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pg_rewind.c
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1 /*-------------------------------------------------------------------------
2  *
3  * pg_rewind.c
4  * Synchronizes a PostgreSQL data directory to a new timeline
5  *
6  * Portions Copyright (c) 1996-2021, PostgreSQL Global Development Group
7  *
8  *-------------------------------------------------------------------------
9  */
10 #include "postgres_fe.h"
11 
12 #include <sys/stat.h>
13 #include <fcntl.h>
14 #include <time.h>
15 #include <unistd.h>
16 
17 #include "access/timeline.h"
18 #include "access/xlog_internal.h"
19 #include "catalog/catversion.h"
20 #include "catalog/pg_control.h"
22 #include "common/file_perm.h"
24 #include "common/string.h"
25 #include "fe_utils/recovery_gen.h"
26 #include "file_ops.h"
27 #include "filemap.h"
28 #include "getopt_long.h"
29 #include "pg_rewind.h"
30 #include "rewind_source.h"
31 #include "storage/bufpage.h"
32 
33 static void usage(const char *progname);
34 
35 static void perform_rewind(filemap_t *filemap, rewind_source *source,
36  XLogRecPtr chkptrec,
37  TimeLineID chkpttli,
38  XLogRecPtr chkptredo);
39 
40 static void createBackupLabel(XLogRecPtr startpoint, TimeLineID starttli,
41  XLogRecPtr checkpointloc);
42 
44  const char *content, size_t size);
45 static void getRestoreCommand(const char *argv0);
46 static void sanityChecks(void);
47 static void findCommonAncestorTimeline(XLogRecPtr *recptr, int *tliIndex);
48 static void ensureCleanShutdown(const char *argv0);
49 static void disconnect_atexit(void);
50 
54 
55 const char *progname;
57 
58 /* Configuration options */
59 char *datadir_target = NULL;
60 char *datadir_source = NULL;
61 char *connstr_source = NULL;
62 char *restore_command = NULL;
63 
64 static bool debug = false;
65 bool showprogress = false;
66 bool dry_run = false;
67 bool do_sync = true;
68 bool restore_wal = false;
69 
70 /* Target history */
73 
74 /* Progress counters */
75 uint64 fetch_size;
76 uint64 fetch_done;
77 
78 static PGconn *conn;
80 
81 static void
82 usage(const char *progname)
83 {
84  printf(_("%s resynchronizes a PostgreSQL cluster with another copy of the cluster.\n\n"), progname);
85  printf(_("Usage:\n %s [OPTION]...\n\n"), progname);
86  printf(_("Options:\n"));
87  printf(_(" -c, --restore-target-wal use restore_command in target configuration to\n"
88  " retrieve WAL files from archives\n"));
89  printf(_(" -D, --target-pgdata=DIRECTORY existing data directory to modify\n"));
90  printf(_(" --source-pgdata=DIRECTORY source data directory to synchronize with\n"));
91  printf(_(" --source-server=CONNSTR source server to synchronize with\n"));
92  printf(_(" -n, --dry-run stop before modifying anything\n"));
93  printf(_(" -N, --no-sync do not wait for changes to be written\n"
94  " safely to disk\n"));
95  printf(_(" -P, --progress write progress messages\n"));
96  printf(_(" -R, --write-recovery-conf write configuration for replication\n"
97  " (requires --source-server)\n"));
98  printf(_(" --debug write a lot of debug messages\n"));
99  printf(_(" --no-ensure-shutdown do not automatically fix unclean shutdown\n"));
100  printf(_(" -V, --version output version information, then exit\n"));
101  printf(_(" -?, --help show this help, then exit\n"));
102  printf(_("\nReport bugs to <%s>.\n"), PACKAGE_BUGREPORT);
103  printf(_("%s home page: <%s>\n"), PACKAGE_NAME, PACKAGE_URL);
104 }
105 
106 
107 int
108 main(int argc, char **argv)
109 {
110  static struct option long_options[] = {
111  {"help", no_argument, NULL, '?'},
112  {"target-pgdata", required_argument, NULL, 'D'},
113  {"write-recovery-conf", no_argument, NULL, 'R'},
114  {"source-pgdata", required_argument, NULL, 1},
115  {"source-server", required_argument, NULL, 2},
116  {"no-ensure-shutdown", no_argument, NULL, 4},
117  {"version", no_argument, NULL, 'V'},
118  {"restore-target-wal", no_argument, NULL, 'c'},
119  {"dry-run", no_argument, NULL, 'n'},
120  {"no-sync", no_argument, NULL, 'N'},
121  {"progress", no_argument, NULL, 'P'},
122  {"debug", no_argument, NULL, 3},
123  {NULL, 0, NULL, 0}
124  };
125  int option_index;
126  int c;
127  XLogRecPtr divergerec;
128  int lastcommontliIndex;
129  XLogRecPtr chkptrec;
130  TimeLineID chkpttli;
131  XLogRecPtr chkptredo;
132  XLogRecPtr target_wal_endrec;
133  size_t size;
134  char *buffer;
135  bool no_ensure_shutdown = false;
136  bool rewind_needed;
137  bool writerecoveryconf = false;
138  filemap_t *filemap;
139 
140  pg_logging_init(argv[0]);
141  set_pglocale_pgservice(argv[0], PG_TEXTDOMAIN("pg_rewind"));
142  progname = get_progname(argv[0]);
143 
144  /* Process command-line arguments */
145  if (argc > 1)
146  {
147  if (strcmp(argv[1], "--help") == 0 || strcmp(argv[1], "-?") == 0)
148  {
149  usage(progname);
150  exit(0);
151  }
152  if (strcmp(argv[1], "--version") == 0 || strcmp(argv[1], "-V") == 0)
153  {
154  puts("pg_rewind (PostgreSQL) " PG_VERSION);
155  exit(0);
156  }
157  }
158 
159  while ((c = getopt_long(argc, argv, "cD:nNPR", long_options, &option_index)) != -1)
160  {
161  switch (c)
162  {
163  case '?':
164  fprintf(stderr, _("Try \"%s --help\" for more information.\n"), progname);
165  exit(1);
166 
167  case 'c':
168  restore_wal = true;
169  break;
170 
171  case 'P':
172  showprogress = true;
173  break;
174 
175  case 'n':
176  dry_run = true;
177  break;
178 
179  case 'N':
180  do_sync = false;
181  break;
182 
183  case 'R':
184  writerecoveryconf = true;
185  break;
186 
187  case 3:
188  debug = true;
190  break;
191 
192  case 'D': /* -D or --target-pgdata */
194  break;
195 
196  case 1: /* --source-pgdata */
198  break;
199 
200  case 2: /* --source-server */
202  break;
203 
204  case 4:
205  no_ensure_shutdown = true;
206  break;
207  }
208  }
209 
210  if (datadir_source == NULL && connstr_source == NULL)
211  {
212  pg_log_error("no source specified (--source-pgdata or --source-server)");
213  fprintf(stderr, _("Try \"%s --help\" for more information.\n"), progname);
214  exit(1);
215  }
216 
217  if (datadir_source != NULL && connstr_source != NULL)
218  {
219  pg_log_error("only one of --source-pgdata or --source-server can be specified");
220  fprintf(stderr, _("Try \"%s --help\" for more information.\n"), progname);
221  exit(1);
222  }
223 
224  if (datadir_target == NULL)
225  {
226  pg_log_error("no target data directory specified (--target-pgdata)");
227  fprintf(stderr, _("Try \"%s --help\" for more information.\n"), progname);
228  exit(1);
229  }
230 
231  if (writerecoveryconf && connstr_source == NULL)
232  {
233  pg_log_error("no source server information (--source-server) specified for --write-recovery-conf");
234  fprintf(stderr, _("Try \"%s --help\" for more information.\n"), progname);
235  exit(1);
236  }
237 
238  if (optind < argc)
239  {
240  pg_log_error("too many command-line arguments (first is \"%s\")",
241  argv[optind]);
242  fprintf(stderr, _("Try \"%s --help\" for more information.\n"), progname);
243  exit(1);
244  }
245 
246  /*
247  * Don't allow pg_rewind to be run as root, to avoid overwriting the
248  * ownership of files in the data directory. We need only check for root
249  * -- any other user won't have sufficient permissions to modify files in
250  * the data directory.
251  */
252 #ifndef WIN32
253  if (geteuid() == 0)
254  {
255  pg_log_error("cannot be executed by \"root\"");
256  fprintf(stderr, _("You must run %s as the PostgreSQL superuser.\n"),
257  progname);
258  exit(1);
259  }
260 #endif
261 
263 
264  /* Set mask based on PGDATA permissions */
266  {
267  pg_log_error("could not read permissions of directory \"%s\": %m",
269  exit(1);
270  }
271 
272  umask(pg_mode_mask);
273 
274  getRestoreCommand(argv[0]);
275 
276  atexit(disconnect_atexit);
277 
278  /*
279  * Ok, we have all the options and we're ready to start. First, connect to
280  * remote server.
281  */
282  if (connstr_source)
283  {
284  conn = PQconnectdb(connstr_source);
285 
286  if (PQstatus(conn) == CONNECTION_BAD)
287  pg_fatal("%s", PQerrorMessage(conn));
288 
289  if (showprogress)
290  pg_log_info("connected to server");
291 
292  source = init_libpq_source(conn);
293  }
294  else
296 
297  /*
298  * Check the status of the target instance.
299  *
300  * If the target instance was not cleanly shut down, start and stop the
301  * target cluster once in single-user mode to enforce recovery to finish,
302  * ensuring that the cluster can be used by pg_rewind. Note that if
303  * no_ensure_shutdown is specified, pg_rewind ignores this step, and users
304  * need to make sure by themselves that the target cluster is in a clean
305  * state.
306  */
307  buffer = slurpFile(datadir_target, "global/pg_control", &size);
308  digestControlFile(&ControlFile_target, buffer, size);
309  pg_free(buffer);
310 
311  if (!no_ensure_shutdown &&
312  ControlFile_target.state != DB_SHUTDOWNED &&
313  ControlFile_target.state != DB_SHUTDOWNED_IN_RECOVERY)
314  {
315  ensureCleanShutdown(argv[0]);
316 
317  buffer = slurpFile(datadir_target, "global/pg_control", &size);
318  digestControlFile(&ControlFile_target, buffer, size);
319  pg_free(buffer);
320  }
321 
322  buffer = source->fetch_file(source, "global/pg_control", &size);
323  digestControlFile(&ControlFile_source, buffer, size);
324  pg_free(buffer);
325 
326  sanityChecks();
327 
328  /*
329  * Find the common ancestor timeline between the clusters.
330  *
331  * If both clusters are already on the same timeline, there's nothing to
332  * do.
333  */
334  if (ControlFile_target.checkPointCopy.ThisTimeLineID ==
335  ControlFile_source.checkPointCopy.ThisTimeLineID)
336  {
337  pg_log_info("source and target cluster are on the same timeline");
338  rewind_needed = false;
339  target_wal_endrec = 0;
340  }
341  else
342  {
343  XLogRecPtr chkptendrec;
344 
345  findCommonAncestorTimeline(&divergerec, &lastcommontliIndex);
346  pg_log_info("servers diverged at WAL location %X/%X on timeline %u",
347  LSN_FORMAT_ARGS(divergerec),
348  targetHistory[lastcommontliIndex].tli);
349 
350  /*
351  * Determine the end-of-WAL on the target.
352  *
353  * The WAL ends at the last shutdown checkpoint, or at
354  * minRecoveryPoint if it was a standby. (If we supported rewinding a
355  * server that was not shut down cleanly, we would need to replay
356  * until we reach the first invalid record, like crash recovery does.)
357  */
358 
359  /* read the checkpoint record on the target to see where it ends. */
360  chkptendrec = readOneRecord(datadir_target,
361  ControlFile_target.checkPoint,
362  targetNentries - 1,
364 
365  if (ControlFile_target.minRecoveryPoint > chkptendrec)
366  {
367  target_wal_endrec = ControlFile_target.minRecoveryPoint;
368  }
369  else
370  {
371  target_wal_endrec = chkptendrec;
372  }
373 
374  /*
375  * Check for the possibility that the target is in fact a direct
376  * ancestor of the source. In that case, there is no divergent history
377  * in the target that needs rewinding.
378  */
379  if (target_wal_endrec > divergerec)
380  {
381  rewind_needed = true;
382  }
383  else
384  {
385  /* the last common checkpoint record must be part of target WAL */
386  Assert(target_wal_endrec == divergerec);
387 
388  rewind_needed = false;
389  }
390  }
391 
392  if (!rewind_needed)
393  {
394  pg_log_info("no rewind required");
395  if (writerecoveryconf && !dry_run)
397  GenerateRecoveryConfig(conn, NULL));
398  exit(0);
399  }
400 
401  findLastCheckpoint(datadir_target, divergerec, lastcommontliIndex,
402  &chkptrec, &chkpttli, &chkptredo, restore_command);
403  pg_log_info("rewinding from last common checkpoint at %X/%X on timeline %u",
404  LSN_FORMAT_ARGS(chkptrec), chkpttli);
405 
406  /* Initialize the hash table to track the status of each file */
407  filehash_init();
408 
409  /*
410  * Collect information about all files in the both data directories.
411  */
412  if (showprogress)
413  pg_log_info("reading source file list");
414  source->traverse_files(source, &process_source_file);
415 
416  if (showprogress)
417  pg_log_info("reading target file list");
419 
420  /*
421  * Read the target WAL from last checkpoint before the point of fork, to
422  * extract all the pages that were modified on the target cluster after
423  * the fork.
424  */
425  if (showprogress)
426  pg_log_info("reading WAL in target");
427  extractPageMap(datadir_target, chkptrec, lastcommontliIndex,
428  target_wal_endrec, restore_command);
429 
430  /*
431  * We have collected all information we need from both systems. Decide
432  * what to do with each file.
433  */
434  filemap = decide_file_actions();
435  if (showprogress)
436  calculate_totals(filemap);
437 
438  /* this is too verbose even for verbose mode */
439  if (debug)
440  print_filemap(filemap);
441 
442  /*
443  * Ok, we're ready to start copying things over.
444  */
445  if (showprogress)
446  {
447  pg_log_info("need to copy %lu MB (total source directory size is %lu MB)",
448  (unsigned long) (filemap->fetch_size / (1024 * 1024)),
449  (unsigned long) (filemap->total_size / (1024 * 1024)));
450 
451  fetch_size = filemap->fetch_size;
452  fetch_done = 0;
453  }
454 
455  /*
456  * We have now collected all the information we need from both systems,
457  * and we are ready to start modifying the target directory.
458  *
459  * This is the point of no return. Once we start copying things, there is
460  * no turning back!
461  */
462  perform_rewind(filemap, source, chkptrec, chkpttli, chkptredo);
463 
464  if (showprogress)
465  pg_log_info("syncing target data directory");
466  sync_target_dir();
467 
468  /* Also update the standby configuration, if requested. */
469  if (writerecoveryconf && !dry_run)
471  GenerateRecoveryConfig(conn, NULL));
472 
473  /* don't need the source connection anymore */
474  source->destroy(source);
475  if (conn)
476  {
477  PQfinish(conn);
478  conn = NULL;
479  }
480 
481  pg_log_info("Done!");
482 
483  return 0;
484 }
485 
486 /*
487  * Perform the rewind.
488  *
489  * We have already collected all the information we need from the
490  * target and the source.
491  */
492 static void
494  XLogRecPtr chkptrec,
495  TimeLineID chkpttli,
496  XLogRecPtr chkptredo)
497 {
498  XLogRecPtr endrec;
499  TimeLineID endtli;
500  ControlFileData ControlFile_new;
501  size_t size;
502  char *buffer;
503 
504  /*
505  * Execute the actions in the file map, fetching data from the source
506  * system as needed.
507  */
508  for (int i = 0; i < filemap->nentries; i++)
509  {
510  file_entry_t *entry = filemap->entries[i];
511 
512  /*
513  * If this is a relation file, copy the modified blocks.
514  *
515  * This is in addition to any other changes.
516  */
517  if (entry->target_pages_to_overwrite.bitmapsize > 0)
518  {
520  BlockNumber blkno;
521  off_t offset;
522 
524  while (datapagemap_next(iter, &blkno))
525  {
526  offset = blkno * BLCKSZ;
527  source->queue_fetch_range(source, entry->path, offset, BLCKSZ);
528  }
529  pg_free(iter);
530  }
531 
532  switch (entry->action)
533  {
534  case FILE_ACTION_NONE:
535  /* nothing else to do */
536  break;
537 
538  case FILE_ACTION_COPY:
539  /* Truncate the old file out of the way, if any */
540  open_target_file(entry->path, true);
541  source->queue_fetch_range(source, entry->path,
542  0, entry->source_size);
543  break;
544 
546  truncate_target_file(entry->path, entry->source_size);
547  break;
548 
550  source->queue_fetch_range(source, entry->path,
551  entry->target_size,
552  entry->source_size - entry->target_size);
553  break;
554 
555  case FILE_ACTION_REMOVE:
556  remove_target(entry);
557  break;
558 
559  case FILE_ACTION_CREATE:
560  create_target(entry);
561  break;
562 
564  pg_fatal("no action decided for file \"%s\"", entry->path);
565  break;
566  }
567  }
568 
569  /* Complete any remaining range-fetches that we queued up above. */
570  source->finish_fetch(source);
571 
573 
574  progress_report(true);
575 
576  /*
577  * Fetch the control file from the source last. This ensures that the
578  * minRecoveryPoint is up-to-date.
579  */
580  buffer = source->fetch_file(source, "global/pg_control", &size);
581  digestControlFile(&ControlFile_source_after, buffer, size);
582  pg_free(buffer);
583 
584  /*
585  * Sanity check: If the source is a local system, the control file should
586  * not have changed since we started.
587  *
588  * XXX: We assume it hasn't been modified, but actually, what could go
589  * wrong? The logic handles a libpq source that's modified concurrently,
590  * why not a local datadir?
591  */
592  if (datadir_source &&
593  memcmp(&ControlFile_source, &ControlFile_source_after,
594  sizeof(ControlFileData)) != 0)
595  {
596  pg_fatal("source system was modified while pg_rewind was running");
597  }
598 
599  if (showprogress)
600  pg_log_info("creating backup label and updating control file");
601 
602  /*
603  * Create a backup label file, to tell the target where to begin the WAL
604  * replay. Normally, from the last common checkpoint between the source
605  * and the target. But if the source is a standby server, it's possible
606  * that the last common checkpoint is *after* the standby's restartpoint.
607  * That implies that the source server has applied the checkpoint record,
608  * but hasn't performed a corresponding restartpoint yet. Make sure we
609  * start at the restartpoint's redo point in that case.
610  *
611  * Use the old version of the source's control file for this. The server
612  * might have finished the restartpoint after we started copying files,
613  * but we must begin from the redo point at the time that started copying.
614  */
615  if (ControlFile_source.checkPointCopy.redo < chkptredo)
616  {
617  chkptredo = ControlFile_source.checkPointCopy.redo;
618  chkpttli = ControlFile_source.checkPointCopy.ThisTimeLineID;
619  chkptrec = ControlFile_source.checkPoint;
620  }
621  createBackupLabel(chkptredo, chkpttli, chkptrec);
622 
623  /*
624  * Update control file of target, to tell the target how far it must
625  * replay the WAL (minRecoveryPoint).
626  */
627  if (connstr_source)
628  {
629  /*
630  * The source is a live server. Like in an online backup, it's
631  * important that we recover all the WAL that was generated while we
632  * were copying files.
633  */
634  if (ControlFile_source_after.state == DB_IN_ARCHIVE_RECOVERY)
635  {
636  /*
637  * Source is a standby server. We must replay to its
638  * minRecoveryPoint.
639  */
640  endrec = ControlFile_source_after.minRecoveryPoint;
641  endtli = ControlFile_source_after.minRecoveryPointTLI;
642  }
643  else
644  {
645  /*
646  * Source is a production, non-standby, server. We must replay to
647  * the last WAL insert location.
648  */
649  if (ControlFile_source_after.state != DB_IN_PRODUCTION)
650  pg_fatal("source system was in unexpected state at end of rewind");
651 
652  endrec = source->get_current_wal_insert_lsn(source);
653  endtli = ControlFile_source_after.checkPointCopy.ThisTimeLineID;
654  }
655  }
656  else
657  {
658  /*
659  * Source is a local data directory. It should've shut down cleanly,
660  * and we must replay to the latest shutdown checkpoint.
661  */
662  endrec = ControlFile_source_after.checkPoint;
663  endtli = ControlFile_source_after.checkPointCopy.ThisTimeLineID;
664  }
665 
666  memcpy(&ControlFile_new, &ControlFile_source_after, sizeof(ControlFileData));
667  ControlFile_new.minRecoveryPoint = endrec;
668  ControlFile_new.minRecoveryPointTLI = endtli;
669  ControlFile_new.state = DB_IN_ARCHIVE_RECOVERY;
670  if (!dry_run)
671  update_controlfile(datadir_target, &ControlFile_new, do_sync);
672 }
673 
674 static void
676 {
677  /* TODO Check that there's no backup_label in either cluster */
678 
679  /* Check system_identifier match */
680  if (ControlFile_target.system_identifier != ControlFile_source.system_identifier)
681  pg_fatal("source and target clusters are from different systems");
682 
683  /* check version */
684  if (ControlFile_target.pg_control_version != PG_CONTROL_VERSION ||
685  ControlFile_source.pg_control_version != PG_CONTROL_VERSION ||
686  ControlFile_target.catalog_version_no != CATALOG_VERSION_NO ||
687  ControlFile_source.catalog_version_no != CATALOG_VERSION_NO)
688  {
689  pg_fatal("clusters are not compatible with this version of pg_rewind");
690  }
691 
692  /*
693  * Target cluster need to use checksums or hint bit wal-logging, this to
694  * prevent from data corruption that could occur because of hint bits.
695  */
696  if (ControlFile_target.data_checksum_version != PG_DATA_CHECKSUM_VERSION &&
697  !ControlFile_target.wal_log_hints)
698  {
699  pg_fatal("target server needs to use either data checksums or \"wal_log_hints = on\"");
700  }
701 
702  /*
703  * Target cluster better not be running. This doesn't guard against
704  * someone starting the cluster concurrently. Also, this is probably more
705  * strict than necessary; it's OK if the target node was not shut down
706  * cleanly, as long as it isn't running at the moment.
707  */
708  if (ControlFile_target.state != DB_SHUTDOWNED &&
709  ControlFile_target.state != DB_SHUTDOWNED_IN_RECOVERY)
710  pg_fatal("target server must be shut down cleanly");
711 
712  /*
713  * When the source is a data directory, also require that the source
714  * server is shut down. There isn't any very strong reason for this
715  * limitation, but better safe than sorry.
716  */
717  if (datadir_source &&
718  ControlFile_source.state != DB_SHUTDOWNED &&
719  ControlFile_source.state != DB_SHUTDOWNED_IN_RECOVERY)
720  pg_fatal("source data directory must be shut down cleanly");
721 }
722 
723 /*
724  * Print a progress report based on the fetch_size and fetch_done variables.
725  *
726  * Progress report is written at maximum once per second, except that the
727  * last progress report is always printed.
728  *
729  * If finished is set to true, this is the last progress report. The cursor
730  * is moved to the next line.
731  */
732 void
733 progress_report(bool finished)
734 {
735  static pg_time_t last_progress_report = 0;
736  int percent;
737  char fetch_done_str[32];
738  char fetch_size_str[32];
739  pg_time_t now;
740 
741  if (!showprogress)
742  return;
743 
744  now = time(NULL);
745  if (now == last_progress_report && !finished)
746  return; /* Max once per second */
747 
748  last_progress_report = now;
749  percent = fetch_size ? (int) ((fetch_done) * 100 / fetch_size) : 0;
750 
751  /*
752  * Avoid overflowing past 100% or the full size. This may make the total
753  * size number change as we approach the end of the backup (the estimate
754  * will always be wrong if WAL is included), but that's better than having
755  * the done column be bigger than the total.
756  */
757  if (percent > 100)
758  percent = 100;
759  if (fetch_done > fetch_size)
761 
762  /*
763  * Separate step to keep platform-dependent format code out of
764  * translatable strings. And we only test for INT64_FORMAT availability
765  * in snprintf, not fprintf.
766  */
767  snprintf(fetch_done_str, sizeof(fetch_done_str), INT64_FORMAT,
768  fetch_done / 1024);
769  snprintf(fetch_size_str, sizeof(fetch_size_str), INT64_FORMAT,
770  fetch_size / 1024);
771 
772  fprintf(stderr, _("%*s/%s kB (%d%%) copied"),
773  (int) strlen(fetch_size_str), fetch_done_str, fetch_size_str,
774  percent);
775 
776  /*
777  * Stay on the same line if reporting to a terminal and we're not done
778  * yet.
779  */
780  fputc((!finished && isatty(fileno(stderr))) ? '\r' : '\n', stderr);
781 }
782 
783 /*
784  * Find minimum from two WAL locations assuming InvalidXLogRecPtr means
785  * infinity as src/include/access/timeline.h states. This routine should
786  * be used only when comparing WAL locations related to history files.
787  */
788 static XLogRecPtr
790 {
791  if (XLogRecPtrIsInvalid(a))
792  return b;
793  else if (XLogRecPtrIsInvalid(b))
794  return a;
795  else
796  return Min(a, b);
797 }
798 
799 /*
800  * Retrieve timeline history for given control file which should behold
801  * either source or target.
802  */
803 static TimeLineHistoryEntry *
804 getTimelineHistory(ControlFileData *controlFile, int *nentries)
805 {
806  TimeLineHistoryEntry *history;
807  TimeLineID tli;
808 
809  tli = controlFile->checkPointCopy.ThisTimeLineID;
810 
811  /*
812  * Timeline 1 does not have a history file, so there is no need to check
813  * and fake an entry with infinite start and end positions.
814  */
815  if (tli == 1)
816  {
817  history = (TimeLineHistoryEntry *) pg_malloc(sizeof(TimeLineHistoryEntry));
818  history->tli = tli;
819  history->begin = history->end = InvalidXLogRecPtr;
820  *nentries = 1;
821  }
822  else
823  {
824  char path[MAXPGPATH];
825  char *histfile;
826 
827  TLHistoryFilePath(path, tli);
828 
829  /* Get history file from appropriate source */
830  if (controlFile == &ControlFile_source)
831  histfile = source->fetch_file(source, path, NULL);
832  else if (controlFile == &ControlFile_target)
833  histfile = slurpFile(datadir_target, path, NULL);
834  else
835  pg_fatal("invalid control file");
836 
837  history = rewind_parseTimeLineHistory(histfile, tli, nentries);
838  pg_free(histfile);
839  }
840 
841  if (debug)
842  {
843  int i;
844 
845  if (controlFile == &ControlFile_source)
846  pg_log_debug("Source timeline history:");
847  else if (controlFile == &ControlFile_target)
848  pg_log_debug("Target timeline history:");
849  else
850  Assert(false);
851 
852  /*
853  * Print the target timeline history.
854  */
855  for (i = 0; i < targetNentries; i++)
856  {
857  TimeLineHistoryEntry *entry;
858 
859  entry = &history[i];
860  pg_log_debug("%u: %X/%X - %X/%X", entry->tli,
861  LSN_FORMAT_ARGS(entry->begin),
862  LSN_FORMAT_ARGS(entry->end));
863  }
864  }
865 
866  return history;
867 }
868 
869 /*
870  * Determine the TLI of the last common timeline in the timeline history of the
871  * two clusters. targetHistory is filled with target timeline history and
872  * targetNentries is number of items in targetHistory. *tliIndex is set to the
873  * index of last common timeline in targetHistory array, and *recptr is set to
874  * the position where the timeline history diverged (ie. the first WAL record
875  * that's not the same in both clusters).
876  *
877  * Control files of both clusters must be read into ControlFile_target/source
878  * before calling this routine.
879  */
880 static void
881 findCommonAncestorTimeline(XLogRecPtr *recptr, int *tliIndex)
882 {
883  TimeLineHistoryEntry *sourceHistory;
884  int sourceNentries;
885  int i,
886  n;
887 
888  /* Retrieve timelines for both source and target */
889  sourceHistory = getTimelineHistory(&ControlFile_source, &sourceNentries);
890  targetHistory = getTimelineHistory(&ControlFile_target, &targetNentries);
891 
892  /*
893  * Trace the history forward, until we hit the timeline diverge. It may
894  * still be possible that the source and target nodes used the same
895  * timeline number in their history but with different start position
896  * depending on the history files that each node has fetched in previous
897  * recovery processes. Hence check the start position of the new timeline
898  * as well and move down by one extra timeline entry if they do not match.
899  */
900  n = Min(sourceNentries, targetNentries);
901  for (i = 0; i < n; i++)
902  {
903  if (sourceHistory[i].tli != targetHistory[i].tli ||
904  sourceHistory[i].begin != targetHistory[i].begin)
905  break;
906  }
907 
908  if (i > 0)
909  {
910  i--;
911  *recptr = MinXLogRecPtr(sourceHistory[i].end, targetHistory[i].end);
912  *tliIndex = i;
913 
914  pg_free(sourceHistory);
915  return;
916  }
917  else
918  {
919  pg_fatal("could not find common ancestor of the source and target cluster's timelines");
920  }
921 }
922 
923 
924 /*
925  * Create a backup_label file that forces recovery to begin at the last common
926  * checkpoint.
927  */
928 static void
929 createBackupLabel(XLogRecPtr startpoint, TimeLineID starttli, XLogRecPtr checkpointloc)
930 {
931  XLogSegNo startsegno;
932  time_t stamp_time;
933  char strfbuf[128];
934  char xlogfilename[MAXFNAMELEN];
935  struct tm *tmp;
936  char buf[1000];
937  int len;
938 
939  XLByteToSeg(startpoint, startsegno, WalSegSz);
940  XLogFileName(xlogfilename, starttli, startsegno, WalSegSz);
941 
942  /*
943  * Construct backup label file
944  */
945  stamp_time = time(NULL);
946  tmp = localtime(&stamp_time);
947  strftime(strfbuf, sizeof(strfbuf), "%Y-%m-%d %H:%M:%S %Z", tmp);
948 
949  len = snprintf(buf, sizeof(buf),
950  "START WAL LOCATION: %X/%X (file %s)\n"
951  "CHECKPOINT LOCATION: %X/%X\n"
952  "BACKUP METHOD: pg_rewind\n"
953  "BACKUP FROM: standby\n"
954  "START TIME: %s\n",
955  /* omit LABEL: line */
956  LSN_FORMAT_ARGS(startpoint), xlogfilename,
957  LSN_FORMAT_ARGS(checkpointloc),
958  strfbuf);
959  if (len >= sizeof(buf))
960  pg_fatal("backup label buffer too small"); /* shouldn't happen */
961 
962  /* TODO: move old file out of the way, if any. */
963  open_target_file("backup_label", true); /* BACKUP_LABEL_FILE */
964  write_target_range(buf, 0, len);
966 }
967 
968 /*
969  * Check CRC of control file
970  */
971 static void
973 {
974  pg_crc32c crc;
975 
976  /* Calculate CRC */
977  INIT_CRC32C(crc);
978  COMP_CRC32C(crc, (char *) ControlFile, offsetof(ControlFileData, crc));
979  FIN_CRC32C(crc);
980 
981  /* And simply compare it */
982  if (!EQ_CRC32C(crc, ControlFile->crc))
983  pg_fatal("unexpected control file CRC");
984 }
985 
986 /*
987  * Verify control file contents in the buffer 'content', and copy it to
988  * *ControlFile.
989  */
990 static void
992  size_t size)
993 {
994  if (size != PG_CONTROL_FILE_SIZE)
995  pg_fatal("unexpected control file size %d, expected %d",
996  (int) size, PG_CONTROL_FILE_SIZE);
997 
998  memcpy(ControlFile, content, sizeof(ControlFileData));
999 
1000  /* set and validate WalSegSz */
1001  WalSegSz = ControlFile->xlog_seg_size;
1002 
1004  pg_fatal(ngettext("WAL segment size must be a power of two between 1 MB and 1 GB, but the control file specifies %d byte",
1005  "WAL segment size must be a power of two between 1 MB and 1 GB, but the control file specifies %d bytes",
1006  WalSegSz),
1007  WalSegSz);
1008 
1009  /* Additional checks on control file */
1010  checkControlFile(ControlFile);
1011 }
1012 
1013 /*
1014  * Get value of GUC parameter restore_command from the target cluster.
1015  *
1016  * This uses a logic based on "postgres -C" to get the value from the
1017  * cluster.
1018  */
1019 static void
1021 {
1022  int rc;
1023  char postgres_exec_path[MAXPGPATH],
1024  postgres_cmd[MAXPGPATH],
1025  cmd_output[MAXPGPATH];
1026 
1027  if (!restore_wal)
1028  return;
1029 
1030  /* find postgres executable */
1031  rc = find_other_exec(argv0, "postgres",
1033  postgres_exec_path);
1034 
1035  if (rc < 0)
1036  {
1037  char full_path[MAXPGPATH];
1038 
1039  if (find_my_exec(argv0, full_path) < 0)
1040  strlcpy(full_path, progname, sizeof(full_path));
1041 
1042  if (rc == -1)
1043  pg_log_error("The program \"%s\" is needed by %s but was not found in the\n"
1044  "same directory as \"%s\".\n"
1045  "Check your installation.",
1046  "postgres", progname, full_path);
1047  else
1048  pg_log_error("The program \"%s\" was found by \"%s\"\n"
1049  "but was not the same version as %s.\n"
1050  "Check your installation.",
1051  "postgres", full_path, progname);
1052  exit(1);
1053  }
1054 
1055  /*
1056  * Build a command able to retrieve the value of GUC parameter
1057  * restore_command, if set.
1058  */
1059  snprintf(postgres_cmd, sizeof(postgres_cmd),
1060  "\"%s\" -D \"%s\" -C restore_command",
1061  postgres_exec_path, datadir_target);
1062 
1063  if (!pipe_read_line(postgres_cmd, cmd_output, sizeof(cmd_output)))
1064  exit(1);
1065 
1066  (void) pg_strip_crlf(cmd_output);
1067 
1068  if (strcmp(cmd_output, "") == 0)
1069  pg_fatal("restore_command is not set in the target cluster");
1070 
1071  restore_command = pg_strdup(cmd_output);
1072 
1073  pg_log_debug("using for rewind restore_command = \'%s\'",
1074  restore_command);
1075 }
1076 
1077 
1078 /*
1079  * Ensure clean shutdown of target instance by launching single-user mode
1080  * postgres to do crash recovery.
1081  */
1082 static void
1084 {
1085  int ret;
1086 #define MAXCMDLEN (2 * MAXPGPATH)
1087  char exec_path[MAXPGPATH];
1088  char cmd[MAXCMDLEN];
1089 
1090  /* locate postgres binary */
1091  if ((ret = find_other_exec(argv0, "postgres",
1093  exec_path)) < 0)
1094  {
1095  char full_path[MAXPGPATH];
1096 
1097  if (find_my_exec(argv0, full_path) < 0)
1098  strlcpy(full_path, progname, sizeof(full_path));
1099 
1100  if (ret == -1)
1101  pg_fatal("The program \"%s\" is needed by %s but was not found in the\n"
1102  "same directory as \"%s\".\n"
1103  "Check your installation.",
1104  "postgres", progname, full_path);
1105  else
1106  pg_fatal("The program \"%s\" was found by \"%s\"\n"
1107  "but was not the same version as %s.\n"
1108  "Check your installation.",
1109  "postgres", full_path, progname);
1110  }
1111 
1112  pg_log_info("executing \"%s\" for target server to complete crash recovery",
1113  exec_path);
1114 
1115  /*
1116  * Skip processing if requested, but only after ensuring presence of
1117  * postgres.
1118  */
1119  if (dry_run)
1120  return;
1121 
1122  /*
1123  * Finally run postgres in single-user mode. There is no need to use
1124  * fsync here. This makes the recovery faster, and the target data folder
1125  * is synced at the end anyway.
1126  */
1127  snprintf(cmd, MAXCMDLEN, "\"%s\" --single -F -D \"%s\" template1 < \"%s\"",
1128  exec_path, datadir_target, DEVNULL);
1129 
1130  if (system(cmd) != 0)
1131  {
1132  pg_log_error("postgres single-user mode in target cluster failed");
1133  pg_fatal("Command was: %s", cmd);
1134  }
1135 }
1136 
1137 static void
1139 {
1140  if (conn != NULL)
1141  PQfinish(conn);
1142 }
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static void createBackupLabel(XLogRecPtr startpoint, TimeLineID starttli, XLogRecPtr checkpointloc)
Definition: pg_rewind.c:929
ConnStatusType PQstatus(const PGconn *conn)
Definition: fe-connect.c:6684
#define COMP_CRC32C(crc, data, len)
Definition: pg_crc32c.h:89
#define FIN_CRC32C(crc)
Definition: pg_crc32c.h:94
#define snprintf
Definition: port.h:216
#define _(x)
Definition: elog.c:89
int pg_mode_mask
Definition: file_perm.c:25
Datum now(PG_FUNCTION_ARGS)
Definition: timestamp.c:1544
XLogRecPtr checkPoint
Definition: pg_control.h:129
XLogRecPtr redo
Definition: pg_control.h:37
#define offsetof(type, field)
Definition: c.h:727
#define pg_log_info(...)
Definition: logging.h:88
PGconn * PQconnectdb(const char *conninfo)
Definition: fe-connect.c:713
const char * progname
Definition: pg_rewind.c:55
XLogRecPtr minRecoveryPoint
Definition: pg_control.h:166
char * slurpFile(const char *datadir, const char *path, size_t *filesize)
Definition: file_ops.c:314
#define TLHistoryFilePath(path, tli)
#define XLByteToSeg(xlrp, logSegNo, wal_segsz_bytes)