Line data Source code
1 : /*-------------------------------------------------------------------------
2 : *
3 : * xlogreader.c
4 : * Generic XLog reading facility
5 : *
6 : * Portions Copyright (c) 2013-2025, 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 "pgstat.h"
38 : #include "storage/bufmgr.h"
39 : #else
40 : #include "common/logging.h"
41 : #endif
42 :
43 : static void report_invalid_record(XLogReaderState *state, const char *fmt,...)
44 : pg_attribute_printf(2, 3);
45 : static void allocate_recordbuf(XLogReaderState *state, uint32 reclength);
46 : static int ReadPageInternal(XLogReaderState *state, XLogRecPtr pageptr,
47 : int reqLen);
48 : static void XLogReaderInvalReadState(XLogReaderState *state);
49 : static XLogPageReadResult XLogDecodeNextRecord(XLogReaderState *state, bool nonblocking);
50 : static bool ValidXLogRecordHeader(XLogReaderState *state, XLogRecPtr RecPtr,
51 : XLogRecPtr PrevRecPtr, XLogRecord *record, bool randAccess);
52 : static bool ValidXLogRecord(XLogReaderState *state, XLogRecord *record,
53 : XLogRecPtr recptr);
54 : static void ResetDecoder(XLogReaderState *state);
55 : static void WALOpenSegmentInit(WALOpenSegment *seg, WALSegmentContext *segcxt,
56 : int segsize, const char *waldir);
57 :
58 : /* size of the buffer allocated for error message. */
59 : #define MAX_ERRORMSG_LEN 1000
60 :
61 : /*
62 : * Default size; large enough that typical users of XLogReader won't often need
63 : * to use the 'oversized' memory allocation code path.
64 : */
65 : #define DEFAULT_DECODE_BUFFER_SIZE (64 * 1024)
66 :
67 : /*
68 : * Construct a string in state->errormsg_buf explaining what's wrong with
69 : * the current record being read.
70 : */
71 : static void
72 0 : report_invalid_record(XLogReaderState *state, const char *fmt,...)
73 : {
74 : va_list args;
75 :
76 0 : fmt = _(fmt);
77 :
78 0 : va_start(args, fmt);
79 0 : vsnprintf(state->errormsg_buf, MAX_ERRORMSG_LEN, fmt, args);
80 0 : va_end(args);
81 :
82 0 : state->errormsg_deferred = true;
83 0 : }
84 :
85 : /*
86 : * Set the size of the decoding buffer. A pointer to a caller supplied memory
87 : * region may also be passed in, in which case non-oversized records will be
88 : * decoded there.
89 : */
90 : void
91 0 : XLogReaderSetDecodeBuffer(XLogReaderState *state, void *buffer, size_t size)
92 : {
93 : Assert(state->decode_buffer == NULL);
94 :
95 0 : state->decode_buffer = buffer;
96 0 : state->decode_buffer_size = size;
97 0 : state->decode_buffer_tail = buffer;
98 0 : state->decode_buffer_head = buffer;
99 0 : }
100 :
101 : /*
102 : * Allocate and initialize a new XLogReader.
103 : *
104 : * Returns NULL if the xlogreader couldn't be allocated.
105 : */
106 : XLogReaderState *
107 84 : XLogReaderAllocate(int wal_segment_size, const char *waldir,
108 : XLogReaderRoutine *routine, void *private_data)
109 : {
110 : XLogReaderState *state;
111 :
112 : state = (XLogReaderState *)
113 84 : palloc_extended(sizeof(XLogReaderState),
114 : MCXT_ALLOC_NO_OOM | MCXT_ALLOC_ZERO);
115 84 : if (!state)
116 0 : return NULL;
117 :
118 : /* initialize caller-provided support functions */
119 84 : state->routine = *routine;
120 :
121 : /*
122 : * Permanently allocate readBuf. We do it this way, rather than just
123 : * making a static array, for two reasons: (1) no need to waste the
124 : * storage in most instantiations of the backend; (2) a static char array
125 : * isn't guaranteed to have any particular alignment, whereas
126 : * palloc_extended() will provide MAXALIGN'd storage.
127 : */
128 84 : state->readBuf = (char *) palloc_extended(XLOG_BLCKSZ,
129 : MCXT_ALLOC_NO_OOM);
130 84 : if (!state->readBuf)
131 : {
132 0 : pfree(state);
133 0 : return NULL;
134 : }
135 :
136 : /* Initialize segment info. */
137 84 : WALOpenSegmentInit(&state->seg, &state->segcxt, wal_segment_size,
138 : waldir);
139 :
140 : /* system_identifier initialized to zeroes above */
141 84 : state->private_data = private_data;
142 : /* ReadRecPtr, EndRecPtr and readLen initialized to zeroes above */
143 84 : state->errormsg_buf = palloc_extended(MAX_ERRORMSG_LEN + 1,
144 : MCXT_ALLOC_NO_OOM);
145 84 : if (!state->errormsg_buf)
146 : {
147 0 : pfree(state->readBuf);
148 0 : pfree(state);
149 0 : return NULL;
150 : }
151 84 : state->errormsg_buf[0] = '\0';
152 :
153 : /*
154 : * Allocate an initial readRecordBuf of minimal size, which can later be
155 : * enlarged if necessary.
156 : */
157 84 : allocate_recordbuf(state, 0);
158 84 : return state;
159 : }
160 :
161 : void
162 84 : XLogReaderFree(XLogReaderState *state)
163 : {
164 84 : if (state->seg.ws_file != -1)
165 0 : state->routine.segment_close(state);
166 :
167 84 : if (state->decode_buffer && state->free_decode_buffer)
168 84 : pfree(state->decode_buffer);
169 :
170 84 : pfree(state->errormsg_buf);
171 84 : if (state->readRecordBuf)
172 84 : pfree(state->readRecordBuf);
173 84 : pfree(state->readBuf);
174 84 : pfree(state);
175 84 : }
176 :
177 : /*
178 : * Allocate readRecordBuf to fit a record of at least the given length.
179 : *
180 : * readRecordBufSize is set to the new buffer size.
181 : *
182 : * To avoid useless small increases, round its size to a multiple of
183 : * XLOG_BLCKSZ, and make sure it's at least 5*Max(BLCKSZ, XLOG_BLCKSZ) to start
184 : * with. (That is enough for all "normal" records, but very large commit or
185 : * abort records might need more space.)
186 : *
187 : * Note: This routine should *never* be called for xl_tot_len until the header
188 : * of the record has been fully validated.
189 : */
190 : static void
191 84 : allocate_recordbuf(XLogReaderState *state, uint32 reclength)
192 : {
193 84 : uint32 newSize = reclength;
194 :
195 84 : newSize += XLOG_BLCKSZ - (newSize % XLOG_BLCKSZ);
196 84 : newSize = Max(newSize, 5 * Max(BLCKSZ, XLOG_BLCKSZ));
197 :
198 84 : if (state->readRecordBuf)
199 0 : pfree(state->readRecordBuf);
200 84 : state->readRecordBuf = (char *) palloc(newSize);
201 84 : state->readRecordBufSize = newSize;
202 84 : }
203 :
204 : /*
205 : * Initialize the passed segment structs.
206 : */
207 : static void
208 84 : WALOpenSegmentInit(WALOpenSegment *seg, WALSegmentContext *segcxt,
209 : int segsize, const char *waldir)
210 : {
211 84 : seg->ws_file = -1;
212 84 : seg->ws_segno = 0;
213 84 : seg->ws_tli = 0;
214 :
215 84 : segcxt->ws_segsize = segsize;
216 84 : if (waldir)
217 84 : snprintf(segcxt->ws_dir, MAXPGPATH, "%s", waldir);
218 84 : }
219 :
220 : /*
221 : * Begin reading WAL at 'RecPtr'.
222 : *
223 : * 'RecPtr' should point to the beginning of a valid WAL record. Pointing at
224 : * the beginning of a page is also OK, if there is a new record right after
225 : * the page header, i.e. not a continuation.
226 : *
227 : * This does not make any attempt to read the WAL yet, and hence cannot fail.
228 : * If the starting address is not correct, the first call to XLogReadRecord()
229 : * will error out.
230 : */
231 : void
232 5374 : XLogBeginRead(XLogReaderState *state, XLogRecPtr RecPtr)
233 : {
234 : Assert(!XLogRecPtrIsInvalid(RecPtr));
235 :
236 5374 : ResetDecoder(state);
237 :
238 : /* Begin at the passed-in record pointer. */
239 5374 : state->EndRecPtr = RecPtr;
240 5374 : state->NextRecPtr = RecPtr;
241 5374 : state->ReadRecPtr = InvalidXLogRecPtr;
242 5374 : state->DecodeRecPtr = InvalidXLogRecPtr;
243 5374 : }
244 :
245 : /*
246 : * Release the last record that was returned by XLogNextRecord(), if any, to
247 : * free up space. Returns the LSN past the end of the record.
248 : */
249 : XLogRecPtr
250 356596 : XLogReleasePreviousRecord(XLogReaderState *state)
251 : {
252 : DecodedXLogRecord *record;
253 : XLogRecPtr next_lsn;
254 :
255 356596 : if (!state->record)
256 183672 : return InvalidXLogRecPtr;
257 :
258 : /*
259 : * Remove it from the decoded record queue. It must be the oldest item
260 : * decoded, decode_queue_head.
261 : */
262 172924 : record = state->record;
263 172924 : next_lsn = record->next_lsn;
264 : Assert(record == state->decode_queue_head);
265 172924 : state->record = NULL;
266 172924 : state->decode_queue_head = record->next;
267 :
268 : /* It might also be the newest item decoded, decode_queue_tail. */
269 172924 : if (state->decode_queue_tail == record)
270 172924 : state->decode_queue_tail = NULL;
271 :
272 : /* Release the space. */
273 172924 : if (unlikely(record->oversized))
274 : {
275 : /* It's not in the decode buffer, so free it to release space. */
276 0 : pfree(record);
277 : }
278 : else
279 : {
280 : /* It must be the head (oldest) record in the decode buffer. */
281 : Assert(state->decode_buffer_head == (char *) record);
282 :
283 : /*
284 : * We need to update head to point to the next record that is in the
285 : * decode buffer, if any, being careful to skip oversized ones
286 : * (they're not in the decode buffer).
287 : */
288 172924 : record = record->next;
289 172924 : while (unlikely(record && record->oversized))
290 0 : record = record->next;
291 :
292 172924 : if (record)
293 : {
294 : /* Adjust head to release space up to the next record. */
295 0 : state->decode_buffer_head = (char *) record;
296 : }
297 : else
298 : {
299 : /*
300 : * Otherwise we might as well just reset head and tail to the
301 : * start of the buffer space, because we're empty. This means
302 : * we'll keep overwriting the same piece of memory if we're not
303 : * doing any prefetching.
304 : */
305 172924 : state->decode_buffer_head = state->decode_buffer;
306 172924 : state->decode_buffer_tail = state->decode_buffer;
307 : }
308 : }
309 :
310 172924 : return next_lsn;
311 : }
312 :
313 : /*
314 : * Attempt to read an XLOG record.
315 : *
316 : * XLogBeginRead() or XLogFindNextRecord() and then XLogReadAhead() must be
317 : * called before the first call to XLogNextRecord(). This functions returns
318 : * records and errors that were put into an internal queue by XLogReadAhead().
319 : *
320 : * On success, a record is returned.
321 : *
322 : * The returned record (or *errormsg) points to an internal buffer that's
323 : * valid until the next call to XLogNextRecord.
324 : */
325 : DecodedXLogRecord *
326 178298 : XLogNextRecord(XLogReaderState *state, char **errormsg)
327 : {
328 : /* Release the last record returned by XLogNextRecord(). */
329 178298 : XLogReleasePreviousRecord(state);
330 :
331 178298 : if (state->decode_queue_head == NULL)
332 : {
333 0 : *errormsg = NULL;
334 0 : if (state->errormsg_deferred)
335 : {
336 0 : if (state->errormsg_buf[0] != '\0')
337 0 : *errormsg = state->errormsg_buf;
338 0 : state->errormsg_deferred = false;
339 : }
340 :
341 : /*
342 : * state->EndRecPtr is expected to have been set by the last call to
343 : * XLogBeginRead() or XLogNextRecord(), and is the location of the
344 : * error.
345 : */
346 : Assert(!XLogRecPtrIsInvalid(state->EndRecPtr));
347 :
348 0 : return NULL;
349 : }
350 :
351 : /*
352 : * Record this as the most recent record returned, so that we'll release
353 : * it next time. This also exposes it to the traditional
354 : * XLogRecXXX(xlogreader) macros, which work with the decoder rather than
355 : * the record for historical reasons.
356 : */
357 178298 : state->record = state->decode_queue_head;
358 :
359 : /*
360 : * Update the pointers to the beginning and one-past-the-end of this
361 : * record, again for the benefit of historical code that expected the
362 : * decoder to track this rather than accessing these fields of the record
363 : * itself.
364 : */
365 178298 : state->ReadRecPtr = state->record->lsn;
366 178298 : state->EndRecPtr = state->record->next_lsn;
367 :
368 178298 : *errormsg = NULL;
369 :
370 178298 : return state->record;
371 : }
372 :
373 : /*
374 : * Attempt to read an XLOG record.
375 : *
376 : * XLogBeginRead() or XLogFindNextRecord() must be called before the first call
377 : * to XLogReadRecord().
378 : *
379 : * If the page_read callback fails to read the requested data, NULL is
380 : * returned. The callback is expected to have reported the error; errormsg
381 : * is set to NULL.
382 : *
383 : * If the reading fails for some other reason, NULL is also returned, and
384 : * *errormsg is set to a string with details of the failure.
385 : *
386 : * The returned pointer (or *errormsg) points to an internal buffer that's
387 : * valid until the next call to XLogReadRecord.
388 : */
389 : XLogRecord *
390 178298 : XLogReadRecord(XLogReaderState *state, char **errormsg)
391 : {
392 : DecodedXLogRecord *decoded;
393 :
394 : /*
395 : * Release last returned record, if there is one. We need to do this so
396 : * that we can check for empty decode queue accurately.
397 : */
398 178298 : XLogReleasePreviousRecord(state);
399 :
400 : /*
401 : * Call XLogReadAhead() in blocking mode to make sure there is something
402 : * in the queue, though we don't use the result.
403 : */
404 178298 : if (!XLogReaderHasQueuedRecordOrError(state))
405 178298 : XLogReadAhead(state, false /* nonblocking */ );
406 :
407 : /* Consume the head record or error. */
408 178298 : decoded = XLogNextRecord(state, errormsg);
409 178298 : if (decoded)
410 : {
411 : /*
412 : * This function returns a pointer to the record's header, not the
413 : * actual decoded record. The caller will access the decoded record
414 : * through the XLogRecGetXXX() macros, which reach the decoded
415 : * recorded as xlogreader->record.
416 : */
417 : Assert(state->record == decoded);
418 178298 : return &decoded->header;
419 : }
420 :
421 0 : return NULL;
422 : }
423 :
424 : /*
425 : * Allocate space for a decoded record. The only member of the returned
426 : * object that is initialized is the 'oversized' flag, indicating that the
427 : * decoded record wouldn't fit in the decode buffer and must eventually be
428 : * freed explicitly.
429 : *
430 : * The caller is responsible for adjusting decode_buffer_tail with the real
431 : * size after successfully decoding a record into this space. This way, if
432 : * decoding fails, then there is nothing to undo unless the 'oversized' flag
433 : * was set and pfree() must be called.
434 : *
435 : * Return NULL if there is no space in the decode buffer and allow_oversized
436 : * is false, or if memory allocation fails for an oversized buffer.
437 : */
438 : static DecodedXLogRecord *
439 178298 : XLogReadRecordAlloc(XLogReaderState *state, size_t xl_tot_len, bool allow_oversized)
440 : {
441 178298 : size_t required_space = DecodeXLogRecordRequiredSpace(xl_tot_len);
442 178298 : DecodedXLogRecord *decoded = NULL;
443 :
444 : /* Allocate a circular decode buffer if we don't have one already. */
445 178298 : if (unlikely(state->decode_buffer == NULL))
446 : {
447 84 : if (state->decode_buffer_size == 0)
448 84 : state->decode_buffer_size = DEFAULT_DECODE_BUFFER_SIZE;
449 84 : state->decode_buffer = palloc(state->decode_buffer_size);
450 84 : state->decode_buffer_head = state->decode_buffer;
451 84 : state->decode_buffer_tail = state->decode_buffer;
452 84 : state->free_decode_buffer = true;
453 : }
454 :
455 : /* Try to allocate space in the circular decode buffer. */
456 178298 : if (state->decode_buffer_tail >= state->decode_buffer_head)
457 : {
458 : /* Empty, or tail is to the right of head. */
459 178298 : if (required_space <=
460 178298 : state->decode_buffer_size -
461 178298 : (state->decode_buffer_tail - state->decode_buffer))
462 : {
463 : /*-
464 : * There is space between tail and end.
465 : *
466 : * +-----+--------------------+-----+
467 : * | |////////////////////|here!|
468 : * +-----+--------------------+-----+
469 : * ^ ^
470 : * | |
471 : * h t
472 : */
473 178298 : decoded = (DecodedXLogRecord *) state->decode_buffer_tail;
474 178298 : decoded->oversized = false;
475 178298 : return decoded;
476 : }
477 0 : else if (required_space <
478 0 : state->decode_buffer_head - state->decode_buffer)
479 : {
480 : /*-
481 : * There is space between start and head.
482 : *
483 : * +-----+--------------------+-----+
484 : * |here!|////////////////////| |
485 : * +-----+--------------------+-----+
486 : * ^ ^
487 : * | |
488 : * h t
489 : */
490 0 : decoded = (DecodedXLogRecord *) state->decode_buffer;
491 0 : decoded->oversized = false;
492 0 : return decoded;
493 : }
494 : }
495 : else
496 : {
497 : /* Tail is to the left of head. */
498 0 : if (required_space <
499 0 : state->decode_buffer_head - state->decode_buffer_tail)
500 : {
501 : /*-
502 : * There is space between tail and head.
503 : *
504 : * +-----+--------------------+-----+
505 : * |/////|here! |/////|
506 : * +-----+--------------------+-----+
507 : * ^ ^
508 : * | |
509 : * t h
510 : */
511 0 : decoded = (DecodedXLogRecord *) state->decode_buffer_tail;
512 0 : decoded->oversized = false;
513 0 : return decoded;
514 : }
515 : }
516 :
517 : /* Not enough space in the decode buffer. Are we allowed to allocate? */
518 0 : if (allow_oversized)
519 : {
520 0 : decoded = palloc(required_space);
521 0 : decoded->oversized = true;
522 0 : return decoded;
523 : }
524 :
525 0 : return NULL;
526 : }
527 :
528 : static XLogPageReadResult
529 178298 : XLogDecodeNextRecord(XLogReaderState *state, bool nonblocking)
530 : {
531 : XLogRecPtr RecPtr;
532 : XLogRecord *record;
533 : XLogRecPtr targetPagePtr;
534 : bool randAccess;
535 : uint32 len,
536 : total_len;
537 : uint32 targetRecOff;
538 : uint32 pageHeaderSize;
539 : bool assembled;
540 : bool gotheader;
541 : int readOff;
542 : DecodedXLogRecord *decoded;
543 : char *errormsg; /* not used */
544 :
545 : /*
546 : * randAccess indicates whether to verify the previous-record pointer of
547 : * the record we're reading. We only do this if we're reading
548 : * sequentially, which is what we initially assume.
549 : */
550 178298 : randAccess = false;
551 :
552 : /* reset error state */
553 178298 : state->errormsg_buf[0] = '\0';
554 178298 : decoded = NULL;
555 :
556 178298 : state->abortedRecPtr = InvalidXLogRecPtr;
557 178298 : state->missingContrecPtr = InvalidXLogRecPtr;
558 :
559 178298 : RecPtr = state->NextRecPtr;
560 :
561 178298 : if (state->DecodeRecPtr != InvalidXLogRecPtr)
562 : {
563 : /* read the record after the one we just read */
564 :
565 : /*
566 : * NextRecPtr is pointing to end+1 of the previous WAL record. If
567 : * we're at a page boundary, no more records can fit on the current
568 : * page. We must skip over the page header, but we can't do that until
569 : * we've read in the page, since the header size is variable.
570 : */
571 : }
572 : else
573 : {
574 : /*
575 : * Caller supplied a position to start at.
576 : *
577 : * In this case, NextRecPtr should already be pointing either to a
578 : * valid record starting position or alternatively to the beginning of
579 : * a page. See the header comments for XLogBeginRead.
580 : */
581 : Assert(RecPtr % XLOG_BLCKSZ == 0 || XRecOffIsValid(RecPtr));
582 5374 : randAccess = true;
583 : }
584 :
585 178298 : restart:
586 178298 : state->nonblocking = nonblocking;
587 178298 : state->currRecPtr = RecPtr;
588 178298 : assembled = false;
589 :
590 178298 : targetPagePtr = RecPtr - (RecPtr % XLOG_BLCKSZ);
591 178298 : targetRecOff = RecPtr % XLOG_BLCKSZ;
592 :
593 : /*
594 : * Read the page containing the record into state->readBuf. Request enough
595 : * byte to cover the whole record header, or at least the part of it that
596 : * fits on the same page.
597 : */
598 178298 : readOff = ReadPageInternal(state, targetPagePtr,
599 178298 : Min(targetRecOff + SizeOfXLogRecord, XLOG_BLCKSZ));
600 178298 : if (readOff == XLREAD_WOULDBLOCK)
601 0 : return XLREAD_WOULDBLOCK;
602 178298 : else if (readOff < 0)
603 0 : goto err;
604 :
605 : /*
606 : * ReadPageInternal always returns at least the page header, so we can
607 : * examine it now.
608 : */
609 178298 : pageHeaderSize = XLogPageHeaderSize((XLogPageHeader) state->readBuf);
610 178298 : if (targetRecOff == 0)
611 : {
612 : /*
613 : * At page start, so skip over page header.
614 : */
615 192 : RecPtr += pageHeaderSize;
616 192 : targetRecOff = pageHeaderSize;
617 : }
618 178106 : else if (targetRecOff < pageHeaderSize)
619 : {
620 0 : report_invalid_record(state, "invalid record offset at %X/%08X: expected at least %u, got %u",
621 0 : LSN_FORMAT_ARGS(RecPtr),
622 : pageHeaderSize, targetRecOff);
623 0 : goto err;
624 : }
625 :
626 178298 : if ((((XLogPageHeader) state->readBuf)->xlp_info & XLP_FIRST_IS_CONTRECORD) &&
627 : targetRecOff == pageHeaderSize)
628 : {
629 0 : report_invalid_record(state, "contrecord is requested by %X/%08X",
630 0 : LSN_FORMAT_ARGS(RecPtr));
631 0 : goto err;
632 : }
633 :
634 : /* ReadPageInternal has verified the page header */
635 : Assert(pageHeaderSize <= readOff);
636 :
637 : /*
638 : * Read the record length.
639 : *
640 : * NB: Even though we use an XLogRecord pointer here, the whole record
641 : * header might not fit on this page. xl_tot_len is the first field of the
642 : * struct, so it must be on this page (the records are MAXALIGNed), but we
643 : * cannot access any other fields until we've verified that we got the
644 : * whole header.
645 : */
646 178298 : record = (XLogRecord *) (state->readBuf + RecPtr % XLOG_BLCKSZ);
647 178298 : total_len = record->xl_tot_len;
648 :
649 : /*
650 : * If the whole record header is on this page, validate it immediately.
651 : * Otherwise do just a basic sanity check on xl_tot_len, and validate the
652 : * rest of the header after reading it from the next page. The xl_tot_len
653 : * check is necessary here to ensure that we enter the "Need to reassemble
654 : * record" code path below; otherwise we might fail to apply
655 : * ValidXLogRecordHeader at all.
656 : */
657 178298 : if (targetRecOff <= XLOG_BLCKSZ - SizeOfXLogRecord)
658 : {
659 177946 : if (!ValidXLogRecordHeader(state, RecPtr, state->DecodeRecPtr, record,
660 : randAccess))
661 0 : goto err;
662 177946 : gotheader = true;
663 : }
664 : else
665 : {
666 : /* There may be no next page if it's too small. */
667 352 : if (total_len < SizeOfXLogRecord)
668 : {
669 0 : report_invalid_record(state,
670 : "invalid record length at %X/%08X: expected at least %u, got %u",
671 0 : LSN_FORMAT_ARGS(RecPtr),
672 : (uint32) SizeOfXLogRecord, total_len);
673 0 : goto err;
674 : }
675 : /* We'll validate the header once we have the next page. */
676 352 : gotheader = false;
677 : }
678 :
679 : /*
680 : * Try to find space to decode this record, if we can do so without
681 : * calling palloc. If we can't, we'll try again below after we've
682 : * validated that total_len isn't garbage bytes from a recycled WAL page.
683 : */
684 178298 : decoded = XLogReadRecordAlloc(state,
685 : total_len,
686 : false /* allow_oversized */ );
687 178298 : if (decoded == NULL && nonblocking)
688 : {
689 : /*
690 : * There is no space in the circular decode buffer, and the caller is
691 : * only reading ahead. The caller should consume existing records to
692 : * make space.
693 : */
694 0 : return XLREAD_WOULDBLOCK;
695 : }
696 :
697 178298 : len = XLOG_BLCKSZ - RecPtr % XLOG_BLCKSZ;
698 178298 : if (total_len > len)
699 : {
700 : /* Need to reassemble record */
701 : char *contdata;
702 : XLogPageHeader pageHeader;
703 : char *buffer;
704 : uint32 gotlen;
705 :
706 8722 : assembled = true;
707 :
708 : /*
709 : * We always have space for a couple of pages, enough to validate a
710 : * boundary-spanning record header.
711 : */
712 : Assert(state->readRecordBufSize >= XLOG_BLCKSZ * 2);
713 : Assert(state->readRecordBufSize >= len);
714 :
715 : /* Copy the first fragment of the record from the first page. */
716 8722 : memcpy(state->readRecordBuf,
717 8722 : state->readBuf + RecPtr % XLOG_BLCKSZ, len);
718 8722 : buffer = state->readRecordBuf + len;
719 8722 : gotlen = len;
720 :
721 : do
722 : {
723 : /* Calculate pointer to beginning of next page */
724 8730 : targetPagePtr += XLOG_BLCKSZ;
725 :
726 : /*
727 : * Read the page header before processing the record data, so we
728 : * can handle the case where the previous record ended as being a
729 : * partial one.
730 : */
731 8730 : readOff = ReadPageInternal(state, targetPagePtr, SizeOfXLogShortPHD);
732 8730 : if (readOff == XLREAD_WOULDBLOCK)
733 0 : return XLREAD_WOULDBLOCK;
734 8730 : else if (readOff < 0)
735 0 : goto err;
736 :
737 : Assert(SizeOfXLogShortPHD <= readOff);
738 :
739 8730 : pageHeader = (XLogPageHeader) state->readBuf;
740 :
741 : /*
742 : * If we were expecting a continuation record and got an
743 : * "overwrite contrecord" flag, that means the continuation record
744 : * was overwritten with a different record. Restart the read by
745 : * assuming the address to read is the location where we found
746 : * this flag; but keep track of the LSN of the record we were
747 : * reading, for later verification.
748 : */
749 8730 : if (pageHeader->xlp_info & XLP_FIRST_IS_OVERWRITE_CONTRECORD)
750 : {
751 0 : state->overwrittenRecPtr = RecPtr;
752 0 : RecPtr = targetPagePtr;
753 0 : goto restart;
754 : }
755 :
756 : /* Check that the continuation on next page looks valid */
757 8730 : if (!(pageHeader->xlp_info & XLP_FIRST_IS_CONTRECORD))
758 : {
759 0 : report_invalid_record(state,
760 : "there is no contrecord flag at %X/%08X",
761 0 : LSN_FORMAT_ARGS(RecPtr));
762 0 : goto err;
763 : }
764 :
765 : /*
766 : * Cross-check that xlp_rem_len agrees with how much of the record
767 : * we expect there to be left.
768 : */
769 8730 : if (pageHeader->xlp_rem_len == 0 ||
770 8730 : total_len != (pageHeader->xlp_rem_len + gotlen))
771 : {
772 0 : report_invalid_record(state,
773 : "invalid contrecord length %u (expected %lld) at %X/%08X",
774 : pageHeader->xlp_rem_len,
775 0 : ((long long) total_len) - gotlen,
776 0 : LSN_FORMAT_ARGS(RecPtr));
777 0 : goto err;
778 : }
779 :
780 : /* Wait for the next page to become available */
781 8730 : readOff = ReadPageInternal(state, targetPagePtr,
782 8730 : Min(total_len - gotlen + SizeOfXLogShortPHD,
783 : XLOG_BLCKSZ));
784 8730 : if (readOff == XLREAD_WOULDBLOCK)
785 0 : return XLREAD_WOULDBLOCK;
786 8730 : else if (readOff < 0)
787 0 : goto err;
788 :
789 : /* Append the continuation from this page to the buffer */
790 8730 : pageHeaderSize = XLogPageHeaderSize(pageHeader);
791 :
792 8730 : if (readOff < pageHeaderSize)
793 0 : readOff = ReadPageInternal(state, targetPagePtr,
794 : pageHeaderSize);
795 :
796 : Assert(pageHeaderSize <= readOff);
797 :
798 8730 : contdata = (char *) state->readBuf + pageHeaderSize;
799 8730 : len = XLOG_BLCKSZ - pageHeaderSize;
800 8730 : if (pageHeader->xlp_rem_len < len)
801 8722 : len = pageHeader->xlp_rem_len;
802 :
803 8730 : if (readOff < pageHeaderSize + len)
804 0 : readOff = ReadPageInternal(state, targetPagePtr,
805 0 : pageHeaderSize + len);
806 :
807 8730 : memcpy(buffer, contdata, len);
808 8730 : buffer += len;
809 8730 : gotlen += len;
810 :
811 : /* If we just reassembled the record header, validate it. */
812 8730 : if (!gotheader)
813 : {
814 352 : record = (XLogRecord *) state->readRecordBuf;
815 352 : if (!ValidXLogRecordHeader(state, RecPtr, state->DecodeRecPtr,
816 : record, randAccess))
817 0 : goto err;
818 352 : gotheader = true;
819 : }
820 :
821 : /*
822 : * We might need a bigger buffer. We have validated the record
823 : * header, in the case that it split over a page boundary. We've
824 : * also cross-checked total_len against xlp_rem_len on the second
825 : * page, and verified xlp_pageaddr on both.
826 : */
827 8730 : if (total_len > state->readRecordBufSize)
828 : {
829 : char save_copy[XLOG_BLCKSZ * 2];
830 :
831 : /*
832 : * Save and restore the data we already had. It can't be more
833 : * than two pages.
834 : */
835 : Assert(gotlen <= lengthof(save_copy));
836 : Assert(gotlen <= state->readRecordBufSize);
837 0 : memcpy(save_copy, state->readRecordBuf, gotlen);
838 0 : allocate_recordbuf(state, total_len);
839 0 : memcpy(state->readRecordBuf, save_copy, gotlen);
840 0 : buffer = state->readRecordBuf + gotlen;
841 : }
842 8730 : } while (gotlen < total_len);
843 : Assert(gotheader);
844 :
845 8722 : record = (XLogRecord *) state->readRecordBuf;
846 8722 : if (!ValidXLogRecord(state, record, RecPtr))
847 0 : goto err;
848 :
849 8722 : pageHeaderSize = XLogPageHeaderSize((XLogPageHeader) state->readBuf);
850 8722 : state->DecodeRecPtr = RecPtr;
851 8722 : state->NextRecPtr = targetPagePtr + pageHeaderSize
852 8722 : + MAXALIGN(pageHeader->xlp_rem_len);
853 : }
854 : else
855 : {
856 : /* Wait for the record data to become available */
857 169576 : readOff = ReadPageInternal(state, targetPagePtr,
858 169576 : Min(targetRecOff + total_len, XLOG_BLCKSZ));
859 169576 : if (readOff == XLREAD_WOULDBLOCK)
860 0 : return XLREAD_WOULDBLOCK;
861 169576 : else if (readOff < 0)
862 0 : goto err;
863 :
864 : /* Record does not cross a page boundary */
865 169576 : if (!ValidXLogRecord(state, record, RecPtr))
866 0 : goto err;
867 :
868 169576 : state->NextRecPtr = RecPtr + MAXALIGN(total_len);
869 :
870 169576 : state->DecodeRecPtr = RecPtr;
871 : }
872 :
873 : /*
874 : * Special processing if it's an XLOG SWITCH record
875 : */
876 178298 : if (record->xl_rmid == RM_XLOG_ID &&
877 12308 : (record->xl_info & ~XLR_INFO_MASK) == XLOG_SWITCH)
878 : {
879 : /* Pretend it extends to end of segment */
880 24 : state->NextRecPtr += state->segcxt.ws_segsize - 1;
881 24 : state->NextRecPtr -= XLogSegmentOffset(state->NextRecPtr, state->segcxt.ws_segsize);
882 : }
883 :
884 : /*
885 : * If we got here without a DecodedXLogRecord, it means we needed to
886 : * validate total_len before trusting it, but by now we've done that.
887 : */
888 178298 : if (decoded == NULL)
889 : {
890 : Assert(!nonblocking);
891 0 : decoded = XLogReadRecordAlloc(state,
892 : total_len,
893 : true /* allow_oversized */ );
894 : /* allocation should always happen under allow_oversized */
895 : Assert(decoded != NULL);
896 : }
897 :
898 178298 : if (DecodeXLogRecord(state, decoded, record, RecPtr, &errormsg))
899 : {
900 : /* Record the location of the next record. */
901 178298 : decoded->next_lsn = state->NextRecPtr;
902 :
903 : /*
904 : * If it's in the decode buffer, mark the decode buffer space as
905 : * occupied.
906 : */
907 178298 : if (!decoded->oversized)
908 : {
909 : /* The new decode buffer head must be MAXALIGNed. */
910 : Assert(decoded->size == MAXALIGN(decoded->size));
911 178298 : if ((char *) decoded == state->decode_buffer)
912 178298 : state->decode_buffer_tail = state->decode_buffer + decoded->size;
913 : else
914 0 : state->decode_buffer_tail += decoded->size;
915 : }
916 :
917 : /* Insert it into the queue of decoded records. */
918 : Assert(state->decode_queue_tail != decoded);
919 178298 : if (state->decode_queue_tail)
920 0 : state->decode_queue_tail->next = decoded;
921 178298 : state->decode_queue_tail = decoded;
922 178298 : if (!state->decode_queue_head)
923 178298 : state->decode_queue_head = decoded;
924 178298 : return XLREAD_SUCCESS;
925 : }
926 :
927 0 : err:
928 0 : if (assembled)
929 : {
930 : /*
931 : * We get here when a record that spans multiple pages needs to be
932 : * assembled, but something went wrong -- perhaps a contrecord piece
933 : * was lost. If caller is WAL replay, it will know where the aborted
934 : * record was and where to direct followup WAL to be written, marking
935 : * the next piece with XLP_FIRST_IS_OVERWRITE_CONTRECORD, which will
936 : * in turn signal downstream WAL consumers that the broken WAL record
937 : * is to be ignored.
938 : */
939 0 : state->abortedRecPtr = RecPtr;
940 0 : state->missingContrecPtr = targetPagePtr;
941 :
942 : /*
943 : * If we got here without reporting an error, make sure an error is
944 : * queued so that XLogPrefetcherReadRecord() doesn't bring us back a
945 : * second time and clobber the above state.
946 : */
947 0 : state->errormsg_deferred = true;
948 : }
949 :
950 0 : if (decoded && decoded->oversized)
951 0 : pfree(decoded);
952 :
953 : /*
954 : * Invalidate the read state. We might read from a different source after
955 : * failure.
956 : */
957 0 : XLogReaderInvalReadState(state);
958 :
959 : /*
960 : * If an error was written to errormsg_buf, it'll be returned to the
961 : * caller of XLogReadRecord() after all successfully decoded records from
962 : * the read queue.
963 : */
964 :
965 0 : return XLREAD_FAIL;
966 : }
967 :
968 : /*
969 : * Try to decode the next available record, and return it. The record will
970 : * also be returned to XLogNextRecord(), which must be called to 'consume'
971 : * each record.
972 : *
973 : * If nonblocking is true, may return NULL due to lack of data or WAL decoding
974 : * space.
975 : */
976 : DecodedXLogRecord *
977 178298 : XLogReadAhead(XLogReaderState *state, bool nonblocking)
978 : {
979 : XLogPageReadResult result;
980 :
981 178298 : if (state->errormsg_deferred)
982 0 : return NULL;
983 :
984 178298 : result = XLogDecodeNextRecord(state, nonblocking);
985 178298 : if (result == XLREAD_SUCCESS)
986 : {
987 : Assert(state->decode_queue_tail != NULL);
988 178298 : return state->decode_queue_tail;
989 : }
990 :
991 0 : return NULL;
992 : }
993 :
994 : /*
995 : * Read a single xlog page including at least [pageptr, reqLen] of valid data
996 : * via the page_read() callback.
997 : *
998 : * Returns XLREAD_FAIL if the required page cannot be read for some
999 : * reason; errormsg_buf is set in that case (unless the error occurs in the
1000 : * page_read callback).
1001 : *
1002 : * Returns XLREAD_WOULDBLOCK if the requested data can't be read without
1003 : * waiting. This can be returned only if the installed page_read callback
1004 : * respects the state->nonblocking flag, and cannot read the requested data
1005 : * immediately.
1006 : *
1007 : * We fetch the page from a reader-local cache if we know we have the required
1008 : * data and if there hasn't been any error since caching the data.
1009 : */
1010 : static int
1011 365334 : ReadPageInternal(XLogReaderState *state, XLogRecPtr pageptr, int reqLen)
1012 : {
1013 : int readLen;
1014 : uint32 targetPageOff;
1015 : XLogSegNo targetSegNo;
1016 : XLogPageHeader hdr;
1017 :
1018 : Assert((pageptr % XLOG_BLCKSZ) == 0);
1019 :
1020 365334 : XLByteToSeg(pageptr, targetSegNo, state->segcxt.ws_segsize);
1021 365334 : targetPageOff = XLogSegmentOffset(pageptr, state->segcxt.ws_segsize);
1022 :
1023 : /* check whether we have all the requested data already */
1024 365334 : if (targetSegNo == state->seg.ws_segno &&
1025 365228 : targetPageOff == state->segoff && reqLen <= state->readLen)
1026 353652 : return state->readLen;
1027 :
1028 : /*
1029 : * Invalidate contents of internal buffer before read attempt. Just set
1030 : * the length to 0, rather than a full XLogReaderInvalReadState(), so we
1031 : * don't forget the segment we last successfully read.
1032 : */
1033 11682 : state->readLen = 0;
1034 :
1035 : /*
1036 : * Data is not in our buffer.
1037 : *
1038 : * Every time we actually read the segment, even if we looked at parts of
1039 : * it before, we need to do verification as the page_read callback might
1040 : * now be rereading data from a different source.
1041 : *
1042 : * Whenever switching to a new WAL segment, we read the first page of the
1043 : * file and validate its header, even if that's not where the target
1044 : * record is. This is so that we can check the additional identification
1045 : * info that is present in the first page's "long" header.
1046 : */
1047 11682 : if (targetSegNo != state->seg.ws_segno && targetPageOff != 0)
1048 : {
1049 50 : XLogRecPtr targetSegmentPtr = pageptr - targetPageOff;
1050 :
1051 50 : readLen = state->routine.page_read(state, targetSegmentPtr, XLOG_BLCKSZ,
1052 : state->currRecPtr,
1053 : state->readBuf);
1054 50 : if (readLen == XLREAD_WOULDBLOCK)
1055 0 : return XLREAD_WOULDBLOCK;
1056 50 : else if (readLen < 0)
1057 0 : goto err;
1058 :
1059 : /* we can be sure to have enough WAL available, we scrolled back */
1060 : Assert(readLen == XLOG_BLCKSZ);
1061 :
1062 50 : if (!XLogReaderValidatePageHeader(state, targetSegmentPtr,
1063 : state->readBuf))
1064 0 : goto err;
1065 : }
1066 :
1067 : /*
1068 : * First, read the requested data length, but at least a short page header
1069 : * so that we can validate it.
1070 : */
1071 11682 : readLen = state->routine.page_read(state, pageptr, Max(reqLen, SizeOfXLogShortPHD),
1072 : state->currRecPtr,
1073 : state->readBuf);
1074 11682 : if (readLen == XLREAD_WOULDBLOCK)
1075 0 : return XLREAD_WOULDBLOCK;
1076 11682 : else if (readLen < 0)
1077 0 : goto err;
1078 :
1079 : Assert(readLen <= XLOG_BLCKSZ);
1080 :
1081 : /* Do we have enough data to check the header length? */
1082 11682 : if (readLen <= SizeOfXLogShortPHD)
1083 0 : goto err;
1084 :
1085 : Assert(readLen >= reqLen);
1086 :
1087 11682 : hdr = (XLogPageHeader) state->readBuf;
1088 :
1089 : /* still not enough */
1090 11682 : if (readLen < XLogPageHeaderSize(hdr))
1091 : {
1092 0 : readLen = state->routine.page_read(state, pageptr, XLogPageHeaderSize(hdr),
1093 : state->currRecPtr,
1094 : state->readBuf);
1095 0 : if (readLen == XLREAD_WOULDBLOCK)
1096 0 : return XLREAD_WOULDBLOCK;
1097 0 : else if (readLen < 0)
1098 0 : goto err;
1099 : }
1100 :
1101 : /*
1102 : * Now that we know we have the full header, validate it.
1103 : */
1104 11682 : if (!XLogReaderValidatePageHeader(state, pageptr, (char *) hdr))
1105 0 : goto err;
1106 :
1107 : /* update read state information */
1108 11682 : state->seg.ws_segno = targetSegNo;
1109 11682 : state->segoff = targetPageOff;
1110 11682 : state->readLen = readLen;
1111 :
1112 11682 : return readLen;
1113 :
1114 0 : err:
1115 0 : XLogReaderInvalReadState(state);
1116 :
1117 0 : return XLREAD_FAIL;
1118 : }
1119 :
1120 : /*
1121 : * Invalidate the xlogreader's read state to force a re-read.
1122 : */
1123 : static void
1124 0 : XLogReaderInvalReadState(XLogReaderState *state)
1125 : {
1126 0 : state->seg.ws_segno = 0;
1127 0 : state->segoff = 0;
1128 0 : state->readLen = 0;
1129 0 : }
1130 :
1131 : /*
1132 : * Validate an XLOG record header.
1133 : *
1134 : * This is just a convenience subroutine to avoid duplicated code in
1135 : * XLogReadRecord. It's not intended for use from anywhere else.
1136 : */
1137 : static bool
1138 178298 : ValidXLogRecordHeader(XLogReaderState *state, XLogRecPtr RecPtr,
1139 : XLogRecPtr PrevRecPtr, XLogRecord *record,
1140 : bool randAccess)
1141 : {
1142 178298 : if (record->xl_tot_len < SizeOfXLogRecord)
1143 : {
1144 0 : report_invalid_record(state,
1145 : "invalid record length at %X/%08X: expected at least %u, got %u",
1146 0 : LSN_FORMAT_ARGS(RecPtr),
1147 : (uint32) SizeOfXLogRecord, record->xl_tot_len);
1148 0 : return false;
1149 : }
1150 178298 : if (!RmgrIdIsValid(record->xl_rmid))
1151 : {
1152 0 : report_invalid_record(state,
1153 : "invalid resource manager ID %u at %X/%08X",
1154 0 : record->xl_rmid, LSN_FORMAT_ARGS(RecPtr));
1155 0 : return false;
1156 : }
1157 178298 : if (randAccess)
1158 : {
1159 : /*
1160 : * We can't exactly verify the prev-link, but surely it should be less
1161 : * than the record's own address.
1162 : */
1163 5374 : if (!(record->xl_prev < RecPtr))
1164 : {
1165 0 : report_invalid_record(state,
1166 : "record with incorrect prev-link %X/%08X at %X/%08X",
1167 0 : LSN_FORMAT_ARGS(record->xl_prev),
1168 0 : LSN_FORMAT_ARGS(RecPtr));
1169 0 : return false;
1170 : }
1171 : }
1172 : else
1173 : {
1174 : /*
1175 : * Record's prev-link should exactly match our previous location. This
1176 : * check guards against torn WAL pages where a stale but valid-looking
1177 : * WAL record starts on a sector boundary.
1178 : */
1179 172924 : if (record->xl_prev != PrevRecPtr)
1180 : {
1181 0 : report_invalid_record(state,
1182 : "record with incorrect prev-link %X/%08X at %X/%08X",
1183 0 : LSN_FORMAT_ARGS(record->xl_prev),
1184 0 : LSN_FORMAT_ARGS(RecPtr));
1185 0 : return false;
1186 : }
1187 : }
1188 :
1189 178298 : return true;
1190 : }
1191 :
1192 :
1193 : /*
1194 : * CRC-check an XLOG record. We do not believe the contents of an XLOG
1195 : * record (other than to the minimal extent of computing the amount of
1196 : * data to read in) until we've checked the CRCs.
1197 : *
1198 : * We assume all of the record (that is, xl_tot_len bytes) has been read
1199 : * into memory at *record. Also, ValidXLogRecordHeader() has accepted the
1200 : * record's header, which means in particular that xl_tot_len is at least
1201 : * SizeOfXLogRecord.
1202 : */
1203 : static bool
1204 178298 : ValidXLogRecord(XLogReaderState *state, XLogRecord *record, XLogRecPtr recptr)
1205 : {
1206 : pg_crc32c crc;
1207 :
1208 : Assert(record->xl_tot_len >= SizeOfXLogRecord);
1209 :
1210 : /* Calculate the CRC */
1211 178298 : INIT_CRC32C(crc);
1212 178298 : COMP_CRC32C(crc, ((char *) record) + SizeOfXLogRecord, record->xl_tot_len - SizeOfXLogRecord);
1213 : /* include the record header last */
1214 178298 : COMP_CRC32C(crc, (char *) record, offsetof(XLogRecord, xl_crc));
1215 178298 : FIN_CRC32C(crc);
1216 :
1217 178298 : if (!EQ_CRC32C(record->xl_crc, crc))
1218 : {
1219 0 : report_invalid_record(state,
1220 : "incorrect resource manager data checksum in record at %X/%08X",
1221 0 : LSN_FORMAT_ARGS(recptr));
1222 0 : return false;
1223 : }
1224 :
1225 178298 : return true;
1226 : }
1227 :
1228 : /*
1229 : * Validate a page header.
1230 : *
1231 : * Check if 'phdr' is valid as the header of the XLog page at position
1232 : * 'recptr'.
1233 : */
1234 : bool
1235 11732 : XLogReaderValidatePageHeader(XLogReaderState *state, XLogRecPtr recptr,
1236 : char *phdr)
1237 : {
1238 : XLogSegNo segno;
1239 : int32 offset;
1240 11732 : XLogPageHeader hdr = (XLogPageHeader) phdr;
1241 :
1242 : Assert((recptr % XLOG_BLCKSZ) == 0);
1243 :
1244 11732 : XLByteToSeg(recptr, segno, state->segcxt.ws_segsize);
1245 11732 : offset = XLogSegmentOffset(recptr, state->segcxt.ws_segsize);
1246 :
1247 11732 : if (hdr->xlp_magic != XLOG_PAGE_MAGIC)
1248 : {
1249 : char fname[MAXFNAMELEN];
1250 :
1251 0 : XLogFileName(fname, state->seg.ws_tli, segno, state->segcxt.ws_segsize);
1252 :
1253 0 : report_invalid_record(state,
1254 : "invalid magic number %04X in WAL segment %s, LSN %X/%08X, offset %u",
1255 0 : hdr->xlp_magic,
1256 : fname,
1257 0 : LSN_FORMAT_ARGS(recptr),
1258 : offset);
1259 0 : return false;
1260 : }
1261 :
1262 11732 : if ((hdr->xlp_info & ~XLP_ALL_FLAGS) != 0)
1263 : {
1264 : char fname[MAXFNAMELEN];
1265 :
1266 0 : XLogFileName(fname, state->seg.ws_tli, segno, state->segcxt.ws_segsize);
1267 :
1268 0 : report_invalid_record(state,
1269 : "invalid info bits %04X in WAL segment %s, LSN %X/%08X, offset %u",
1270 0 : hdr->xlp_info,
1271 : fname,
1272 0 : LSN_FORMAT_ARGS(recptr),
1273 : offset);
1274 0 : return false;
1275 : }
1276 :
1277 11732 : if (hdr->xlp_info & XLP_LONG_HEADER)
1278 : {
1279 132 : XLogLongPageHeader longhdr = (XLogLongPageHeader) hdr;
1280 :
1281 132 : if (state->system_identifier &&
1282 0 : longhdr->xlp_sysid != state->system_identifier)
1283 : {
1284 0 : report_invalid_record(state,
1285 : "WAL file is from different database system: WAL file database system identifier is %" PRIu64 ", pg_control database system identifier is %" PRIu64,
1286 : longhdr->xlp_sysid,
1287 : state->system_identifier);
1288 0 : return false;
1289 : }
1290 132 : else if (longhdr->xlp_seg_size != state->segcxt.ws_segsize)
1291 : {
1292 0 : report_invalid_record(state,
1293 : "WAL file is from different database system: incorrect segment size in page header");
1294 0 : return false;
1295 : }
1296 132 : else if (longhdr->xlp_xlog_blcksz != XLOG_BLCKSZ)
1297 : {
1298 0 : report_invalid_record(state,
1299 : "WAL file is from different database system: incorrect XLOG_BLCKSZ in page header");
1300 0 : return false;
1301 : }
1302 : }
1303 11600 : else if (offset == 0)
1304 : {
1305 : char fname[MAXFNAMELEN];
1306 :
1307 0 : XLogFileName(fname, state->seg.ws_tli, segno, state->segcxt.ws_segsize);
1308 :
1309 : /* hmm, first page of file doesn't have a long header? */
1310 0 : report_invalid_record(state,
1311 : "invalid info bits %04X in WAL segment %s, LSN %X/%08X, offset %u",
1312 0 : hdr->xlp_info,
1313 : fname,
1314 0 : LSN_FORMAT_ARGS(recptr),
1315 : offset);
1316 0 : return false;
1317 : }
1318 :
1319 : /*
1320 : * Check that the address on the page agrees with what we expected. This
1321 : * check typically fails when an old WAL segment is recycled, and hasn't
1322 : * yet been overwritten with new data yet.
1323 : */
1324 11732 : if (hdr->xlp_pageaddr != recptr)
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 : "unexpected pageaddr %X/%08X in WAL segment %s, LSN %X/%08X, offset %u",
1332 0 : LSN_FORMAT_ARGS(hdr->xlp_pageaddr),
1333 : fname,
1334 0 : LSN_FORMAT_ARGS(recptr),
1335 : offset);
1336 0 : return false;
1337 : }
1338 :
1339 : /*
1340 : * Since child timelines are always assigned a TLI greater than their
1341 : * immediate parent's TLI, we should never see TLI go backwards across
1342 : * successive pages of a consistent WAL sequence.
1343 : *
1344 : * Sometimes we re-read a segment that's already been (partially) read. So
1345 : * we only verify TLIs for pages that are later than the last remembered
1346 : * LSN.
1347 : */
1348 11732 : if (recptr > state->latestPagePtr)
1349 : {
1350 9056 : if (hdr->xlp_tli < state->latestPageTLI)
1351 : {
1352 : char fname[MAXFNAMELEN];
1353 :
1354 0 : XLogFileName(fname, state->seg.ws_tli, segno, state->segcxt.ws_segsize);
1355 :
1356 0 : report_invalid_record(state,
1357 : "out-of-sequence timeline ID %u (after %u) in WAL segment %s, LSN %X/%08X, offset %u",
1358 : hdr->xlp_tli,
1359 : state->latestPageTLI,
1360 : fname,
1361 0 : LSN_FORMAT_ARGS(recptr),
1362 : offset);
1363 0 : return false;
1364 : }
1365 : }
1366 11732 : state->latestPagePtr = recptr;
1367 11732 : state->latestPageTLI = hdr->xlp_tli;
1368 :
1369 11732 : return true;
1370 : }
1371 :
1372 : /*
1373 : * Forget about an error produced by XLogReaderValidatePageHeader().
1374 : */
1375 : void
1376 0 : XLogReaderResetError(XLogReaderState *state)
1377 : {
1378 0 : state->errormsg_buf[0] = '\0';
1379 0 : state->errormsg_deferred = false;
1380 0 : }
1381 :
1382 : /*
1383 : * Find the first record with an lsn >= RecPtr.
1384 : *
1385 : * This is different from XLogBeginRead() in that RecPtr doesn't need to point
1386 : * to a valid record boundary. Useful for checking whether RecPtr is a valid
1387 : * xlog address for reading, and to find the first valid address after some
1388 : * address when dumping records for debugging purposes.
1389 : *
1390 : * This positions the reader, like XLogBeginRead(), so that the next call to
1391 : * XLogReadRecord() will read the next valid record.
1392 : */
1393 : XLogRecPtr
1394 0 : XLogFindNextRecord(XLogReaderState *state, XLogRecPtr RecPtr)
1395 : {
1396 : XLogRecPtr tmpRecPtr;
1397 0 : XLogRecPtr found = InvalidXLogRecPtr;
1398 : XLogPageHeader header;
1399 : char *errormsg;
1400 :
1401 : Assert(!XLogRecPtrIsInvalid(RecPtr));
1402 :
1403 : /* Make sure ReadPageInternal() can't return XLREAD_WOULDBLOCK. */
1404 0 : state->nonblocking = false;
1405 :
1406 : /*
1407 : * skip over potential continuation data, keeping in mind that it may span
1408 : * multiple pages
1409 : */
1410 0 : tmpRecPtr = RecPtr;
1411 : while (true)
1412 0 : {
1413 : XLogRecPtr targetPagePtr;
1414 : int targetRecOff;
1415 : uint32 pageHeaderSize;
1416 : int readLen;
1417 :
1418 : /*
1419 : * Compute targetRecOff. It should typically be equal or greater than
1420 : * short page-header since a valid record can't start anywhere before
1421 : * that, except when caller has explicitly specified the offset that
1422 : * falls somewhere there or when we are skipping multi-page
1423 : * continuation record. It doesn't matter though because
1424 : * ReadPageInternal() is prepared to handle that and will read at
1425 : * least short page-header worth of data
1426 : */
1427 0 : targetRecOff = tmpRecPtr % XLOG_BLCKSZ;
1428 :
1429 : /* scroll back to page boundary */
1430 0 : targetPagePtr = tmpRecPtr - targetRecOff;
1431 :
1432 : /* Read the page containing the record */
1433 0 : readLen = ReadPageInternal(state, targetPagePtr, targetRecOff);
1434 0 : if (readLen < 0)
1435 0 : goto err;
1436 :
1437 0 : header = (XLogPageHeader) state->readBuf;
1438 :
1439 0 : pageHeaderSize = XLogPageHeaderSize(header);
1440 :
1441 : /* make sure we have enough data for the page header */
1442 0 : readLen = ReadPageInternal(state, targetPagePtr, pageHeaderSize);
1443 0 : if (readLen < 0)
1444 0 : goto err;
1445 :
1446 : /* skip over potential continuation data */
1447 0 : if (header->xlp_info & XLP_FIRST_IS_CONTRECORD)
1448 : {
1449 : /*
1450 : * If the length of the remaining continuation data is more than
1451 : * what can fit in this page, the continuation record crosses over
1452 : * this page. Read the next page and try again. xlp_rem_len in the
1453 : * next page header will contain the remaining length of the
1454 : * continuation data
1455 : *
1456 : * Note that record headers are MAXALIGN'ed
1457 : */
1458 0 : if (MAXALIGN(header->xlp_rem_len) >= (XLOG_BLCKSZ - pageHeaderSize))
1459 0 : tmpRecPtr = targetPagePtr + XLOG_BLCKSZ;
1460 : else
1461 : {
1462 : /*
1463 : * The previous continuation record ends in this page. Set
1464 : * tmpRecPtr to point to the first valid record
1465 : */
1466 0 : tmpRecPtr = targetPagePtr + pageHeaderSize
1467 0 : + MAXALIGN(header->xlp_rem_len);
1468 0 : break;
1469 : }
1470 : }
1471 : else
1472 : {
1473 0 : tmpRecPtr = targetPagePtr + pageHeaderSize;
1474 0 : break;
1475 : }
1476 : }
1477 :
1478 : /*
1479 : * we know now that tmpRecPtr is an address pointing to a valid XLogRecord
1480 : * because either we're at the first record after the beginning of a page
1481 : * or we just jumped over the remaining data of a continuation.
1482 : */
1483 0 : XLogBeginRead(state, tmpRecPtr);
1484 0 : while (XLogReadRecord(state, &errormsg) != NULL)
1485 : {
1486 : /* past the record we've found, break out */
1487 0 : if (RecPtr <= state->ReadRecPtr)
1488 : {
1489 : /* Rewind the reader to the beginning of the last record. */
1490 0 : found = state->ReadRecPtr;
1491 0 : XLogBeginRead(state, found);
1492 0 : return found;
1493 : }
1494 : }
1495 :
1496 0 : err:
1497 0 : XLogReaderInvalReadState(state);
1498 :
1499 0 : return InvalidXLogRecPtr;
1500 : }
1501 :
1502 : /*
1503 : * Helper function to ease writing of XLogReaderRoutine->page_read callbacks.
1504 : * If this function is used, caller must supply a segment_open callback in
1505 : * 'state', as that is used here.
1506 : *
1507 : * Read 'count' bytes into 'buf', starting at location 'startptr', from WAL
1508 : * fetched from timeline 'tli'.
1509 : *
1510 : * Returns true if succeeded, false if an error occurs, in which case
1511 : * 'errinfo' receives error details.
1512 : */
1513 : bool
1514 0 : WALRead(XLogReaderState *state,
1515 : char *buf, XLogRecPtr startptr, Size count, TimeLineID tli,
1516 : WALReadError *errinfo)
1517 : {
1518 : char *p;
1519 : XLogRecPtr recptr;
1520 : Size nbytes;
1521 : #ifndef FRONTEND
1522 : instr_time io_start;
1523 : #endif
1524 :
1525 0 : p = buf;
1526 0 : recptr = startptr;
1527 0 : nbytes = count;
1528 :
1529 0 : while (nbytes > 0)
1530 : {
1531 : uint32 startoff;
1532 : int segbytes;
1533 : int readbytes;
1534 :
1535 0 : startoff = XLogSegmentOffset(recptr, state->segcxt.ws_segsize);
1536 :
1537 : /*
1538 : * If the data we want is not in a segment we have open, close what we
1539 : * have (if anything) and open the next one, using the caller's
1540 : * provided segment_open callback.
1541 : */
1542 0 : if (state->seg.ws_file < 0 ||
1543 0 : !XLByteInSeg(recptr, state->seg.ws_segno, state->segcxt.ws_segsize) ||
1544 0 : tli != state->seg.ws_tli)
1545 : {
1546 : XLogSegNo nextSegNo;
1547 :
1548 0 : if (state->seg.ws_file >= 0)
1549 0 : state->routine.segment_close(state);
1550 :
1551 0 : XLByteToSeg(recptr, nextSegNo, state->segcxt.ws_segsize);
1552 0 : state->routine.segment_open(state, nextSegNo, &tli);
1553 :
1554 : /* This shouldn't happen -- indicates a bug in segment_open */
1555 : Assert(state->seg.ws_file >= 0);
1556 :
1557 : /* Update the current segment info. */
1558 0 : state->seg.ws_tli = tli;
1559 0 : state->seg.ws_segno = nextSegNo;
1560 : }
1561 :
1562 : /* How many bytes are within this segment? */
1563 0 : if (nbytes > (state->segcxt.ws_segsize - startoff))
1564 0 : segbytes = state->segcxt.ws_segsize - startoff;
1565 : else
1566 0 : segbytes = nbytes;
1567 :
1568 : #ifndef FRONTEND
1569 : /* Measure I/O timing when reading segment */
1570 : io_start = pgstat_prepare_io_time(track_wal_io_timing);
1571 :
1572 : pgstat_report_wait_start(WAIT_EVENT_WAL_READ);
1573 : #endif
1574 :
1575 : /* Reset errno first; eases reporting non-errno-affecting errors */
1576 0 : errno = 0;
1577 0 : readbytes = pg_pread(state->seg.ws_file, p, segbytes, (off_t) startoff);
1578 :
1579 : #ifndef FRONTEND
1580 : pgstat_report_wait_end();
1581 :
1582 : pgstat_count_io_op_time(IOOBJECT_WAL, IOCONTEXT_NORMAL, IOOP_READ,
1583 : io_start, 1, readbytes);
1584 : #endif
1585 :
1586 0 : if (readbytes <= 0)
1587 : {
1588 0 : errinfo->wre_errno = errno;
1589 0 : errinfo->wre_req = segbytes;
1590 0 : errinfo->wre_read = readbytes;
1591 0 : errinfo->wre_off = startoff;
1592 0 : errinfo->wre_seg = state->seg;
1593 0 : return false;
1594 : }
1595 :
1596 : /* Update state for read */
1597 0 : recptr += readbytes;
1598 0 : nbytes -= readbytes;
1599 0 : p += readbytes;
1600 : }
1601 :
1602 0 : return true;
1603 : }
1604 :
1605 : /* ----------------------------------------
1606 : * Functions for decoding the data and block references in a record.
1607 : * ----------------------------------------
1608 : */
1609 :
1610 : /*
1611 : * Private function to reset the state, forgetting all decoded records, if we
1612 : * are asked to move to a new read position.
1613 : */
1614 : static void
1615 5374 : ResetDecoder(XLogReaderState *state)
1616 : {
1617 : DecodedXLogRecord *r;
1618 :
1619 : /* Reset the decoded record queue, freeing any oversized records. */
1620 16038 : while ((r = state->decode_queue_head) != NULL)
1621 : {
1622 5290 : state->decode_queue_head = r->next;
1623 5290 : if (r->oversized)
1624 0 : pfree(r);
1625 : }
1626 5374 : state->decode_queue_tail = NULL;
1627 5374 : state->decode_queue_head = NULL;
1628 5374 : state->record = NULL;
1629 :
1630 : /* Reset the decode buffer to empty. */
1631 5374 : state->decode_buffer_tail = state->decode_buffer;
1632 5374 : state->decode_buffer_head = state->decode_buffer;
1633 :
1634 : /* Clear error state. */
1635 5374 : state->errormsg_buf[0] = '\0';
1636 5374 : state->errormsg_deferred = false;
1637 5374 : }
1638 :
1639 : /*
1640 : * Compute the maximum possible amount of padding that could be required to
1641 : * decode a record, given xl_tot_len from the record's header. This is the
1642 : * amount of output buffer space that we need to decode a record, though we
1643 : * might not finish up using it all.
1644 : *
1645 : * This computation is pessimistic and assumes the maximum possible number of
1646 : * blocks, due to lack of better information.
1647 : */
1648 : size_t
1649 178298 : DecodeXLogRecordRequiredSpace(size_t xl_tot_len)
1650 : {
1651 178298 : size_t size = 0;
1652 :
1653 : /* Account for the fixed size part of the decoded record struct. */
1654 178298 : size += offsetof(DecodedXLogRecord, blocks[0]);
1655 : /* Account for the flexible blocks array of maximum possible size. */
1656 178298 : size += sizeof(DecodedBkpBlock) * (XLR_MAX_BLOCK_ID + 1);
1657 : /* Account for all the raw main and block data. */
1658 178298 : size += xl_tot_len;
1659 : /* We might insert padding before main_data. */
1660 178298 : size += (MAXIMUM_ALIGNOF - 1);
1661 : /* We might insert padding before each block's data. */
1662 178298 : size += (MAXIMUM_ALIGNOF - 1) * (XLR_MAX_BLOCK_ID + 1);
1663 : /* We might insert padding at the end. */
1664 178298 : size += (MAXIMUM_ALIGNOF - 1);
1665 :
1666 178298 : return size;
1667 : }
1668 :
1669 : /*
1670 : * Decode a record. "decoded" must point to a MAXALIGNed memory area that has
1671 : * space for at least DecodeXLogRecordRequiredSpace(record) bytes. On
1672 : * success, decoded->size contains the actual space occupied by the decoded
1673 : * record, which may turn out to be less.
1674 : *
1675 : * Only decoded->oversized member must be initialized already, and will not be
1676 : * modified. Other members will be initialized as required.
1677 : *
1678 : * On error, a human-readable error message is returned in *errormsg, and
1679 : * the return value is false.
1680 : */
1681 : bool
1682 178298 : DecodeXLogRecord(XLogReaderState *state,
1683 : DecodedXLogRecord *decoded,
1684 : XLogRecord *record,
1685 : XLogRecPtr lsn,
1686 : char **errormsg)
1687 : {
1688 : /*
1689 : * read next _size bytes from record buffer, but check for overrun first.
1690 : */
1691 : #define COPY_HEADER_FIELD(_dst, _size) \
1692 : do { \
1693 : if (remaining < _size) \
1694 : goto shortdata_err; \
1695 : memcpy(_dst, ptr, _size); \
1696 : ptr += _size; \
1697 : remaining -= _size; \
1698 : } while(0)
1699 :
1700 : char *ptr;
1701 : char *out;
1702 : uint32 remaining;
1703 : uint32 datatotal;
1704 178298 : RelFileLocator *rlocator = NULL;
1705 : uint8 block_id;
1706 :
1707 178298 : decoded->header = *record;
1708 178298 : decoded->lsn = lsn;
1709 178298 : decoded->next = NULL;
1710 178298 : decoded->record_origin = InvalidRepOriginId;
1711 178298 : decoded->toplevel_xid = InvalidTransactionId;
1712 178298 : decoded->main_data = NULL;
1713 178298 : decoded->main_data_len = 0;
1714 178298 : decoded->max_block_id = -1;
1715 178298 : ptr = (char *) record;
1716 178298 : ptr += SizeOfXLogRecord;
1717 178298 : remaining = record->xl_tot_len - SizeOfXLogRecord;
1718 :
1719 : /* Decode the headers */
1720 178298 : datatotal = 0;
1721 353310 : while (remaining > datatotal)
1722 : {
1723 341156 : COPY_HEADER_FIELD(&block_id, sizeof(uint8));
1724 :
1725 341156 : if (block_id == XLR_BLOCK_ID_DATA_SHORT)
1726 : {
1727 : /* XLogRecordDataHeaderShort */
1728 : uint8 main_data_len;
1729 :
1730 166108 : COPY_HEADER_FIELD(&main_data_len, sizeof(uint8));
1731 :
1732 166108 : decoded->main_data_len = main_data_len;
1733 166108 : datatotal += main_data_len;
1734 166108 : break; /* by convention, the main data fragment is
1735 : * always last */
1736 : }
1737 175048 : else if (block_id == XLR_BLOCK_ID_DATA_LONG)
1738 : {
1739 : /* XLogRecordDataHeaderLong */
1740 : uint32 main_data_len;
1741 :
1742 36 : COPY_HEADER_FIELD(&main_data_len, sizeof(uint32));
1743 36 : decoded->main_data_len = main_data_len;
1744 36 : datatotal += main_data_len;
1745 36 : break; /* by convention, the main data fragment is
1746 : * always last */
1747 : }
1748 175012 : else if (block_id == XLR_BLOCK_ID_ORIGIN)
1749 : {
1750 0 : COPY_HEADER_FIELD(&decoded->record_origin, sizeof(RepOriginId));
1751 : }
1752 175012 : else if (block_id == XLR_BLOCK_ID_TOPLEVEL_XID)
1753 : {
1754 0 : COPY_HEADER_FIELD(&decoded->toplevel_xid, sizeof(TransactionId));
1755 : }
1756 175012 : else if (block_id <= XLR_MAX_BLOCK_ID)
1757 : {
1758 : /* XLogRecordBlockHeader */
1759 : DecodedBkpBlock *blk;
1760 : uint8 fork_flags;
1761 :
1762 : /* mark any intervening block IDs as not in use */
1763 175012 : for (int i = decoded->max_block_id + 1; i < block_id; ++i)
1764 0 : decoded->blocks[i].in_use = false;
1765 :
1766 175012 : if (block_id <= decoded->max_block_id)
1767 : {
1768 0 : report_invalid_record(state,
1769 : "out-of-order block_id %u at %X/%08X",
1770 : block_id,
1771 0 : LSN_FORMAT_ARGS(state->ReadRecPtr));
1772 0 : goto err;
1773 : }
1774 175012 : decoded->max_block_id = block_id;
1775 :
1776 175012 : blk = &decoded->blocks[block_id];
1777 175012 : blk->in_use = true;
1778 175012 : blk->apply_image = false;
1779 :
1780 175012 : COPY_HEADER_FIELD(&fork_flags, sizeof(uint8));
1781 175012 : blk->forknum = fork_flags & BKPBLOCK_FORK_MASK;
1782 175012 : blk->flags = fork_flags;
1783 175012 : blk->has_image = ((fork_flags & BKPBLOCK_HAS_IMAGE) != 0);
1784 175012 : blk->has_data = ((fork_flags & BKPBLOCK_HAS_DATA) != 0);
1785 :
1786 175012 : blk->prefetch_buffer = InvalidBuffer;
1787 :
1788 175012 : COPY_HEADER_FIELD(&blk->data_len, sizeof(uint16));
1789 : /* cross-check that the HAS_DATA flag is set iff data_length > 0 */
1790 175012 : if (blk->has_data && blk->data_len == 0)
1791 : {
1792 0 : report_invalid_record(state,
1793 : "BKPBLOCK_HAS_DATA set, but no data included at %X/%08X",
1794 0 : LSN_FORMAT_ARGS(state->ReadRecPtr));
1795 0 : goto err;
1796 : }
1797 175012 : if (!blk->has_data && blk->data_len != 0)
1798 : {
1799 0 : report_invalid_record(state,
1800 : "BKPBLOCK_HAS_DATA not set, but data length is %u at %X/%08X",
1801 0 : (unsigned int) blk->data_len,
1802 0 : LSN_FORMAT_ARGS(state->ReadRecPtr));
1803 0 : goto err;
1804 : }
1805 175012 : datatotal += blk->data_len;
1806 :
1807 175012 : if (blk->has_image)
1808 : {
1809 12286 : COPY_HEADER_FIELD(&blk->bimg_len, sizeof(uint16));
1810 12286 : COPY_HEADER_FIELD(&blk->hole_offset, sizeof(uint16));
1811 12286 : COPY_HEADER_FIELD(&blk->bimg_info, sizeof(uint8));
1812 :
1813 12286 : blk->apply_image = ((blk->bimg_info & BKPIMAGE_APPLY) != 0);
1814 :
1815 12286 : if (BKPIMAGE_COMPRESSED(blk->bimg_info))
1816 : {
1817 0 : if (blk->bimg_info & BKPIMAGE_HAS_HOLE)
1818 0 : COPY_HEADER_FIELD(&blk->hole_length, sizeof(uint16));
1819 : else
1820 0 : blk->hole_length = 0;
1821 : }
1822 : else
1823 12286 : blk->hole_length = BLCKSZ - blk->bimg_len;
1824 12286 : datatotal += blk->bimg_len;
1825 :
1826 : /*
1827 : * cross-check that hole_offset > 0, hole_length > 0 and
1828 : * bimg_len < BLCKSZ if the HAS_HOLE flag is set.
1829 : */
1830 12286 : if ((blk->bimg_info & BKPIMAGE_HAS_HOLE) &&
1831 12214 : (blk->hole_offset == 0 ||
1832 12214 : blk->hole_length == 0 ||
1833 12214 : blk->bimg_len == BLCKSZ))
1834 : {
1835 0 : report_invalid_record(state,
1836 : "BKPIMAGE_HAS_HOLE set, but hole offset %u length %u block image length %u at %X/%08X",
1837 0 : (unsigned int) blk->hole_offset,
1838 0 : (unsigned int) blk->hole_length,
1839 0 : (unsigned int) blk->bimg_len,
1840 0 : LSN_FORMAT_ARGS(state->ReadRecPtr));
1841 0 : goto err;
1842 : }
1843 :
1844 : /*
1845 : * cross-check that hole_offset == 0 and hole_length == 0 if
1846 : * the HAS_HOLE flag is not set.
1847 : */
1848 12286 : if (!(blk->bimg_info & BKPIMAGE_HAS_HOLE) &&
1849 72 : (blk->hole_offset != 0 || blk->hole_length != 0))
1850 : {
1851 0 : report_invalid_record(state,
1852 : "BKPIMAGE_HAS_HOLE not set, but hole offset %u length %u at %X/%08X",
1853 0 : (unsigned int) blk->hole_offset,
1854 0 : (unsigned int) blk->hole_length,
1855 0 : LSN_FORMAT_ARGS(state->ReadRecPtr));
1856 0 : goto err;
1857 : }
1858 :
1859 : /*
1860 : * Cross-check that bimg_len < BLCKSZ if it is compressed.
1861 : */
1862 12286 : if (BKPIMAGE_COMPRESSED(blk->bimg_info) &&
1863 0 : blk->bimg_len == BLCKSZ)
1864 : {
1865 0 : report_invalid_record(state,
1866 : "BKPIMAGE_COMPRESSED set, but block image length %u at %X/%08X",
1867 0 : (unsigned int) blk->bimg_len,
1868 0 : LSN_FORMAT_ARGS(state->ReadRecPtr));
1869 0 : goto err;
1870 : }
1871 :
1872 : /*
1873 : * cross-check that bimg_len = BLCKSZ if neither HAS_HOLE is
1874 : * set nor COMPRESSED().
1875 : */
1876 12286 : if (!(blk->bimg_info & BKPIMAGE_HAS_HOLE) &&
1877 72 : !BKPIMAGE_COMPRESSED(blk->bimg_info) &&
1878 72 : blk->bimg_len != BLCKSZ)
1879 : {
1880 0 : report_invalid_record(state,
1881 : "neither BKPIMAGE_HAS_HOLE nor BKPIMAGE_COMPRESSED set, but block image length is %u at %X/%08X",
1882 0 : (unsigned int) blk->data_len,
1883 0 : LSN_FORMAT_ARGS(state->ReadRecPtr));
1884 0 : goto err;
1885 : }
1886 : }
1887 175012 : if (!(fork_flags & BKPBLOCK_SAME_REL))
1888 : {
1889 174340 : COPY_HEADER_FIELD(&blk->rlocator, sizeof(RelFileLocator));
1890 174340 : rlocator = &blk->rlocator;
1891 : }
1892 : else
1893 : {
1894 672 : if (rlocator == NULL)
1895 : {
1896 0 : report_invalid_record(state,
1897 : "BKPBLOCK_SAME_REL set but no previous rel at %X/%08X",
1898 0 : LSN_FORMAT_ARGS(state->ReadRecPtr));
1899 0 : goto err;
1900 : }
1901 :
1902 672 : blk->rlocator = *rlocator;
1903 : }
1904 175012 : COPY_HEADER_FIELD(&blk->blkno, sizeof(BlockNumber));
1905 : }
1906 : else
1907 : {
1908 0 : report_invalid_record(state,
1909 : "invalid block_id %u at %X/%08X",
1910 0 : block_id, LSN_FORMAT_ARGS(state->ReadRecPtr));
1911 0 : goto err;
1912 : }
1913 : }
1914 :
1915 178298 : if (remaining != datatotal)
1916 0 : goto shortdata_err;
1917 :
1918 : /*
1919 : * Ok, we've parsed the fragment headers, and verified that the total
1920 : * length of the payload in the fragments is equal to the amount of data
1921 : * left. Copy the data of each fragment to contiguous space after the
1922 : * blocks array, inserting alignment padding before the data fragments so
1923 : * they can be cast to struct pointers by REDO routines.
1924 : */
1925 178298 : out = ((char *) decoded) +
1926 178298 : offsetof(DecodedXLogRecord, blocks) +
1927 178298 : sizeof(decoded->blocks[0]) * (decoded->max_block_id + 1);
1928 :
1929 : /* block data first */
1930 353310 : for (block_id = 0; block_id <= decoded->max_block_id; block_id++)
1931 : {
1932 175012 : DecodedBkpBlock *blk = &decoded->blocks[block_id];
1933 :
1934 175012 : if (!blk->in_use)
1935 0 : continue;
1936 :
1937 : Assert(blk->has_image || !blk->apply_image);
1938 :
1939 175012 : if (blk->has_image)
1940 : {
1941 : /* no need to align image */
1942 12286 : blk->bkp_image = out;
1943 12286 : memcpy(out, ptr, blk->bimg_len);
1944 12286 : ptr += blk->bimg_len;
1945 12286 : out += blk->bimg_len;
1946 : }
1947 175012 : if (blk->has_data)
1948 : {
1949 81230 : out = (char *) MAXALIGN(out);
1950 81230 : blk->data = out;
1951 81230 : memcpy(blk->data, ptr, blk->data_len);
1952 81230 : ptr += blk->data_len;
1953 81230 : out += blk->data_len;
1954 : }
1955 : }
1956 :
1957 : /* and finally, the main data */
1958 178298 : if (decoded->main_data_len > 0)
1959 : {
1960 166144 : out = (char *) MAXALIGN(out);
1961 166144 : decoded->main_data = out;
1962 166144 : memcpy(decoded->main_data, ptr, decoded->main_data_len);
1963 166144 : ptr += decoded->main_data_len;
1964 166144 : out += decoded->main_data_len;
1965 : }
1966 :
1967 : /* Report the actual size we used. */
1968 178298 : decoded->size = MAXALIGN(out - (char *) decoded);
1969 : Assert(DecodeXLogRecordRequiredSpace(record->xl_tot_len) >=
1970 : decoded->size);
1971 :
1972 178298 : return true;
1973 :
1974 0 : shortdata_err:
1975 0 : report_invalid_record(state,
1976 : "record with invalid length at %X/%08X",
1977 0 : LSN_FORMAT_ARGS(state->ReadRecPtr));
1978 0 : err:
1979 0 : *errormsg = state->errormsg_buf;
1980 :
1981 0 : return false;
1982 : }
1983 :
1984 : /*
1985 : * Returns information about the block that a block reference refers to.
1986 : *
1987 : * This is like XLogRecGetBlockTagExtended, except that the block reference
1988 : * must exist and there's no access to prefetch_buffer.
1989 : */
1990 : void
1991 0 : XLogRecGetBlockTag(XLogReaderState *record, uint8 block_id,
1992 : RelFileLocator *rlocator, ForkNumber *forknum,
1993 : BlockNumber *blknum)
1994 : {
1995 0 : if (!XLogRecGetBlockTagExtended(record, block_id, rlocator, forknum,
1996 : blknum, NULL))
1997 : {
1998 : #ifndef FRONTEND
1999 : elog(ERROR, "could not locate backup block with ID %d in WAL record",
2000 : block_id);
2001 : #else
2002 0 : pg_fatal("could not locate backup block with ID %d in WAL record",
2003 : block_id);
2004 : #endif
2005 : }
2006 0 : }
2007 :
2008 : /*
2009 : * Returns information about the block that a block reference refers to,
2010 : * optionally including the buffer that the block may already be in.
2011 : *
2012 : * If the WAL record contains a block reference with the given ID, *rlocator,
2013 : * *forknum, *blknum and *prefetch_buffer are filled in (if not NULL), and
2014 : * returns true. Otherwise returns false.
2015 : */
2016 : bool
2017 170970 : XLogRecGetBlockTagExtended(XLogReaderState *record, uint8 block_id,
2018 : RelFileLocator *rlocator, ForkNumber *forknum,
2019 : BlockNumber *blknum,
2020 : Buffer *prefetch_buffer)
2021 : {
2022 : DecodedBkpBlock *bkpb;
2023 :
2024 170970 : if (!XLogRecHasBlockRef(record, block_id))
2025 0 : return false;
2026 :
2027 170970 : bkpb = &record->record->blocks[block_id];
2028 170970 : if (rlocator)
2029 170970 : *rlocator = bkpb->rlocator;
2030 170970 : if (forknum)
2031 170970 : *forknum = bkpb->forknum;
2032 170970 : if (blknum)
2033 170970 : *blknum = bkpb->blkno;
2034 170970 : if (prefetch_buffer)
2035 0 : *prefetch_buffer = bkpb->prefetch_buffer;
2036 170970 : return true;
2037 : }
2038 :
2039 : /*
2040 : * Returns the data associated with a block reference, or NULL if there is
2041 : * no data (e.g. because a full-page image was taken instead). The returned
2042 : * pointer points to a MAXALIGNed buffer.
2043 : */
2044 : char *
2045 0 : XLogRecGetBlockData(XLogReaderState *record, uint8 block_id, Size *len)
2046 : {
2047 : DecodedBkpBlock *bkpb;
2048 :
2049 0 : if (block_id > record->record->max_block_id ||
2050 0 : !record->record->blocks[block_id].in_use)
2051 0 : return NULL;
2052 :
2053 0 : bkpb = &record->record->blocks[block_id];
2054 :
2055 0 : if (!bkpb->has_data)
2056 : {
2057 0 : if (len)
2058 0 : *len = 0;
2059 0 : return NULL;
2060 : }
2061 : else
2062 : {
2063 0 : if (len)
2064 0 : *len = bkpb->data_len;
2065 0 : return bkpb->data;
2066 : }
2067 : }
2068 :
2069 : /*
2070 : * Restore a full-page image from a backup block attached to an XLOG record.
2071 : *
2072 : * Returns true if a full-page image is restored, and false on failure with
2073 : * an error to be consumed by the caller.
2074 : */
2075 : bool
2076 0 : RestoreBlockImage(XLogReaderState *record, uint8 block_id, char *page)
2077 : {
2078 : DecodedBkpBlock *bkpb;
2079 : char *ptr;
2080 : PGAlignedBlock tmp;
2081 :
2082 0 : if (block_id > record->record->max_block_id ||
2083 0 : !record->record->blocks[block_id].in_use)
2084 : {
2085 0 : report_invalid_record(record,
2086 : "could not restore image at %X/%08X with invalid block %d specified",
2087 0 : LSN_FORMAT_ARGS(record->ReadRecPtr),
2088 : block_id);
2089 0 : return false;
2090 : }
2091 0 : if (!record->record->blocks[block_id].has_image)
2092 : {
2093 0 : report_invalid_record(record, "could not restore image at %X/%08X with invalid state, block %d",
2094 0 : LSN_FORMAT_ARGS(record->ReadRecPtr),
2095 : block_id);
2096 0 : return false;
2097 : }
2098 :
2099 0 : bkpb = &record->record->blocks[block_id];
2100 0 : ptr = bkpb->bkp_image;
2101 :
2102 0 : if (BKPIMAGE_COMPRESSED(bkpb->bimg_info))
2103 : {
2104 : /* If a backup block image is compressed, decompress it */
2105 0 : bool decomp_success = true;
2106 :
2107 0 : if ((bkpb->bimg_info & BKPIMAGE_COMPRESS_PGLZ) != 0)
2108 : {
2109 0 : if (pglz_decompress(ptr, bkpb->bimg_len, tmp.data,
2110 0 : BLCKSZ - bkpb->hole_length, true) < 0)
2111 0 : decomp_success = false;
2112 : }
2113 0 : else if ((bkpb->bimg_info & BKPIMAGE_COMPRESS_LZ4) != 0)
2114 : {
2115 : #ifdef USE_LZ4
2116 0 : if (LZ4_decompress_safe(ptr, tmp.data,
2117 0 : bkpb->bimg_len, BLCKSZ - bkpb->hole_length) <= 0)
2118 0 : decomp_success = false;
2119 : #else
2120 : report_invalid_record(record, "could not restore image at %X/%08X compressed with %s not supported by build, block %d",
2121 : LSN_FORMAT_ARGS(record->ReadRecPtr),
2122 : "LZ4",
2123 : block_id);
2124 : return false;
2125 : #endif
2126 : }
2127 0 : else if ((bkpb->bimg_info & BKPIMAGE_COMPRESS_ZSTD) != 0)
2128 : {
2129 : #ifdef USE_ZSTD
2130 : size_t decomp_result = ZSTD_decompress(tmp.data,
2131 : BLCKSZ - bkpb->hole_length,
2132 : ptr, bkpb->bimg_len);
2133 :
2134 : if (ZSTD_isError(decomp_result))
2135 : decomp_success = false;
2136 : #else
2137 0 : report_invalid_record(record, "could not restore image at %X/%08X compressed with %s not supported by build, block %d",
2138 0 : LSN_FORMAT_ARGS(record->ReadRecPtr),
2139 : "zstd",
2140 : block_id);
2141 0 : return false;
2142 : #endif
2143 : }
2144 : else
2145 : {
2146 0 : report_invalid_record(record, "could not restore image at %X/%08X compressed with unknown method, block %d",
2147 0 : LSN_FORMAT_ARGS(record->ReadRecPtr),
2148 : block_id);
2149 0 : return false;
2150 : }
2151 :
2152 0 : if (!decomp_success)
2153 : {
2154 0 : report_invalid_record(record, "could not decompress image at %X/%08X, block %d",
2155 0 : LSN_FORMAT_ARGS(record->ReadRecPtr),
2156 : block_id);
2157 0 : return false;
2158 : }
2159 :
2160 0 : ptr = tmp.data;
2161 : }
2162 :
2163 : /* generate page, taking into account hole if necessary */
2164 0 : if (bkpb->hole_length == 0)
2165 : {
2166 0 : memcpy(page, ptr, BLCKSZ);
2167 : }
2168 : else
2169 : {
2170 0 : memcpy(page, ptr, bkpb->hole_offset);
2171 : /* must zero-fill the hole */
2172 0 : MemSet(page + bkpb->hole_offset, 0, bkpb->hole_length);
2173 0 : memcpy(page + (bkpb->hole_offset + bkpb->hole_length),
2174 0 : ptr + bkpb->hole_offset,
2175 0 : BLCKSZ - (bkpb->hole_offset + bkpb->hole_length));
2176 : }
2177 :
2178 0 : return true;
2179 : }
2180 :
2181 : #ifndef FRONTEND
2182 :
2183 : /*
2184 : * Extract the FullTransactionId from a WAL record.
2185 : */
2186 : FullTransactionId
2187 : XLogRecGetFullXid(XLogReaderState *record)
2188 : {
2189 : /*
2190 : * This function is only safe during replay, because it depends on the
2191 : * replay state. See AdvanceNextFullTransactionIdPastXid() for more.
2192 : */
2193 : Assert(AmStartupProcess() || !IsUnderPostmaster);
2194 :
2195 : return FullTransactionIdFromAllowableAt(TransamVariables->nextXid,
2196 : XLogRecGetXid(record));
2197 : }
2198 :
2199 : #endif
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