1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
|
/*********************************************************************
* bfs *
* Copyright (C) 2015 Tavian Barnes <tavianator@tavianator.com> *
* *
* This program is free software. It comes without any warranty, to *
* the extent permitted by applicable law. You can redistribute it *
* and/or modify it under the terms of the Do What The Fuck You Want *
* To Public License, Version 2, as published by Sam Hocevar. See *
* the COPYING file or http://www.wtfpl.net/ for more details. *
*********************************************************************/
/**
* bftw() implementation.
*
* The goal of this implementation is to avoid re-traversal by using openat() as
* much as possible. Since the number of open file descriptors is limited, the
* 'dircache' maintains a priority queue of open 'dircache_entry's, ordered by
* their reference counts to keep the most-referenced parent directories open.
*
* The 'dirqueue' is a simple FIFO of 'dircache_entry's left to explore.
*/
#include "bftw.h"
#include "dstring.h"
#include "util.h"
#include <assert.h>
#include <dirent.h>
#include <errno.h>
#include <fcntl.h>
#include <limits.h>
#include <stdbool.h>
#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <unistd.h>
/**
* A single entry in the dircache.
*/
struct dircache_entry {
/** The parent entry, if any. */
struct dircache_entry *parent;
/** This directory's depth in the walk. */
size_t depth;
/** Reference count. */
size_t refcount;
/** Index in the priority queue. */
size_t heap_index;
/** An open file descriptor to this directory, or -1. */
int fd;
/** The device number, for cycle detection. */
dev_t dev;
/** The inode number, for cycle detection. */
ino_t ino;
/** The offset of this directory in the full path. */
size_t nameoff;
/** The length of the directory's name. */
size_t namelen;
/** The directory's name. */
char name[];
};
/**
* A directory cache.
*/
struct dircache {
/** A min-heap of open entries, ordered by refcount. */
struct dircache_entry **heap;
/** Current heap size. */
size_t size;
/** Maximum heap size. */
size_t capacity;
};
/** Initialize a dircache. */
static int dircache_init(struct dircache *cache, size_t capacity) {
cache->heap = malloc(capacity*sizeof(struct dircache_entry *));
if (!cache->heap) {
return -1;
}
cache->size = 0;
cache->capacity = capacity;
return 0;
}
/** Destroy a dircache. */
static void dircache_free(struct dircache *cache) {
assert(cache->size == 0);
free(cache->heap);
}
/** Move an entry to a particular place in the heap. */
static void dircache_heap_move(struct dircache *cache, struct dircache_entry *entry, size_t i) {
cache->heap[i] = entry;
entry->heap_index = i;
}
/** Bubble an entry up the heap. */
static void dircache_bubble_up(struct dircache *cache, struct dircache_entry *entry) {
size_t i = entry->heap_index;
while (i > 0) {
size_t pi = (i - 1)/2;
struct dircache_entry *parent = cache->heap[pi];
if (entry->refcount >= parent->refcount) {
break;
}
dircache_heap_move(cache, parent, i);
i = pi;
}
dircache_heap_move(cache, entry, i);
}
/** Bubble an entry down the heap. */
static void dircache_bubble_down(struct dircache *cache, struct dircache_entry *entry) {
size_t i = entry->heap_index;
while (true) {
size_t ci = 2*i + 1;
if (ci >= cache->size) {
break;
}
struct dircache_entry *child = cache->heap[ci];
size_t ri = ci + 1;
if (ri < cache->size) {
struct dircache_entry *right = cache->heap[ri];
if (child->refcount > right->refcount) {
ci = ri;
child = right;
}
}
dircache_heap_move(cache, child, i);
i = ci;
}
dircache_heap_move(cache, entry, i);
}
/** Increment a dircache_entry's reference count. */
static void dircache_entry_incref(struct dircache *cache, struct dircache_entry *entry) {
++entry->refcount;
if (entry->fd >= 0) {
dircache_bubble_down(cache, entry);
}
}
/** Decrement a dircache_entry's reference count. */
static void dircache_entry_decref(struct dircache *cache, struct dircache_entry *entry) {
--entry->refcount;
if (entry->fd >= 0) {
dircache_bubble_up(cache, entry);
}
}
/** Add a dircache_entry to the priority queue. */
static void dircache_push(struct dircache *cache, struct dircache_entry *entry) {
assert(cache->size < cache->capacity);
assert(entry->fd >= 0);
size_t size = cache->size++;
entry->heap_index = size;
dircache_bubble_up(cache, entry);
}
/** Close a dircache_entry and remove it from the priority queue. */
static void dircache_pop(struct dircache *cache, struct dircache_entry *entry) {
assert(cache->size > 0);
assert(entry->fd >= 0);
close(entry->fd);
entry->fd = -1;
size_t size = --cache->size;
size_t i = entry->heap_index;
if (i != size) {
struct dircache_entry *end = cache->heap[size];
end->heap_index = i;
dircache_bubble_down(cache, end);
}
}
/** Add an entry to the dircache. */
static struct dircache_entry *dircache_add(struct dircache *cache, struct dircache_entry *parent, const char *name) {
size_t namelen = strlen(name);
size_t size = sizeof(struct dircache_entry) + namelen;
bool needs_slash = false;
if (namelen == 0 || name[namelen - 1] != '/') {
needs_slash = true;
++size;
}
struct dircache_entry *entry = malloc(size);
if (!entry) {
return NULL;
}
entry->parent = parent;
if (parent) {
entry->depth = parent->depth + 1;
entry->nameoff = parent->nameoff + parent->namelen;
} else {
entry->depth = 0;
entry->nameoff = 0;
}
entry->refcount = 1;
entry->fd = -1;
entry->dev = -1;
entry->ino = -1;
memcpy(entry->name, name, namelen);
if (needs_slash) {
entry->name[namelen++] = '/';
}
entry->namelen = namelen;
while (parent) {
dircache_entry_incref(cache, parent);
parent = parent->parent;
}
return entry;
}
/**
* Get the full path to a dircache_entry.
*
* @param entry
* The entry to look up.
* @param[out] path
* Will hold the full path to the entry, with a trailing '/'.
*/
static int dircache_entry_path(const struct dircache_entry *entry, char **path) {
size_t namelen = entry->namelen;
size_t pathlen = entry->nameoff + namelen;
if (dstresize(path, pathlen) != 0) {
return -1;
}
// Build the path backwards
do {
char *segment = *path + entry->nameoff;
namelen = entry->namelen;
memcpy(segment, entry->name, namelen);
entry = entry->parent;
} while (entry);
return 0;
}
/**
* Get the appropriate (fd, path) pair for the *at() family of functions.
*
* @param cache
* The cache containing the entry.
* @param entry
* The entry being accessed.
* @param[out] at_fd
* Will hold the appropriate file descriptor to use.
* @param[in,out] at_path
* Will hold the appropriate path to use.
* @return The closest open ancestor entry.
*/
static struct dircache_entry *dircache_entry_base(struct dircache *cache, struct dircache_entry *entry, int *at_fd, const char **at_path) {
struct dircache_entry *base = entry;
do {
base = base->parent;
} while (base && base->fd < 0);
if (base) {
*at_fd = base->fd;
*at_path += base->nameoff + base->namelen;
}
return base;
}
/**
* Check if we should retry an operation due to EMFILE.
*
* @param cache
* The cache in question.
* @param save
* A dircache_entry that must be preserved.
*/
static bool dircache_should_retry(struct dircache *cache, const struct dircache_entry *save) {
if (errno == EMFILE && cache->size > 1) {
// Too many open files, shrink the cache
struct dircache_entry *entry = cache->heap[0];
if (entry == save) {
entry = cache->heap[1];
}
dircache_pop(cache, entry);
cache->capacity = cache->size;
return true;
} else {
return false;
}
}
/**
* Open a dircache_entry.
*
* @param cache
* The cache containing the entry.
* @param entry
* The entry to open.
* @param path
* The full path to the entry (see dircache_entry_path()).
* @return
* The opened DIR *, or NULL on error.
*/
static DIR *dircache_entry_open(struct dircache *cache, struct dircache_entry *entry, const char *path) {
assert(entry->fd < 0);
if (cache->size == cache->capacity) {
dircache_pop(cache, cache->heap[0]);
}
int at_fd = AT_FDCWD;
const char *at_path = path;
struct dircache_entry *base = dircache_entry_base(cache, entry, &at_fd, &at_path);
int flags = O_RDONLY | O_DIRECTORY | O_CLOEXEC;
int fd = openat(at_fd, at_path, flags);
if (fd < 0 && dircache_should_retry(cache, base)) {
fd = openat(at_fd, at_path, flags);
}
if (fd < 0) {
return NULL;
}
entry->fd = fd;
dircache_push(cache, entry);
// Now we dup() the fd and pass it to fdopendir(). This way we can
// close the DIR* as soon as we're done with it, reducing the memory
// footprint significantly, while keeping the fd around for future
// openat() calls.
fd = fcntl(entry->fd, F_DUPFD_CLOEXEC, 0);
if (fd < 0 && dircache_should_retry(cache, entry)) {
fd = fcntl(entry->fd, F_DUPFD_CLOEXEC, 0);
}
if (fd < 0) {
return NULL;
}
DIR *dir = fdopendir(fd);
if (!dir) {
close(fd);
}
return dir;
}
/** Free a dircache_entry. */
static void dircache_entry_free(struct dircache *cache, struct dircache_entry *entry) {
if (entry) {
assert(entry->refcount == 0);
if (entry->fd >= 0) {
dircache_pop(cache, entry);
}
free(entry);
}
}
/**
* A queue of 'dircache_entry's to examine.
*/
struct dirqueue {
/** The circular buffer of entries. */
struct dircache_entry **entries;
/** Bitmask for circular buffer indices; one less than the capacity. */
size_t mask;
/** The index of the front of the queue. */
size_t front;
/** The index of the back of the queue. */
size_t back;
};
/** Initialize a dirqueue. */
static int dirqueue_init(struct dirqueue *queue) {
size_t size = 256;
queue->entries = malloc(size*sizeof(struct dircache_entry *));
if (!queue->entries) {
return -1;
}
queue->mask = size - 1;
queue->front = 0;
queue->back = 0;
return 0;
}
/** Add an entry to the dirqueue. */
static int dirqueue_push(struct dirqueue *queue, struct dircache_entry *entry) {
size_t back = queue->back;
queue->entries[back] = entry;
back += 1;
back &= queue->mask;
if (back == queue->front) {
size_t old_size = queue->mask + 1;
size_t new_size = 2*old_size;
struct dircache_entry **entries = realloc(queue->entries, new_size*sizeof(struct dircache_entry *));
if (!entries) {
return -1;
}
size_t old_front = queue->front;
size_t new_front = old_size + old_front;
size_t tail_size = old_size - old_front;
memcpy(entries + new_front, entries + old_front, tail_size*sizeof(struct dircache_entry *));
queue->entries = entries;
queue->mask = new_size - 1;
queue->front = new_front;
}
queue->back = back;
return 0;
}
/** Remove an entry from the dirqueue. */
static struct dircache_entry *dirqueue_pop(struct dirqueue *queue) {
if (queue->front == queue->back) {
return NULL;
}
struct dircache_entry *entry = queue->entries[queue->front];
queue->front += 1;
queue->front &= queue->mask;
return entry;
}
/** Destroy a dirqueue. */
static void dirqueue_free(struct dirqueue *queue) {
free(queue->entries);
}
/** Fill in ftwbuf fields with information from a struct dirent. */
static void ftwbuf_use_dirent(struct BFTW *ftwbuf, const struct dirent *de) {
#if defined(_DIRENT_HAVE_D_TYPE) || defined(DT_UNKNOWN)
switch (de->d_type) {
#ifdef DT_BLK
case DT_BLK:
ftwbuf->typeflag = BFTW_BLK;
break;
#endif
#ifdef DT_CHR
case DT_CHR:
ftwbuf->typeflag = BFTW_CHR;
break;
#endif
#ifdef DT_DIR
case DT_DIR:
ftwbuf->typeflag = BFTW_DIR;
break;
#endif
#ifdef DT_DOOR
case DT_DOOR:
ftwbuf->typeflag = BFTW_DOOR;
break;
#endif
#ifdef DT_FIFO
case DT_FIFO:
ftwbuf->typeflag = BFTW_FIFO;
break;
#endif
#ifdef DT_LNK
case DT_LNK:
ftwbuf->typeflag = BFTW_LNK;
break;
#endif
#ifdef DT_PORT
case DT_PORT:
ftwbuf->typeflag = BFTW_PORT;
break;
#endif
#ifdef DT_REG
case DT_REG:
ftwbuf->typeflag = BFTW_REG;
break;
#endif
#ifdef DT_SOCK
case DT_SOCK:
ftwbuf->typeflag = BFTW_SOCK;
break;
#endif
#ifdef DT_WHT
case DT_WHT:
ftwbuf->typeflag = BFTW_WHT;
break;
#endif
}
#endif
}
/** Call stat() and use the results. */
static int ftwbuf_stat(struct BFTW *ftwbuf, struct stat *sb, int flags) {
int ret = fstatat(ftwbuf->at_fd, ftwbuf->at_path, sb, flags);
if (ret != 0) {
return ret;
}
ftwbuf->statbuf = sb;
switch (sb->st_mode & S_IFMT) {
#ifdef S_IFBLK
case S_IFBLK:
ftwbuf->typeflag = BFTW_BLK;
break;
#endif
#ifdef S_IFCHR
case S_IFCHR:
ftwbuf->typeflag = BFTW_CHR;
break;
#endif
#ifdef S_IFDIR
case S_IFDIR:
ftwbuf->typeflag = BFTW_DIR;
break;
#endif
#ifdef S_IFDOOR
case S_IFDOOR:
ftwbuf->typeflag = BFTW_DOOR;
break;
#endif
#ifdef S_IFIFO
case S_IFIFO:
ftwbuf->typeflag = BFTW_FIFO;
break;
#endif
#ifdef S_IFLNK
case S_IFLNK:
ftwbuf->typeflag = BFTW_LNK;
break;
#endif
#ifdef S_IFPORT
case S_IFPORT:
ftwbuf->typeflag = BFTW_PORT;
break;
#endif
#ifdef S_IFREG
case S_IFREG:
ftwbuf->typeflag = BFTW_REG;
break;
#endif
#ifdef S_IFSOCK
case S_IFSOCK:
ftwbuf->typeflag = BFTW_SOCK;
break;
#endif
#ifdef S_IFWHT
case S_IFWHT:
ftwbuf->typeflag = BFTW_WHT;
break;
#endif
}
return 0;
}
/**
* Possible bftw() traversal statuses.
*/
enum bftw_status {
/** The current path is state.current. */
BFTW_CURRENT,
/** The current path is a child of state.current. */
BFTW_CHILD,
/** dircache_entry's are being garbage collected. */
BFTW_GC,
};
/**
* Holds the current state of the bftw() traversal.
*/
struct bftw_state {
/** bftw() callback. */
bftw_fn *fn;
/** bftw() flags. */
int flags;
/** bftw() callback data. */
void *ptr;
/** The appropriate errno value, if any. */
int error;
/** The cache of open directories. */
struct dircache cache;
/** The queue of directories left to explore. */
struct dirqueue queue;
/** The current dircache entry. */
struct dircache_entry *current;
/** The current traversal status. */
enum bftw_status status;
/** The root path of the walk. */
const char *root;
/** The current path being explored. */
char *path;
/** Extra data about the current file. */
struct BFTW ftwbuf;
/** stat() buffer for the current file. */
struct stat statbuf;
};
/**
* Initialize the bftw() state.
*/
static int bftw_state_init(struct bftw_state *state, const char *root, bftw_fn *fn, int nopenfd, int flags, void *ptr) {
state->root = root;
state->fn = fn;
state->flags = flags;
state->ptr = ptr;
state->error = 0;
if (nopenfd < 2) {
errno = EMFILE;
return -1;
}
// -1 to account for dup()
if (dircache_init(&state->cache, nopenfd - 1) != 0) {
goto err;
}
if (dirqueue_init(&state->queue) != 0) {
goto err_cache;
}
state->current = NULL;
state->status = BFTW_CURRENT;
state->path = dstralloc(0);
if (!state->path) {
goto err_queue;
}
return 0;
err_queue:
dirqueue_free(&state->queue);
err_cache:
dircache_free(&state->cache);
err:
return -1;
}
/**
* Concatenate a subpath to the current path.
*/
static int bftw_path_concat(struct bftw_state *state, const char *subpath) {
size_t nameoff = 0;
struct dircache_entry *current = state->current;
if (current) {
nameoff = current->nameoff + current->namelen;
}
state->status = BFTW_CHILD;
if (dstresize(&state->path, nameoff) != 0) {
return -1;
}
return dstrcat(&state->path, subpath);
}
/**
* Trim the path to just the current directory.
*/
static void bftw_path_trim(struct bftw_state *state) {
struct dircache_entry *current = state->current;
size_t length;
if (current->depth == 0) {
// Use exactly the string passed to bftw(), including any
// trailing slashes
length = strlen(state->root);
} else {
length = current->nameoff + current->namelen;
if (current->namelen > 1) {
// Trim the trailing slash
--length;
}
}
dstresize(&state->path, length);
if (state->status == BFTW_CHILD) {
state->status = BFTW_CURRENT;
}
}
/**
* Record an error.
*/
static void bftw_set_error(struct bftw_state *state, int error) {
state->ftwbuf.error = error;
state->ftwbuf.typeflag = BFTW_ERROR;
if (!(state->flags & BFTW_RECOVER)) {
state->error = error;
}
}
/**
* Figure out the name offset in a path.
*/
static size_t basename_offset(const char *path) {
size_t i;
// Strip trailing slashes
for (i = strlen(path); i > 0 && path[i - 1] == '/'; --i);
// Find the beginning of the name
for (; i > 0 && path[i - 1] != '/'; --i);
return i;
}
/**
* Initialize the buffers with data about the current path.
*/
static void bftw_init_buffers(struct bftw_state *state, const struct dirent *de) {
struct BFTW *ftwbuf = &state->ftwbuf;
ftwbuf->path = state->path;
ftwbuf->error = 0;
ftwbuf->visit = (state->status == BFTW_GC ? BFTW_POST : BFTW_PRE);
ftwbuf->statbuf = NULL;
ftwbuf->at_fd = AT_FDCWD;
ftwbuf->at_path = ftwbuf->path;
struct dircache_entry *current = state->current;
if (current) {
ftwbuf->nameoff = current->nameoff;
ftwbuf->depth = current->depth;
if (state->status == BFTW_CHILD) {
ftwbuf->nameoff += current->namelen;
++ftwbuf->depth;
ftwbuf->at_fd = current->fd;
ftwbuf->at_path += ftwbuf->nameoff;
} else {
dircache_entry_base(&state->cache, current, &ftwbuf->at_fd, &ftwbuf->at_path);
}
} else {
ftwbuf->nameoff = basename_offset(ftwbuf->path);
ftwbuf->depth = 0;
}
ftwbuf->typeflag = BFTW_UNKNOWN;
if (de) {
ftwbuf_use_dirent(ftwbuf, de);
} else if (state->status != BFTW_CHILD) {
ftwbuf->typeflag = BFTW_DIR;
}
int follow_flags = BFTW_LOGICAL;
if (ftwbuf->depth == 0) {
follow_flags |= BFTW_COMFOLLOW;
}
bool follow = state->flags & follow_flags;
ftwbuf->at_flags = follow ? 0 : AT_SYMLINK_NOFOLLOW;
bool detect_cycles = (state->flags & BFTW_DETECT_CYCLES)
&& state->status == BFTW_CHILD;
bool xdev = state->flags & BFTW_XDEV;
if ((state->flags & BFTW_STAT)
|| ftwbuf->typeflag == BFTW_UNKNOWN
|| (ftwbuf->typeflag == BFTW_LNK && follow)
|| (ftwbuf->typeflag == BFTW_DIR && (detect_cycles || xdev))) {
int ret = ftwbuf_stat(ftwbuf, &state->statbuf, ftwbuf->at_flags);
if (ret != 0 && follow && errno == ENOENT) {
// Could be a broken symlink, retry without following
ftwbuf->at_flags = AT_SYMLINK_NOFOLLOW;
ret = ftwbuf_stat(ftwbuf, &state->statbuf, ftwbuf->at_flags);
}
if (ret != 0) {
bftw_set_error(state, errno);
return;
}
if (ftwbuf->typeflag == BFTW_DIR && detect_cycles) {
dev_t dev = ftwbuf->statbuf->st_dev;
ino_t ino = ftwbuf->statbuf->st_ino;
for (const struct dircache_entry *entry = current; entry; entry = entry->parent) {
if (dev == entry->dev && ino == entry->ino) {
bftw_set_error(state, ELOOP);
return;
}
}
}
}
}
/** internal action: Abort the traversal. */
#define BFTW_FAIL (-1)
/**
* Invoke the callback on the given path.
*/
static int bftw_handle_path(struct bftw_state *state) {
// Never give the callback BFTW_ERROR unless BFTW_RECOVER is specified
if (state->ftwbuf.typeflag == BFTW_ERROR && !(state->flags & BFTW_RECOVER)) {
return BFTW_FAIL;
}
// Defensive copy
struct BFTW ftwbuf = state->ftwbuf;
enum bftw_action action = state->fn(&ftwbuf, state->ptr);
switch (action) {
case BFTW_CONTINUE:
case BFTW_SKIP_SIBLINGS:
case BFTW_SKIP_SUBTREE:
case BFTW_STOP:
return action;
default:
state->error = EINVAL;
return BFTW_FAIL;
}
}
/**
* Add a new entry to the cache.
*/
static struct dircache_entry *bftw_add(struct bftw_state *state, const char *name) {
struct dircache_entry *entry = dircache_add(&state->cache, state->current, name);
if (!entry) {
return NULL;
}
const struct stat *statbuf = state->ftwbuf.statbuf;
if (statbuf) {
entry->dev = statbuf->st_dev;
entry->ino = statbuf->st_ino;
}
return entry;
}
/**
* Push a new entry onto the queue.
*/
static int bftw_push(struct bftw_state *state, const char *name) {
struct dircache_entry *entry = bftw_add(state, name);
if (!entry) {
return -1;
}
return dirqueue_push(&state->queue, entry);
}
/**
* Pop an entry off the queue.
*/
static int bftw_pop(struct bftw_state *state, bool invoke_callback) {
int ret = BFTW_CONTINUE;
struct dircache_entry *entry = state->current;
if (!(state->flags & BFTW_DEPTH)) {
invoke_callback = false;
}
if (entry && invoke_callback) {
if (dircache_entry_path(entry, &state->path) != 0) {
ret = BFTW_FAIL;
invoke_callback = false;
}
}
state->status = BFTW_GC;
while (entry) {
struct dircache_entry *current = entry;
entry = entry->parent;
dircache_entry_decref(&state->cache, current);
if (current->refcount > 0) {
continue;
}
if (invoke_callback) {
state->current = current;
bftw_path_trim(state);
bftw_init_buffers(state, NULL);
int action = bftw_handle_path(state);
switch (action) {
case BFTW_CONTINUE:
case BFTW_SKIP_SIBLINGS:
case BFTW_SKIP_SUBTREE:
break;
case BFTW_STOP:
case BFTW_FAIL:
ret = action;
invoke_callback = false;
break;
}
}
dircache_entry_free(&state->cache, current);
}
state->current = dirqueue_pop(&state->queue);
state->status = BFTW_CURRENT;
return ret;
}
/**
* Dispose of the bftw() state.
*/
static void bftw_state_free(struct bftw_state *state) {
while (state->current) {
bftw_pop(state, false);
}
dirqueue_free(&state->queue);
dircache_free(&state->cache);
dstrfree(state->path);
}
int bftw(const char *path, bftw_fn *fn, int nopenfd, enum bftw_flags flags, void *ptr) {
int ret = -1, error;
struct bftw_state state;
if (bftw_state_init(&state, path, fn, nopenfd, flags, ptr) != 0) {
return -1;
}
// Handle 'path' itself first
if (bftw_path_concat(&state, path) != 0) {
goto fail;
}
bftw_init_buffers(&state, NULL);
switch (bftw_handle_path(&state)) {
case BFTW_CONTINUE:
case BFTW_SKIP_SIBLINGS:
break;
case BFTW_SKIP_SUBTREE:
case BFTW_STOP:
goto done;
case BFTW_FAIL:
goto fail;
}
if (state.ftwbuf.typeflag != BFTW_DIR) {
goto done;
}
// Now start the breadth-first search
state.current = bftw_add(&state, path);
if (!state.current) {
goto fail;
}
do {
if (dircache_entry_path(state.current, &state.path) != 0) {
goto fail;
}
DIR *dir = dircache_entry_open(&state.cache, state.current, state.path);
if (!dir) {
goto dir_error;
}
while (true) {
struct dirent *de;
if (xreaddir(dir, &de) != 0) {
goto dir_error;
}
if (!de) {
break;
}
if (strcmp(de->d_name, ".") == 0 || strcmp(de->d_name, "..") == 0) {
continue;
}
if (bftw_path_concat(&state, de->d_name) != 0) {
goto fail;
}
bftw_init_buffers(&state, de);
switch (bftw_handle_path(&state)) {
case BFTW_CONTINUE:
break;
case BFTW_SKIP_SIBLINGS:
closedir(dir);
goto next;
case BFTW_SKIP_SUBTREE:
continue;
case BFTW_STOP:
closedir(dir);
goto done;
case BFTW_FAIL:
closedir(dir);
goto fail;
}
if (state.ftwbuf.typeflag == BFTW_DIR) {
const struct stat *statbuf = state.ftwbuf.statbuf;
if ((flags & BFTW_XDEV)
&& statbuf
&& statbuf->st_dev != state.current->dev) {
continue;
}
if (bftw_push(&state, de->d_name) != 0) {
closedir(dir);
goto fail;
}
}
}
closedir(dir);
next:
switch (bftw_pop(&state, true)) {
case BFTW_CONTINUE:
case BFTW_SKIP_SIBLINGS:
case BFTW_SKIP_SUBTREE:
break;
case BFTW_STOP:
goto done;
case BFTW_FAIL:
goto fail;
}
continue;
dir_error:
error = errno;
if (dir) {
closedir(dir);
}
bftw_path_trim(&state);
bftw_init_buffers(&state, NULL);
bftw_set_error(&state, error);
switch (bftw_handle_path(&state)) {
case BFTW_CONTINUE:
case BFTW_SKIP_SIBLINGS:
case BFTW_SKIP_SUBTREE:
goto next;
case BFTW_STOP:
goto done;
case BFTW_FAIL:
goto fail;
}
} while (state.current);
done:
if (state.error == 0) {
ret = 0;
}
fail:
if (state.error == 0) {
state.error = errno;
}
bftw_state_free(&state);
errno = state.error;
return ret;
}
|