Line data Source code
1 : /*-------------------------------------------------------------------------
2 : *
3 : * xlogfuncs.c
4 : *
5 : * PostgreSQL write-ahead log manager user interface functions
6 : *
7 : * This file contains WAL control and information functions.
8 : *
9 : *
10 : * Portions Copyright (c) 1996-2017, PostgreSQL Global Development Group
11 : * Portions Copyright (c) 1994, Regents of the University of California
12 : *
13 : * src/backend/access/transam/xlogfuncs.c
14 : *
15 : *-------------------------------------------------------------------------
16 : */
17 : #include "postgres.h"
18 :
19 : #include "access/htup_details.h"
20 : #include "access/xlog.h"
21 : #include "access/xlog_internal.h"
22 : #include "access/xlogutils.h"
23 : #include "catalog/catalog.h"
24 : #include "catalog/pg_type.h"
25 : #include "funcapi.h"
26 : #include "miscadmin.h"
27 : #include "replication/walreceiver.h"
28 : #include "storage/smgr.h"
29 : #include "utils/builtins.h"
30 : #include "utils/memutils.h"
31 : #include "utils/numeric.h"
32 : #include "utils/guc.h"
33 : #include "utils/pg_lsn.h"
34 : #include "utils/timestamp.h"
35 : #include "utils/tuplestore.h"
36 : #include "storage/fd.h"
37 : #include "storage/ipc.h"
38 :
39 :
40 : /*
41 : * Store label file and tablespace map during non-exclusive backups.
42 : */
43 : static StringInfo label_file;
44 : static StringInfo tblspc_map_file;
45 :
46 : /*
47 : * Called when the backend exits with a running non-exclusive base backup,
48 : * to clean up state.
49 : */
50 : static void
51 0 : nonexclusive_base_backup_cleanup(int code, Datum arg)
52 : {
53 0 : do_pg_abort_backup();
54 0 : ereport(WARNING,
55 : (errmsg("aborting backup due to backend exiting before pg_stop_backup was called")));
56 0 : }
57 :
58 : /*
59 : * pg_start_backup: set up for taking an on-line backup dump
60 : *
61 : * Essentially what this does is to create a backup label file in $PGDATA,
62 : * where it will be archived as part of the backup dump. The label file
63 : * contains the user-supplied label string (typically this would be used
64 : * to tell where the backup dump will be stored) and the starting time and
65 : * starting WAL location for the dump.
66 : *
67 : * Permission checking for this function is managed through the normal
68 : * GRANT system.
69 : */
70 : Datum
71 0 : pg_start_backup(PG_FUNCTION_ARGS)
72 : {
73 0 : text *backupid = PG_GETARG_TEXT_PP(0);
74 0 : bool fast = PG_GETARG_BOOL(1);
75 0 : bool exclusive = PG_GETARG_BOOL(2);
76 : char *backupidstr;
77 : XLogRecPtr startpoint;
78 : DIR *dir;
79 0 : SessionBackupState status = get_backup_status();
80 :
81 0 : backupidstr = text_to_cstring(backupid);
82 :
83 0 : if (status == SESSION_BACKUP_NON_EXCLUSIVE)
84 0 : ereport(ERROR,
85 : (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
86 : errmsg("a backup is already in progress in this session")));
87 :
88 : /* Make sure we can open the directory with tablespaces in it */
89 0 : dir = AllocateDir("pg_tblspc");
90 0 : if (!dir)
91 0 : ereport(ERROR,
92 : (errmsg("could not open directory \"%s\": %m", "pg_tblspc")));
93 :
94 0 : if (exclusive)
95 : {
96 0 : startpoint = do_pg_start_backup(backupidstr, fast, NULL, NULL,
97 : dir, NULL, NULL, false, true);
98 : }
99 : else
100 : {
101 : MemoryContext oldcontext;
102 :
103 : /*
104 : * Label file and tablespace map file need to be long-lived, since
105 : * they are read in pg_stop_backup.
106 : */
107 0 : oldcontext = MemoryContextSwitchTo(TopMemoryContext);
108 0 : label_file = makeStringInfo();
109 0 : tblspc_map_file = makeStringInfo();
110 0 : MemoryContextSwitchTo(oldcontext);
111 :
112 0 : startpoint = do_pg_start_backup(backupidstr, fast, NULL, label_file,
113 : dir, NULL, tblspc_map_file, false, true);
114 :
115 0 : before_shmem_exit(nonexclusive_base_backup_cleanup, (Datum) 0);
116 : }
117 :
118 0 : FreeDir(dir);
119 :
120 0 : PG_RETURN_LSN(startpoint);
121 : }
122 :
123 : /*
124 : * pg_stop_backup: finish taking an on-line backup dump
125 : *
126 : * We write an end-of-backup WAL record, and remove the backup label file
127 : * created by pg_start_backup, creating a backup history file in pg_wal
128 : * instead (whence it will immediately be archived). The backup history file
129 : * contains the same info found in the label file, plus the backup-end time
130 : * and WAL location. Before 9.0, the backup-end time was read from the backup
131 : * history file at the beginning of archive recovery, but we now use the WAL
132 : * record for that and the file is for informational and debug purposes only.
133 : *
134 : * Note: different from CancelBackup which just cancels online backup mode.
135 : *
136 : * Note: this version is only called to stop an exclusive backup. The function
137 : * pg_stop_backup_v2 (overloaded as pg_stop_backup in SQL) is called to
138 : * stop non-exclusive backups.
139 : *
140 : * Permission checking for this function is managed through the normal
141 : * GRANT system.
142 : */
143 : Datum
144 0 : pg_stop_backup(PG_FUNCTION_ARGS)
145 : {
146 : XLogRecPtr stoppoint;
147 0 : SessionBackupState status = get_backup_status();
148 :
149 0 : if (status == SESSION_BACKUP_NON_EXCLUSIVE)
150 0 : ereport(ERROR,
151 : (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
152 : errmsg("non-exclusive backup in progress"),
153 : errhint("Did you mean to use pg_stop_backup('f')?")));
154 :
155 : /*
156 : * Exclusive backups were typically started in a different connection, so
157 : * don't try to verify that status of backup is set to
158 : * SESSION_BACKUP_EXCLUSIVE in this function. Actual verification that an
159 : * exclusive backup is in fact running is handled inside
160 : * do_pg_stop_backup.
161 : */
162 0 : stoppoint = do_pg_stop_backup(NULL, true, NULL);
163 :
164 0 : PG_RETURN_LSN(stoppoint);
165 : }
166 :
167 :
168 : /*
169 : * pg_stop_backup_v2: finish taking exclusive or nonexclusive on-line backup.
170 : *
171 : * Works the same as pg_stop_backup, except for non-exclusive backups it returns
172 : * the backup label and tablespace map files as text fields in as part of the
173 : * resultset.
174 : *
175 : * The first parameter (variable 'exclusive') allows the user to tell us if
176 : * this is an exclusive or a non-exclusive backup.
177 : *
178 : * The second parameter (variable 'waitforarchive'), which is optional,
179 : * allows the user to choose if they want to wait for the WAL to be archived
180 : * or if we should just return as soon as the WAL record is written.
181 : *
182 : * Permission checking for this function is managed through the normal
183 : * GRANT system.
184 : */
185 : Datum
186 0 : pg_stop_backup_v2(PG_FUNCTION_ARGS)
187 : {
188 0 : ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
189 : TupleDesc tupdesc;
190 : Tuplestorestate *tupstore;
191 : MemoryContext per_query_ctx;
192 : MemoryContext oldcontext;
193 : Datum values[3];
194 : bool nulls[3];
195 :
196 0 : bool exclusive = PG_GETARG_BOOL(0);
197 0 : bool waitforarchive = PG_GETARG_BOOL(1);
198 : XLogRecPtr stoppoint;
199 0 : SessionBackupState status = get_backup_status();
200 :
201 : /* check to see if caller supports us returning a tuplestore */
202 0 : if (rsinfo == NULL || !IsA(rsinfo, ReturnSetInfo))
203 0 : ereport(ERROR,
204 : (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
205 : errmsg("set-valued function called in context that cannot accept a set")));
206 0 : if (!(rsinfo->allowedModes & SFRM_Materialize))
207 0 : ereport(ERROR,
208 : (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
209 : errmsg("materialize mode required, but it is not " \
210 : "allowed in this context")));
211 :
212 : /* Build a tuple descriptor for our result type */
213 0 : if (get_call_result_type(fcinfo, NULL, &tupdesc) != TYPEFUNC_COMPOSITE)
214 0 : elog(ERROR, "return type must be a row type");
215 :
216 0 : per_query_ctx = rsinfo->econtext->ecxt_per_query_memory;
217 0 : oldcontext = MemoryContextSwitchTo(per_query_ctx);
218 :
219 0 : tupstore = tuplestore_begin_heap(true, false, work_mem);
220 0 : rsinfo->returnMode = SFRM_Materialize;
221 0 : rsinfo->setResult = tupstore;
222 0 : rsinfo->setDesc = tupdesc;
223 :
224 0 : MemoryContextSwitchTo(oldcontext);
225 :
226 0 : MemSet(values, 0, sizeof(values));
227 0 : MemSet(nulls, 0, sizeof(nulls));
228 :
229 0 : if (exclusive)
230 : {
231 0 : if (status == SESSION_BACKUP_NON_EXCLUSIVE)
232 0 : ereport(ERROR,
233 : (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
234 : errmsg("non-exclusive backup in progress"),
235 : errhint("Did you mean to use pg_stop_backup('f')?")));
236 :
237 : /*
238 : * Stop the exclusive backup, and since we're in an exclusive backup
239 : * return NULL for both backup_label and tablespace_map.
240 : */
241 0 : stoppoint = do_pg_stop_backup(NULL, waitforarchive, NULL);
242 :
243 0 : nulls[1] = true;
244 0 : nulls[2] = true;
245 : }
246 : else
247 : {
248 0 : if (status != SESSION_BACKUP_NON_EXCLUSIVE)
249 0 : ereport(ERROR,
250 : (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
251 : errmsg("non-exclusive backup is not in progress"),
252 : errhint("Did you mean to use pg_stop_backup('t')?")));
253 :
254 : /*
255 : * Stop the non-exclusive backup. Return a copy of the backup label
256 : * and tablespace map so they can be written to disk by the caller.
257 : */
258 0 : stoppoint = do_pg_stop_backup(label_file->data, waitforarchive, NULL);
259 0 : cancel_before_shmem_exit(nonexclusive_base_backup_cleanup, (Datum) 0);
260 :
261 0 : values[1] = CStringGetTextDatum(label_file->data);
262 0 : values[2] = CStringGetTextDatum(tblspc_map_file->data);
263 :
264 : /* Free structures allocated in TopMemoryContext */
265 0 : pfree(label_file->data);
266 0 : pfree(label_file);
267 0 : label_file = NULL;
268 0 : pfree(tblspc_map_file->data);
269 0 : pfree(tblspc_map_file);
270 0 : tblspc_map_file = NULL;
271 : }
272 :
273 : /* Stoppoint is included on both exclusive and nonexclusive backups */
274 0 : values[0] = LSNGetDatum(stoppoint);
275 :
276 0 : tuplestore_putvalues(tupstore, tupdesc, values, nulls);
277 : tuplestore_donestoring(typstore);
278 :
279 0 : return (Datum) 0;
280 : }
281 :
282 : /*
283 : * pg_switch_wal: switch to next xlog file
284 : *
285 : * Permission checking for this function is managed through the normal
286 : * GRANT system.
287 : */
288 : Datum
289 0 : pg_switch_wal(PG_FUNCTION_ARGS)
290 : {
291 : XLogRecPtr switchpoint;
292 :
293 0 : if (RecoveryInProgress())
294 0 : ereport(ERROR,
295 : (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
296 : errmsg("recovery is in progress"),
297 : errhint("WAL control functions cannot be executed during recovery.")));
298 :
299 0 : switchpoint = RequestXLogSwitch(false);
300 :
301 : /*
302 : * As a convenience, return the WAL location of the switch record
303 : */
304 0 : PG_RETURN_LSN(switchpoint);
305 : }
306 :
307 : /*
308 : * pg_create_restore_point: a named point for restore
309 : *
310 : * Permission checking for this function is managed through the normal
311 : * GRANT system.
312 : */
313 : Datum
314 0 : pg_create_restore_point(PG_FUNCTION_ARGS)
315 : {
316 0 : text *restore_name = PG_GETARG_TEXT_PP(0);
317 : char *restore_name_str;
318 : XLogRecPtr restorepoint;
319 :
320 0 : if (RecoveryInProgress())
321 0 : ereport(ERROR,
322 : (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
323 : (errmsg("recovery is in progress"),
324 : errhint("WAL control functions cannot be executed during recovery."))));
325 :
326 0 : if (!XLogIsNeeded())
327 0 : ereport(ERROR,
328 : (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
329 : errmsg("WAL level not sufficient for creating a restore point"),
330 : errhint("wal_level must be set to \"replica\" or \"logical\" at server start.")));
331 :
332 0 : restore_name_str = text_to_cstring(restore_name);
333 :
334 0 : if (strlen(restore_name_str) >= MAXFNAMELEN)
335 0 : ereport(ERROR,
336 : (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
337 : errmsg("value too long for restore point (maximum %d characters)", MAXFNAMELEN - 1)));
338 :
339 0 : restorepoint = XLogRestorePoint(restore_name_str);
340 :
341 : /*
342 : * As a convenience, return the WAL location of the restore point record
343 : */
344 0 : PG_RETURN_LSN(restorepoint);
345 : }
346 :
347 : /*
348 : * Report the current WAL write location (same format as pg_start_backup etc)
349 : *
350 : * This is useful for determining how much of WAL is visible to an external
351 : * archiving process. Note that the data before this point is written out
352 : * to the kernel, but is not necessarily synced to disk.
353 : */
354 : Datum
355 0 : pg_current_wal_lsn(PG_FUNCTION_ARGS)
356 : {
357 : XLogRecPtr current_recptr;
358 :
359 0 : if (RecoveryInProgress())
360 0 : ereport(ERROR,
361 : (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
362 : errmsg("recovery is in progress"),
363 : errhint("WAL control functions cannot be executed during recovery.")));
364 :
365 0 : current_recptr = GetXLogWriteRecPtr();
366 :
367 0 : PG_RETURN_LSN(current_recptr);
368 : }
369 :
370 : /*
371 : * Report the current WAL insert location (same format as pg_start_backup etc)
372 : *
373 : * This function is mostly for debugging purposes.
374 : */
375 : Datum
376 0 : pg_current_wal_insert_lsn(PG_FUNCTION_ARGS)
377 : {
378 : XLogRecPtr current_recptr;
379 :
380 0 : if (RecoveryInProgress())
381 0 : ereport(ERROR,
382 : (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
383 : errmsg("recovery is in progress"),
384 : errhint("WAL control functions cannot be executed during recovery.")));
385 :
386 0 : current_recptr = GetXLogInsertRecPtr();
387 :
388 0 : PG_RETURN_LSN(current_recptr);
389 : }
390 :
391 : /*
392 : * Report the current WAL flush location (same format as pg_start_backup etc)
393 : *
394 : * This function is mostly for debugging purposes.
395 : */
396 : Datum
397 0 : pg_current_wal_flush_lsn(PG_FUNCTION_ARGS)
398 : {
399 : XLogRecPtr current_recptr;
400 :
401 0 : if (RecoveryInProgress())
402 0 : ereport(ERROR,
403 : (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
404 : errmsg("recovery is in progress"),
405 : errhint("WAL control functions cannot be executed during recovery.")));
406 :
407 0 : current_recptr = GetFlushRecPtr();
408 :
409 0 : PG_RETURN_LSN(current_recptr);
410 : }
411 :
412 : /*
413 : * Report the last WAL receive location (same format as pg_start_backup etc)
414 : *
415 : * This is useful for determining how much of WAL is guaranteed to be received
416 : * and synced to disk by walreceiver.
417 : */
418 : Datum
419 0 : pg_last_wal_receive_lsn(PG_FUNCTION_ARGS)
420 : {
421 : XLogRecPtr recptr;
422 :
423 0 : recptr = GetWalRcvWriteRecPtr(NULL, NULL);
424 :
425 0 : if (recptr == 0)
426 0 : PG_RETURN_NULL();
427 :
428 0 : PG_RETURN_LSN(recptr);
429 : }
430 :
431 : /*
432 : * Report the last WAL replay location (same format as pg_start_backup etc)
433 : *
434 : * This is useful for determining how much of WAL is visible to read-only
435 : * connections during recovery.
436 : */
437 : Datum
438 0 : pg_last_wal_replay_lsn(PG_FUNCTION_ARGS)
439 : {
440 : XLogRecPtr recptr;
441 :
442 0 : recptr = GetXLogReplayRecPtr(NULL);
443 :
444 0 : if (recptr == 0)
445 0 : PG_RETURN_NULL();
446 :
447 0 : PG_RETURN_LSN(recptr);
448 : }
449 :
450 : /*
451 : * Compute an xlog file name and decimal byte offset given a WAL location,
452 : * such as is returned by pg_stop_backup() or pg_switch_wal().
453 : *
454 : * Note that a location exactly at a segment boundary is taken to be in
455 : * the previous segment. This is usually the right thing, since the
456 : * expected usage is to determine which xlog file(s) are ready to archive.
457 : */
458 : Datum
459 0 : pg_walfile_name_offset(PG_FUNCTION_ARGS)
460 : {
461 : XLogSegNo xlogsegno;
462 : uint32 xrecoff;
463 0 : XLogRecPtr locationpoint = PG_GETARG_LSN(0);
464 : char xlogfilename[MAXFNAMELEN];
465 : Datum values[2];
466 : bool isnull[2];
467 : TupleDesc resultTupleDesc;
468 : HeapTuple resultHeapTuple;
469 : Datum result;
470 :
471 0 : if (RecoveryInProgress())
472 0 : ereport(ERROR,
473 : (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
474 : errmsg("recovery is in progress"),
475 : errhint("pg_walfile_name_offset() cannot be executed during recovery.")));
476 :
477 : /*
478 : * Construct a tuple descriptor for the result row. This must match this
479 : * function's pg_proc entry!
480 : */
481 0 : resultTupleDesc = CreateTemplateTupleDesc(2, false);
482 0 : TupleDescInitEntry(resultTupleDesc, (AttrNumber) 1, "file_name",
483 : TEXTOID, -1, 0);
484 0 : TupleDescInitEntry(resultTupleDesc, (AttrNumber) 2, "file_offset",
485 : INT4OID, -1, 0);
486 :
487 0 : resultTupleDesc = BlessTupleDesc(resultTupleDesc);
488 :
489 : /*
490 : * xlogfilename
491 : */
492 0 : XLByteToPrevSeg(locationpoint, xlogsegno);
493 0 : XLogFileName(xlogfilename, ThisTimeLineID, xlogsegno);
494 :
495 0 : values[0] = CStringGetTextDatum(xlogfilename);
496 0 : isnull[0] = false;
497 :
498 : /*
499 : * offset
500 : */
501 0 : xrecoff = locationpoint % XLogSegSize;
502 :
503 0 : values[1] = UInt32GetDatum(xrecoff);
504 0 : isnull[1] = false;
505 :
506 : /*
507 : * Tuple jam: Having first prepared your Datums, then squash together
508 : */
509 0 : resultHeapTuple = heap_form_tuple(resultTupleDesc, values, isnull);
510 :
511 0 : result = HeapTupleGetDatum(resultHeapTuple);
512 :
513 0 : PG_RETURN_DATUM(result);
514 : }
515 :
516 : /*
517 : * Compute an xlog file name given a WAL location,
518 : * such as is returned by pg_stop_backup() or pg_switch_wal().
519 : */
520 : Datum
521 0 : pg_walfile_name(PG_FUNCTION_ARGS)
522 : {
523 : XLogSegNo xlogsegno;
524 0 : XLogRecPtr locationpoint = PG_GETARG_LSN(0);
525 : char xlogfilename[MAXFNAMELEN];
526 :
527 0 : if (RecoveryInProgress())
528 0 : ereport(ERROR,
529 : (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
530 : errmsg("recovery is in progress"),
531 : errhint("pg_walfile_name() cannot be executed during recovery.")));
532 :
533 0 : XLByteToPrevSeg(locationpoint, xlogsegno);
534 0 : XLogFileName(xlogfilename, ThisTimeLineID, xlogsegno);
535 :
536 0 : PG_RETURN_TEXT_P(cstring_to_text(xlogfilename));
537 : }
538 :
539 : /*
540 : * pg_wal_replay_pause - pause recovery now
541 : *
542 : * Permission checking for this function is managed through the normal
543 : * GRANT system.
544 : */
545 : Datum
546 0 : pg_wal_replay_pause(PG_FUNCTION_ARGS)
547 : {
548 0 : if (!RecoveryInProgress())
549 0 : ereport(ERROR,
550 : (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
551 : errmsg("recovery is not in progress"),
552 : errhint("Recovery control functions can only be executed during recovery.")));
553 :
554 0 : SetRecoveryPause(true);
555 :
556 0 : PG_RETURN_VOID();
557 : }
558 :
559 : /*
560 : * pg_wal_replay_resume - resume recovery now
561 : *
562 : * Permission checking for this function is managed through the normal
563 : * GRANT system.
564 : */
565 : Datum
566 0 : pg_wal_replay_resume(PG_FUNCTION_ARGS)
567 : {
568 0 : if (!RecoveryInProgress())
569 0 : ereport(ERROR,
570 : (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
571 : errmsg("recovery is not in progress"),
572 : errhint("Recovery control functions can only be executed during recovery.")));
573 :
574 0 : SetRecoveryPause(false);
575 :
576 0 : PG_RETURN_VOID();
577 : }
578 :
579 : /*
580 : * pg_is_wal_replay_paused
581 : */
582 : Datum
583 0 : pg_is_wal_replay_paused(PG_FUNCTION_ARGS)
584 : {
585 0 : if (!RecoveryInProgress())
586 0 : ereport(ERROR,
587 : (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
588 : errmsg("recovery is not in progress"),
589 : errhint("Recovery control functions can only be executed during recovery.")));
590 :
591 0 : PG_RETURN_BOOL(RecoveryIsPaused());
592 : }
593 :
594 : /*
595 : * Returns timestamp of latest processed commit/abort record.
596 : *
597 : * When the server has been started normally without recovery the function
598 : * returns NULL.
599 : */
600 : Datum
601 0 : pg_last_xact_replay_timestamp(PG_FUNCTION_ARGS)
602 : {
603 : TimestampTz xtime;
604 :
605 0 : xtime = GetLatestXTime();
606 0 : if (xtime == 0)
607 0 : PG_RETURN_NULL();
608 :
609 0 : PG_RETURN_TIMESTAMPTZ(xtime);
610 : }
611 :
612 : /*
613 : * Returns bool with current recovery mode, a global state.
614 : */
615 : Datum
616 0 : pg_is_in_recovery(PG_FUNCTION_ARGS)
617 : {
618 0 : PG_RETURN_BOOL(RecoveryInProgress());
619 : }
620 :
621 : /*
622 : * Compute the difference in bytes between two WAL locations.
623 : */
624 : Datum
625 0 : pg_wal_lsn_diff(PG_FUNCTION_ARGS)
626 : {
627 : Datum result;
628 :
629 0 : result = DirectFunctionCall2(pg_lsn_mi,
630 : PG_GETARG_DATUM(0),
631 : PG_GETARG_DATUM(1));
632 :
633 0 : PG_RETURN_NUMERIC(result);
634 : }
635 :
636 : /*
637 : * Returns bool with current on-line backup mode, a global state.
638 : */
639 : Datum
640 0 : pg_is_in_backup(PG_FUNCTION_ARGS)
641 : {
642 0 : PG_RETURN_BOOL(BackupInProgress());
643 : }
644 :
645 : /*
646 : * Returns start time of an online exclusive backup.
647 : *
648 : * When there's no exclusive backup in progress, the function
649 : * returns NULL.
650 : */
651 : Datum
652 0 : pg_backup_start_time(PG_FUNCTION_ARGS)
653 : {
654 : Datum xtime;
655 : FILE *lfp;
656 : char fline[MAXPGPATH];
657 : char backup_start_time[30];
658 :
659 : /*
660 : * See if label file is present
661 : */
662 0 : lfp = AllocateFile(BACKUP_LABEL_FILE, "r");
663 0 : if (lfp == NULL)
664 : {
665 0 : if (errno != ENOENT)
666 0 : ereport(ERROR,
667 : (errcode_for_file_access(),
668 : errmsg("could not read file \"%s\": %m",
669 : BACKUP_LABEL_FILE)));
670 0 : PG_RETURN_NULL();
671 : }
672 :
673 : /*
674 : * Parse the file to find the START TIME line.
675 : */
676 0 : backup_start_time[0] = '\0';
677 0 : while (fgets(fline, sizeof(fline), lfp) != NULL)
678 : {
679 0 : if (sscanf(fline, "START TIME: %25[^\n]\n", backup_start_time) == 1)
680 0 : break;
681 : }
682 :
683 : /* Check for a read error. */
684 0 : if (ferror(lfp))
685 0 : ereport(ERROR,
686 : (errcode_for_file_access(),
687 : errmsg("could not read file \"%s\": %m", BACKUP_LABEL_FILE)));
688 :
689 : /* Close the backup label file. */
690 0 : if (FreeFile(lfp))
691 0 : ereport(ERROR,
692 : (errcode_for_file_access(),
693 : errmsg("could not close file \"%s\": %m", BACKUP_LABEL_FILE)));
694 :
695 0 : if (strlen(backup_start_time) == 0)
696 0 : ereport(ERROR,
697 : (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
698 : errmsg("invalid data in file \"%s\"", BACKUP_LABEL_FILE)));
699 :
700 : /*
701 : * Convert the time string read from file to TimestampTz form.
702 : */
703 0 : xtime = DirectFunctionCall3(timestamptz_in,
704 : CStringGetDatum(backup_start_time),
705 : ObjectIdGetDatum(InvalidOid),
706 : Int32GetDatum(-1));
707 :
708 0 : PG_RETURN_DATUM(xtime);
709 : }
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