Line data Source code
1 : /*-------------------------------------------------------------------------
2 : *
3 : * filemap.c
4 : * A data structure for keeping track of files that have changed.
5 : *
6 : * This source file contains the logic to decide what to do with different
7 : * kinds of files, and the data structure to support it. Before modifying
8 : * anything, pg_rewind collects information about all the files and their
9 : * attributes in the target and source data directories. It also scans the
10 : * WAL log in the target, and collects information about data blocks that
11 : * were changed. All this information is stored in a hash table, using the
12 : * file path relative to the root of the data directory as the key.
13 : *
14 : * After collecting all the information required, the decide_file_actions()
15 : * function scans the hash table and decides what action needs to be taken
16 : * for each file. Finally, it sorts the array to the final order that the
17 : * actions should be executed in.
18 : *
19 : * Copyright (c) 2013-2025, PostgreSQL Global Development Group
20 : *
21 : *-------------------------------------------------------------------------
22 : */
23 :
24 : #include "postgres_fe.h"
25 :
26 : #include <sys/stat.h>
27 : #include <unistd.h>
28 :
29 : #include "catalog/pg_tablespace_d.h"
30 : #include "common/file_utils.h"
31 : #include "common/hashfn_unstable.h"
32 : #include "common/string.h"
33 : #include "datapagemap.h"
34 : #include "filemap.h"
35 : #include "pg_rewind.h"
36 :
37 : /*
38 : * Define a hash table which we can use to store information about the files
39 : * appearing in source and target systems.
40 : */
41 : #define SH_PREFIX filehash
42 : #define SH_ELEMENT_TYPE file_entry_t
43 : #define SH_KEY_TYPE const char *
44 : #define SH_KEY path
45 : #define SH_HASH_KEY(tb, key) hash_string(key)
46 : #define SH_EQUAL(tb, a, b) (strcmp(a, b) == 0)
47 : #define SH_SCOPE static inline
48 : #define SH_RAW_ALLOCATOR pg_malloc0
49 : #define SH_DECLARE
50 : #define SH_DEFINE
51 : #include "lib/simplehash.h"
52 :
53 : #define FILEHASH_INITIAL_SIZE 1000
54 :
55 : static filehash_hash *filehash;
56 :
57 : static bool isRelDataFile(const char *path);
58 : static char *datasegpath(RelFileLocator rlocator, ForkNumber forknum,
59 : BlockNumber segno);
60 :
61 : static file_entry_t *insert_filehash_entry(const char *path);
62 : static file_entry_t *lookup_filehash_entry(const char *path);
63 :
64 : /*
65 : * A separate hash table which tracks WAL files that must not be deleted.
66 : */
67 : typedef struct keepwal_entry
68 : {
69 : const char *path;
70 : uint32 status;
71 : } keepwal_entry;
72 :
73 : #define SH_PREFIX keepwal
74 : #define SH_ELEMENT_TYPE keepwal_entry
75 : #define SH_KEY_TYPE const char *
76 : #define SH_KEY path
77 : #define SH_HASH_KEY(tb, key) hash_string(key)
78 : #define SH_EQUAL(tb, a, b) (strcmp(a, b) == 0)
79 : #define SH_SCOPE static inline
80 : #define SH_RAW_ALLOCATOR pg_malloc0
81 : #define SH_DECLARE
82 : #define SH_DEFINE
83 : #include "lib/simplehash.h"
84 :
85 : #define KEEPWAL_INITIAL_SIZE 1000
86 :
87 :
88 : static keepwal_hash *keepwal = NULL;
89 : static bool keepwal_entry_exists(const char *path);
90 :
91 : static int final_filemap_cmp(const void *a, const void *b);
92 :
93 : static bool check_file_excluded(const char *path, bool is_source);
94 :
95 : /*
96 : * Definition of one element part of an exclusion list, used to exclude
97 : * contents when rewinding. "name" is the name of the file or path to
98 : * check for exclusion. If "match_prefix" is true, any items matching
99 : * the name as prefix are excluded.
100 : */
101 : struct exclude_list_item
102 : {
103 : const char *name;
104 : bool match_prefix;
105 : };
106 :
107 : /*
108 : * The contents of these directories are removed or recreated during server
109 : * start so they are not included in data processed by pg_rewind.
110 : *
111 : * Note: those lists should be kept in sync with what basebackup.c provides.
112 : * Some of the values, contrary to what basebackup.c uses, are hardcoded as
113 : * they are defined in backend-only headers. So this list is maintained
114 : * with a best effort in mind.
115 : */
116 : static const char *const excludeDirContents[] =
117 : {
118 : /*
119 : * Skip temporary statistics files. PG_STAT_TMP_DIR must be skipped
120 : * because extensions like pg_stat_statements store data there.
121 : */
122 : "pg_stat_tmp", /* defined as PG_STAT_TMP_DIR */
123 :
124 : /*
125 : * It is generally not useful to backup the contents of this directory
126 : * even if the intention is to restore to another primary. See backup.sgml
127 : * for a more detailed description.
128 : */
129 : "pg_replslot", /* defined as PG_REPLSLOT_DIR */
130 :
131 : /* Contents removed on startup, see dsm_cleanup_for_mmap(). */
132 : "pg_dynshmem", /* defined as PG_DYNSHMEM_DIR */
133 :
134 : /* Contents removed on startup, see AsyncShmemInit(). */
135 : "pg_notify",
136 :
137 : /*
138 : * Old contents are loaded for possible debugging but are not required for
139 : * normal operation, see SerialInit().
140 : */
141 : "pg_serial",
142 :
143 : /* Contents removed on startup, see DeleteAllExportedSnapshotFiles(). */
144 : "pg_snapshots",
145 :
146 : /* Contents zeroed on startup, see StartupSUBTRANS(). */
147 : "pg_subtrans",
148 :
149 : /* end of list */
150 : NULL
151 : };
152 :
153 : /*
154 : * List of files excluded from filemap processing. Files are excluded
155 : * if their prefix match.
156 : */
157 : static const struct exclude_list_item excludeFiles[] =
158 : {
159 : /* Skip auto conf temporary file. */
160 : {"postgresql.auto.conf.tmp", false}, /* defined as PG_AUTOCONF_FILENAME */
161 :
162 : /* Skip current log file temporary file */
163 : {"current_logfiles.tmp", false}, /* defined as
164 : * LOG_METAINFO_DATAFILE_TMP */
165 :
166 : /* Skip relation cache because it is rebuilt on startup */
167 : {"pg_internal.init", true}, /* defined as RELCACHE_INIT_FILENAME */
168 :
169 : /*
170 : * If there is a backup_label or tablespace_map file, it indicates that a
171 : * recovery failed and this cluster probably can't be rewound, but exclude
172 : * them anyway if they are found.
173 : */
174 : {"backup_label", false}, /* defined as BACKUP_LABEL_FILE */
175 : {"tablespace_map", false}, /* defined as TABLESPACE_MAP */
176 :
177 : /*
178 : * If there's a backup_manifest, it belongs to a backup that was used to
179 : * start this server. It is *not* correct for this backup. Our
180 : * backup_manifest is injected into the backup separately if users want
181 : * it.
182 : */
183 : {"backup_manifest", false},
184 :
185 : {"postmaster.pid", false},
186 : {"postmaster.opts", false},
187 :
188 : /* end of list */
189 : {NULL, false}
190 : };
191 :
192 : /*
193 : * Initialize the hash table for the file map.
194 : */
195 : void
196 28 : filehash_init(void)
197 : {
198 28 : filehash = filehash_create(FILEHASH_INITIAL_SIZE, NULL);
199 28 : }
200 :
201 : /* Look up entry for 'path', creating a new one if it doesn't exist */
202 : static file_entry_t *
203 64028 : insert_filehash_entry(const char *path)
204 : {
205 : file_entry_t *entry;
206 : bool found;
207 :
208 64028 : entry = filehash_insert(filehash, path, &found);
209 64028 : if (!found)
210 : {
211 33400 : entry->path = pg_strdup(path);
212 33400 : entry->isrelfile = isRelDataFile(path);
213 :
214 33400 : entry->target_exists = false;
215 33400 : entry->target_type = FILE_TYPE_UNDEFINED;
216 33400 : entry->target_size = 0;
217 33400 : entry->target_link_target = NULL;
218 33400 : entry->target_pages_to_overwrite.bitmap = NULL;
219 33400 : entry->target_pages_to_overwrite.bitmapsize = 0;
220 :
221 33400 : entry->source_exists = false;
222 33400 : entry->source_type = FILE_TYPE_UNDEFINED;
223 33400 : entry->source_size = 0;
224 33400 : entry->source_link_target = NULL;
225 :
226 33400 : entry->action = FILE_ACTION_UNDECIDED;
227 : }
228 :
229 64028 : return entry;
230 : }
231 :
232 : static file_entry_t *
233 169040 : lookup_filehash_entry(const char *path)
234 : {
235 169040 : return filehash_lookup(filehash, path);
236 : }
237 :
238 : /*
239 : * Initialize a hash table to store WAL file names that must be kept.
240 : */
241 : void
242 28 : keepwal_init(void)
243 : {
244 : /* An initial hash size out of thin air */
245 28 : keepwal = keepwal_create(KEEPWAL_INITIAL_SIZE, NULL);
246 28 : }
247 :
248 : /* Mark the given file to prevent its removal */
249 : void
250 38 : keepwal_add_entry(const char *path)
251 : {
252 : keepwal_entry *entry;
253 : bool found;
254 :
255 : /* Should only be called with keepwal initialized */
256 : Assert(keepwal != NULL);
257 :
258 38 : entry = keepwal_insert(keepwal, path, &found);
259 :
260 38 : if (!found)
261 38 : entry->path = pg_strdup(path);
262 38 : }
263 :
264 : /* Return true if file is marked as not to be removed, false otherwise */
265 : static bool
266 1304 : keepwal_entry_exists(const char *path)
267 : {
268 1304 : return keepwal_lookup(keepwal, path) != NULL;
269 : }
270 :
271 : /*
272 : * Callback for processing source file list.
273 : *
274 : * This is called once for every file in the source server. We record the
275 : * type and size of the file, so that decide_file_action() can later decide what
276 : * to do with it.
277 : */
278 : void
279 32048 : process_source_file(const char *path, file_type_t type, size_t size,
280 : const char *link_target)
281 : {
282 : file_entry_t *entry;
283 :
284 : /*
285 : * Pretend that pg_wal is a directory, even if it's really a symlink. We
286 : * don't want to mess with the symlink itself, nor complain if it's a
287 : * symlink in source but not in target or vice versa.
288 : */
289 32048 : if (strcmp(path, "pg_wal") == 0 && type == FILE_TYPE_SYMLINK)
290 0 : type = FILE_TYPE_DIRECTORY;
291 :
292 : /*
293 : * sanity check: a filename that looks like a data file better be a
294 : * regular file
295 : */
296 32048 : if (type != FILE_TYPE_REGULAR && isRelDataFile(path))
297 0 : pg_fatal("data file \"%s\" in source is not a regular file", path);
298 :
299 : /* Remember this source file */
300 32048 : entry = insert_filehash_entry(path);
301 32048 : if (entry->source_exists)
302 0 : pg_fatal("duplicate source file \"%s\"", path);
303 32048 : entry->source_exists = true;
304 32048 : entry->source_type = type;
305 32048 : entry->source_size = size;
306 32048 : entry->source_link_target = link_target ? pg_strdup(link_target) : NULL;
307 32048 : }
308 :
309 : /*
310 : * Callback for processing target file list.
311 : *
312 : * Record the type and size of the file, like process_source_file() does.
313 : */
314 : void
315 31980 : process_target_file(const char *path, file_type_t type, size_t size,
316 : const char *link_target)
317 : {
318 : file_entry_t *entry;
319 :
320 : /*
321 : * Do not apply any exclusion filters here. This has advantage to remove
322 : * from the target data folder all paths which have been filtered out from
323 : * the source data folder when processing the source files.
324 : */
325 :
326 : /*
327 : * Like in process_source_file, pretend that pg_wal is always a directory.
328 : */
329 31980 : if (strcmp(path, "pg_wal") == 0 && type == FILE_TYPE_SYMLINK)
330 4 : type = FILE_TYPE_DIRECTORY;
331 :
332 : /* Remember this target file */
333 31980 : entry = insert_filehash_entry(path);
334 31980 : if (entry->target_exists)
335 0 : pg_fatal("duplicate source file \"%s\"", path);
336 31980 : entry->target_exists = true;
337 31980 : entry->target_type = type;
338 31980 : entry->target_size = size;
339 31980 : entry->target_link_target = link_target ? pg_strdup(link_target) : NULL;
340 31980 : }
341 :
342 : /*
343 : * This callback gets called while we read the WAL in the target, for every
344 : * block that has changed in the target system. It decides if the given
345 : * 'blkno' in the target relfile needs to be overwritten from the source, and
346 : * if so, records it in 'target_pages_to_overwrite' bitmap.
347 : *
348 : * NOTE: All the files on both systems must have already been added to the
349 : * hash table!
350 : */
351 : void
352 169040 : process_target_wal_block_change(ForkNumber forknum, RelFileLocator rlocator,
353 : BlockNumber blkno)
354 : {
355 : char *path;
356 : file_entry_t *entry;
357 : BlockNumber blkno_inseg;
358 : int segno;
359 :
360 169040 : segno = blkno / RELSEG_SIZE;
361 169040 : blkno_inseg = blkno % RELSEG_SIZE;
362 :
363 169040 : path = datasegpath(rlocator, forknum, segno);
364 169040 : entry = lookup_filehash_entry(path);
365 169040 : pfree(path);
366 :
367 : /*
368 : * If the block still exists in both systems, remember it. Otherwise we
369 : * can safely ignore it.
370 : *
371 : * If the block is beyond the EOF in the source system, or the file
372 : * doesn't exist in the source at all, we're going to truncate/remove it
373 : * away from the target anyway. Likewise, if it doesn't exist in the
374 : * target anymore, we will copy it over with the "tail" from the source
375 : * system, anyway.
376 : *
377 : * It is possible to find WAL for a file that doesn't exist on either
378 : * system anymore. It means that the relation was dropped later in the
379 : * target system, and independently on the source system too, or that it
380 : * was created and dropped in the target system and it never existed in
381 : * the source. Either way, we can safely ignore it.
382 : */
383 169040 : if (entry)
384 : {
385 : Assert(entry->isrelfile);
386 :
387 169040 : if (entry->target_exists)
388 : {
389 169032 : if (entry->target_type != FILE_TYPE_REGULAR)
390 0 : pg_fatal("unexpected page modification for non-regular file \"%s\"",
391 : entry->path);
392 :
393 169032 : if (entry->source_exists)
394 : {
395 : off_t end_offset;
396 :
397 165748 : end_offset = (blkno_inseg + 1) * BLCKSZ;
398 165748 : if (end_offset <= entry->source_size && end_offset <= entry->target_size)
399 5748 : datapagemap_add(&entry->target_pages_to_overwrite, blkno_inseg);
400 : }
401 : }
402 : }
403 169040 : }
404 :
405 : /*
406 : * Is this the path of file that pg_rewind can skip copying?
407 : */
408 : static bool
409 33368 : check_file_excluded(const char *path, bool is_source)
410 : {
411 : char localpath[MAXPGPATH];
412 : int excludeIdx;
413 : const char *filename;
414 :
415 : /*
416 : * Skip all temporary files, .../pgsql_tmp/... and .../pgsql_tmp.*
417 : */
418 33368 : if (strstr(path, "/" PG_TEMP_FILE_PREFIX) != NULL ||
419 33340 : strstr(path, "/" PG_TEMP_FILES_DIR "/") != NULL)
420 : {
421 28 : return true;
422 : }
423 :
424 : /* check individual files... */
425 299492 : for (excludeIdx = 0; excludeFiles[excludeIdx].name != NULL; excludeIdx++)
426 : {
427 266292 : int cmplen = strlen(excludeFiles[excludeIdx].name);
428 :
429 266292 : filename = last_dir_separator(path);
430 266292 : if (filename == NULL)
431 5804 : filename = path;
432 : else
433 260488 : filename++;
434 :
435 266292 : if (!excludeFiles[excludeIdx].match_prefix)
436 232952 : cmplen++;
437 266292 : if (strncmp(filename, excludeFiles[excludeIdx].name, cmplen) == 0)
438 : {
439 140 : if (is_source)
440 140 : pg_log_debug("entry \"%s\" excluded from source file list",
441 : path);
442 : else
443 0 : pg_log_debug("entry \"%s\" excluded from target file list",
444 : path);
445 140 : return true;
446 : }
447 : }
448 :
449 : /*
450 : * ... And check some directories. Note that this includes any contents
451 : * within the directories themselves.
452 : */
453 265572 : for (excludeIdx = 0; excludeDirContents[excludeIdx] != NULL; excludeIdx++)
454 : {
455 232400 : snprintf(localpath, sizeof(localpath), "%s/",
456 : excludeDirContents[excludeIdx]);
457 232400 : if (strstr(path, localpath) == path)
458 : {
459 28 : if (is_source)
460 28 : pg_log_debug("entry \"%s\" excluded from source file list",
461 : path);
462 : else
463 0 : pg_log_debug("entry \"%s\" excluded from target file list",
464 : path);
465 28 : return true;
466 : }
467 : }
468 :
469 33172 : return false;
470 : }
471 :
472 : static const char *
473 11176 : action_to_str(file_action_t action)
474 : {
475 11176 : switch (action)
476 : {
477 830 : case FILE_ACTION_NONE:
478 830 : return "NONE";
479 8872 : case FILE_ACTION_COPY:
480 8872 : return "COPY";
481 8 : case FILE_ACTION_TRUNCATE:
482 8 : return "TRUNCATE";
483 10 : case FILE_ACTION_COPY_TAIL:
484 10 : return "COPY_TAIL";
485 18 : case FILE_ACTION_CREATE:
486 18 : return "CREATE";
487 1438 : case FILE_ACTION_REMOVE:
488 1438 : return "REMOVE";
489 :
490 0 : default:
491 0 : return "unknown";
492 : }
493 : }
494 :
495 : /*
496 : * Calculate the totals needed for progress reports.
497 : */
498 : void
499 0 : calculate_totals(filemap_t *filemap)
500 : {
501 : file_entry_t *entry;
502 : int i;
503 :
504 0 : filemap->total_size = 0;
505 0 : filemap->fetch_size = 0;
506 :
507 0 : for (i = 0; i < filemap->nentries; i++)
508 : {
509 0 : entry = filemap->entries[i];
510 :
511 0 : if (entry->source_type != FILE_TYPE_REGULAR)
512 0 : continue;
513 :
514 0 : filemap->total_size += entry->source_size;
515 :
516 0 : if (entry->action == FILE_ACTION_COPY)
517 : {
518 0 : filemap->fetch_size += entry->source_size;
519 0 : continue;
520 : }
521 :
522 0 : if (entry->action == FILE_ACTION_COPY_TAIL)
523 0 : filemap->fetch_size += (entry->source_size - entry->target_size);
524 :
525 0 : if (entry->target_pages_to_overwrite.bitmapsize > 0)
526 : {
527 : datapagemap_iterator_t *iter;
528 : BlockNumber blk;
529 :
530 0 : iter = datapagemap_iterate(&entry->target_pages_to_overwrite);
531 0 : while (datapagemap_next(iter, &blk))
532 0 : filemap->fetch_size += BLCKSZ;
533 :
534 0 : pg_free(iter);
535 : }
536 : }
537 0 : }
538 :
539 : void
540 28 : print_filemap(filemap_t *filemap)
541 : {
542 : file_entry_t *entry;
543 : int i;
544 :
545 33428 : for (i = 0; i < filemap->nentries; i++)
546 : {
547 33400 : entry = filemap->entries[i];
548 33400 : if (entry->action != FILE_ACTION_NONE ||
549 23054 : entry->target_pages_to_overwrite.bitmapsize > 0)
550 : {
551 11176 : pg_log_debug("%s (%s)", entry->path,
552 : action_to_str(entry->action));
553 :
554 11176 : if (entry->target_pages_to_overwrite.bitmapsize > 0)
555 846 : datapagemap_print(&entry->target_pages_to_overwrite);
556 : }
557 : }
558 28 : fflush(stdout);
559 28 : }
560 :
561 : /*
562 : * Does it look like a relation data file?
563 : *
564 : * For our purposes, only files belonging to the main fork are considered
565 : * relation files. Other forks are always copied in toto, because we cannot
566 : * reliably track changes to them, because WAL only contains block references
567 : * for the main fork.
568 : */
569 : static bool
570 34186 : isRelDataFile(const char *path)
571 : {
572 : RelFileLocator rlocator;
573 : unsigned int segNo;
574 : int nmatch;
575 : bool matched;
576 :
577 : /*----
578 : * Relation data files can be in one of the following directories:
579 : *
580 : * global/
581 : * shared relations
582 : *
583 : * base/<db oid>/
584 : * regular relations, default tablespace
585 : *
586 : * pg_tblspc/<tblspc oid>/<tblspc version>/
587 : * within a non-default tablespace (the name of the directory
588 : * depends on version)
589 : *
590 : * And the relation data files themselves have a filename like:
591 : *
592 : * <oid>.<segment number>
593 : *
594 : *----
595 : */
596 34186 : rlocator.spcOid = InvalidOid;
597 34186 : rlocator.dbOid = InvalidOid;
598 34186 : rlocator.relNumber = InvalidRelFileNumber;
599 34186 : segNo = 0;
600 34186 : matched = false;
601 :
602 34186 : nmatch = sscanf(path, "global/%u.%u", &rlocator.relNumber, &segNo);
603 34186 : if (nmatch == 1 || nmatch == 2)
604 : {
605 1624 : rlocator.spcOid = GLOBALTABLESPACE_OID;
606 1624 : rlocator.dbOid = 0;
607 1624 : matched = true;
608 : }
609 : else
610 : {
611 32562 : nmatch = sscanf(path, "base/%u/%u.%u",
612 : &rlocator.dbOid, &rlocator.relNumber, &segNo);
613 32562 : if (nmatch == 2 || nmatch == 3)
614 : {
615 29974 : rlocator.spcOid = DEFAULTTABLESPACE_OID;
616 29974 : matched = true;
617 : }
618 : else
619 : {
620 2588 : nmatch = sscanf(path, "pg_tblspc/%u/" TABLESPACE_VERSION_DIRECTORY "/%u/%u.%u",
621 : &rlocator.spcOid, &rlocator.dbOid, &rlocator.relNumber,
622 : &segNo);
623 2588 : if (nmatch == 3 || nmatch == 4)
624 24 : matched = true;
625 : }
626 : }
627 :
628 : /*
629 : * The sscanf tests above can match files that have extra characters at
630 : * the end. To eliminate such cases, cross-check that GetRelationPath
631 : * creates the exact same filename, when passed the RelFileLocator
632 : * information we extracted from the filename.
633 : */
634 34186 : if (matched)
635 : {
636 31622 : char *check_path = datasegpath(rlocator, MAIN_FORKNUM, segNo);
637 :
638 31622 : if (strcmp(check_path, path) != 0)
639 7704 : matched = false;
640 :
641 31622 : pfree(check_path);
642 : }
643 :
644 34186 : return matched;
645 : }
646 :
647 : /*
648 : * A helper function to create the path of a relation file and segment.
649 : *
650 : * The returned path is palloc'd
651 : */
652 : static char *
653 200662 : datasegpath(RelFileLocator rlocator, ForkNumber forknum, BlockNumber segno)
654 : {
655 : char *path;
656 : char *segpath;
657 :
658 200662 : path = relpathperm(rlocator, forknum);
659 200662 : if (segno > 0)
660 : {
661 0 : segpath = psprintf("%s.%u", path, segno);
662 0 : pfree(path);
663 0 : return segpath;
664 : }
665 : else
666 200662 : return path;
667 : }
668 :
669 : /*
670 : * In the final stage, the filemap is sorted so that removals come last.
671 : * From disk space usage point of view, it would be better to do removals
672 : * first, but for now, safety first. If a whole directory is deleted, all
673 : * files and subdirectories inside it need to removed first. On creation,
674 : * parent directory needs to be created before files and directories inside
675 : * it. To achieve that, the file_action_t enum is ordered so that we can
676 : * just sort on that first. Furthermore, sort REMOVE entries in reverse
677 : * path order, so that "foo/bar" subdirectory is removed before "foo".
678 : */
679 : static int
680 354464 : final_filemap_cmp(const void *a, const void *b)
681 : {
682 354464 : file_entry_t *fa = *((file_entry_t **) a);
683 354464 : file_entry_t *fb = *((file_entry_t **) b);
684 :
685 354464 : if (fa->action > fb->action)
686 9584 : return 1;
687 344880 : if (fa->action < fb->action)
688 20862 : return -1;
689 :
690 324018 : if (fa->action == FILE_ACTION_REMOVE)
691 11264 : return strcmp(fb->path, fa->path);
692 : else
693 312754 : return strcmp(fa->path, fb->path);
694 : }
695 :
696 : /*
697 : * Decide what action to perform to a file.
698 : */
699 : static file_action_t
700 33400 : decide_file_action(file_entry_t *entry)
701 : {
702 33400 : const char *path = entry->path;
703 :
704 : /*
705 : * Don't touch the control file. It is handled specially, after copying
706 : * all the other files.
707 : */
708 33400 : if (strcmp(path, "global/pg_control") == 0)
709 28 : return FILE_ACTION_NONE;
710 :
711 : /* Skip macOS system files */
712 33372 : if (strstr(path, ".DS_Store") != NULL)
713 4 : return FILE_ACTION_NONE;
714 :
715 : /*
716 : * Remove all files matching the exclusion filters in the target.
717 : */
718 33368 : if (check_file_excluded(path, true))
719 : {
720 196 : if (entry->target_exists)
721 140 : return FILE_ACTION_REMOVE;
722 : else
723 56 : return FILE_ACTION_NONE;
724 : }
725 :
726 : /*
727 : * Handle cases where the file is missing from one of the systems.
728 : */
729 33172 : if (!entry->target_exists && entry->source_exists)
730 : {
731 : /*
732 : * File exists in source, but not in target. Copy it in toto. (If it's
733 : * a relation data file, WAL replay after rewinding should re-create
734 : * it anyway. But there's no harm in copying it now.)
735 : */
736 1360 : switch (entry->source_type)
737 : {
738 18 : case FILE_TYPE_DIRECTORY:
739 : case FILE_TYPE_SYMLINK:
740 18 : return FILE_ACTION_CREATE;
741 1342 : case FILE_TYPE_REGULAR:
742 1342 : return FILE_ACTION_COPY;
743 0 : case FILE_TYPE_UNDEFINED:
744 0 : pg_fatal("unknown file type for \"%s\"", entry->path);
745 : break;
746 : }
747 : }
748 31812 : else if (entry->target_exists && !entry->source_exists)
749 : {
750 : /*
751 : * For files that exist in target but not in source, we check the
752 : * keepwal hash table; any files listed therein must not be removed.
753 : */
754 1304 : if (keepwal_entry_exists(path))
755 : {
756 6 : pg_log_debug("Not removing file \"%s\" because it is required for recovery", path);
757 6 : return FILE_ACTION_NONE;
758 : }
759 1298 : return FILE_ACTION_REMOVE;
760 : }
761 30508 : else if (!entry->target_exists && !entry->source_exists)
762 : {
763 : /*
764 : * Doesn't exist in either server. Why does it have an entry in the
765 : * first place??
766 : */
767 : Assert(false);
768 0 : return FILE_ACTION_NONE;
769 : }
770 :
771 : /*
772 : * Otherwise, the file exists on both systems
773 : */
774 : Assert(entry->target_exists && entry->source_exists);
775 :
776 30508 : if (entry->source_type != entry->target_type)
777 : {
778 : /* But it's a different kind of object. Strange.. */
779 0 : pg_fatal("file \"%s\" is of different type in source and target", entry->path);
780 : }
781 :
782 : /*
783 : * PG_VERSION files should be identical on both systems, but avoid
784 : * overwriting them for paranoia.
785 : */
786 30508 : if (pg_str_endswith(entry->path, "PG_VERSION"))
787 120 : return FILE_ACTION_NONE;
788 :
789 30388 : switch (entry->source_type)
790 : {
791 764 : case FILE_TYPE_DIRECTORY:
792 764 : return FILE_ACTION_NONE;
793 :
794 0 : case FILE_TYPE_SYMLINK:
795 :
796 : /*
797 : * XXX: Should we check if it points to the same target?
798 : */
799 0 : return FILE_ACTION_NONE;
800 :
801 29624 : case FILE_TYPE_REGULAR:
802 29624 : if (!entry->isrelfile)
803 : {
804 : /*
805 : * It's a non-data file that we have no special processing
806 : * for. Copy it in toto.
807 : */
808 7530 : return FILE_ACTION_COPY;
809 : }
810 : else
811 : {
812 : /*
813 : * It's a data file that exists in both systems.
814 : *
815 : * If it's larger in target, we can truncate it. There will
816 : * also be a WAL record of the truncation in the source
817 : * system, so WAL replay would eventually truncate the target
818 : * too, but we might as well do it now.
819 : *
820 : * If it's smaller in the target, it means that it has been
821 : * truncated in the target, or enlarged in the source, or
822 : * both. If it was truncated in the target, we need to copy
823 : * the missing tail from the source system. If it was enlarged
824 : * in the source system, there will be WAL records in the
825 : * source system for the new blocks, so we wouldn't need to
826 : * copy them here. But we don't know which scenario we're
827 : * dealing with, and there's no harm in copying the missing
828 : * blocks now, so do it now.
829 : *
830 : * If it's the same size, do nothing here. Any blocks modified
831 : * in the target will be copied based on parsing the target
832 : * system's WAL, and any blocks modified in the source will be
833 : * updated after rewinding, when the source system's WAL is
834 : * replayed.
835 : */
836 22094 : if (entry->target_size < entry->source_size)
837 10 : return FILE_ACTION_COPY_TAIL;
838 22084 : else if (entry->target_size > entry->source_size)
839 8 : return FILE_ACTION_TRUNCATE;
840 : else
841 22076 : return FILE_ACTION_NONE;
842 : }
843 : break;
844 :
845 0 : case FILE_TYPE_UNDEFINED:
846 0 : pg_fatal("unknown file type for \"%s\"", path);
847 : break;
848 : }
849 :
850 : /* unreachable */
851 0 : pg_fatal("could not decide what to do with file \"%s\"", path);
852 : }
853 :
854 : /*
855 : * Decide what to do with each file.
856 : *
857 : * Returns a 'filemap' with the entries in the order that their actions
858 : * should be executed.
859 : */
860 : filemap_t *
861 28 : decide_file_actions(void)
862 : {
863 : int i;
864 : filehash_iterator it;
865 : file_entry_t *entry;
866 : filemap_t *filemap;
867 :
868 28 : filehash_start_iterate(filehash, &it);
869 33428 : while ((entry = filehash_iterate(filehash, &it)) != NULL)
870 : {
871 33400 : entry->action = decide_file_action(entry);
872 : }
873 :
874 : /*
875 : * Turn the hash table into an array, and sort in the order that the
876 : * actions should be performed.
877 : */
878 28 : filemap = pg_malloc(offsetof(filemap_t, entries) +
879 28 : filehash->members * sizeof(file_entry_t *));
880 28 : filemap->nentries = filehash->members;
881 28 : filehash_start_iterate(filehash, &it);
882 28 : i = 0;
883 33428 : while ((entry = filehash_iterate(filehash, &it)) != NULL)
884 : {
885 33400 : filemap->entries[i++] = entry;
886 : }
887 :
888 28 : qsort(&filemap->entries, filemap->nentries, sizeof(file_entry_t *),
889 : final_filemap_cmp);
890 :
891 28 : return filemap;
892 : }
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