summaryrefslogtreecommitdiffstats
path: root/lib/copydir.c
blob: 926033afc02681d1dae481dff6b8832f3381d786 (plain)
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
/*
 * SPDX-FileCopyrightText: 1991 - 1994, Julianne Frances Haugh
 * SPDX-FileCopyrightText: 1996 - 2001, Marek Michałkiewicz
 * SPDX-FileCopyrightText: 2003 - 2006, Tomasz Kłoczko
 * SPDX-FileCopyrightText: 2007 - 2010, Nicolas François
 *
 * SPDX-License-Identifier: BSD-3-Clause
 */

#include <config.h>

#ident "$Id$"

#include <assert.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <sys/time.h>
#include <fcntl.h>
#include <stdio.h>

#include "alloc.h"
#include "attr.h"
#include "prototypes.h"
#include "defines.h"
#ifdef WITH_SELINUX
#include <selinux/selinux.h>
#endif				/* WITH_SELINUX */
#if defined(WITH_ACL) || defined(WITH_ATTR)
#include <stdarg.h>
#include <attr/error_context.h>
#endif				/* WITH_ACL || WITH_ATTR */
#ifdef WITH_ACL
#include <acl/libacl.h>
#endif				/* WITH_ACL */
#ifdef WITH_ATTR
#include <attr/libattr.h>
#endif				/* WITH_ATTR */
#include "shadowlog.h"
#include "string/sprintf.h"


static /*@null@*/const char *src_orig;
static /*@null@*/const char *dst_orig;

struct link_name {
	dev_t ln_dev;
	ino_t ln_ino;
	nlink_t ln_count;
	char *ln_name;
	/*@dependent@*/struct link_name *ln_next;
};
static /*@exposed@*/struct link_name *links;

struct path_info {
	const char *full_path;
	int dirfd;
	const char *name;
};

static int copy_entry (const struct path_info *src, const struct path_info *dst,
                       bool reset_selinux,
                       uid_t old_uid, uid_t new_uid,
                       gid_t old_gid, gid_t new_gid);
static int copy_dir (const struct path_info *src, const struct path_info *dst,
                     bool reset_selinux,
                     const struct stat *statp, const struct timespec mt[],
                     uid_t old_uid, uid_t new_uid,
                     gid_t old_gid, gid_t new_gid);
static /*@null@*/char *readlink_malloc (const char *filename);
static int copy_symlink (const struct path_info *src, const struct path_info *dst,
                         MAYBE_UNUSED bool reset_selinux,
                         const struct stat *statp, const struct timespec mt[],
                         uid_t old_uid, uid_t new_uid,
                         gid_t old_gid, gid_t new_gid);
static int copy_hardlink (const struct path_info *dst,
                          MAYBE_UNUSED bool reset_selinux,
                          struct link_name *lp);
static int copy_special (const struct path_info *src, const struct path_info *dst,
                         bool reset_selinux,
                         const struct stat *statp, const struct timespec mt[],
                         uid_t old_uid, uid_t new_uid,
                         gid_t old_gid, gid_t new_gid);
static int copy_file (const struct path_info *src, const struct path_info *dst,
                      bool reset_selinux,
                      const struct stat *statp, const struct timespec mt[],
                      uid_t old_uid, uid_t new_uid,
                      gid_t old_gid, gid_t new_gid);
static int chownat_if_needed (const struct path_info *dst, const struct stat *statp,
                            uid_t old_uid, uid_t new_uid,
                            gid_t old_gid, gid_t new_gid);
static int fchown_if_needed (int fdst, const struct stat *statp,
                             uid_t old_uid, uid_t new_uid,
                             gid_t old_gid, gid_t new_gid);

#if defined(WITH_ACL) || defined(WITH_ATTR)
/*
 * error_acl - format the error messages for the ACL and EQ libraries.
 */
format_attr(printf, 2, 3)
static void error_acl (MAYBE_UNUSED struct error_context *ctx, const char *fmt, ...)
{
	va_list ap;
	FILE *shadow_logfd = log_get_logfd();

	/* ignore the case when destination does not support ACLs
	 * or extended attributes */
	if (ENOTSUP == errno) {
		errno = 0;
		return;
	}

	va_start (ap, fmt);
	(void) fprintf (shadow_logfd, _("%s: "), log_get_progname());
	if (vfprintf (shadow_logfd, fmt, ap) != 0) {
		(void) fputs (_(": "), shadow_logfd);
	}
	(void) fprintf (shadow_logfd, "%s\n", strerror (errno));
	va_end (ap);
}

static struct error_context ctx = {
	error_acl, NULL, NULL
};
#endif				/* WITH_ACL || WITH_ATTR */

#ifdef WITH_ACL
static int perm_copy_path(const struct path_info *src,
						  const struct path_info *dst,
						  struct error_context *errctx)
{
	int src_fd, dst_fd, ret;

	src_fd = openat(src->dirfd, src->name, O_RDONLY | O_NOFOLLOW | O_NONBLOCK | O_CLOEXEC);
	if (src_fd < 0) {
		return -1;
	}

	dst_fd = openat(dst->dirfd, dst->name, O_RDONLY | O_NOFOLLOW | O_NONBLOCK | O_CLOEXEC);
	if (dst_fd < 0) {
		(void) close (src_fd);
		return -1;
	}

	ret = perm_copy_fd(src->full_path, src_fd, dst->full_path, dst_fd, errctx);
	(void) close (src_fd);
	(void) close (dst_fd);
	return ret;
}
#endif				/* WITH_ACL */

#ifdef WITH_ATTR
static int attr_copy_path(const struct path_info *src,
						  const struct path_info *dst,
						  int (*callback) (const char *, struct error_context *),
						  struct error_context *errctx)
{
	int src_fd, dst_fd, ret;

	src_fd = openat(src->dirfd, src->name, O_RDONLY | O_NOFOLLOW | O_NONBLOCK | O_CLOEXEC);
	if (src_fd < 0) {
		return -1;
	}

	dst_fd = openat(dst->dirfd, dst->name, O_RDONLY | O_NOFOLLOW | O_NONBLOCK | O_CLOEXEC);
	if (dst_fd < 0) {
		(void) close (src_fd);
		return -1;
	}

	ret = attr_copy_fd(src->full_path, src_fd, dst->full_path, dst_fd, callback, errctx);
	(void) close (src_fd);
	(void) close (dst_fd);
	return ret;
}
#endif				/* WITH_ATTR */

/*
 * remove_link - delete a link from the linked list
 */
static void remove_link (/*@only@*/struct link_name *ln)
{
	struct link_name *lp;

	if (links == ln) {
		links = ln->ln_next;
		free (ln->ln_name);
		free (ln);
		return;
	}
	for (lp = links; NULL !=lp; lp = lp->ln_next) {
		if (lp->ln_next == ln) {
			break;
		}
	}

	if (NULL == lp) {
		free (ln->ln_name);
		free (ln);
		return;
	}

	lp->ln_next = lp->ln_next->ln_next;
	free (ln->ln_name);
	free (ln);
}

/*
 * check_link - see if a file is really a link
 */

static /*@exposed@*/ /*@null@*/struct link_name *check_link (const char *name, const struct stat *sb)
{
	struct link_name  *lp;

	/* copy_tree () must be the entry point */
	assert (NULL != src_orig);
	assert (NULL != dst_orig);

	for (lp = links; NULL != lp; lp = lp->ln_next) {
		if ((lp->ln_dev == sb->st_dev) && (lp->ln_ino == sb->st_ino)) {
			return lp;
		}
	}

	if (sb->st_nlink == 1) {
		return NULL;
	}

	lp = XMALLOC(1, struct link_name);
	lp->ln_dev = sb->st_dev;
	lp->ln_ino = sb->st_ino;
	lp->ln_count = sb->st_nlink;
	xasprintf(&lp->ln_name, "%s%s", dst_orig, name + strlen(src_orig));
	lp->ln_next = links;
	links = lp;

	return NULL;
}

static int copy_tree_impl (const struct path_info *src, const struct path_info *dst,
               bool copy_root, bool reset_selinux,
               uid_t old_uid, uid_t new_uid,
               gid_t old_gid, gid_t new_gid)
{
	int dst_fd, src_fd, err = 0;
	bool set_orig = false;
	const struct dirent *ent;
	DIR *dir;

	if (copy_root) {
		struct stat sb;

		if (   fstatat (dst->dirfd, dst->name, &sb, 0) == 0
		    || errno != ENOENT) {
			return -1;
		}

		if (fstatat (src->dirfd, src->name, &sb, AT_SYMLINK_NOFOLLOW) == -1) {
			return -1;
		}

		if (!S_ISDIR (sb.st_mode)) {
			fprintf (log_get_logfd(),
			         "%s: %s is not a directory",
			         log_get_progname(), src->full_path);
			return -1;
		}

		return copy_entry (src, dst, reset_selinux,
		                   old_uid, new_uid, old_gid, new_gid);
	}

	/*
	 * Make certain both directories exist.  This routine is called
	 * after the home directory is created, or recursively after the
	 * target is created.  It assumes the target directory exists.
	 */

	src_fd = openat (src->dirfd, src->name, O_DIRECTORY | O_RDONLY | O_NOFOLLOW | O_CLOEXEC);
	if (src_fd < 0) {
		return -1;
	}

	dst_fd = openat (dst->dirfd, dst->name, O_DIRECTORY | O_RDONLY | O_NOFOLLOW | O_CLOEXEC);
	if (dst_fd < 0) {
		(void) close (src_fd);
		return -1;
	}

	/*
	 * Open the source directory and read each entry.  Every file
	 * entry in the directory is copied with the UID and GID set
	 * to the provided values.  As an added security feature only
	 * regular files (and directories ...) are copied, and no file
	 * is made set-ID.
	 */
	dir = fdopendir (src_fd);
	if (NULL == dir) {
		(void) close (src_fd);
		(void) close (dst_fd);
		return -1;
	}

	if (src_orig == NULL) {
		src_orig = src->full_path;
		dst_orig = dst->full_path;
		set_orig = true;
	}
	while ((0 == err) && (ent = readdir (dir)) != NULL) {
		char              *src_name = NULL;
		char              *dst_name;
		struct path_info  src_entry, dst_entry;
		/*
		 * Skip the "." and ".." entries
		 */
		if (strcmp(ent->d_name, ".") == 0 ||
		    strcmp(ent->d_name, "..") == 0)
		{
			continue;
		}

		if (asprintf(&src_name, "%s/%s", src->full_path, ent->d_name) == -1)
		{
			err = -1;
			continue;
		}
		if (asprintf(&dst_name, "%s/%s", dst->full_path, ent->d_name) == -1)
		{
			err = -1;
			goto skip;
		}

		src_entry.full_path = src_name;
		src_entry.dirfd = dirfd(dir);
		src_entry.name = ent->d_name;

		dst_entry.full_path = dst_name;
		dst_entry.dirfd = dst_fd;
		dst_entry.name = ent->d_name;

		err = copy_entry(&src_entry, &dst_entry, reset_selinux,
				 old_uid, new_uid, old_gid, new_gid);

		free(dst_name);
skip:
		free(src_name);
	}
	(void) closedir (dir);
	(void) close (dst_fd);

	if (set_orig) {
		src_orig = NULL;
		dst_orig = NULL;
		/* FIXME: clean links
		 * Since there can be hardlinks elsewhere on the device,
		 * we cannot check that all the hardlinks were found:
		assert (NULL == links);
		 */
	}

#ifdef WITH_SELINUX
	/* Reset SELinux to create files with default contexts.
	 * Note that the context is only reset on exit of copy_tree (it is
	 * assumed that the program would quit without needing a restored
	 * context if copy_tree failed previously), and that copy_tree can
	 * be called recursively (hence the context is set on the
	 * sub-functions of copy_entry).
	 */
	if (reset_selinux_file_context () != 0) {
		err = -1;
	}
#endif				/* WITH_SELINUX */

	return err;
}

/*
 * copy_entry - copy the entry of a directory
 *
 *	Copy the entry src to dst.
 *	Depending on the type of entry, this function will forward the
 *	request to copy_dir(), copy_symlink(), copy_hardlink(),
 *	copy_special(), or copy_file().
 *
 *	The access and modification time will not be modified.
 *
 *	The permissions will be set to new_uid/new_gid.
 *
 *	If new_uid (resp. new_gid) is equal to -1, the user (resp. group) will
 *	not be modified.
 *
 *	Only the files owned (resp. group-owned) by old_uid (resp.
 *	old_gid) will be modified, unless old_uid (resp. old_gid) is set
 *	to -1.
 */
static int copy_entry (const struct path_info *src, const struct path_info *dst,
                       bool reset_selinux,
                       uid_t old_uid, uid_t new_uid,
                       gid_t old_gid, gid_t new_gid)
{
	int err = 0;
	struct stat sb;
	struct stat tmp_sb;
	struct link_name *lp;
	struct timespec mt[2];

	if (fstatat(src->dirfd, src->name, &sb, AT_SYMLINK_NOFOLLOW) == -1) {
		/* If we cannot stat the file, do not care. */
		return 0;
	}

	mt[0].tv_sec  = sb.st_atim.tv_sec;
	mt[0].tv_nsec = sb.st_atim.tv_nsec;

	mt[1].tv_sec  = sb.st_mtim.tv_sec;
	mt[1].tv_nsec = sb.st_mtim.tv_nsec;

	if (S_ISDIR (sb.st_mode)) {
		err = copy_dir (src, dst, reset_selinux, &sb, mt,
				old_uid, new_uid, old_gid, new_gid);
	}

	/*
	* If the destination already exists do nothing.
	* This is after the copy_dir above to still iterate into subdirectories.
	*/
	if (fstatat(dst->dirfd, dst->name, &tmp_sb, AT_SYMLINK_NOFOLLOW) != -1) {
		return err;
	}

	/*
	* Copy any symbolic links
	*/

	else if (S_ISLNK (sb.st_mode)) {
		err = copy_symlink (src, dst, reset_selinux, &sb, mt,
				    old_uid, new_uid, old_gid, new_gid);
	}

	/*
	* See if this is a previously copied link
	*/

	else if ((lp = check_link (src->full_path, &sb)) != NULL) {
		err = copy_hardlink (dst, reset_selinux, lp);
	}

	/*
	* Deal with FIFOs and special files.  The user really
	* shouldn't have any of these, but it seems like it
	* would be nice to copy everything ...
	*/

	else if (!S_ISREG (sb.st_mode)) {
		err = copy_special (src, dst, reset_selinux, &sb, mt,
				    old_uid, new_uid, old_gid, new_gid);
	}

	/*
	* Create the new file and copy the contents.  The new
	* file will be owned by the provided UID and GID values.
	*/

	else {
		err = copy_file (src, dst, reset_selinux, &sb, mt,
				 old_uid, new_uid, old_gid, new_gid);
	}

	return err;
}

/*
 * copy_dir - copy a directory
 *
 *	Copy a directory (recursively) from src to dst.
 *
 *	statp, mt, old_uid, new_uid, old_gid, and new_gid are used to set
 *	the access and modification and the access rights.
 *
 *	Return 0 on success, -1 on error.
 */
static int copy_dir (const struct path_info *src, const struct path_info *dst,
                     bool reset_selinux,
                     const struct stat *statp, const struct timespec mt[],
                     uid_t old_uid, uid_t new_uid,
                     gid_t old_gid, gid_t new_gid)
{
	int err = 0;
	struct stat dst_sb;

	/*
	 * Create a new target directory, make it owned by
	 * the user and then recursively copy that directory.
	 */

#ifdef WITH_SELINUX
	if (set_selinux_file_context (dst->full_path, S_IFDIR) != 0) {
		return -1;
	}
#endif				/* WITH_SELINUX */
        /*
         * If the destination is already a directory, don't change it
         * but copy into it (recursively).
        */
        if (fstatat(dst->dirfd, dst->name, &dst_sb, AT_SYMLINK_NOFOLLOW) == 0 && S_ISDIR(dst_sb.st_mode)) {
            return (copy_tree_impl (src, dst, false, reset_selinux,
                           old_uid, new_uid, old_gid, new_gid) != 0);
        }

	if (   (mkdirat (dst->dirfd, dst->name, 0700) != 0)
	    || (chownat_if_needed (dst, statp,
	                         old_uid, new_uid, old_gid, new_gid) != 0)
	    || (fchmodat (dst->dirfd, dst->name, statp->st_mode & 07777, AT_SYMLINK_NOFOLLOW) != 0)
#ifdef WITH_ACL
	    || (   (perm_copy_path (src, dst, &ctx) != 0)
	        && (errno != 0))
#endif				/* WITH_ACL */
#ifdef WITH_ATTR
	/*
	 * If the third parameter is NULL, all extended attributes
	 * except those that define Access Control Lists are copied.
	 * ACLs are excluded by default because copying them between
	 * file systems with and without ACL support needs some
	 * additional logic so that no unexpected permissions result.
	 */
	    || (   !reset_selinux
	        && (attr_copy_path (src, dst, NULL, &ctx) != 0)
	        && (errno != 0))
#endif				/* WITH_ATTR */
	    || (copy_tree_impl (src, dst, false, reset_selinux,
	                   old_uid, new_uid, old_gid, new_gid) != 0)
	    || (utimensat (dst->dirfd, dst->name, mt, AT_SYMLINK_NOFOLLOW) != 0)) {
		err = -1;
	}

	return err;
}

/*
 * readlink_malloc - wrapper for readlink
 *
 * return NULL on error.
 * The return string shall be freed by the caller.
 */
static /*@null@*/char *readlink_malloc (const char *filename)
{
	size_t size = 1024;

	while (true) {
		ssize_t nchars;
		char *buffer = MALLOC(size, char);
		if (NULL == buffer) {
			return NULL;
		}

		nchars = readlink (filename, buffer, size);

		if (nchars < 0) {
			free(buffer);
			return NULL;
		}

		if ((size_t) nchars < size) { /* The buffer was large enough */
			/* readlink does not nul-terminate */
			buffer[nchars] = '\0';
			return buffer;
		}

		/* Try again with a bigger buffer */
		free (buffer);
		size *= 2;
	}
}

/*
 * copy_symlink - copy a symlink
 *
 *	Copy a symlink from src to dst.
 *
 *	statp, mt, old_uid, new_uid, old_gid, and new_gid are used to set
 *	the access and modification and the access rights.
 *
 *	Return 0 on success, -1 on error.
 */
static int copy_symlink (const struct path_info *src, const struct path_info *dst,
                         MAYBE_UNUSED bool reset_selinux,
                         const struct stat *statp, const struct timespec mt[],
                         uid_t old_uid, uid_t new_uid,
                         gid_t old_gid, gid_t new_gid)
{
	char *oldlink;

	/* copy_tree () must be the entry point */
	assert (NULL != src_orig);
	assert (NULL != dst_orig);

	/*
	 * Get the name of the file which the link points
	 * to.  If that name begins with the original
	 * source directory name, that part of the link
	 * name will be replaced with the original
	 * destination directory name.
	 */

	oldlink = readlink_malloc (src->full_path);
	if (NULL == oldlink) {
		return -1;
	}

	/* If src was a link to an entry of the src_orig directory itself,
	 * create a link to the corresponding entry in the dst_orig
	 * directory.
	 */
	if (strncmp(oldlink, src_orig, strlen(src_orig)) == 0) {
		char  *dummy;

		xasprintf(&dummy, "%s%s", dst_orig, oldlink + strlen(src_orig));
		free(oldlink);
		oldlink = dummy;
	}

#ifdef WITH_SELINUX
	if (set_selinux_file_context (dst->full_path, S_IFLNK) != 0) {
		free (oldlink);
		return -1;
	}
#endif				/* WITH_SELINUX */
	if (   (symlinkat (oldlink, dst->dirfd, dst->name) != 0)
	    || (chownat_if_needed (dst, statp,
	                          old_uid, new_uid, old_gid, new_gid) != 0)) {
		/* FIXME: there are no modes on symlinks, right?
		 *        ACL could be copied, but this would be much more
		 *        complex than calling perm_copy_file.
		 *        Ditto for Extended Attributes.
		 *        We currently only document that ACL and Extended
		 *        Attributes are not copied.
		 */
		free (oldlink);
		return -1;
	}
	free (oldlink);

	if (utimensat (dst->dirfd, dst->name, mt, AT_SYMLINK_NOFOLLOW) != 0) {
		return -1;
	}

	return 0;
}

/*
 * copy_hardlink - copy a hardlink
 *
 *	Copy a hardlink from src to dst.
 *
 *	Return 0 on success, -1 on error.
 */
static int copy_hardlink (const struct path_info *dst,
                          MAYBE_UNUSED bool reset_selinux,
                          struct link_name *lp)
{
	/* FIXME: selinux, ACL, Extended Attributes needed? */

	if (linkat (AT_FDCWD, lp->ln_name, dst->dirfd, dst->name, 0) != 0) {
		return -1;
	}

	/* If the file could be unlinked, decrement the links counter,
	 * and forget about this link if it was the last reference */
	lp->ln_count--;
	if (lp->ln_count <= 0) {
		remove_link (lp);
	}

	return 0;
}


/*
 * copy_special - copy a special file
 *
 *	Copy a special file from src to dst.
 *
 *	statp, mt, old_uid, new_uid, old_gid, and new_gid are used to set
 *	the access and modification and the access rights.
 *
 *	Return 0 on success, -1 on error.
 */
static int
copy_special(const struct path_info *src, const struct path_info *dst,
             bool reset_selinux,
             const struct stat *statp, const struct timespec mt[],
             uid_t old_uid, uid_t new_uid,
             gid_t old_gid, gid_t new_gid)
{
#if defined(WITH_SELINUX)
	if (set_selinux_file_context(dst->full_path, statp->st_mode & S_IFMT) != 0)
		return -1;
#endif

	if (mknodat(dst->dirfd, dst->name, statp->st_mode & ~07777U, statp->st_rdev) == -1)
		return -1;

	if (chownat_if_needed(dst, statp, old_uid, new_uid, old_gid, new_gid) == -1)
		return -1;

	if (fchmodat(dst->dirfd, dst->name, statp->st_mode & 07777, AT_SYMLINK_NOFOLLOW) == -1)
		return -1;

#if defined(WITH_ACL)
	if (perm_copy_path(src, dst, &ctx) == -1 && errno != 0)
		return -1;
#endif

#if defined(WITH_ATTR)
	/*
	 * If the third parameter is NULL, all extended attributes
	 * except those that define Access Control Lists are copied.
	 * ACLs are excluded by default because copying them between
	 * file systems with and without ACL support needs some
	 * additional logic so that no unexpected permissions result.
	 */
	if (!reset_selinux) {
		if (attr_copy_path(src, dst, NULL, &ctx) == -1 && errno != 0)
			return -1;
	}
#endif

	if (utimensat(dst->dirfd, dst->name, mt, AT_SYMLINK_NOFOLLOW) == -1)
		return -1;

	return 0;
}

/*
 * copy_file - copy a file
 *
 *	Copy a file from src to dst.
 *
 *	statp, mt, old_uid, new_uid, old_gid, and new_gid are used to set
 *	the access and modification and the access rights.
 *
 *	Return 0 on success, -1 on error.
 */
static int copy_file (const struct path_info *src, const struct path_info *dst,
                      bool reset_selinux,
                      const struct stat *statp, const struct timespec mt[],
                      uid_t old_uid, uid_t new_uid,
                      gid_t old_gid, gid_t new_gid)
{
	int err = 0;
	int ifd;
	int ofd;

	ifd = openat (src->dirfd, src->name, O_RDONLY|O_NOFOLLOW|O_CLOEXEC);
	if (ifd < 0) {
		return -1;
	}
#ifdef WITH_SELINUX
	if (set_selinux_file_context (dst->full_path, S_IFREG) != 0) {
		(void) close (ifd);
		return -1;
	}
#endif				/* WITH_SELINUX */
	ofd = openat (dst->dirfd, dst->name, O_WRONLY | O_CREAT | O_EXCL | O_TRUNC | O_NOFOLLOW | O_CLOEXEC, 0600);
	if (   (ofd < 0)
	    || (fchown_if_needed (ofd, statp,
	                          old_uid, new_uid, old_gid, new_gid) != 0)
	    || (fchmod (ofd, statp->st_mode & 07777) != 0)
#ifdef WITH_ACL
	    || (   (perm_copy_fd (src->full_path, ifd, dst->full_path, ofd, &ctx) != 0)
	        && (errno != 0))
#endif				/* WITH_ACL */
#ifdef WITH_ATTR
	/*
	 * If the third parameter is NULL, all extended attributes
	 * except those that define Access Control Lists are copied.
	 * ACLs are excluded by default because copying them between
	 * file systems with and without ACL support needs some
	 * additional logic so that no unexpected permissions result.
	 */
	    || (   !reset_selinux
	        && (attr_copy_fd (src->full_path, ifd, dst->full_path, ofd, NULL, &ctx) != 0)
	        && (errno != 0))
#endif				/* WITH_ATTR */
	   ) {
		if (ofd >= 0) {
			(void) close (ofd);
		}
		(void) close (ifd);
		return -1;
	}

	while (true) {
		char buf[8192];
		ssize_t cnt;

		cnt = read (ifd, buf, sizeof buf);
		if (cnt < 0) {
			if (errno == EINTR) {
				continue;
			}
			(void) close (ofd);
			(void) close (ifd);
			return -1;
		}
		if (cnt == 0) {
			break;
		}

		if (write_full(ofd, buf, cnt) == -1) {
			(void) close (ofd);
			(void) close (ifd);
			return -1;
		}
	}

	(void) close (ifd);
	if (close (ofd) != 0 && errno != EINTR) {
		return -1;
	}

	if (utimensat (dst->dirfd, dst->name, mt, AT_SYMLINK_NOFOLLOW) != 0) {
		return -1;
	}

	return err;
}

#define def_chown_if_needed(chown_function, type_dst)                  \
static int chown_function ## _if_needed (type_dst dst,                 \
                                         const struct stat *statp,     \
                                         uid_t old_uid, uid_t new_uid, \
                                         gid_t old_gid, gid_t new_gid) \
{                                                                      \
	uid_t tmpuid = (uid_t) -1;                                     \
	gid_t tmpgid = (gid_t) -1;                                     \
                                                                       \
	/* Use new_uid if old_uid is set to -1 or if the file was      \
	 * owned by the user. */                                       \
	if (((uid_t) -1 == old_uid) || (statp->st_uid == old_uid)) {   \
		tmpuid = new_uid;                                      \
	}                                                              \
	/* Otherwise, or if new_uid was set to -1, we keep the same    \
	 * owner. */                                                   \
	if ((uid_t) -1 == tmpuid) {                                    \
		tmpuid = statp->st_uid;                                \
	}                                                              \
                                                                       \
	if (((gid_t) -1 == old_gid) || (statp->st_gid == old_gid)) {   \
		tmpgid = new_gid;                                      \
	}                                                              \
	if ((gid_t) -1 == tmpgid) {                                    \
		tmpgid = statp->st_gid;                                \
	}                                                              \
                                                                       \
	return chown_function (dst, tmpuid, tmpgid);                   \
}

def_chown_if_needed (fchown, int)

static int chownat_if_needed (const struct path_info *dst,
							  const struct stat *statp,
                              uid_t old_uid, uid_t new_uid,
                              gid_t old_gid, gid_t new_gid)
{
	uid_t tmpuid = (uid_t) -1;
	gid_t tmpgid = (gid_t) -1;

	/* Use new_uid if old_uid is set to -1 or if the file was
	 * owned by the user. */
	if (((uid_t) -1 == old_uid) || (statp->st_uid == old_uid)) {
		tmpuid = new_uid;
	}
	/* Otherwise, or if new_uid was set to -1, we keep the same
	 * owner. */
	if ((uid_t) -1 == tmpuid) {
		tmpuid = statp->st_uid;
	}

	if (((gid_t) -1 == old_gid) || (statp->st_gid == old_gid)) {
		tmpgid = new_gid;
	}
	if ((gid_t) -1 == tmpgid) {
		tmpgid = statp->st_gid;
	}

	return fchownat (dst->dirfd, dst->name, tmpuid, tmpgid, AT_SYMLINK_NOFOLLOW);
}

/*
 * copy_tree - copy files in a directory tree
 *
 *	copy_tree() walks a directory tree and copies ordinary files
 *	as it goes.
 *
 *	When reset_selinux is enabled, extended attributes (and thus
 *	SELinux attributes) are not copied.
 *
 *	old_uid and new_uid are used to set the ownership of the copied
 *	files. Unless old_uid is set to -1, only the files owned by
 *	old_uid have their ownership changed to new_uid. In addition, if
 *	new_uid is set to -1, no ownership will be changed.
 *
 *	The same logic applies for the group-ownership and
 *	old_gid/new_gid.
 */
int copy_tree (const char *src_root, const char *dst_root,
               bool copy_root, bool reset_selinux,
               uid_t old_uid, uid_t new_uid,
               gid_t old_gid, gid_t new_gid)
{
	const struct path_info src = {
		.full_path = src_root,
		.dirfd = AT_FDCWD,
		.name = src_root
	};
	const struct path_info dst = {
		.full_path = dst_root,
		.dirfd = AT_FDCWD,
		.name = dst_root
	};

	return copy_tree_impl(&src, &dst, copy_root, reset_selinux,
						  old_uid, new_uid, old_gid, new_gid);
}