Line data Source code
1 : /*-------------------------------------------------------------------------
2 : *
3 : * xlogreader.c
4 : * Generic XLog reading facility
5 : *
6 : * Portions Copyright (c) 2013-2022, 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 5012 : XLogBeginRead(XLogReaderState *state, XLogRecPtr RecPtr)
265 : {
266 : Assert(!XLogRecPtrIsInvalid(RecPtr));
267 :
268 5012 : ResetDecoder(state);
269 :
270 : /* Begin at the passed-in record pointer. */
271 5012 : state->EndRecPtr = RecPtr;
272 5012 : state->NextRecPtr = RecPtr;
273 5012 : state->ReadRecPtr = InvalidXLogRecPtr;
274 5012 : state->DecodeRecPtr = InvalidXLogRecPtr;
275 5012 : }
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 355932 : XLogReleasePreviousRecord(XLogReaderState *state)
283 : {
284 : DecodedXLogRecord *record;
285 : XLogRecPtr next_lsn;
286 :
287 355932 : if (!state->record)
288 182978 : 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 172954 : record = state->record;
295 172954 : next_lsn = record->next_lsn;
296 : Assert(record == state->decode_queue_head);
297 172954 : state->record = NULL;
298 172954 : state->decode_queue_head = record->next;
299 :
300 : /* It might also be the newest item decoded, decode_queue_tail. */
301 172954 : if (state->decode_queue_tail == record)
302 172954 : state->decode_queue_tail = NULL;
303 :
304 : /* Release the space. */
305 172954 : 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 172954 : record = record->next;
321 172954 : while (unlikely(record && record->oversized))
322 0 : record = record->next;
323 :
324 172954 : 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 172954 : state->decode_buffer_head = state->decode_buffer;
338 172954 : state->decode_buffer_tail = state->decode_buffer;
339 : }
340 : }
341 :
342 172954 : 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 177966 : XLogNextRecord(XLogReaderState *state, char **errormsg)
359 : {
360 : /* Release the last record returned by XLogNextRecord(). */
361 177966 : XLogReleasePreviousRecord(state);
362 :
363 177966 : 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 177966 : 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 177966 : state->ReadRecPtr = state->record->lsn;
398 177966 : state->EndRecPtr = state->record->next_lsn;
399 :
400 177966 : *errormsg = NULL;
401 :
402 177966 : 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 177966 : 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 177966 : 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 177966 : if (!XLogReaderHasQueuedRecordOrError(state))
437 177966 : XLogReadAhead(state, false /* nonblocking */ );
438 :
439 : /* Consume the head record or error. */
440 177966 : decoded = XLogNextRecord(state, errormsg);
441 177966 : 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 177966 : 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 177966 : XLogReadRecordAlloc(XLogReaderState *state, size_t xl_tot_len, bool allow_oversized)
472 : {
473 177966 : size_t required_space = DecodeXLogRecordRequiredSpace(xl_tot_len);
474 177966 : DecodedXLogRecord *decoded = NULL;
475 :
476 : /* Allocate a circular decode buffer if we don't have one already. */
477 177966 : 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 177966 : if (state->decode_buffer_tail >= state->decode_buffer_head)
489 : {
490 : /* Empty, or tail is to the right of head. */
491 177966 : if (state->decode_buffer_tail + required_space <=
492 177966 : state->decode_buffer + state->decode_buffer_size)
493 : {
494 : /* There is space between tail and end. */
495 177966 : decoded = (DecodedXLogRecord *) state->decode_buffer_tail;
496 177966 : decoded->oversized = false;
497 177966 : 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 177966 : 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 177966 : randAccess = false;
557 :
558 : /* reset error state */
559 177966 : state->errormsg_buf[0] = '\0';
560 177966 : decoded = NULL;
561 :
562 177966 : state->abortedRecPtr = InvalidXLogRecPtr;
563 177966 : state->missingContrecPtr = InvalidXLogRecPtr;
564 :
565 177966 : RecPtr = state->NextRecPtr;
566 :
567 177966 : 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 5012 : randAccess = true;
589 : }
590 :
591 177966 : restart:
592 177966 : state->nonblocking = nonblocking;
593 177966 : state->currRecPtr = RecPtr;
594 177966 : assembled = false;
595 :
596 177966 : targetPagePtr = RecPtr - (RecPtr % XLOG_BLCKSZ);
597 177966 : 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 177966 : readOff = ReadPageInternal(state, targetPagePtr,
605 177966 : Min(targetRecOff + SizeOfXLogRecord, XLOG_BLCKSZ));
606 177966 : if (readOff == XLREAD_WOULDBLOCK)
607 0 : return XLREAD_WOULDBLOCK;
608 177966 : 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 177966 : pageHeaderSize = XLogPageHeaderSize((XLogPageHeader) state->readBuf);
616 177966 : if (targetRecOff == 0)
617 : {
618 : /*
619 : * At page start, so skip over page header.
620 : */
621 180 : RecPtr += pageHeaderSize;
622 180 : targetRecOff = pageHeaderSize;
623 : }
624 177786 : else if (targetRecOff < pageHeaderSize)
625 : {
626 0 : report_invalid_record(state, "invalid record offset at %X/%X",
627 0 : LSN_FORMAT_ARGS(RecPtr));
628 0 : goto err;
629 : }
630 :
631 177966 : if ((((XLogPageHeader) state->readBuf)->xlp_info & XLP_FIRST_IS_CONTRECORD) &&
632 : targetRecOff == pageHeaderSize)
633 : {
634 0 : report_invalid_record(state, "contrecord is requested by %X/%X",
635 0 : LSN_FORMAT_ARGS(RecPtr));
636 0 : goto err;
637 : }
638 :
639 : /* ReadPageInternal has verified the page header */
640 : Assert(pageHeaderSize <= readOff);
641 :
642 : /*
643 : * Read the record length.
644 : *
645 : * NB: Even though we use an XLogRecord pointer here, the whole record
646 : * header might not fit on this page. xl_tot_len is the first field of the
647 : * struct, so it must be on this page (the records are MAXALIGNed), but we
648 : * cannot access any other fields until we've verified that we got the
649 : * whole header.
650 : */
651 177966 : record = (XLogRecord *) (state->readBuf + RecPtr % XLOG_BLCKSZ);
652 177966 : total_len = record->xl_tot_len;
653 :
654 : /*
655 : * If the whole record header is on this page, validate it immediately.
656 : * Otherwise do just a basic sanity check on xl_tot_len, and validate the
657 : * rest of the header after reading it from the next page. The xl_tot_len
658 : * check is necessary here to ensure that we enter the "Need to reassemble
659 : * record" code path below; otherwise we might fail to apply
660 : * ValidXLogRecordHeader at all.
661 : */
662 177966 : if (targetRecOff <= XLOG_BLCKSZ - SizeOfXLogRecord)
663 : {
664 177638 : if (!ValidXLogRecordHeader(state, RecPtr, state->DecodeRecPtr, record,
665 : randAccess))
666 0 : goto err;
667 177638 : gotheader = true;
668 : }
669 : else
670 : {
671 : /* XXX: more validation should be done here */
672 328 : if (total_len < SizeOfXLogRecord)
673 : {
674 0 : report_invalid_record(state,
675 : "invalid record length at %X/%X: wanted %u, got %u",
676 0 : LSN_FORMAT_ARGS(RecPtr),
677 : (uint32) SizeOfXLogRecord, total_len);
678 0 : goto err;
679 : }
680 328 : gotheader = false;
681 : }
682 :
683 : /*
684 : * Find space to decode this record. Don't allow oversized allocation if
685 : * the caller requested nonblocking. Otherwise, we *have* to try to
686 : * decode the record now because the caller has nothing else to do, so
687 : * allow an oversized record to be palloc'd if that turns out to be
688 : * necessary.
689 : */
690 177966 : decoded = XLogReadRecordAlloc(state,
691 : total_len,
692 177966 : !nonblocking /* allow_oversized */ );
693 177966 : if (decoded == NULL)
694 : {
695 : /*
696 : * There is no space in the decode buffer. The caller should help
697 : * with that problem by consuming some records.
698 : */
699 0 : if (nonblocking)
700 0 : return XLREAD_WOULDBLOCK;
701 :
702 : /* We failed to allocate memory for an oversized record. */
703 0 : report_invalid_record(state,
704 : "out of memory while trying to decode a record of length %u", total_len);
705 0 : goto err;
706 : }
707 :
708 177966 : len = XLOG_BLCKSZ - RecPtr % XLOG_BLCKSZ;
709 177966 : if (total_len > len)
710 : {
711 : /* Need to reassemble record */
712 : char *contdata;
713 : XLogPageHeader pageHeader;
714 : char *buffer;
715 : uint32 gotlen;
716 :
717 8124 : assembled = true;
718 :
719 : /*
720 : * Enlarge readRecordBuf as needed.
721 : */
722 8124 : if (total_len > state->readRecordBufSize &&
723 0 : !allocate_recordbuf(state, total_len))
724 : {
725 : /* We treat this as a "bogus data" condition */
726 0 : report_invalid_record(state, "record length %u at %X/%X too long",
727 0 : total_len, LSN_FORMAT_ARGS(RecPtr));
728 0 : goto err;
729 : }
730 :
731 : /* Copy the first fragment of the record from the first page. */
732 8124 : memcpy(state->readRecordBuf,
733 8124 : state->readBuf + RecPtr % XLOG_BLCKSZ, len);
734 8124 : buffer = state->readRecordBuf + len;
735 8124 : gotlen = len;
736 :
737 : do
738 : {
739 : /* Calculate pointer to beginning of next page */
740 8136 : targetPagePtr += XLOG_BLCKSZ;
741 :
742 : /* Wait for the next page to become available */
743 8136 : readOff = ReadPageInternal(state, targetPagePtr,
744 8136 : Min(total_len - gotlen + SizeOfXLogShortPHD,
745 : XLOG_BLCKSZ));
746 :
747 8136 : if (readOff == XLREAD_WOULDBLOCK)
748 0 : return XLREAD_WOULDBLOCK;
749 8136 : else if (readOff < 0)
750 0 : goto err;
751 :
752 : Assert(SizeOfXLogShortPHD <= readOff);
753 :
754 8136 : pageHeader = (XLogPageHeader) state->readBuf;
755 :
756 : /*
757 : * If we were expecting a continuation record and got an
758 : * "overwrite contrecord" flag, that means the continuation record
759 : * was overwritten with a different record. Restart the read by
760 : * assuming the address to read is the location where we found
761 : * this flag; but keep track of the LSN of the record we were
762 : * reading, for later verification.
763 : */
764 8136 : if (pageHeader->xlp_info & XLP_FIRST_IS_OVERWRITE_CONTRECORD)
765 : {
766 0 : state->overwrittenRecPtr = RecPtr;
767 0 : RecPtr = targetPagePtr;
768 0 : goto restart;
769 : }
770 :
771 : /* Check that the continuation on next page looks valid */
772 8136 : if (!(pageHeader->xlp_info & XLP_FIRST_IS_CONTRECORD))
773 : {
774 0 : report_invalid_record(state,
775 : "there is no contrecord flag at %X/%X",
776 0 : LSN_FORMAT_ARGS(RecPtr));
777 0 : goto err;
778 : }
779 :
780 : /*
781 : * Cross-check that xlp_rem_len agrees with how much of the record
782 : * we expect there to be left.
783 : */
784 8136 : if (pageHeader->xlp_rem_len == 0 ||
785 8136 : total_len != (pageHeader->xlp_rem_len + gotlen))
786 : {
787 0 : report_invalid_record(state,
788 : "invalid contrecord length %u (expected %lld) at %X/%X",
789 : pageHeader->xlp_rem_len,
790 0 : ((long long) total_len) - gotlen,
791 0 : LSN_FORMAT_ARGS(RecPtr));
792 0 : goto err;
793 : }
794 :
795 : /* Append the continuation from this page to the buffer */
796 8136 : pageHeaderSize = XLogPageHeaderSize(pageHeader);
797 :
798 8136 : if (readOff < pageHeaderSize)
799 0 : readOff = ReadPageInternal(state, targetPagePtr,
800 : pageHeaderSize);
801 :
802 : Assert(pageHeaderSize <= readOff);
803 :
804 8136 : contdata = (char *) state->readBuf + pageHeaderSize;
805 8136 : len = XLOG_BLCKSZ - pageHeaderSize;
806 8136 : if (pageHeader->xlp_rem_len < len)
807 8124 : len = pageHeader->xlp_rem_len;
808 :
809 8136 : if (readOff < pageHeaderSize + len)
810 0 : readOff = ReadPageInternal(state, targetPagePtr,
811 0 : pageHeaderSize + len);
812 :
813 8136 : memcpy(buffer, (char *) contdata, len);
814 8136 : buffer += len;
815 8136 : gotlen += len;
816 :
817 : /* If we just reassembled the record header, validate it. */
818 8136 : if (!gotheader)
819 : {
820 328 : record = (XLogRecord *) state->readRecordBuf;
821 328 : if (!ValidXLogRecordHeader(state, RecPtr, state->DecodeRecPtr,
822 : record, randAccess))
823 0 : goto err;
824 328 : gotheader = true;
825 : }
826 8136 : } while (gotlen < total_len);
827 :
828 : Assert(gotheader);
829 :
830 8124 : record = (XLogRecord *) state->readRecordBuf;
831 8124 : if (!ValidXLogRecord(state, record, RecPtr))
832 0 : goto err;
833 :
834 8124 : pageHeaderSize = XLogPageHeaderSize((XLogPageHeader) state->readBuf);
835 8124 : state->DecodeRecPtr = RecPtr;
836 8124 : state->NextRecPtr = targetPagePtr + pageHeaderSize
837 8124 : + MAXALIGN(pageHeader->xlp_rem_len);
838 : }
839 : else
840 : {
841 : /* Wait for the record data to become available */
842 169842 : readOff = ReadPageInternal(state, targetPagePtr,
843 169842 : Min(targetRecOff + total_len, XLOG_BLCKSZ));
844 169842 : if (readOff == XLREAD_WOULDBLOCK)
845 0 : return XLREAD_WOULDBLOCK;
846 169842 : else if (readOff < 0)
847 0 : goto err;
848 :
849 : /* Record does not cross a page boundary */
850 169842 : if (!ValidXLogRecord(state, record, RecPtr))
851 0 : goto err;
852 :
853 169842 : state->NextRecPtr = RecPtr + MAXALIGN(total_len);
854 :
855 169842 : state->DecodeRecPtr = RecPtr;
856 : }
857 :
858 : /*
859 : * Special processing if it's an XLOG SWITCH record
860 : */
861 177966 : if (record->xl_rmid == RM_XLOG_ID &&
862 11538 : (record->xl_info & ~XLR_INFO_MASK) == XLOG_SWITCH)
863 : {
864 : /* Pretend it extends to end of segment */
865 16 : state->NextRecPtr += state->segcxt.ws_segsize - 1;
866 16 : state->NextRecPtr -= XLogSegmentOffset(state->NextRecPtr, state->segcxt.ws_segsize);
867 : }
868 :
869 177966 : if (DecodeXLogRecord(state, decoded, record, RecPtr, &errormsg))
870 : {
871 : /* Record the location of the next record. */
872 177966 : decoded->next_lsn = state->NextRecPtr;
873 :
874 : /*
875 : * If it's in the decode buffer, mark the decode buffer space as
876 : * occupied.
877 : */
878 177966 : if (!decoded->oversized)
879 : {
880 : /* The new decode buffer head must be MAXALIGNed. */
881 : Assert(decoded->size == MAXALIGN(decoded->size));
882 177966 : if ((char *) decoded == state->decode_buffer)
883 177966 : state->decode_buffer_tail = state->decode_buffer + decoded->size;
884 : else
885 0 : state->decode_buffer_tail += decoded->size;
886 : }
887 :
888 : /* Insert it into the queue of decoded records. */
889 : Assert(state->decode_queue_tail != decoded);
890 177966 : if (state->decode_queue_tail)
891 0 : state->decode_queue_tail->next = decoded;
892 177966 : state->decode_queue_tail = decoded;
893 177966 : if (!state->decode_queue_head)
894 177966 : state->decode_queue_head = decoded;
895 177966 : return XLREAD_SUCCESS;
896 : }
897 : else
898 0 : return XLREAD_FAIL;
899 :
900 0 : err:
901 0 : if (assembled)
902 : {
903 : /*
904 : * We get here when a record that spans multiple pages needs to be
905 : * assembled, but something went wrong -- perhaps a contrecord piece
906 : * was lost. If caller is WAL replay, it will know where the aborted
907 : * record was and where to direct followup WAL to be written, marking
908 : * the next piece with XLP_FIRST_IS_OVERWRITE_CONTRECORD, which will
909 : * in turn signal downstream WAL consumers that the broken WAL record
910 : * is to be ignored.
911 : */
912 0 : state->abortedRecPtr = RecPtr;
913 0 : state->missingContrecPtr = targetPagePtr;
914 :
915 : /*
916 : * If we got here without reporting an error, report one now so that
917 : * XLogPrefetcherReadRecord() doesn't bring us back a second time and
918 : * clobber the above state. Otherwise, the existing error takes
919 : * precedence.
920 : */
921 0 : if (!state->errormsg_buf[0])
922 0 : report_invalid_record(state,
923 : "missing contrecord at %X/%X",
924 0 : LSN_FORMAT_ARGS(RecPtr));
925 : }
926 :
927 0 : if (decoded && decoded->oversized)
928 0 : pfree(decoded);
929 :
930 : /*
931 : * Invalidate the read state. We might read from a different source after
932 : * failure.
933 : */
934 0 : XLogReaderInvalReadState(state);
935 :
936 : /*
937 : * If an error was written to errmsg_buf, it'll be returned to the caller
938 : * of XLogReadRecord() after all successfully decoded records from the
939 : * read queue.
940 : */
941 :
942 0 : return XLREAD_FAIL;
943 : }
944 :
945 : /*
946 : * Try to decode the next available record, and return it. The record will
947 : * also be returned to XLogNextRecord(), which must be called to 'consume'
948 : * each record.
949 : *
950 : * If nonblocking is true, may return NULL due to lack of data or WAL decoding
951 : * space.
952 : */
953 : DecodedXLogRecord *
954 177966 : XLogReadAhead(XLogReaderState *state, bool nonblocking)
955 : {
956 : XLogPageReadResult result;
957 :
958 177966 : if (state->errormsg_deferred)
959 0 : return NULL;
960 :
961 177966 : result = XLogDecodeNextRecord(state, nonblocking);
962 177966 : if (result == XLREAD_SUCCESS)
963 : {
964 : Assert(state->decode_queue_tail != NULL);
965 177966 : return state->decode_queue_tail;
966 : }
967 :
968 0 : return NULL;
969 : }
970 :
971 : /*
972 : * Read a single xlog page including at least [pageptr, reqLen] of valid data
973 : * via the page_read() callback.
974 : *
975 : * Returns XLREAD_FAIL if the required page cannot be read for some
976 : * reason; errormsg_buf is set in that case (unless the error occurs in the
977 : * page_read callback).
978 : *
979 : * Returns XLREAD_WOULDBLOCK if the requested data can't be read without
980 : * waiting. This can be returned only if the installed page_read callback
981 : * respects the state->nonblocking flag, and cannot read the requested data
982 : * immediately.
983 : *
984 : * We fetch the page from a reader-local cache if we know we have the required
985 : * data and if there hasn't been any error since caching the data.
986 : */
987 : static int
988 355944 : ReadPageInternal(XLogReaderState *state, XLogRecPtr pageptr, int reqLen)
989 : {
990 : int readLen;
991 : uint32 targetPageOff;
992 : XLogSegNo targetSegNo;
993 : XLogPageHeader hdr;
994 :
995 : Assert((pageptr % XLOG_BLCKSZ) == 0);
996 :
997 355944 : XLByteToSeg(pageptr, targetSegNo, state->segcxt.ws_segsize);
998 355944 : targetPageOff = XLogSegmentOffset(pageptr, state->segcxt.ws_segsize);
999 :
1000 : /* check whether we have all the requested data already */
1001 355944 : if (targetSegNo == state->seg.ws_segno &&
1002 355850 : targetPageOff == state->segoff && reqLen <= state->readLen)
1003 345154 : return state->readLen;
1004 :
1005 : /*
1006 : * Invalidate contents of internal buffer before read attempt. Just set
1007 : * the length to 0, rather than a full XLogReaderInvalReadState(), so we
1008 : * don't forget the segment we last successfully read.
1009 : */
1010 10790 : state->readLen = 0;
1011 :
1012 : /*
1013 : * Data is not in our buffer.
1014 : *
1015 : * Every time we actually read the segment, even if we looked at parts of
1016 : * it before, we need to do verification as the page_read callback might
1017 : * now be rereading data from a different source.
1018 : *
1019 : * Whenever switching to a new WAL segment, we read the first page of the
1020 : * file and validate its header, even if that's not where the target
1021 : * record is. This is so that we can check the additional identification
1022 : * info that is present in the first page's "long" header.
1023 : */
1024 10790 : if (targetSegNo != state->seg.ws_segno && targetPageOff != 0)
1025 : {
1026 40 : XLogRecPtr targetSegmentPtr = pageptr - targetPageOff;
1027 :
1028 40 : readLen = state->routine.page_read(state, targetSegmentPtr, XLOG_BLCKSZ,
1029 : state->currRecPtr,
1030 : state->readBuf);
1031 40 : if (readLen == XLREAD_WOULDBLOCK)
1032 0 : return XLREAD_WOULDBLOCK;
1033 40 : else if (readLen < 0)
1034 0 : goto err;
1035 :
1036 : /* we can be sure to have enough WAL available, we scrolled back */
1037 : Assert(readLen == XLOG_BLCKSZ);
1038 :
1039 40 : if (!XLogReaderValidatePageHeader(state, targetSegmentPtr,
1040 : state->readBuf))
1041 0 : goto err;
1042 : }
1043 :
1044 : /*
1045 : * First, read the requested data length, but at least a short page header
1046 : * so that we can validate it.
1047 : */
1048 10790 : readLen = state->routine.page_read(state, pageptr, Max(reqLen, SizeOfXLogShortPHD),
1049 : state->currRecPtr,
1050 : state->readBuf);
1051 10790 : if (readLen == XLREAD_WOULDBLOCK)
1052 0 : return XLREAD_WOULDBLOCK;
1053 10790 : else if (readLen < 0)
1054 0 : goto err;
1055 :
1056 : Assert(readLen <= XLOG_BLCKSZ);
1057 :
1058 : /* Do we have enough data to check the header length? */
1059 10790 : if (readLen <= SizeOfXLogShortPHD)
1060 0 : goto err;
1061 :
1062 : Assert(readLen >= reqLen);
1063 :
1064 10790 : hdr = (XLogPageHeader) state->readBuf;
1065 :
1066 : /* still not enough */
1067 10790 : if (readLen < XLogPageHeaderSize(hdr))
1068 : {
1069 0 : readLen = state->routine.page_read(state, pageptr, XLogPageHeaderSize(hdr),
1070 : state->currRecPtr,
1071 : state->readBuf);
1072 0 : if (readLen == XLREAD_WOULDBLOCK)
1073 0 : return XLREAD_WOULDBLOCK;
1074 0 : else if (readLen < 0)
1075 0 : goto err;
1076 : }
1077 :
1078 : /*
1079 : * Now that we know we have the full header, validate it.
1080 : */
1081 10790 : if (!XLogReaderValidatePageHeader(state, pageptr, (char *) hdr))
1082 0 : goto err;
1083 :
1084 : /* update read state information */
1085 10790 : state->seg.ws_segno = targetSegNo;
1086 10790 : state->segoff = targetPageOff;
1087 10790 : state->readLen = readLen;
1088 :
1089 10790 : return readLen;
1090 :
1091 0 : err:
1092 0 : XLogReaderInvalReadState(state);
1093 :
1094 0 : return XLREAD_FAIL;
1095 : }
1096 :
1097 : /*
1098 : * Invalidate the xlogreader's read state to force a re-read.
1099 : */
1100 : static void
1101 0 : XLogReaderInvalReadState(XLogReaderState *state)
1102 : {
1103 0 : state->seg.ws_segno = 0;
1104 0 : state->segoff = 0;
1105 0 : state->readLen = 0;
1106 0 : }
1107 :
1108 : /*
1109 : * Validate an XLOG record header.
1110 : *
1111 : * This is just a convenience subroutine to avoid duplicated code in
1112 : * XLogReadRecord. It's not intended for use from anywhere else.
1113 : */
1114 : static bool
1115 177966 : ValidXLogRecordHeader(XLogReaderState *state, XLogRecPtr RecPtr,
1116 : XLogRecPtr PrevRecPtr, XLogRecord *record,
1117 : bool randAccess)
1118 : {
1119 177966 : if (record->xl_tot_len < SizeOfXLogRecord)
1120 : {
1121 0 : report_invalid_record(state,
1122 : "invalid record length at %X/%X: wanted %u, got %u",
1123 0 : LSN_FORMAT_ARGS(RecPtr),
1124 : (uint32) SizeOfXLogRecord, record->xl_tot_len);
1125 0 : return false;
1126 : }
1127 177966 : if (!RmgrIdIsValid(record->xl_rmid))
1128 : {
1129 0 : report_invalid_record(state,
1130 : "invalid resource manager ID %u at %X/%X",
1131 0 : record->xl_rmid, LSN_FORMAT_ARGS(RecPtr));
1132 0 : return false;
1133 : }
1134 177966 : if (randAccess)
1135 : {
1136 : /*
1137 : * We can't exactly verify the prev-link, but surely it should be less
1138 : * than the record's own address.
1139 : */
1140 5012 : if (!(record->xl_prev < RecPtr))
1141 : {
1142 0 : report_invalid_record(state,
1143 : "record with incorrect prev-link %X/%X at %X/%X",
1144 0 : LSN_FORMAT_ARGS(record->xl_prev),
1145 0 : LSN_FORMAT_ARGS(RecPtr));
1146 0 : return false;
1147 : }
1148 : }
1149 : else
1150 : {
1151 : /*
1152 : * Record's prev-link should exactly match our previous location. This
1153 : * check guards against torn WAL pages where a stale but valid-looking
1154 : * WAL record starts on a sector boundary.
1155 : */
1156 172954 : if (record->xl_prev != PrevRecPtr)
1157 : {
1158 0 : report_invalid_record(state,
1159 : "record with incorrect prev-link %X/%X at %X/%X",
1160 0 : LSN_FORMAT_ARGS(record->xl_prev),
1161 0 : LSN_FORMAT_ARGS(RecPtr));
1162 0 : return false;
1163 : }
1164 : }
1165 :
1166 177966 : return true;
1167 : }
1168 :
1169 :
1170 : /*
1171 : * CRC-check an XLOG record. We do not believe the contents of an XLOG
1172 : * record (other than to the minimal extent of computing the amount of
1173 : * data to read in) until we've checked the CRCs.
1174 : *
1175 : * We assume all of the record (that is, xl_tot_len bytes) has been read
1176 : * into memory at *record. Also, ValidXLogRecordHeader() has accepted the
1177 : * record's header, which means in particular that xl_tot_len is at least
1178 : * SizeOfXLogRecord.
1179 : */
1180 : static bool
1181 177966 : ValidXLogRecord(XLogReaderState *state, XLogRecord *record, XLogRecPtr recptr)
1182 : {
1183 : pg_crc32c crc;
1184 :
1185 : /* Calculate the CRC */
1186 177966 : INIT_CRC32C(crc);
1187 177966 : COMP_CRC32C(crc, ((char *) record) + SizeOfXLogRecord, record->xl_tot_len - SizeOfXLogRecord);
1188 : /* include the record header last */
1189 177966 : COMP_CRC32C(crc, (char *) record, offsetof(XLogRecord, xl_crc));
1190 177966 : FIN_CRC32C(crc);
1191 :
1192 177966 : if (!EQ_CRC32C(record->xl_crc, crc))
1193 : {
1194 0 : report_invalid_record(state,
1195 : "incorrect resource manager data checksum in record at %X/%X",
1196 0 : LSN_FORMAT_ARGS(recptr));
1197 0 : return false;
1198 : }
1199 :
1200 177966 : return true;
1201 : }
1202 :
1203 : /*
1204 : * Validate a page header.
1205 : *
1206 : * Check if 'phdr' is valid as the header of the XLog page at position
1207 : * 'recptr'.
1208 : */
1209 : bool
1210 10830 : XLogReaderValidatePageHeader(XLogReaderState *state, XLogRecPtr recptr,
1211 : char *phdr)
1212 : {
1213 : XLogRecPtr recaddr;
1214 : XLogSegNo segno;
1215 : int32 offset;
1216 10830 : XLogPageHeader hdr = (XLogPageHeader) phdr;
1217 :
1218 : Assert((recptr % XLOG_BLCKSZ) == 0);
1219 :
1220 10830 : XLByteToSeg(recptr, segno, state->segcxt.ws_segsize);
1221 10830 : offset = XLogSegmentOffset(recptr, state->segcxt.ws_segsize);
1222 :
1223 10830 : XLogSegNoOffsetToRecPtr(segno, offset, state->segcxt.ws_segsize, recaddr);
1224 :
1225 10830 : if (hdr->xlp_magic != XLOG_PAGE_MAGIC)
1226 : {
1227 : char fname[MAXFNAMELEN];
1228 :
1229 0 : XLogFileName(fname, state->seg.ws_tli, segno, state->segcxt.ws_segsize);
1230 :
1231 0 : report_invalid_record(state,
1232 : "invalid magic number %04X in WAL segment %s, offset %u",
1233 0 : hdr->xlp_magic,
1234 : fname,
1235 : offset);
1236 0 : return false;
1237 : }
1238 :
1239 10830 : if ((hdr->xlp_info & ~XLP_ALL_FLAGS) != 0)
1240 : {
1241 : char fname[MAXFNAMELEN];
1242 :
1243 0 : XLogFileName(fname, state->seg.ws_tli, segno, state->segcxt.ws_segsize);
1244 :
1245 0 : report_invalid_record(state,
1246 : "invalid info bits %04X in WAL segment %s, offset %u",
1247 0 : hdr->xlp_info,
1248 : fname,
1249 : offset);
1250 0 : return false;
1251 : }
1252 :
1253 10830 : if (hdr->xlp_info & XLP_LONG_HEADER)
1254 : {
1255 102 : XLogLongPageHeader longhdr = (XLogLongPageHeader) hdr;
1256 :
1257 102 : 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 102 : 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 102 : 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 10728 : 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, offset %u",
1288 0 : hdr->xlp_info,
1289 : fname,
1290 : offset);
1291 0 : return false;
1292 : }
1293 :
1294 : /*
1295 : * Check that the address on the page agrees with what we expected. This
1296 : * check typically fails when an old WAL segment is recycled, and hasn't
1297 : * yet been overwritten with new data yet.
1298 : */
1299 10830 : if (hdr->xlp_pageaddr != recaddr)
1300 : {
1301 : char fname[MAXFNAMELEN];
1302 :
1303 0 : XLogFileName(fname, state->seg.ws_tli, segno, state->segcxt.ws_segsize);
1304 :
1305 0 : report_invalid_record(state,
1306 : "unexpected pageaddr %X/%X in WAL segment %s, offset %u",
1307 0 : LSN_FORMAT_ARGS(hdr->xlp_pageaddr),
1308 : fname,
1309 : offset);
1310 0 : return false;
1311 : }
1312 :
1313 : /*
1314 : * Since child timelines are always assigned a TLI greater than their
1315 : * immediate parent's TLI, we should never see TLI go backwards across
1316 : * successive pages of a consistent WAL sequence.
1317 : *
1318 : * Sometimes we re-read a segment that's already been (partially) read. So
1319 : * we only verify TLIs for pages that are later than the last remembered
1320 : * LSN.
1321 : */
1322 10830 : if (recptr > state->latestPagePtr)
1323 : {
1324 8434 : if (hdr->xlp_tli < state->latestPageTLI)
1325 : {
1326 : char fname[MAXFNAMELEN];
1327 :
1328 0 : XLogFileName(fname, state->seg.ws_tli, segno, state->segcxt.ws_segsize);
1329 :
1330 0 : report_invalid_record(state,
1331 : "out-of-sequence timeline ID %u (after %u) in WAL segment %s, offset %u",
1332 : hdr->xlp_tli,
1333 : state->latestPageTLI,
1334 : fname,
1335 : offset);
1336 0 : return false;
1337 : }
1338 : }
1339 10830 : state->latestPagePtr = recptr;
1340 10830 : state->latestPageTLI = hdr->xlp_tli;
1341 :
1342 10830 : return true;
1343 : }
1344 :
1345 : /*
1346 : * Forget about an error produced by XLogReaderValidatePageHeader().
1347 : */
1348 : void
1349 0 : XLogReaderResetError(XLogReaderState *state)
1350 : {
1351 0 : state->errormsg_buf[0] = '\0';
1352 0 : state->errormsg_deferred = false;
1353 0 : }
1354 :
1355 : /*
1356 : * Find the first record with an lsn >= RecPtr.
1357 : *
1358 : * This is different from XLogBeginRead() in that RecPtr doesn't need to point
1359 : * to a valid record boundary. Useful for checking whether RecPtr is a valid
1360 : * xlog address for reading, and to find the first valid address after some
1361 : * address when dumping records for debugging purposes.
1362 : *
1363 : * This positions the reader, like XLogBeginRead(), so that the next call to
1364 : * XLogReadRecord() will read the next valid record.
1365 : */
1366 : XLogRecPtr
1367 0 : XLogFindNextRecord(XLogReaderState *state, XLogRecPtr RecPtr)
1368 : {
1369 : XLogRecPtr tmpRecPtr;
1370 0 : XLogRecPtr found = InvalidXLogRecPtr;
1371 : XLogPageHeader header;
1372 : char *errormsg;
1373 :
1374 : Assert(!XLogRecPtrIsInvalid(RecPtr));
1375 :
1376 : /* Make sure ReadPageInternal() can't return XLREAD_WOULDBLOCK. */
1377 0 : state->nonblocking = false;
1378 :
1379 : /*
1380 : * skip over potential continuation data, keeping in mind that it may span
1381 : * multiple pages
1382 : */
1383 0 : tmpRecPtr = RecPtr;
1384 : while (true)
1385 0 : {
1386 : XLogRecPtr targetPagePtr;
1387 : int targetRecOff;
1388 : uint32 pageHeaderSize;
1389 : int readLen;
1390 :
1391 : /*
1392 : * Compute targetRecOff. It should typically be equal or greater than
1393 : * short page-header since a valid record can't start anywhere before
1394 : * that, except when caller has explicitly specified the offset that
1395 : * falls somewhere there or when we are skipping multi-page
1396 : * continuation record. It doesn't matter though because
1397 : * ReadPageInternal() is prepared to handle that and will read at
1398 : * least short page-header worth of data
1399 : */
1400 0 : targetRecOff = tmpRecPtr % XLOG_BLCKSZ;
1401 :
1402 : /* scroll back to page boundary */
1403 0 : targetPagePtr = tmpRecPtr - targetRecOff;
1404 :
1405 : /* Read the page containing the record */
1406 0 : readLen = ReadPageInternal(state, targetPagePtr, targetRecOff);
1407 0 : if (readLen < 0)
1408 0 : goto err;
1409 :
1410 0 : header = (XLogPageHeader) state->readBuf;
1411 :
1412 0 : pageHeaderSize = XLogPageHeaderSize(header);
1413 :
1414 : /* make sure we have enough data for the page header */
1415 0 : readLen = ReadPageInternal(state, targetPagePtr, pageHeaderSize);
1416 0 : if (readLen < 0)
1417 0 : goto err;
1418 :
1419 : /* skip over potential continuation data */
1420 0 : if (header->xlp_info & XLP_FIRST_IS_CONTRECORD)
1421 : {
1422 : /*
1423 : * If the length of the remaining continuation data is more than
1424 : * what can fit in this page, the continuation record crosses over
1425 : * this page. Read the next page and try again. xlp_rem_len in the
1426 : * next page header will contain the remaining length of the
1427 : * continuation data
1428 : *
1429 : * Note that record headers are MAXALIGN'ed
1430 : */
1431 0 : if (MAXALIGN(header->xlp_rem_len) >= (XLOG_BLCKSZ - pageHeaderSize))
1432 0 : tmpRecPtr = targetPagePtr + XLOG_BLCKSZ;
1433 : else
1434 : {
1435 : /*
1436 : * The previous continuation record ends in this page. Set
1437 : * tmpRecPtr to point to the first valid record
1438 : */
1439 0 : tmpRecPtr = targetPagePtr + pageHeaderSize
1440 0 : + MAXALIGN(header->xlp_rem_len);
1441 0 : break;
1442 : }
1443 : }
1444 : else
1445 : {
1446 0 : tmpRecPtr = targetPagePtr + pageHeaderSize;
1447 0 : break;
1448 : }
1449 : }
1450 :
1451 : /*
1452 : * we know now that tmpRecPtr is an address pointing to a valid XLogRecord
1453 : * because either we're at the first record after the beginning of a page
1454 : * or we just jumped over the remaining data of a continuation.
1455 : */
1456 0 : XLogBeginRead(state, tmpRecPtr);
1457 0 : while (XLogReadRecord(state, &errormsg) != NULL)
1458 : {
1459 : /* past the record we've found, break out */
1460 0 : if (RecPtr <= state->ReadRecPtr)
1461 : {
1462 : /* Rewind the reader to the beginning of the last record. */
1463 0 : found = state->ReadRecPtr;
1464 0 : XLogBeginRead(state, found);
1465 0 : return found;
1466 : }
1467 : }
1468 :
1469 0 : err:
1470 0 : XLogReaderInvalReadState(state);
1471 :
1472 0 : return InvalidXLogRecPtr;
1473 : }
1474 :
1475 : /*
1476 : * Helper function to ease writing of XLogRoutine->page_read callbacks.
1477 : * If this function is used, caller must supply a segment_open callback in
1478 : * 'state', as that is used here.
1479 : *
1480 : * Read 'count' bytes into 'buf', starting at location 'startptr', from WAL
1481 : * fetched from timeline 'tli'.
1482 : *
1483 : * Returns true if succeeded, false if an error occurs, in which case
1484 : * 'errinfo' receives error details.
1485 : *
1486 : * XXX probably this should be improved to suck data directly from the
1487 : * WAL buffers when possible.
1488 : */
1489 : bool
1490 0 : WALRead(XLogReaderState *state,
1491 : char *buf, XLogRecPtr startptr, Size count, TimeLineID tli,
1492 : WALReadError *errinfo)
1493 : {
1494 : char *p;
1495 : XLogRecPtr recptr;
1496 : Size nbytes;
1497 :
1498 0 : p = buf;
1499 0 : recptr = startptr;
1500 0 : nbytes = count;
1501 :
1502 0 : while (nbytes > 0)
1503 : {
1504 : uint32 startoff;
1505 : int segbytes;
1506 : int readbytes;
1507 :
1508 0 : startoff = XLogSegmentOffset(recptr, state->segcxt.ws_segsize);
1509 :
1510 : /*
1511 : * If the data we want is not in a segment we have open, close what we
1512 : * have (if anything) and open the next one, using the caller's
1513 : * provided openSegment callback.
1514 : */
1515 0 : if (state->seg.ws_file < 0 ||
1516 0 : !XLByteInSeg(recptr, state->seg.ws_segno, state->segcxt.ws_segsize) ||
1517 0 : tli != state->seg.ws_tli)
1518 : {
1519 : XLogSegNo nextSegNo;
1520 :
1521 0 : if (state->seg.ws_file >= 0)
1522 0 : state->routine.segment_close(state);
1523 :
1524 0 : XLByteToSeg(recptr, nextSegNo, state->segcxt.ws_segsize);
1525 0 : state->routine.segment_open(state, nextSegNo, &tli);
1526 :
1527 : /* This shouldn't happen -- indicates a bug in segment_open */
1528 : Assert(state->seg.ws_file >= 0);
1529 :
1530 : /* Update the current segment info. */
1531 0 : state->seg.ws_tli = tli;
1532 0 : state->seg.ws_segno = nextSegNo;
1533 : }
1534 :
1535 : /* How many bytes are within this segment? */
1536 0 : if (nbytes > (state->segcxt.ws_segsize - startoff))
1537 0 : segbytes = state->segcxt.ws_segsize - startoff;
1538 : else
1539 0 : segbytes = nbytes;
1540 :
1541 : #ifndef FRONTEND
1542 : pgstat_report_wait_start(WAIT_EVENT_WAL_READ);
1543 : #endif
1544 :
1545 : /* Reset errno first; eases reporting non-errno-affecting errors */
1546 0 : errno = 0;
1547 0 : readbytes = pg_pread(state->seg.ws_file, p, segbytes, (off_t) startoff);
1548 :
1549 : #ifndef FRONTEND
1550 : pgstat_report_wait_end();
1551 : #endif
1552 :
1553 0 : if (readbytes <= 0)
1554 : {
1555 0 : errinfo->wre_errno = errno;
1556 0 : errinfo->wre_req = segbytes;
1557 0 : errinfo->wre_read = readbytes;
1558 0 : errinfo->wre_off = startoff;
1559 0 : errinfo->wre_seg = state->seg;
1560 0 : return false;
1561 : }
1562 :
1563 : /* Update state for read */
1564 0 : recptr += readbytes;
1565 0 : nbytes -= readbytes;
1566 0 : p += readbytes;
1567 : }
1568 :
1569 0 : return true;
1570 : }
1571 :
1572 : /* ----------------------------------------
1573 : * Functions for decoding the data and block references in a record.
1574 : * ----------------------------------------
1575 : */
1576 :
1577 : /*
1578 : * Private function to reset the state, forgetting all decoded records, if we
1579 : * are asked to move to a new read position.
1580 : */
1581 : static void
1582 5012 : ResetDecoder(XLogReaderState *state)
1583 : {
1584 : DecodedXLogRecord *r;
1585 :
1586 : /* Reset the decoded record queue, freeing any oversized records. */
1587 9946 : while ((r = state->decode_queue_head) != NULL)
1588 : {
1589 4934 : state->decode_queue_head = r->next;
1590 4934 : if (r->oversized)
1591 0 : pfree(r);
1592 : }
1593 5012 : state->decode_queue_tail = NULL;
1594 5012 : state->decode_queue_head = NULL;
1595 5012 : state->record = NULL;
1596 :
1597 : /* Reset the decode buffer to empty. */
1598 5012 : state->decode_buffer_tail = state->decode_buffer;
1599 5012 : state->decode_buffer_head = state->decode_buffer;
1600 :
1601 : /* Clear error state. */
1602 5012 : state->errormsg_buf[0] = '\0';
1603 5012 : state->errormsg_deferred = false;
1604 5012 : }
1605 :
1606 : /*
1607 : * Compute the maximum possible amount of padding that could be required to
1608 : * decode a record, given xl_tot_len from the record's header. This is the
1609 : * amount of output buffer space that we need to decode a record, though we
1610 : * might not finish up using it all.
1611 : *
1612 : * This computation is pessimistic and assumes the maximum possible number of
1613 : * blocks, due to lack of better information.
1614 : */
1615 : size_t
1616 177966 : DecodeXLogRecordRequiredSpace(size_t xl_tot_len)
1617 : {
1618 177966 : size_t size = 0;
1619 :
1620 : /* Account for the fixed size part of the decoded record struct. */
1621 177966 : size += offsetof(DecodedXLogRecord, blocks[0]);
1622 : /* Account for the flexible blocks array of maximum possible size. */
1623 177966 : size += sizeof(DecodedBkpBlock) * (XLR_MAX_BLOCK_ID + 1);
1624 : /* Account for all the raw main and block data. */
1625 177966 : size += xl_tot_len;
1626 : /* We might insert padding before main_data. */
1627 177966 : size += (MAXIMUM_ALIGNOF - 1);
1628 : /* We might insert padding before each block's data. */
1629 177966 : size += (MAXIMUM_ALIGNOF - 1) * (XLR_MAX_BLOCK_ID + 1);
1630 : /* We might insert padding at the end. */
1631 177966 : size += (MAXIMUM_ALIGNOF - 1);
1632 :
1633 177966 : return size;
1634 : }
1635 :
1636 : /*
1637 : * Decode a record. "decoded" must point to a MAXALIGNed memory area that has
1638 : * space for at least DecodeXLogRecordRequiredSpace(record) bytes. On
1639 : * success, decoded->size contains the actual space occupied by the decoded
1640 : * record, which may turn out to be less.
1641 : *
1642 : * Only decoded->oversized member must be initialized already, and will not be
1643 : * modified. Other members will be initialized as required.
1644 : *
1645 : * On error, a human-readable error message is returned in *errormsg, and
1646 : * the return value is false.
1647 : */
1648 : bool
1649 177966 : DecodeXLogRecord(XLogReaderState *state,
1650 : DecodedXLogRecord *decoded,
1651 : XLogRecord *record,
1652 : XLogRecPtr lsn,
1653 : char **errormsg)
1654 : {
1655 : /*
1656 : * read next _size bytes from record buffer, but check for overrun first.
1657 : */
1658 : #define COPY_HEADER_FIELD(_dst, _size) \
1659 : do { \
1660 : if (remaining < _size) \
1661 : goto shortdata_err; \
1662 : memcpy(_dst, ptr, _size); \
1663 : ptr += _size; \
1664 : remaining -= _size; \
1665 : } while(0)
1666 :
1667 : char *ptr;
1668 : char *out;
1669 : uint32 remaining;
1670 : uint32 datatotal;
1671 177966 : RelFileLocator *rlocator = NULL;
1672 : uint8 block_id;
1673 :
1674 177966 : decoded->header = *record;
1675 177966 : decoded->lsn = lsn;
1676 177966 : decoded->next = NULL;
1677 177966 : decoded->record_origin = InvalidRepOriginId;
1678 177966 : decoded->toplevel_xid = InvalidTransactionId;
1679 177966 : decoded->main_data = NULL;
1680 177966 : decoded->main_data_len = 0;
1681 177966 : decoded->max_block_id = -1;
1682 177966 : ptr = (char *) record;
1683 177966 : ptr += SizeOfXLogRecord;
1684 177966 : remaining = record->xl_tot_len - SizeOfXLogRecord;
1685 :
1686 : /* Decode the headers */
1687 177966 : datatotal = 0;
1688 352706 : while (remaining > datatotal)
1689 : {
1690 341316 : COPY_HEADER_FIELD(&block_id, sizeof(uint8));
1691 :
1692 341316 : if (block_id == XLR_BLOCK_ID_DATA_SHORT)
1693 : {
1694 : /* XLogRecordDataHeaderShort */
1695 : uint8 main_data_len;
1696 :
1697 166544 : COPY_HEADER_FIELD(&main_data_len, sizeof(uint8));
1698 :
1699 166544 : decoded->main_data_len = main_data_len;
1700 166544 : datatotal += main_data_len;
1701 166544 : break; /* by convention, the main data fragment is
1702 : * always last */
1703 : }
1704 174772 : else if (block_id == XLR_BLOCK_ID_DATA_LONG)
1705 : {
1706 : /* XLogRecordDataHeaderLong */
1707 : uint32 main_data_len;
1708 :
1709 32 : COPY_HEADER_FIELD(&main_data_len, sizeof(uint32));
1710 32 : decoded->main_data_len = main_data_len;
1711 32 : datatotal += main_data_len;
1712 32 : break; /* by convention, the main data fragment is
1713 : * always last */
1714 : }
1715 174740 : else if (block_id == XLR_BLOCK_ID_ORIGIN)
1716 : {
1717 0 : COPY_HEADER_FIELD(&decoded->record_origin, sizeof(RepOriginId));
1718 : }
1719 174740 : else if (block_id == XLR_BLOCK_ID_TOPLEVEL_XID)
1720 : {
1721 0 : COPY_HEADER_FIELD(&decoded->toplevel_xid, sizeof(TransactionId));
1722 : }
1723 174740 : else if (block_id <= XLR_MAX_BLOCK_ID)
1724 : {
1725 : /* XLogRecordBlockHeader */
1726 : DecodedBkpBlock *blk;
1727 : uint8 fork_flags;
1728 :
1729 : /* mark any intervening block IDs as not in use */
1730 174740 : for (int i = decoded->max_block_id + 1; i < block_id; ++i)
1731 0 : decoded->blocks[i].in_use = false;
1732 :
1733 174740 : if (block_id <= decoded->max_block_id)
1734 : {
1735 0 : report_invalid_record(state,
1736 : "out-of-order block_id %u at %X/%X",
1737 : block_id,
1738 0 : LSN_FORMAT_ARGS(state->ReadRecPtr));
1739 0 : goto err;
1740 : }
1741 174740 : decoded->max_block_id = block_id;
1742 :
1743 174740 : blk = &decoded->blocks[block_id];
1744 174740 : blk->in_use = true;
1745 174740 : blk->apply_image = false;
1746 :
1747 174740 : COPY_HEADER_FIELD(&fork_flags, sizeof(uint8));
1748 174740 : blk->forknum = fork_flags & BKPBLOCK_FORK_MASK;
1749 174740 : blk->flags = fork_flags;
1750 174740 : blk->has_image = ((fork_flags & BKPBLOCK_HAS_IMAGE) != 0);
1751 174740 : blk->has_data = ((fork_flags & BKPBLOCK_HAS_DATA) != 0);
1752 :
1753 174740 : blk->prefetch_buffer = InvalidBuffer;
1754 :
1755 174740 : COPY_HEADER_FIELD(&blk->data_len, sizeof(uint16));
1756 : /* cross-check that the HAS_DATA flag is set iff data_length > 0 */
1757 174740 : if (blk->has_data && blk->data_len == 0)
1758 : {
1759 0 : report_invalid_record(state,
1760 : "BKPBLOCK_HAS_DATA set, but no data included at %X/%X",
1761 0 : LSN_FORMAT_ARGS(state->ReadRecPtr));
1762 0 : goto err;
1763 : }
1764 174740 : if (!blk->has_data && blk->data_len != 0)
1765 : {
1766 0 : report_invalid_record(state,
1767 : "BKPBLOCK_HAS_DATA not set, but data length is %u at %X/%X",
1768 0 : (unsigned int) blk->data_len,
1769 0 : LSN_FORMAT_ARGS(state->ReadRecPtr));
1770 0 : goto err;
1771 : }
1772 174740 : datatotal += blk->data_len;
1773 :
1774 174740 : if (blk->has_image)
1775 : {
1776 11472 : COPY_HEADER_FIELD(&blk->bimg_len, sizeof(uint16));
1777 11472 : COPY_HEADER_FIELD(&blk->hole_offset, sizeof(uint16));
1778 11472 : COPY_HEADER_FIELD(&blk->bimg_info, sizeof(uint8));
1779 :
1780 11472 : blk->apply_image = ((blk->bimg_info & BKPIMAGE_APPLY) != 0);
1781 :
1782 11472 : if (BKPIMAGE_COMPRESSED(blk->bimg_info))
1783 : {
1784 0 : if (blk->bimg_info & BKPIMAGE_HAS_HOLE)
1785 0 : COPY_HEADER_FIELD(&blk->hole_length, sizeof(uint16));
1786 : else
1787 0 : blk->hole_length = 0;
1788 : }
1789 : else
1790 11472 : blk->hole_length = BLCKSZ - blk->bimg_len;
1791 11472 : datatotal += blk->bimg_len;
1792 :
1793 : /*
1794 : * cross-check that hole_offset > 0, hole_length > 0 and
1795 : * bimg_len < BLCKSZ if the HAS_HOLE flag is set.
1796 : */
1797 11472 : if ((blk->bimg_info & BKPIMAGE_HAS_HOLE) &&
1798 11340 : (blk->hole_offset == 0 ||
1799 11340 : blk->hole_length == 0 ||
1800 11340 : blk->bimg_len == BLCKSZ))
1801 : {
1802 0 : report_invalid_record(state,
1803 : "BKPIMAGE_HAS_HOLE set, but hole offset %u length %u block image length %u at %X/%X",
1804 0 : (unsigned int) blk->hole_offset,
1805 0 : (unsigned int) blk->hole_length,
1806 0 : (unsigned int) blk->bimg_len,
1807 0 : LSN_FORMAT_ARGS(state->ReadRecPtr));
1808 0 : goto err;
1809 : }
1810 :
1811 : /*
1812 : * cross-check that hole_offset == 0 and hole_length == 0 if
1813 : * the HAS_HOLE flag is not set.
1814 : */
1815 11472 : if (!(blk->bimg_info & BKPIMAGE_HAS_HOLE) &&
1816 132 : (blk->hole_offset != 0 || blk->hole_length != 0))
1817 : {
1818 0 : report_invalid_record(state,
1819 : "BKPIMAGE_HAS_HOLE not set, but hole offset %u length %u at %X/%X",
1820 0 : (unsigned int) blk->hole_offset,
1821 0 : (unsigned int) blk->hole_length,
1822 0 : LSN_FORMAT_ARGS(state->ReadRecPtr));
1823 0 : goto err;
1824 : }
1825 :
1826 : /*
1827 : * Cross-check that bimg_len < BLCKSZ if it is compressed.
1828 : */
1829 11472 : if (BKPIMAGE_COMPRESSED(blk->bimg_info) &&
1830 0 : blk->bimg_len == BLCKSZ)
1831 : {
1832 0 : report_invalid_record(state,
1833 : "BKPIMAGE_COMPRESSED set, but block image length %u at %X/%X",
1834 0 : (unsigned int) blk->bimg_len,
1835 0 : LSN_FORMAT_ARGS(state->ReadRecPtr));
1836 0 : goto err;
1837 : }
1838 :
1839 : /*
1840 : * cross-check that bimg_len = BLCKSZ if neither HAS_HOLE is
1841 : * set nor COMPRESSED().
1842 : */
1843 11472 : if (!(blk->bimg_info & BKPIMAGE_HAS_HOLE) &&
1844 132 : !BKPIMAGE_COMPRESSED(blk->bimg_info) &&
1845 132 : blk->bimg_len != BLCKSZ)
1846 : {
1847 0 : report_invalid_record(state,
1848 : "neither BKPIMAGE_HAS_HOLE nor BKPIMAGE_COMPRESSED set, but block image length is %u at %X/%X",
1849 0 : (unsigned int) blk->data_len,
1850 0 : LSN_FORMAT_ARGS(state->ReadRecPtr));
1851 0 : goto err;
1852 : }
1853 : }
1854 174740 : if (!(fork_flags & BKPBLOCK_SAME_REL))
1855 : {
1856 174068 : COPY_HEADER_FIELD(&blk->rlocator, sizeof(RelFileLocator));
1857 174068 : rlocator = &blk->rlocator;
1858 : }
1859 : else
1860 : {
1861 672 : if (rlocator == NULL)
1862 : {
1863 0 : report_invalid_record(state,
1864 : "BKPBLOCK_SAME_REL set but no previous rel at %X/%X",
1865 0 : LSN_FORMAT_ARGS(state->ReadRecPtr));
1866 0 : goto err;
1867 : }
1868 :
1869 672 : blk->rlocator = *rlocator;
1870 : }
1871 174740 : COPY_HEADER_FIELD(&blk->blkno, sizeof(BlockNumber));
1872 : }
1873 : else
1874 : {
1875 0 : report_invalid_record(state,
1876 : "invalid block_id %u at %X/%X",
1877 0 : block_id, LSN_FORMAT_ARGS(state->ReadRecPtr));
1878 0 : goto err;
1879 : }
1880 : }
1881 :
1882 177966 : if (remaining != datatotal)
1883 0 : goto shortdata_err;
1884 :
1885 : /*
1886 : * Ok, we've parsed the fragment headers, and verified that the total
1887 : * length of the payload in the fragments is equal to the amount of data
1888 : * left. Copy the data of each fragment to contiguous space after the
1889 : * blocks array, inserting alignment padding before the data fragments so
1890 : * they can be cast to struct pointers by REDO routines.
1891 : */
1892 177966 : out = ((char *) decoded) +
1893 177966 : offsetof(DecodedXLogRecord, blocks) +
1894 177966 : sizeof(decoded->blocks[0]) * (decoded->max_block_id + 1);
1895 :
1896 : /* block data first */
1897 352706 : for (block_id = 0; block_id <= decoded->max_block_id; block_id++)
1898 : {
1899 174740 : DecodedBkpBlock *blk = &decoded->blocks[block_id];
1900 :
1901 174740 : if (!blk->in_use)
1902 0 : continue;
1903 :
1904 : Assert(blk->has_image || !blk->apply_image);
1905 :
1906 174740 : if (blk->has_image)
1907 : {
1908 : /* no need to align image */
1909 11472 : blk->bkp_image = out;
1910 11472 : memcpy(out, ptr, blk->bimg_len);
1911 11472 : ptr += blk->bimg_len;
1912 11472 : out += blk->bimg_len;
1913 : }
1914 174740 : if (blk->has_data)
1915 : {
1916 81780 : out = (char *) MAXALIGN(out);
1917 81780 : blk->data = out;
1918 81780 : memcpy(blk->data, ptr, blk->data_len);
1919 81780 : ptr += blk->data_len;
1920 81780 : out += blk->data_len;
1921 : }
1922 : }
1923 :
1924 : /* and finally, the main data */
1925 177966 : if (decoded->main_data_len > 0)
1926 : {
1927 166576 : out = (char *) MAXALIGN(out);
1928 166576 : decoded->main_data = out;
1929 166576 : memcpy(decoded->main_data, ptr, decoded->main_data_len);
1930 166576 : ptr += decoded->main_data_len;
1931 166576 : out += decoded->main_data_len;
1932 : }
1933 :
1934 : /* Report the actual size we used. */
1935 177966 : decoded->size = MAXALIGN(out - (char *) decoded);
1936 : Assert(DecodeXLogRecordRequiredSpace(record->xl_tot_len) >=
1937 : decoded->size);
1938 :
1939 177966 : return true;
1940 :
1941 0 : shortdata_err:
1942 0 : report_invalid_record(state,
1943 : "record with invalid length at %X/%X",
1944 0 : LSN_FORMAT_ARGS(state->ReadRecPtr));
1945 0 : err:
1946 0 : *errormsg = state->errormsg_buf;
1947 :
1948 0 : return false;
1949 : }
1950 :
1951 : /*
1952 : * Returns information about the block that a block reference refers to.
1953 : *
1954 : * This is like XLogRecGetBlockTagExtended, except that the block reference
1955 : * must exist and there's no access to prefetch_buffer.
1956 : */
1957 : void
1958 0 : XLogRecGetBlockTag(XLogReaderState *record, uint8 block_id,
1959 : RelFileLocator *rlocator, ForkNumber *forknum,
1960 : BlockNumber *blknum)
1961 : {
1962 0 : if (!XLogRecGetBlockTagExtended(record, block_id, rlocator, forknum,
1963 : blknum, NULL))
1964 : {
1965 : #ifndef FRONTEND
1966 : elog(ERROR, "could not locate backup block with ID %d in WAL record",
1967 : block_id);
1968 : #else
1969 0 : pg_fatal("could not locate backup block with ID %d in WAL record",
1970 : block_id);
1971 : #endif
1972 : }
1973 0 : }
1974 :
1975 : /*
1976 : * Returns information about the block that a block reference refers to,
1977 : * optionally including the buffer that the block may already be in.
1978 : *
1979 : * If the WAL record contains a block reference with the given ID, *rlocator,
1980 : * *forknum, *blknum and *prefetch_buffer are filled in (if not NULL), and
1981 : * returns true. Otherwise returns false.
1982 : */
1983 : bool
1984 171036 : XLogRecGetBlockTagExtended(XLogReaderState *record, uint8 block_id,
1985 : RelFileLocator *rlocator, ForkNumber *forknum,
1986 : BlockNumber *blknum,
1987 : Buffer *prefetch_buffer)
1988 : {
1989 : DecodedBkpBlock *bkpb;
1990 :
1991 171036 : if (!XLogRecHasBlockRef(record, block_id))
1992 0 : return false;
1993 :
1994 171036 : bkpb = &record->record->blocks[block_id];
1995 171036 : if (rlocator)
1996 171036 : *rlocator = bkpb->rlocator;
1997 171036 : if (forknum)
1998 171036 : *forknum = bkpb->forknum;
1999 171036 : if (blknum)
2000 171036 : *blknum = bkpb->blkno;
2001 171036 : if (prefetch_buffer)
2002 0 : *prefetch_buffer = bkpb->prefetch_buffer;
2003 171036 : return true;
2004 : }
2005 :
2006 : /*
2007 : * Returns the data associated with a block reference, or NULL if there is
2008 : * no data (e.g. because a full-page image was taken instead). The returned
2009 : * pointer points to a MAXALIGNed buffer.
2010 : */
2011 : char *
2012 0 : XLogRecGetBlockData(XLogReaderState *record, uint8 block_id, Size *len)
2013 : {
2014 : DecodedBkpBlock *bkpb;
2015 :
2016 0 : if (block_id > record->record->max_block_id ||
2017 0 : !record->record->blocks[block_id].in_use)
2018 0 : return NULL;
2019 :
2020 0 : bkpb = &record->record->blocks[block_id];
2021 :
2022 0 : if (!bkpb->has_data)
2023 : {
2024 0 : if (len)
2025 0 : *len = 0;
2026 0 : return NULL;
2027 : }
2028 : else
2029 : {
2030 0 : if (len)
2031 0 : *len = bkpb->data_len;
2032 0 : return bkpb->data;
2033 : }
2034 : }
2035 :
2036 : /*
2037 : * Restore a full-page image from a backup block attached to an XLOG record.
2038 : *
2039 : * Returns true if a full-page image is restored, and false on failure with
2040 : * an error to be consumed by the caller.
2041 : */
2042 : bool
2043 0 : RestoreBlockImage(XLogReaderState *record, uint8 block_id, char *page)
2044 : {
2045 : DecodedBkpBlock *bkpb;
2046 : char *ptr;
2047 : PGAlignedBlock tmp;
2048 :
2049 0 : if (block_id > record->record->max_block_id ||
2050 0 : !record->record->blocks[block_id].in_use)
2051 : {
2052 0 : report_invalid_record(record,
2053 : "could not restore image at %X/%X with invalid block %d specified",
2054 0 : LSN_FORMAT_ARGS(record->ReadRecPtr),
2055 : block_id);
2056 0 : return false;
2057 : }
2058 0 : if (!record->record->blocks[block_id].has_image)
2059 : {
2060 0 : report_invalid_record(record, "could not restore image at %X/%X with invalid state, block %d",
2061 0 : LSN_FORMAT_ARGS(record->ReadRecPtr),
2062 : block_id);
2063 0 : return false;
2064 : }
2065 :
2066 0 : bkpb = &record->record->blocks[block_id];
2067 0 : ptr = bkpb->bkp_image;
2068 :
2069 0 : if (BKPIMAGE_COMPRESSED(bkpb->bimg_info))
2070 : {
2071 : /* If a backup block image is compressed, decompress it */
2072 0 : bool decomp_success = true;
2073 :
2074 0 : if ((bkpb->bimg_info & BKPIMAGE_COMPRESS_PGLZ) != 0)
2075 : {
2076 0 : if (pglz_decompress(ptr, bkpb->bimg_len, tmp.data,
2077 0 : BLCKSZ - bkpb->hole_length, true) < 0)
2078 0 : decomp_success = false;
2079 : }
2080 0 : else if ((bkpb->bimg_info & BKPIMAGE_COMPRESS_LZ4) != 0)
2081 : {
2082 : #ifdef USE_LZ4
2083 0 : if (LZ4_decompress_safe(ptr, tmp.data,
2084 0 : bkpb->bimg_len, BLCKSZ - bkpb->hole_length) <= 0)
2085 0 : decomp_success = false;
2086 : #else
2087 : report_invalid_record(record, "could not restore image at %X/%X compressed with %s not supported by build, block %d",
2088 : LSN_FORMAT_ARGS(record->ReadRecPtr),
2089 : "LZ4",
2090 : block_id);
2091 : return false;
2092 : #endif
2093 : }
2094 0 : else if ((bkpb->bimg_info & BKPIMAGE_COMPRESS_ZSTD) != 0)
2095 : {
2096 : #ifdef USE_ZSTD
2097 : size_t decomp_result = ZSTD_decompress(tmp.data,
2098 : BLCKSZ - bkpb->hole_length,
2099 : ptr, bkpb->bimg_len);
2100 :
2101 : if (ZSTD_isError(decomp_result))
2102 : decomp_success = false;
2103 : #else
2104 0 : report_invalid_record(record, "could not restore image at %X/%X compressed with %s not supported by build, block %d",
2105 0 : LSN_FORMAT_ARGS(record->ReadRecPtr),
2106 : "zstd",
2107 : block_id);
2108 0 : return false;
2109 : #endif
2110 : }
2111 : else
2112 : {
2113 0 : report_invalid_record(record, "could not restore image at %X/%X compressed with unknown method, block %d",
2114 0 : LSN_FORMAT_ARGS(record->ReadRecPtr),
2115 : block_id);
2116 0 : return false;
2117 : }
2118 :
2119 0 : if (!decomp_success)
2120 : {
2121 0 : report_invalid_record(record, "could not decompress image at %X/%X, block %d",
2122 0 : LSN_FORMAT_ARGS(record->ReadRecPtr),
2123 : block_id);
2124 0 : return false;
2125 : }
2126 :
2127 0 : ptr = tmp.data;
2128 : }
2129 :
2130 : /* generate page, taking into account hole if necessary */
2131 0 : if (bkpb->hole_length == 0)
2132 : {
2133 0 : memcpy(page, ptr, BLCKSZ);
2134 : }
2135 : else
2136 : {
2137 0 : memcpy(page, ptr, bkpb->hole_offset);
2138 : /* must zero-fill the hole */
2139 0 : MemSet(page + bkpb->hole_offset, 0, bkpb->hole_length);
2140 0 : memcpy(page + (bkpb->hole_offset + bkpb->hole_length),
2141 0 : ptr + bkpb->hole_offset,
2142 0 : BLCKSZ - (bkpb->hole_offset + bkpb->hole_length));
2143 : }
2144 :
2145 0 : return true;
2146 : }
2147 :
2148 : #ifndef FRONTEND
2149 :
2150 : /*
2151 : * Extract the FullTransactionId from a WAL record.
2152 : */
2153 : FullTransactionId
2154 : XLogRecGetFullXid(XLogReaderState *record)
2155 : {
2156 : TransactionId xid,
2157 : next_xid;
2158 : uint32 epoch;
2159 :
2160 : /*
2161 : * This function is only safe during replay, because it depends on the
2162 : * replay state. See AdvanceNextFullTransactionIdPastXid() for more.
2163 : */
2164 : Assert(AmStartupProcess() || !IsUnderPostmaster);
2165 :
2166 : xid = XLogRecGetXid(record);
2167 : next_xid = XidFromFullTransactionId(ShmemVariableCache->nextXid);
2168 : epoch = EpochFromFullTransactionId(ShmemVariableCache->nextXid);
2169 :
2170 : /*
2171 : * If xid is numerically greater than next_xid, it has to be from the last
2172 : * epoch.
2173 : */
2174 : if (unlikely(xid > next_xid))
2175 : --epoch;
2176 :
2177 : return FullTransactionIdFromEpochAndXid(epoch, xid);
2178 : }
2179 :
2180 : #endif
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