summaryrefslogtreecommitdiff
path: root/src/copy.c
blob: 862ce466f1adf1b0c86cbd18ae9186b5a8eae1f1 (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
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
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606
1607
1608
/* copy.c -- core functions for copying files and directories
   Copyright (C) 89, 90, 91, 1995-2002 Free Software Foundation.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2, or (at your option)
   any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software Foundation,
   Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */

/* Extracted from cp.c and librarified by Jim Meyering.  */

#ifdef _AIX
 #pragma alloca
#endif

#include <config.h>
#include <stdio.h>
#include <assert.h>
#include <sys/types.h>

#if HAVE_HURD_H
# include <hurd.h>
#endif

#include "system.h"
#include "error.h"
#include "backupfile.h"
#include "savedir.h"
#include "copy.h"
#include "cp-hash.h"
#include "hash.h"
#include "hash-pjw.h"
#include "same.h"
#include "dirname.h"
#include "full-write.h"
#include "path-concat.h"
#include "quote.h"
#include "same.h"
#include "xreadlink.h"

#define DO_CHOWN(Chown, File, New_uid, New_gid)				\
  (Chown (File, New_uid, New_gid)					\
   /* If non-root uses -p, it's ok if we can't preserve ownership.	\
      But root probably wants to know, e.g. if NFS disallows it,	\
      or if the target system doesn't support file ownership.  */	\
   && ((errno != EPERM && errno != EINVAL) || x->myeuid == 0))

#define SAME_OWNER(A, B) ((A).st_uid == (B).st_uid)
#define SAME_GROUP(A, B) ((A).st_gid == (B).st_gid)
#define SAME_OWNER_AND_GROUP(A, B) (SAME_OWNER (A, B) && SAME_GROUP (A, B))

#define UNWRITABLE(File_name, File_mode)		\
  ( /* euidaccess is not meaningful for symlinks */	\
    ! S_ISLNK (File_mode)				\
    && euidaccess (File_name, W_OK) != 0)

struct dir_list
{
  struct dir_list *parent;
  ino_t ino;
  dev_t dev;
};

/* Describe a just-created or just-renamed destination file.  */
struct F_triple
{
  char const* name;
  ino_t st_ino;
  dev_t st_dev;
};

/* Initial size of the above hash table.  */
#define DEST_INFO_INITIAL_CAPACITY 61

int euidaccess ();
int yesno ();

static int copy_internal (const char *src_path, const char *dst_path,
			  int new_dst, dev_t device,
			  struct dir_list *ancestors,
			  const struct cp_options *x,
			  int command_line_arg,
			  int *copy_into_self,
			  int *rename_succeeded);

/* Pointers to the file names:  they're used in the diagnostic that is issued
   when we detect the user is trying to copy a directory into itself.  */
static char const *top_level_src_path;
static char const *top_level_dst_path;

/* The invocation name of this program.  */
extern char *program_name;

/* Encapsulate selection of the file mode to be applied to
   new non-directories.  */

static mode_t
get_dest_mode (const struct cp_options *option, mode_t mode)
{
  /* In some applications (e.g., install), use precisely the
     specified mode.  */
  if (option->set_mode)
    return option->mode;

  /* Honor the umask for `cp', but not for `mv' or `cp -p'.
     In addition, `cp' without -p must clear the set-user-ID and set-group-ID
     bits.  POSIX requires it do that when creating new files.  */
  if (!option->move_mode && !option->preserve_mode)
    mode &= (option->umask_kill & ~(S_ISUID | S_ISGID));

  return mode;
}

/* FIXME: describe */
/* FIXME: rewrite this to use a hash table so we avoid the quadratic
   performance hit that's probably noticeable only on trees deeper
   than a few hundred levels.  See use of active_dir_map in remove.c  */

static int
is_ancestor (const struct stat *sb, const struct dir_list *ancestors)
{
  while (ancestors != 0)
    {
      if (ancestors->ino == sb->st_ino && ancestors->dev == sb->st_dev)
	return 1;
      ancestors = ancestors->parent;
    }
  return 0;
}

/* Read the contents of the directory SRC_PATH_IN, and recursively
   copy the contents to DST_PATH_IN.  NEW_DST is nonzero if
   DST_PATH_IN is a directory that was created previously in the
   recursion.   SRC_SB and ANCESTORS describe SRC_PATH_IN.
   Set *COPY_INTO_SELF to nonzero if SRC_PATH_IN is a parent of
   (or the same as) DST_PATH_IN;  otherwise, set it to zero.
   Return 0 if successful, -1 if an error occurs. */

static int
copy_dir (const char *src_path_in, const char *dst_path_in, int new_dst,
	  const struct stat *src_sb, struct dir_list *ancestors,
	  const struct cp_options *x, int *copy_into_self)
{
  char *name_space;
  char *namep;
  struct cp_options non_command_line_options = *x;
  int ret = 0;

  name_space = savedir (src_path_in);
  if (name_space == NULL)
    {
      /* This diagnostic is a bit vague because savedir can fail in
         several different ways.  */
      error (0, errno, _("cannot access %s"), quote (src_path_in));
      return -1;
    }

  /* For cp's -H option, dereference command line arguments, but do not
     dereference symlinks that are found via recursive traversal.  */
  if (x->dereference == DEREF_COMMAND_LINE_ARGUMENTS)
    non_command_line_options.xstat = lstat;

  namep = name_space;
  while (*namep != '\0')
    {
      int local_copy_into_self;
      char *src_path = path_concat (src_path_in, namep, NULL);
      char *dst_path = path_concat (dst_path_in, namep, NULL);

      if (dst_path == NULL || src_path == NULL)
	xalloc_die ();

      ret |= copy_internal (src_path, dst_path, new_dst, src_sb->st_dev,
			    ancestors, &non_command_line_options, 0,
			    &local_copy_into_self, NULL);
      *copy_into_self |= local_copy_into_self;

      free (dst_path);
      free (src_path);

      namep += strlen (namep) + 1;
    }
  free (name_space);
  return -ret;
}

/* Copy a regular file from SRC_PATH to DST_PATH.
   If the source file contains holes, copies holes and blocks of zeros
   in the source file as holes in the destination file.
   (Holes are read as zeroes by the `read' system call.)
   Use DST_MODE as the 3rd argument in the call to open.
   X provides many option settings.
   Return 0 if successful, -1 if an error occurred.
   *NEW_DST is as in copy_internal.  SRC_SB is the result
   of calling xstat (aka stat in this case) on SRC_PATH.  */

static int
copy_reg (const char *src_path, const char *dst_path,
	  const struct cp_options *x, mode_t dst_mode, int *new_dst,
	  struct stat const *src_sb)
{
  char *buf;
  int buf_size;
  int dest_desc;
  int source_desc;
  struct stat sb;
  struct stat src_open_sb;
  char *cp;
  int *ip;
  int return_val = 0;
  off_t n_read_total = 0;
  int last_write_made_hole = 0;
  int make_holes = (x->sparse_mode == SPARSE_ALWAYS);

  source_desc = open (src_path, O_RDONLY);
  if (source_desc < 0)
    {
      error (0, errno, _("cannot open %s for reading"), quote (src_path));
      return -1;
    }

  if (fstat (source_desc, &src_open_sb))
    {
      error (0, errno, _("cannot fstat %s"), quote (src_path));
      return_val = -1;
      goto close_src_desc;
    }

  /* Compare the source dev/ino from the open file to the incoming,
     saved ones obtained via a previous call to stat.  */
  if (! SAME_INODE (*src_sb, src_open_sb))
    {
      error (0, 0,
	     _("skipping file %s, as it was replaced while being copied"),
	     quote (src_path));
      return_val = -1;
      goto close_src_desc;
    }

  /* These semantics are required for cp.
     The if-block will be taken in move_mode.  */
  if (*new_dst)
    {
      dest_desc = open (dst_path, O_WRONLY | O_CREAT, dst_mode);
    }
  else
    {
      dest_desc = open (dst_path, O_WRONLY | O_TRUNC, dst_mode);

      if (dest_desc < 0 && x->unlink_dest_after_failed_open)
	{
	  if (unlink (dst_path))
	    {
	      error (0, errno, _("cannot remove %s"), quote (dst_path));
	      return_val = -1;
	      goto close_src_desc;
	    }

	  /* Tell caller that the destination file was unlinked.  */
	  *new_dst = 1;

	  /* Try the open again, but this time with different flags.  */
	  dest_desc = open (dst_path, O_WRONLY | O_CREAT, dst_mode);
	}
    }

  if (dest_desc < 0)
    {
      error (0, errno, _("cannot create regular file %s"), quote (dst_path));
      return_val = -1;
      goto close_src_desc;
    }

  /* Determine the optimal buffer size.  */

  if (fstat (dest_desc, &sb))
    {
      error (0, errno, _("cannot fstat %s"), quote (dst_path));
      return_val = -1;
      goto close_src_and_dst_desc;
    }

  buf_size = ST_BLKSIZE (sb);

#if HAVE_STRUCT_STAT_ST_BLOCKS
  if (x->sparse_mode == SPARSE_AUTO && S_ISREG (sb.st_mode))
    {
      /* Use a heuristic to determine whether SRC_PATH contains any
	 sparse blocks. */

      if (fstat (source_desc, &sb))
	{
	  error (0, errno, _("cannot fstat %s"), quote (src_path));
	  return_val = -1;
	  goto close_src_and_dst_desc;
	}

      /* If the file has fewer blocks than would normally
	 be needed for a file of its size, then
	 at least one of the blocks in the file is a hole. */
      if (S_ISREG (sb.st_mode)
	  && sb.st_size / ST_NBLOCKSIZE > ST_NBLOCKS (sb))
	make_holes = 1;
    }
#endif

  /* Make a buffer with space for a sentinel at the end.  */

  buf = (char *) alloca (buf_size + sizeof (int));

  for (;;)
    {
      ssize_t n_read = read (source_desc, buf, buf_size);
      if (n_read < 0)
	{
#ifdef EINTR
	  if (errno == EINTR)
	    continue;
#endif
	  error (0, errno, _("reading %s"), quote (src_path));
	  return_val = -1;
	  goto close_src_and_dst_desc;
	}
      if (n_read == 0)
	break;

      n_read_total += n_read;

      ip = 0;
      if (make_holes)
	{
	  buf[n_read] = 1;	/* Sentinel to stop loop.  */

	  /* Find first nonzero *word*, or the word with the sentinel.  */

	  ip = (int *) buf;
	  while (*ip++ == 0)
	    ;

	  /* Find the first nonzero *byte*, or the sentinel.  */

	  cp = (char *) (ip - 1);
	  while (*cp++ == 0)
	    ;

	  /* If we found the sentinel, the whole input block was zero,
	     and we can make a hole.  */

	  if (cp > buf + n_read)
	    {
	      /* Make a hole.  */
	      if (lseek (dest_desc, (off_t) n_read, SEEK_CUR) < 0L)
		{
		  error (0, errno, _("cannot lseek %s"), quote (dst_path));
		  return_val = -1;
		  goto close_src_and_dst_desc;
		}
	      last_write_made_hole = 1;
	    }
	  else
	    /* Clear to indicate that a normal write is needed. */
	    ip = 0;
	}
      if (ip == 0)
	{
	  size_t n = n_read;
	  if (full_write (dest_desc, buf, n) != n)
	    {
	      error (0, errno, _("writing %s"), quote (dst_path));
	      return_val = -1;
	      goto close_src_and_dst_desc;
	    }
	  last_write_made_hole = 0;
	}
    }

  /* If the file ends with a `hole', something needs to be written at
     the end.  Otherwise the kernel would truncate the file at the end
     of the last write operation.  */

  if (last_write_made_hole)
    {
#if HAVE_FTRUNCATE
      /* Write a null character and truncate it again.  */
      if (full_write (dest_desc, "", 1) != 1
	  || ftruncate (dest_desc, n_read_total) < 0)
#else
      /* Seek backwards one character and write a null.  */
      if (lseek (dest_desc, (off_t) -1, SEEK_CUR) < 0L
	  || full_write (dest_desc, "", 1) != 1)
#endif
	{
	  error (0, errno, _("writing %s"), quote (dst_path));
	  return_val = -1;
	}
    }

close_src_and_dst_desc:
  if (close (dest_desc) < 0)
    {
      error (0, errno, _("closing %s"), quote (dst_path));
      return_val = -1;
    }
close_src_desc:
  if (close (source_desc) < 0)
    {
      error (0, errno, _("closing %s"), quote (src_path));
      return_val = -1;
    }

  return return_val;
}

/* Return nonzero if it's ok that the source and destination
   files are the `same' by some measure.  The goal is to avoid
   making the `copy' operation remove both copies of the file
   in that case, while still allowing the user to e.g., move or
   copy a regular file onto a symlink that points to it.
   Try to minimize the cost of this function in the common case.  */

static int
same_file_ok (const char *src_path, const struct stat *src_sb,
	      const char *dst_path, const struct stat *dst_sb,
	      const struct cp_options *x, int *return_now)
{
  const struct stat *src_sb_link;
  const struct stat *dst_sb_link;
  struct stat tmp_dst_sb;
  struct stat tmp_src_sb;

  int same_link;
  int same = (SAME_INODE (*src_sb, *dst_sb));

  *return_now = 0;

  /* FIXME: this should (at the very least) be moved into the following
     if-block.  More likely, it should be removed, because it inhibits
     making backups.  But removing it will result in a change in behavior
     that will probably have to be documented -- and tests will have to
     be updated.  */
  if (same && x->hard_link)
    {
      *return_now = 1;
      return 1;
    }

  if (x->xstat == lstat)
    {
      same_link = same;

      /* If both the source and destination files are symlinks (and we'll
	 know this here IFF preserving symlinks (aka xstat == lstat),
	 then it's ok -- as long as they are distinct.  */
      if (S_ISLNK (src_sb->st_mode) && S_ISLNK (dst_sb->st_mode))
	return ! same_name (src_path, dst_path);

      src_sb_link = src_sb;
      dst_sb_link = dst_sb;
    }
  else
    {
      if (!same)
	return 1;

      if (lstat (dst_path, &tmp_dst_sb)
	  || lstat (src_path, &tmp_src_sb))
	return 1;

      src_sb_link = &tmp_src_sb;
      dst_sb_link = &tmp_dst_sb;

      same_link = SAME_INODE (*src_sb_link, *dst_sb_link);

      /* If both are symlinks, then it's ok, but only if the destination
	 will be unlinked before being opened.  This is like the test
	 above, but with the addition of the unlink_dest_before_opening
	 conjunct because otherwise, with two symlinks to the same target,
	 we'd end up truncating the source file.  */
      if (S_ISLNK (src_sb_link->st_mode) && S_ISLNK (dst_sb_link->st_mode)
	  && x->unlink_dest_before_opening)
	return 1;
    }

  /* The backup code ensures there's a copy, so it's usually ok to
     remove any destination file.  One exception is when both
     source and destination are the same directory entry.  In that
     case, moving the destination file aside (in making the backup)
     would also rename the source file and result in an error.  */
  if (x->backup_type != none)
    {
      if (!same_link)
	{
	  /* In copy mode when dereferencing symlinks, if the source is a
	     symlink and the dest is not, then backing up the destination
	     (moving it aside) would make it a dangling symlink, and the
	     subsequent attempt to open it in copy_reg would fail with
	     a misleading diagnostic.  Avoid that by returning zero in
	     that case so the caller can make cp (or mv when it has to
	     resort to reading the source file) fail now.  */

	  /* FIXME-note: even with the following kludge, we can still provoke
	     the offending diagnostic.  It's just a little harder to do :-)
	     $ rm -f a b c; touch c; ln -s c b; ln -s b a; cp -b a b
	     cp: cannot open `a' for reading: No such file or directory
	     That's misleading, since a subsequent `ls' shows that `a'
	     is still there.
	     One solution would be to open the source file *before* moving
	     aside the destination, but that'd involve a big rewrite. */
	  if ( ! x->move_mode
	       && x->dereference != DEREF_NEVER
	       && S_ISLNK (src_sb_link->st_mode)
	       && ! S_ISLNK (dst_sb_link->st_mode))
	    return 0;

	  return 1;
	}

      return ! same_name (src_path, dst_path);
    }

#if 0
  /* FIXME: use or remove */

  /* If we're making a backup, we'll detect the problem case in
     copy_reg because SRC_PATH will no longer exist.  Allowing
     the test to be deferred lets cp do some useful things.
     But when creating hardlinks and SRC_PATH is a symlink
     but DST_PATH is not we must test anyway.  */
  if (x->hard_link
      || !S_ISLNK (src_sb_link->st_mode)
      || S_ISLNK (dst_sb_link->st_mode))
    return 1;

  if (x->dereference != DEREF_NEVER)
    return 1;
#endif

  /* They may refer to the same file if we're in move mode and the
     target is a symlink.  That is ok, since we remove any existing
     destination file before opening it -- via `rename' if they're on
     the same file system, via `unlink (DST_PATH)' otherwise.
     It's also ok if they're distinct hard links to the same file.  */
  if ((x->move_mode || x->unlink_dest_before_opening)
      && (S_ISLNK (dst_sb_link->st_mode)
	  || (same_link && !same_name (src_path, dst_path))))
    return 1;

  /* If neither is a symlink, then it's ok as long as they aren't
     hard links to the same file.  */
  if (!S_ISLNK (src_sb_link->st_mode) && !S_ISLNK (dst_sb_link->st_mode))
    {
      if (!SAME_INODE (*src_sb_link, *dst_sb_link))
	return 1;

      /* If they are the same file, it's ok if we're making hard links.  */
      if (x->hard_link)
	{
	  *return_now = 1;
	  return 1;
	}
    }

  /* It's ok to remove a destination symlink.  But that works only when we
     unlink before opening the destination and when the source and destination
     files are on the same partition.  */
  if (x->unlink_dest_before_opening
      && S_ISLNK (dst_sb_link->st_mode))
    return dst_sb_link->st_dev == src_sb_link->st_dev;

  if (x->xstat == lstat)
    {
      if ( ! S_ISLNK (src_sb_link->st_mode))
	tmp_src_sb = *src_sb_link;
      else if (stat (src_path, &tmp_src_sb))
	return 1;

      if ( ! S_ISLNK (dst_sb_link->st_mode))
	tmp_dst_sb = *dst_sb_link;
      else if (stat (dst_path, &tmp_dst_sb))
	return 1;

      if ( ! SAME_INODE (tmp_src_sb, tmp_dst_sb))
	return 1;

      /* FIXME: shouldn't this be testing whether we're making symlinks?  */
      if (x->hard_link)
	{
	  *return_now = 1;
	  return 1;
	}
    }

  return 0;
}

static void
overwrite_prompt (char const *dst_path, struct stat const *dst_sb)
{
  if (euidaccess (dst_path, W_OK) != 0)
    {
      fprintf (stderr,
	       _("%s: overwrite %s, overriding mode %04lo? "),
	       program_name, quote (dst_path),
	       (unsigned long) (dst_sb->st_mode & CHMOD_MODE_BITS));
    }
  else
    {
      fprintf (stderr, _("%s: overwrite %s? "),
	       program_name, quote (dst_path));
    }
}

/* Hash an F_triple.  */
static unsigned int
triple_hash (void const *x, unsigned int table_size)
{
  struct F_triple const *p = x;

  /* Also take the name into account, so that when moving N hard links to the
     same file (all listed on the command line) all into the same directory,
     we don't experience any N^2 behavior.  */
  /* FIXME-maybe: is it worth the overhead of doing this
     just to avoid N^2 in such an unusual case?  N would have
     to be very large to make the N^2 factor noticable, and
     one would probably encounter a limit on the length of
     a command line before it became a problem.  */
  unsigned int tmp = hash_pjw (p->name, table_size);

  /* Ignoring the device number here should be fine.  */
  return (tmp | p->st_ino) % table_size;
}

/* Hash an F_triple.  */
static unsigned int
triple_hash_no_name (void const *x, unsigned int table_size)
{
  struct F_triple const *p = x;

  /* Ignoring the device number here should be fine.  */
  return p->st_ino % table_size;
}

/* Compare two F_triple structs.  */
static bool
triple_compare (void const *x, void const *y)
{
  struct F_triple const *a = x;
  struct F_triple const *b = y;
  return (SAME_INODE (*a, *b) && same_name (a->name, b->name)) ? true : false;
}

/* Free an F_triple.  */
static void
triple_free (void *x)
{
  struct F_triple *a = x;
  free ((char *) (a->name));
  free (a);
}

/* Initialize the hash table implementing a set of F_triple entries
   corresponding to destination files.  */
void
dest_info_init (struct cp_options *x)
{
  x->dest_info
    = hash_initialize (DEST_INFO_INITIAL_CAPACITY,
		       NULL,
		       triple_hash,
		       triple_compare,
		       triple_free);
}

/* Initialize the hash table implementing a set of F_triple entries
   corresponding to source files listed on the command line.  */
void
src_info_init (struct cp_options *x)
{

  /* Note that we use triple_hash_no_name here.
     Contrast with the use of triple_hash above.
     That is necessary because a source file may be specified
     in many different ways.  We want to warn about this
       cp a a d/
     as well as this:
       cp a ./a d/
  */
  x->src_info
    = hash_initialize (DEST_INFO_INITIAL_CAPACITY,
		       NULL,
		       triple_hash_no_name,
		       triple_compare,
		       triple_free);
}

/* Return nonzero if there is an entry in hash table, HT,
   for the file described by FILENAME and STATS.
   Otherwise, return zero.  */
static int
seen_file (Hash_table const *ht, char const *filename,
	   struct stat const *stats)
{
  struct F_triple new_ent;

  if (ht == NULL)
    return 0;

  new_ent.name = filename;
  new_ent.st_ino = stats->st_ino;
  new_ent.st_dev = stats->st_dev;

  return !!hash_lookup (ht, &new_ent);
}

/* Record destination filename, FILENAME, and dev/ino from *STATS,
   in the hash table, HT.  If HT is NULL, return immediately.
   If STATS is NULL, call lstat on FILENAME to get the device
   and inode numbers.  If that lstat fails, simply return.
   If memory allocation fails, exit immediately.  */
static void
record_file (Hash_table *ht, char const *filename,
	     struct stat const *stats)
{
  struct F_triple *ent;

  if (ht == NULL)
    return;

  ent = (struct F_triple *) xmalloc (sizeof *ent);
  ent->name = xstrdup (filename);
  if (stats)
    {
      ent->st_ino = stats->st_ino;
      ent->st_dev = stats->st_dev;
    }
  else
    {
      struct stat sb;
      if (lstat (filename, &sb))
	return;
      ent->st_ino = sb.st_ino;
      ent->st_dev = sb.st_dev;
    }

  {
    struct F_triple *ent_from_table = hash_insert (ht, ent);
    if (ent_from_table == NULL)
      {
	/* Insertion failed due to lack of memory.  */
	xalloc_die ();
      }

    if (ent_from_table != ent)
      {
	/* There was alread a matching entry in the table, so ENT was
	   not inserted.  Free it.  */
	triple_free (ent);
      }
  }
}

/* Copy the file SRC_PATH to the file DST_PATH.  The files may be of
   any type.  NEW_DST should be nonzero if the file DST_PATH cannot
   exist because its parent directory was just created; NEW_DST should
   be zero if DST_PATH might already exist.  DEVICE is the device
   number of the parent directory, or 0 if the parent of this file is
   not known.  ANCESTORS points to a linked, null terminated list of
   devices and inodes of parent directories of SRC_PATH.  COMMAND_LINE_ARG
   is nonzero iff SRC_PATH was specified on the command line.
   Set *COPY_INTO_SELF to nonzero if SRC_PATH is a parent of (or the
   same as) DST_PATH;  otherwise, set it to zero.
   Return 0 if successful, 1 if an error occurs. */

static int
copy_internal (const char *src_path, const char *dst_path,
	       int new_dst,
	       dev_t device,
	       struct dir_list *ancestors,
	       const struct cp_options *x,
	       int command_line_arg,
	       int *copy_into_self,
	       int *rename_succeeded)
{
  struct stat src_sb;
  struct stat dst_sb;
  mode_t src_mode;
  mode_t src_type;
  char *earlier_file = NULL;
  char *dst_backup = NULL;
  int backup_succeeded = 0;
  int delayed_fail;
  int copied_as_regular = 0;
  int ran_chown = 0;
  int preserve_metadata;

  if (x->move_mode && rename_succeeded)
    *rename_succeeded = 0;

  *copy_into_self = 0;
  if ((*(x->xstat)) (src_path, &src_sb))
    {
      error (0, errno, _("cannot stat %s"), quote (src_path));
      return 1;
    }

  src_type = src_sb.st_mode;

  src_mode = src_sb.st_mode;

  if (S_ISDIR (src_type) && !x->recursive)
    {
      error (0, 0, _("omitting directory %s"), quote (src_path));
      return 1;
    }

  /* Detect the case in which the same source file appears more than
     once on the command line and no backup option has been selected.
     If so, simply warn and don't copy it the second time.
     This check is enabled only if x->src_info is non-NULL.  */
  if (command_line_arg)
    {
      if ( ! S_ISDIR (src_sb.st_mode)
	   && x->backup_type == none
	   && seen_file (x->src_info, src_path, &src_sb))
	{
	  error (0, 0, _("warning: source file %s specified more than once"),
		 quote (src_path));
	  return 0;
	}

      record_file (x->src_info, src_path, &src_sb);
    }

  if (!new_dst)
    {
      if ((*(x->xstat)) (dst_path, &dst_sb))
	{
	  if (errno != ENOENT)
	    {
	      error (0, errno, _("cannot stat %s"), quote (dst_path));
	      return 1;
	    }
	  else
	    {
	      new_dst = 1;
	    }
	}
      else
	{
	  int return_now;
	  int ok = same_file_ok (src_path, &src_sb, dst_path, &dst_sb,
				 x, &return_now);
	  if (return_now)
	    return 0;

	  if (! ok)
	    {
	      error (0, 0, _("%s and %s are the same file"),
		     quote_n (0, src_path), quote_n (1, dst_path));
	      return 1;
	    }

	  if (!S_ISDIR (dst_sb.st_mode))
	    {
	      if (S_ISDIR (src_type))
		{
		  error (0, 0,
		     _("cannot overwrite non-directory %s with directory %s"),
			 quote_n (0, dst_path), quote_n (1, src_path));
		  return 1;
		}

	      /* Don't let the user destroy their data, even if they try hard:
		 This mv command must fail (likewise for cp):
		   rm -rf a b c; mkdir a b c; touch a/f b/f; mv a/f b/f c
		 Otherwise, the contents of b/f would be lost.
		 In the case of `cp', b/f would be lost if the user simulated
		 a move using cp and rm.
		 Note that it works fine if you use --backup=numbered.  */
	      if (command_line_arg
		  && x->backup_type != numbered
		  && seen_file (x->dest_info, dst_path, &dst_sb))
		{
		  error (0, 0,
			 _("will not overwrite just-created %s with %s"),
			 quote_n (0, dst_path), quote_n (1, src_path));
		  return 1;
		}
	    }

	  if (!S_ISDIR (src_type))
	    {
	      if (S_ISDIR (dst_sb.st_mode))
		{
		  error (0, 0,
		       _("cannot overwrite directory %s with non-directory"),
			 quote (dst_path));
		  return 1;
		}

	      if (x->update && MTIME_CMP (src_sb, dst_sb) <= 0)
		{
		  /* We're using --update and the source file is older
		     than the destination file, so there is no need to
		     copy or move.  */
		  /* Pretend the rename succeeded, so the caller (mv)
		     doesn't end up removing the source file.  */
		  if (rename_succeeded)
		    *rename_succeeded = 1;
		  return 0;
		}
	    }

	  /* When there is an existing destination file, we may end up
	     returning early, and hence not copying/moving the file.
	     This may be due to an interactive `negative' reply to the
	     prompt about the existing file.  It may also be due to the
	     use of the --reply=no option.  */
	  if (!S_ISDIR (src_type))
	    {
	      /* cp and mv treat -i and -f differently.  */
	      if (x->move_mode)
		{
		  if ((x->interactive == I_ALWAYS_NO
		       && UNWRITABLE (dst_path, dst_sb.st_mode))
		      || ((x->interactive == I_ASK_USER
			   || (x->interactive == I_UNSPECIFIED
			       && x->stdin_tty
			       && UNWRITABLE (dst_path, dst_sb.st_mode)))
			  && (overwrite_prompt (dst_path, &dst_sb), 1)
			  && ! yesno ()))
		    {
		      /* Pretend the rename succeeded, so the caller (mv)
			 doesn't end up removing the source file.  */
		      if (rename_succeeded)
			*rename_succeeded = 1;
		      return 0;
		    }
		}
	      else
		{
		  if (x->interactive == I_ALWAYS_NO
		      || (x->interactive == I_ASK_USER
			  && (overwrite_prompt (dst_path, &dst_sb), 1)
			  && ! yesno ()))
		    {
		      return 0;
		    }
		}
	    }

	  if (x->move_mode)
	    {
	      /* In move_mode, DEST may not be an existing directory.  */
	      if (S_ISDIR (dst_sb.st_mode))
		{
		  error (0, 0, _("cannot overwrite directory %s"),
			 quote (dst_path));
		  return 1;
		}

	      /* Don't allow user to move a directory onto a non-directory.  */
	      if (S_ISDIR (src_sb.st_mode) && !S_ISDIR (dst_sb.st_mode))
		{
		  error (0, 0,
		       _("cannot move directory onto non-directory: %s -> %s"),
			 quote_n (0, src_path), quote_n (0, dst_path));
		  return 1;
		}
	    }

	  if (x->backup_type != none && !S_ISDIR (dst_sb.st_mode))
	    {
	      char *tmp_backup = find_backup_file_name (dst_path,
							x->backup_type);
	      if (tmp_backup == NULL)
		xalloc_die ();

	      /* Detect (and fail) when creating the backup file would
		 destroy the source file.  Before, running the commands
		 cd /tmp; rm -f a a~; : > a; echo A > a~; cp --b=simple a~ a
		 would leave two zero-length files: a and a~.  */
	      /* FIXME: but simply change e.g., the final a~ to `./a~'
		 and the source will still be destroyed.  */
	      if (STREQ (tmp_backup, src_path))
		{
		  const char *fmt;
		  fmt = (x->move_mode
		 ? _("backing up %s would destroy source;  %s not moved")
		 : _("backing up %s would destroy source;  %s not copied"));
		  error (0, 0, fmt,
			 quote_n (0, dst_path),
			 quote_n (1, src_path));
		  free (tmp_backup);
		  return 1;
		}

	      dst_backup = (char *) alloca (strlen (tmp_backup) + 1);
	      strcpy (dst_backup, tmp_backup);
	      free (tmp_backup);
	      if (rename (dst_path, dst_backup))
		{
		  if (errno != ENOENT)
		    {
		      error (0, errno, _("cannot backup %s"), quote (dst_path));
		      return 1;
		    }
		  else
		    {
		      dst_backup = NULL;
		    }
		}
	      else
		{
		  backup_succeeded = 1;
		}
	      new_dst = 1;
	    }
	  else if (! S_ISDIR (dst_sb.st_mode)
		   && (x->unlink_dest_before_opening
		       || (x->xstat == lstat
			   && ! S_ISREG (src_sb.st_mode))))
	    {
	      if (unlink (dst_path) && errno != ENOENT)
		{
		  error (0, errno, _("cannot remove %s"), quote (dst_path));
		  return 1;
		}
	      new_dst = 1;
	    }
	}
    }

  /* If the source is a directory, we don't always create the destination
     directory.  So --verbose should not announce anything until we're
     sure we'll create a directory. */
  if (x->verbose && !S_ISDIR (src_type))
    {
      printf ("%s -> %s", quote_n (0, src_path), quote_n (1, dst_path));
      if (backup_succeeded)
	printf (_(" (backup: %s)"), quote (dst_backup));
      putchar ('\n');
    }

  /* Associate the destination path with the source device and inode
     so that if we encounter a matching dev/ino pair in the source tree
     we can arrange to create a hard link between the corresponding names
     in the destination tree.

     Sometimes, when preserving links, we have to record dev/ino even
     though st_nlink == 1:
     - when using -H and processing a command line argument;
	that command line argument could be a symlink pointing to another
	command line argument.  With `cp -H --preserve=link', we hard-link
	those two destination files.
     - likewise for -L except that it applies to all files, not just
	command line arguments.

     Also record directory dev/ino when using --recursive.  We'll use that
     info to detect this problem: cp -R dir dir.  FIXME-maybe: ideally,
     directory info would be recorded in a separate hash table, since
     such entries are useful only while a single command line hierarchy
     is being copied -- so that separate table could be cleared between
     command line args.  Using the same hash table to preserve hard
     links means that it may not be cleared.  */

  if ((x->preserve_links
       && (1 < src_sb.st_nlink
	   || (command_line_arg
	       && x->dereference == DEREF_COMMAND_LINE_ARGUMENTS)
	   || x->dereference == DEREF_ALWAYS))
      || (x->recursive && S_ISDIR (src_type)))
    {
      earlier_file = remember_copied (dst_path, src_sb.st_ino, src_sb.st_dev);
    }

  /* Did we copy this inode somewhere else (in this command line argument)
     and therefore this is a second hard link to the inode?  */

  if (earlier_file)
    {
      /* Avoid damaging the destination filesystem by refusing to preserve
	 hard-linked directories (which are found at least in Netapp snapshot
	 directories).  */
      if (S_ISDIR (src_type))
	{
	  /* If src_path and earlier_file refer to the same directory entry,
	     then warn about copying a directory into itself.  */
	  if (same_name (src_path, earlier_file))
	    {
	      error (0, 0, _("cannot copy a directory, %s, into itself, %s"),
		     quote_n (0, top_level_src_path),
		     quote_n (1, top_level_dst_path));
	      *copy_into_self = 1;
	    }
	  else
	    {
	      error (0, 0, _("will not create hard link %s to directory %s"),
		     quote_n (0, dst_path), quote_n (1, earlier_file));
	    }

	  goto un_backup;
	}

      if (link (earlier_file, dst_path))
	{
	  error (0, errno, _("cannot create hard link %s to %s"),
		 quote_n (0, dst_path), quote_n (1, earlier_file));
	  goto un_backup;
	}

      return 0;
    }

  if (x->move_mode)
    {
      if (rename (src_path, dst_path) == 0)
	{
	  if (x->verbose && S_ISDIR (src_type))
	    printf ("%s -> %s\n", quote_n (0, src_path), quote_n (1, dst_path));
	  if (rename_succeeded)
	    *rename_succeeded = 1;

	  if (command_line_arg)
	    {
	      /* Record destination dev/ino/filename, so that if we are asked
		 to overwrite that file again, we can detect it and fail.  */
	      /* It's fine to use the _source_ stat buffer (src_sb) to get the
	         _destination_ dev/ino, since the rename above can't have
		 changed those, and `mv' always uses lstat.
		 We could limit it further by operating
		 only on non-directories.  */
	      record_file (x->dest_info, dst_path, &src_sb);
	    }

	  return 0;
	}

      /* FIXME: someday, consider what to do when moving a directory into
	 itself but when source and destination are on different devices.  */

      /* This happens when attempting to rename a directory to a
	 subdirectory of itself.  */
      if (errno == EINVAL

	  /* When src_path is on an NFS file system, some types of
	     clients, e.g., SunOS4.1.4 and IRIX-5.3, set errno to EIO
	     instead.  Testing for this here risks misinterpreting a real
	     I/O error as an attempt to move a directory into itself, so
	     FIXME: consider not doing this.  */
	  || errno == EIO

	  /* And with SunOS-4.1.4 client and OpenBSD-2.3 server,
	     we get ENOTEMPTY.  */
	  || errno == ENOTEMPTY)
	{
	  /* FIXME: this is a little fragile in that it relies on rename(2)
	     failing with a specific errno value.  Expect problems on
	     non-POSIX systems.  */
	  error (0, 0, _("cannot move %s to a subdirectory of itself, %s"),
		 quote_n (0, top_level_src_path),
		 quote_n (1, top_level_dst_path));

	  /* Note that there is no need to call forget_created here,
	     (compare with the other calls in this file) since the
	     destination directory didn't exist before.  */

	  *copy_into_self = 1;
	  /* FIXME-cleanup: Don't return zero here; adjust mv.c accordingly.
	     The only caller that uses this code (mv.c) ends up setting its
	     exit status to nonzero when copy_into_self is nonzero.  */
	  return 0;
	}

      /* WARNING: there probably exist systems for which an inter-device
	 rename fails with a value of errno not handled here.
	 If/as those are reported, add them to the condition below.
	 If this happens to you, please do the following and send the output
	 to the bug-reporting address (e.g., in the output of cp --help):
	   touch k; perl -e 'rename "k","/tmp/k" or print "$!(",$!+0,")\n"'
	 where your current directory is on one partion and /tmp is the other.
	 Also, please try to find the E* errno macro name corresponding to
	 the diagnostic and parenthesized integer, and include that in your
	 e-mail.  One way to do that is to run a command like this
	   find /usr/include/. -type f \
	     | xargs grep 'define.*\<E[A-Z]*\>.*\<18\>' /dev/null
	 where you'd replace `18' with the integer in parentheses that
	 was output from the perl one-liner above.
	 If necessary, of course, change `/tmp' to some other directory.  */
      if (errno != EXDEV)
	{
	  /* There are many ways this can happen due to a race condition.
	     When something happens between the initial xstat and the
	     subsequent rename, we can get many different types of errors.
	     For example, if the destination is initially a non-directory
	     or non-existent, but it is created as a directory, the rename
	     fails.  If two `mv' commands try to rename the same file at
	     about the same time, one will succeed and the other will fail.
	     If the permissions on the directory containing the source or
	     destination file are made too restrictive, the rename will
	     fail.  Etc.  */
	  error (0, errno,
		 _("cannot move %s to %s"),
		 quote_n (0, src_path), quote_n (1, dst_path));
	  forget_created (src_sb.st_ino, src_sb.st_dev);
	  return 1;
	}

      /* The rename attempt has failed.  Remove any existing destination
	 file so that a cross-device `mv' acts as if it were really using
	 the rename syscall.  */
      if (unlink (dst_path) && errno != ENOENT)
	{
	  error (0, errno,
	     _("inter-device move failed: %s to %s; unable to remove target"),
		 quote_n (0, src_path), quote_n (1, dst_path));
	  forget_created (src_sb.st_ino, src_sb.st_dev);
	  return 1;
	}

      new_dst = 1;
    }

  delayed_fail = 0;

  /* In certain modes (cp's --symbolic-link), and for certain file types
     (symlinks and hard links) it doesn't make sense to preserve metadata,
     or it's possible to preserve only some of it.
     In such cases, set this variable to zero.  */
  preserve_metadata = 1;

  if (S_ISDIR (src_type))
    {
      struct dir_list *dir;

      /* If this directory has been copied before during the
         recursion, there is a symbolic link to an ancestor
         directory of the symbolic link.  It is impossible to
         continue to copy this, unless we've got an infinite disk.  */

      if (is_ancestor (&src_sb, ancestors))
	{
	  error (0, 0, _("cannot copy cyclic symbolic link %s"),
		 quote (src_path));
	  goto un_backup;
	}

      /* Insert the current directory in the list of parents.  */

      dir = (struct dir_list *) alloca (sizeof (struct dir_list));
      dir->parent = ancestors;
      dir->ino = src_sb.st_ino;
      dir->dev = src_sb.st_dev;

      if (new_dst || !S_ISDIR (dst_sb.st_mode))
	{
	  /* Create the new directory writable and searchable, so
             we can create new entries in it.  */

	  if (mkdir (dst_path, (src_mode & x->umask_kill) | S_IRWXU))
	    {
	      error (0, errno, _("cannot create directory %s"),
		     quote (dst_path));
	      goto un_backup;
	    }

	  /* Insert the created directory's inode and device
             numbers into the search structure, so that we can
             avoid copying it again.  */

	  if (remember_created (dst_path))
	    goto un_backup;

	  if (x->verbose)
	    printf ("%s -> %s\n", quote_n (0, src_path), quote_n (1, dst_path));
	}

      /* Are we crossing a file system boundary?  */
      if (x->one_file_system && device != 0 && device != src_sb.st_dev)
	return 0;

      /* Copy the contents of the directory.  */

      if (copy_dir (src_path, dst_path, new_dst, &src_sb, dir, x,
		    copy_into_self))
	{
	  /* Don't just return here -- otherwise, the failure to read a
	     single file in a source directory would cause the containing
	     destination directory not to have owner/perms set properly.  */
	  delayed_fail = 1;
	}
    }
#ifdef S_ISLNK
  else if (x->symbolic_link)
    {
      preserve_metadata = 0;

      if (*src_path != '/')
	{
	  /* Check that DST_PATH denotes a file in the current directory.  */
	  struct stat dot_sb;
	  struct stat dst_parent_sb;
	  char *dst_parent;
	  int in_current_dir;

	  dst_parent = dir_name (dst_path);

	  in_current_dir = (STREQ (".", dst_parent)
			    /* If either stat call fails, it's ok not to report
			       the failure and say dst_path is in the current
			       directory.  Other things will fail later.  */
			    || stat (".", &dot_sb)
			    || stat (dst_parent, &dst_parent_sb)
			    || SAME_INODE (dot_sb, dst_parent_sb));
	  free (dst_parent);

	  if (! in_current_dir)
	    {
	      error (0, 0,
	   _("%s: can make relative symbolic links only in current directory"),
		     quote (dst_path));
	      goto un_backup;
	    }
	}
      if (symlink (src_path, dst_path))
	{
	  error (0, errno, _("cannot create symbolic link %s to %s"),
		 quote_n (0, dst_path), quote_n (1, src_path));
	  goto un_backup;
	}
    }
#endif
  else if (x->hard_link)
    {
      preserve_metadata = 0;
      if (link (src_path, dst_path))
	{
	  error (0, errno, _("cannot create link %s"), quote (dst_path));
	  goto un_backup;
	}
    }
  else if (S_ISREG (src_type)
	   || (x->copy_as_regular && !S_ISDIR (src_type)
#ifdef S_ISLNK
	       && !S_ISLNK (src_type)
#endif
	       ))
    {
      copied_as_regular = 1;
      /* POSIX says the permission bits of the source file must be
	 used as the 3rd argument in the open call, but that's not consistent
	 with historical practice.  */
      if (copy_reg (src_path, dst_path, x,
		    get_dest_mode (x, src_mode), &new_dst, &src_sb))
	goto un_backup;
    }
  else
#ifdef S_ISFIFO
  if (S_ISFIFO (src_type))
    {
      if (mkfifo (dst_path, get_dest_mode (x, src_mode)))
	{
	  error (0, errno, _("cannot create fifo %s"), quote (dst_path));
	  goto un_backup;
	}
    }
  else
#endif
    if (S_ISBLK (src_type) || S_ISCHR (src_type)
#ifdef S_ISSOCK
	|| S_ISSOCK (src_type)
#endif
	)
    {
      if (mknod (dst_path, get_dest_mode (x, src_mode), src_sb.st_rdev))
	{
	  error (0, errno, _("cannot create special file %s"),
		 quote (dst_path));
	  goto un_backup;
	}
    }
  else
#ifdef S_ISLNK
  if (S_ISLNK (src_type))
    {
      char *src_link_val = xreadlink (src_path);
      if (src_link_val == NULL)
	{
	  error (0, errno, _("cannot read symbolic link %s"), quote (src_path));
	  goto un_backup;
	}

      if (!symlink (src_link_val, dst_path))
	free (src_link_val);
      else
	{
	  int saved_errno = errno;
	  int same_link = 0;
	  if (x->update && !new_dst && S_ISLNK (dst_sb.st_mode))
	    {
	      /* See if the destination is already the desired symlink.  */
	      size_t src_link_len = strlen (src_link_val);
	      char *dest_link_val = (char *) alloca (src_link_len + 1);
	      int dest_link_len = readlink (dst_path, dest_link_val,
					    src_link_len + 1);
	      if ((size_t) dest_link_len == src_link_len
		  && strncmp (dest_link_val, src_link_val, src_link_len) == 0)
		same_link = 1;
	    }
	  free (src_link_val);

	  if (! same_link)
	    {
	      error (0, saved_errno, _("cannot create symbolic link %s"),
		     quote (dst_path));
	      goto un_backup;
	    }
	}

      /* There's no need to preserve timestamps or permissions.  */
      preserve_metadata = 0;

      if (x->preserve_ownership)
	{
	  /* Preserve the owner and group of the just-`copied'
	     symbolic link, if possible.  */
# if HAVE_LCHOWN
	  if (DO_CHOWN (lchown, dst_path, src_sb.st_uid, src_sb.st_gid))
	    {
	      error (0, errno, _("failed to preserve ownership for %s"),
		     dst_path);
	      goto un_backup;
	    }
# else
	  /* Can't preserve ownership of symlinks.
	     FIXME: maybe give a warning or even error for symlinks
	     in directories with the sticky bit set -- there, not
	     preserving owner/group is a potential security problem.  */
# endif
	}
    }
  else
#endif
    {
      error (0, 0, _("%s has unknown file type"), quote (src_path));
      goto un_backup;
    }

  if (command_line_arg)
    record_file (x->dest_info, dst_path, NULL);

  if ( ! preserve_metadata)
    return 0;

  /* POSIX says that `cp -p' must restore the following:
     - permission bits
     - setuid, setgid bits
     - owner and group
     If it fails to restore any of those, we may give a warning but
     the destination must not be removed.
     FIXME: implement the above. */

  /* Adjust the times (and if possible, ownership) for the copy.
     chown turns off set[ug]id bits for non-root,
     so do the chmod last.  */

  if (x->preserve_timestamps)
    {
      struct utimbuf utb;

      /* There's currently no interface to set file timestamps with
	 better than 1-second resolution, so discard any fractional
	 part of the source timestamp.  */

      utb.actime = src_sb.st_atime;
      utb.modtime = src_sb.st_mtime;

      if (utime (dst_path, &utb))
	{
	  error (0, errno, _("preserving times for %s"), quote (dst_path));
	  if (x->require_preserve)
	    return 1;
	}
    }

  /* Avoid calling chown if we know it's not necessary.  */
  if (x->preserve_ownership
      && (new_dst || !SAME_OWNER_AND_GROUP (src_sb, dst_sb)))
    {
      ran_chown = 1;
      if (DO_CHOWN (chown, dst_path, src_sb.st_uid, src_sb.st_gid))
	{
	  error (0, errno, _("failed to preserve ownership for %s"),
		 quote (dst_path));
	  if (x->require_preserve)
	    return 1;
	}
    }

#if HAVE_STRUCT_STAT_ST_AUTHOR
  /* Preserve the st_author field.  */
  {
    file_t file = file_name_lookup (dst_path, 0, 0);
    if (file_chauthor (file, src_sb.st_author))
      error (0, errno, _("failed to preserve authorship for %s"),
	     quote (dst_path));
    mach_port_deallocate (mach_task_self (), file);
  }
#endif

  /* Permissions of newly-created regular files were set upon `open' in
     copy_reg.  But don't return early if there were any special bits and
     we had to run chown, because the chown must have reset those bits.  */
  if ((new_dst && copied_as_regular)
      && !(ran_chown && (src_mode & ~S_IRWXUGO)))
    return delayed_fail;

  if ((x->preserve_mode || new_dst)
      && (x->copy_as_regular || S_ISREG (src_type) || S_ISDIR (src_type)))
    {
      if (chmod (dst_path, get_dest_mode (x, src_mode)))
	{
	  error (0, errno, _("setting permissions for %s"), quote (dst_path));
	  if (x->set_mode || x->require_preserve)
	    return 1;
	}
    }

  return delayed_fail;

un_backup:

  /* We didn't create the destination.
     Remove the entry associating the source dev/ino with the
     destination file name, so we don't try to `preserve' a link
     to a file we didn't create.  */
  forget_created (src_sb.st_ino, src_sb.st_dev);

  if (dst_backup)
    {
      if (rename (dst_backup, dst_path))
	error (0, errno, _("cannot un-backup %s"), quote (dst_path));
      else
	{
	  if (x->verbose)
	    printf (_("%s -> %s (unbackup)\n"),
		    quote_n (0, dst_backup), quote_n (1, dst_path));
	}
    }
  return 1;
}

static int
valid_options (const struct cp_options *co)
{
  assert (co != NULL);

  assert (VALID_BACKUP_TYPE (co->backup_type));

  /* FIXME: for some reason this assertion always fails,
     at least on Solaris2.5.1.  Just disable it for now.  */
  /* assert (co->xstat == lstat || co->xstat == stat); */

  /* Make sure xstat and dereference are consistent.  */
  /* FIXME */

  assert (VALID_SPARSE_MODE (co->sparse_mode));

  return 1;
}

/* Copy the file SRC_PATH to the file DST_PATH.  The files may be of
   any type.  NONEXISTENT_DST should be nonzero if the file DST_PATH
   is known not to exist (e.g., because its parent directory was just
   created);  NONEXISTENT_DST should be zero if DST_PATH might already
   exist.  OPTIONS is ... FIXME-describe
   Set *COPY_INTO_SELF to nonzero if SRC_PATH is a parent of (or the
   same as) DST_PATH;  otherwise, set it to zero.
   Return 0 if successful, 1 if an error occurs. */

int
copy (const char *src_path, const char *dst_path,
      int nonexistent_dst, const struct cp_options *options,
      int *copy_into_self, int *rename_succeeded)
{
  assert (valid_options (options));

  /* Record the file names: they're used in case of error, when copying
     a directory into itself.  I don't like to make these tools do *any*
     extra work in the common case when that work is solely to handle
     exceptional cases, but in this case, I don't see a way to derive the
     top level source and destination directory names where they're used.
     An alternative is to use COPY_INTO_SELF and print the diagnostic
     from every caller -- but I don't want to do that.  */
  top_level_src_path = src_path;
  top_level_dst_path = dst_path;

  return copy_internal (src_path, dst_path, nonexistent_dst, 0, NULL,
			options, 1, copy_into_self, rename_succeeded);
}