_FORMAT_ARGS(state->ReadRecPtr));
    1948           0 : err:
    1949           0 :     *errormsg = state->errormsg_buf;
    1950             : 
    1951           0 :     return false;
    1952             : }
    1953             : 
    1954             : /*
    1955             :  * Returns information about the block that a block reference refers to.
    1956             :  *
    1957             :  * This is like XLogRecGetBlockTagExtended, except that the block reference
    1958             :  * must exist and there's no access to prefetch_buffer.
    1959             :  */
    1960             : void
    1961           0 : XLogRecGetBlockTag(XLogReaderState *record, uint8 block_id,
    1962             :                    RelFileLocator *rlocator, ForkNumber *forknum,
    1963             :                    BlockNumber *blknum)
    1964             : {
    1965           0 :     if (!XLogRecGetBlockTagExtended(record, block_id, rlocator, forknum,
    1966             :                                     blknum, NULL))
    1967             :     {
    1968             : #ifndef FRONTEND
    1969             :         elog(ERROR, "could not locate backup block with ID %d in WAL record",
    1970             :              block_id);
    1971             : #else
    1972           0 :         pg_fatal("could not locate backup block with ID %d in WAL record",
    1973             :                  block_id);
    1974             : #endif
    1975             :     }
    1976           0 : }
    1977             : 
    1978             : /*
    1979             :  * Returns information about the block that a block reference refers to,
    1980             :  * optionally including the buffer that the block may already be in.
    1981             :  *
    1982             :  * If the WAL record contains a block reference with the given ID, *rlocator,
    1983             :  * *forknum, *blknum and *prefetch_buffer are filled in (if not NULL), and
    1984             :  * returns true.  Otherwise returns false.
    1985             :  */
    1986             : bool
    1987      171308 : XLogRecGetBlockTagExtended(XLogReaderState *record, uint8 block_id,
    1988             :                            RelFileLocator *rlocator, ForkNumber *forknum,
    1989             :                            BlockNumber *blknum,
    1990             :                            Buffer *prefetch_buffer)
    1991             : {
    1992             :     DecodedBkpBlock *bkpb;
    1993             : 
    1994      171308 :     if (!XLogRecHasBlockRef(record, block_id))
    1995           0 :         return false;
    1996             : 
    1997      171308 :     bkpb = &record->record->blocks[block_id];
    1998      171308 :     if (rlocator)
    1999      171308 :         *rlocator = bkpb->rlocator;
    2000      171308 :     if (forknum)
    2001      171308 :         *forknum = bkpb->forknum;
    2002      171308 :     if (blknum)
    2003      171308 :         *blknum = bkpb->blkno;
    2004      171308 :     if (prefetch_buffer)
    2005           0 :         *prefetch_buffer = bkpb->prefetch_buffer;
    2006      171308 :     return true;
    2007             : }
    2008             : 
    2009             : /*
    2010             :  * Returns the data associated with a block reference, or NULL if there is
    2011             :  * no data (e.g. because a full-page image was taken instead). The returned
    2012             :  * pointer points to a MAXALIGNed buffer.
    2013             :  */
    2014             : char *
    2015           0 : XLogRecGetBlockData(XLogReaderState *record, uint8 block_id, Size *len)
    2016             : {
    2017             :     DecodedBkpBlock *bkpb;
    2018             : 
    2019           0 :     if (block_id > record->record->max_block_id ||
    2020           0 :         !record->record->blocks[block_id].in_use)
    2021           0 :         return NULL;
    2022             : 
    2023           0 :     bkpb = &record->record->blocks[block_id];
    2024             : 
    2025           0 :     if (!bkpb->has_data)
    2026             :     {
    2027           0 :         if (len)
    2028           0 :             *len = 0;
    2029           0 :         return NULL;
    2030             :     }
    2031             :     else
    2032             :     {
    2033           0 :         if (len)
    2034           0 :             *len = bkpb->data_len;
    2035           0 :         return bkpb->data;
    2036             :     }
    2037             : }
    2038             : 
    2039             : /*
    2040             :  * Restore a full-page image from a backup block attached to an XLOG record.
    2041             :  *
    2042             :  * Returns true if a full-page image is restored, and false on failure with
    2043             :  * an error to be consumed by the caller.
    2044             :  */
    2045             : bool
    2046           0 : RestoreBlockImage(XLogReaderState *record, uint8 block_id, char *page)
    2047             : {
    2048             :     DecodedBkpBlock *bkpb;
    2049             :     char       *ptr;
    2050             :     PGAlignedBlock tmp;
    2051             : 
    2052           0 :     if (block_id > record->record->max_block_id ||
    2053           0 :         !record->record->blocks[block_id].in_use)
    2054             :     {
    2055           0 :         report_invalid_record(record,
    2056             :                               "could not restore image at %X/%X with invalid block %d specified",
    2057           0 :                               LSN_FORMAT_ARGS(record->ReadRecPtr),
    2058             :                               block_id);
    2059           0 :         return false;
    2060             :     }
    2061           0 :     if (!record->record->blocks[block_id].has_image)
    2062             :     {
    2063           0 :         report_invalid_record(record, "could not restore image at %X/%X with invalid state, block %d",
    2064           0 :                               LSN_FORMAT_ARGS(record->ReadRecPtr),
    2065             :                               block_id);
    2066           0 :         return false;
    2067             :     }
    2068             : 
    2069           0 :     bkpb = &record->record->blocks[block_id];
    2070           0 :     ptr = bkpb->bkp_image;
    2071             : 
    2072           0 :     if (BKPIMAGE_COMPRESSED(bkpb->bimg_info))
    2073             :     {
    2074             :         /* If a backup block image is compressed, decompress it */
    2075           0 :         bool        decomp_success = true;
    2076             : 
    2077           0 :         if ((bkpb->bimg_info & BKPIMAGE_COMPRESS_PGLZ) != 0)
    2078             :         {
    2079           0 :             if (pglz_decompress(ptr, bkpb->bimg_len, tmp.data,
    2080           0 :                                 BLCKSZ - bkpb->hole_length, true) < 0)
    2081           0 :                 decomp_success = false;
    2082             :         }
    2083           0 :         else if ((bkpb->bimg_info & BKPIMAGE_COMPRESS_LZ4) != 0)
    2084             :         {
    2085             : #ifdef USE_LZ4
    2086           0 :             if (LZ4_decompress_safe(ptr, tmp.data,
    2087           0 :                                     bkpb->bimg_len, BLCKSZ - bkpb->hole_length) <= 0)
    2088           0 :                 decomp_success = false;
    2089             : #else
    2090             :             report_invalid_record(record, "could not restore image at %X/%X compressed with %s not supported by build, block %d",
    2091             :                                   LSN_FORMAT_ARGS(record->ReadRecPtr),
    2092             :                                   "LZ4",
    2093             :                                   block_id);
    2094             :             return false;
    2095             : #endif
    2096             :         }
    2097           0 :         else if ((bkpb->bimg_info & BKPIMAGE_COMPRESS_ZSTD) != 0)
    2098             :         {
    2099             : #ifdef USE_ZSTD
    2100             :             size_t      decomp_result = ZSTD_decompress(tmp.data,
    2101             :                                                         BLCKSZ - bkpb->hole_length,
    2102             :                                                         ptr, bkpb->bimg_len);
    2103             : 
    2104             :             if (ZSTD_isError(decomp_result))
    2105             :                 decomp_success = false;
    2106             : #else
    2107           0 :             report_invalid_record(record, "could not restore image at %X/%X compressed with %s not supported by build, block %d",
    2108           0 :                                   LSN_FORMAT_ARGS(record->ReadRecPtr),
    2109             :                                   "zstd",
    2110             :                                   block_id);
    2111           0 :             return false;
    2112             : #endif
    2113             :         }
    2114             :         else
    2115             :         {
    2116           0 :             report_invalid_record(record, "could not restore image at %X/%X compressed with unknown method, block %d",
    2117           0 :                                   LSN_FORMAT_ARGS(record->ReadRecPtr),
    2118             :                                   block_id);
    2119           0 :             return false;
    2120             :         }
    2121             : 
    2122           0 :         if (!decomp_success)
    2123             :         {
    2124           0 :             report_invalid_record(record, "could not decompress image at %X/%X, block %d",
    2125           0 :                                   LSN_FORMAT_ARGS(record->ReadRecPtr),
    2126             :                                   block_id);
    2127           0 :             return false;
    2128             :         }
    2129             : 
    2130           0 :         ptr = tmp.data;
    2131             :     }
    2132             : 
    2133             :     /* generate page, taking into account hole if necessary */
    2134           0 :     if (bkpb->hole_length == 0)
    2135             :     {
    2136           0 :         memcpy(page, ptr, BLCKSZ);
    2137             :     }
    2138             :     else
    2139             :     {
    2140           0 :         memcpy(page, ptr, bkpb->hole_offset);
    2141             :         /* must zero-fill the hole */
    2142           0 :         MemSet(page + bkpb->hole_offset, 0, bkpb->hole_length);
    2143           0 :         memcpy(page + (bkpb->hole_offset + bkpb->hole_length),
    2144           0 :                ptr + bkpb->hole_offset,
    2145           0 :                BLCKSZ - (bkpb->hole_offset + bkpb->hole_length));
    2146             :     }
    2147             : 
    2148           0 :     return true;
    2149             : }
    2150             : 
    2151             : #ifndef FRONTEND
    2152             : 
    2153             : /*
    2154             :  * Extract the FullTransactionId from a WAL record.
    2155             :  */
    2156             : FullTransactionId
    2157             : XLogRecGetFullXid(XLogReaderState *record)
    2158             : {
    2159             :     TransactionId xid,
    2160             :                 next_xid;
    2161             :     uint32      epoch;
    2162             : 
    2163             :     /*
    2164             :      * This function is only safe during replay, because it depends on the
    2165             :      * replay state.  See AdvanceNextFullTransactionIdPastXid() for more.
    2166             :      */
    2167             :     Assert(AmStartupProcess() || !IsUnderPostmaster);
    2168             : 
    2169             :     xid = XLogRecGetXid(record);
    2170             :     next_xid = XidFromFullTransactionId(ShmemVariableCache->nextXid);
    2171             :     epoch = EpochFromFullTransactionId(ShmemVariableCache->nextXid);
    2172             : 
    2173             :     /*
    2174             :      * If xid is numerically greater than next_xid, it has to be from the last
    2175             :      * epoch.
    2176             :      */
    2177             :     if (unlikely(xid > next_xid))
    2178             :         --epoch;
    2179             : 
    2180             :     return FullTransactionIdFromEpochAndXid(epoch, xid);
    2181             : }
    2182             : 
    2183             : #endif

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