summaryrefslogtreecommitdiff
path: root/src/dd.c
blob: 0028b53e4e1b7a1c12c8408601962df7084b0970 (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
1609
1610
1611
1612
1613
1614
1615
1616
1617
1618
1619
1620
1621
1622
1623
1624
1625
1626
1627
1628
1629
1630
1631
1632
1633
1634
1635
1636
1637
1638
1639
1640
1641
1642
1643
1644
1645
1646
1647
1648
1649
1650
1651
1652
1653
1654
1655
1656
1657
1658
1659
1660
1661
1662
1663
1664
1665
1666
1667
1668
1669
1670
1671
1672
1673
1674
1675
1676
1677
1678
1679
1680
1681
1682
1683
1684
1685
1686
1687
1688
1689
1690
1691
1692
1693
1694
1695
1696
1697
1698
1699
1700
1701
1702
1703
1704
1705
1706
1707
1708
1709
1710
1711
1712
1713
1714
1715
1716
1717
1718
1719
1720
1721
1722
1723
1724
1725
1726
1727
1728
1729
1730
1731
1732
1733
1734
1735
1736
1737
1738
1739
1740
1741
1742
1743
1744
1745
1746
1747
1748
1749
1750
1751
1752
1753
1754
1755
1756
1757
1758
1759
1760
1761
1762
1763
1764
1765
1766
1767
1768
1769
1770
1771
1772
1773
1774
1775
1776
1777
1778
1779
1780
1781
1782
1783
1784
1785
1786
1787
1788
1789
1790
1791
1792
1793
1794
1795
1796
1797
1798
1799
1800
1801
1802
1803
1804
1805
1806
1807
1808
1809
1810
1811
1812
1813
1814
1815
1816
1817
1818
1819
1820
1821
1822
1823
1824
1825
1826
1827
1828
1829
1830
1831
1832
1833
1834
1835
1836
1837
1838
1839
1840
1841
1842
1843
1844
1845
1846
1847
1848
1849
1850
1851
1852
1853
1854
1855
1856
1857
1858
1859
1860
1861
1862
1863
1864
1865
1866
1867
1868
1869
1870
1871
1872
1873
1874
1875
1876
1877
1878
1879
1880
1881
1882
1883
1884
1885
1886
1887
1888
1889
1890
1891
1892
1893
1894
1895
1896
1897
1898
1899
1900
1901
1902
1903
1904
1905
1906
1907
1908
1909
1910
1911
1912
1913
1914
1915
/* dd -- convert a file while copying it.
   Copyright (C) 85, 90, 91, 1995-2009 Free Software Foundation, Inc.

   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 3 of the License, 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, see <http://www.gnu.org/licenses/>.  */

/* Written by Paul Rubin, David MacKenzie, and Stuart Kemp. */

#include <config.h>

#define SWAB_ALIGN_OFFSET 2

#include <sys/types.h>
#include <signal.h>
#include <getopt.h>

#include "system.h"
#include "error.h"
#include "fd-reopen.h"
#include "gethrxtime.h"
#include "human.h"
#include "long-options.h"
#include "quote.h"
#include "quotearg.h"
#include "xstrtol.h"
#include "xtime.h"

static void process_signals (void);

/* The official name of this program (e.g., no `g' prefix).  */
#define PROGRAM_NAME "dd"

#define AUTHORS \
  proper_name ("Paul Rubin"), \
  proper_name ("David MacKenzie"), \
  proper_name ("Stuart Kemp")

/* Use SA_NOCLDSTOP as a proxy for whether the sigaction machinery is
   present.  SA_NODEFER and SA_RESETHAND are XSI extensions.  */
#ifndef SA_NOCLDSTOP
# define SA_NOCLDSTOP 0
# define sigprocmask(How, Set, Oset) /* empty */
# define sigset_t int
# if ! HAVE_SIGINTERRUPT
#  define siginterrupt(sig, flag) /* empty */
# endif
#endif
#ifndef SA_NODEFER
# define SA_NODEFER 0
#endif
#ifndef SA_RESETHAND
# define SA_RESETHAND 0
#endif

#ifndef SIGINFO
# define SIGINFO SIGUSR1
#endif

/* This may belong in GNULIB's fcntl module instead.
   Define O_CIO to 0 if it is not supported by this OS. */
#ifndef O_CIO
# define O_CIO 0
#endif

#if ! HAVE_FDATASYNC
# define fdatasync(fd) (errno = ENOSYS, -1)
#endif

#define output_char(c)				\
  do						\
    {						\
      obuf[oc++] = (c);				\
      if (oc >= output_blocksize)		\
	write_output ();			\
    }						\
  while (0)

/* Default input and output blocksize. */
#define DEFAULT_BLOCKSIZE 512

/* How many bytes to add to the input and output block sizes before invoking
   malloc.  See dd_copy for details.  INPUT_BLOCK_SLOP must be no less than
   OUTPUT_BLOCK_SLOP.  */
#define INPUT_BLOCK_SLOP (2 * SWAB_ALIGN_OFFSET + 2 * page_size - 1)
#define OUTPUT_BLOCK_SLOP (page_size - 1)

/* Maximum blocksize for the given SLOP.
   Keep it smaller than SIZE_MAX - SLOP, so that we can
   allocate buffers that size.  Keep it smaller than SSIZE_MAX, for
   the benefit of system calls like "read".  And keep it smaller than
   OFF_T_MAX, for the benefit of the large-offset seek code.  */
#define MAX_BLOCKSIZE(slop) MIN (SIZE_MAX - (slop), MIN (SSIZE_MAX, OFF_T_MAX))

/* Conversions bit masks. */
enum
  {
    C_ASCII = 01,

    C_EBCDIC = 02,
    C_IBM = 04,
    C_BLOCK = 010,
    C_UNBLOCK = 020,
    C_LCASE = 040,
    C_UCASE = 0100,
    C_SWAB = 0200,
    C_NOERROR = 0400,
    C_NOTRUNC = 01000,
    C_SYNC = 02000,

    /* Use separate input and output buffers, and combine partial
       input blocks. */
    C_TWOBUFS = 04000,

    C_NOCREAT = 010000,
    C_EXCL = 020000,
    C_FDATASYNC = 040000,
    C_FSYNC = 0100000
  };

/* Status bit masks.  */
enum
  {
    STATUS_NOXFER = 01
  };

/* The name of the input file, or NULL for the standard input. */
static char const *input_file = NULL;

/* The name of the output file, or NULL for the standard output. */
static char const *output_file = NULL;

/* The page size on this host.  */
static size_t page_size;

/* The number of bytes in which atomic reads are done. */
static size_t input_blocksize = 0;

/* The number of bytes in which atomic writes are done. */
static size_t output_blocksize = 0;

/* Conversion buffer size, in bytes.  0 prevents conversions. */
static size_t conversion_blocksize = 0;

/* Skip this many records of `input_blocksize' bytes before input. */
static uintmax_t skip_records = 0;

/* Skip this many records of `output_blocksize' bytes before output. */
static uintmax_t seek_records = 0;

/* Copy only this many records.  The default is effectively infinity.  */
static uintmax_t max_records = (uintmax_t) -1;

/* Bit vector of conversions to apply. */
static int conversions_mask = 0;

/* Open flags for the input and output files.  */
static int input_flags = 0;
static int output_flags = 0;

/* Status flags for what is printed to stderr.  */
static int status_flags = 0;

/* If nonzero, filter characters through the translation table.  */
static bool translation_needed = false;

/* Number of partial blocks written. */
static uintmax_t w_partial = 0;

/* Number of full blocks written. */
static uintmax_t w_full = 0;

/* Number of partial blocks read. */
static uintmax_t r_partial = 0;

/* Number of full blocks read. */
static uintmax_t r_full = 0;

/* Number of bytes written.  */
static uintmax_t w_bytes = 0;

/* Time that dd started.  */
static xtime_t start_time;

/* True if input is seekable.  */
static bool input_seekable;

/* Error number corresponding to initial attempt to lseek input.
   If ESPIPE, do not issue any more diagnostics about it.  */
static int input_seek_errno;

/* File offset of the input, in bytes, along with a flag recording
   whether it overflowed.  */
static uintmax_t input_offset;
static bool input_offset_overflow;

/* Records truncated by conv=block. */
static uintmax_t r_truncate = 0;

/* Output representation of newline and space characters.
   They change if we're converting to EBCDIC.  */
static char newline_character = '\n';
static char space_character = ' ';

/* Output buffer. */
static char *obuf;

/* Current index into `obuf'. */
static size_t oc = 0;

/* Index into current line, for `conv=block' and `conv=unblock'.  */
static size_t col = 0;

/* The set of signals that are caught.  */
static sigset_t caught_signals;

/* If nonzero, the value of the pending fatal signal.  */
static sig_atomic_t volatile interrupt_signal;

/* A count of the number of pending info signals that have been received.  */
static sig_atomic_t volatile info_signal_count;

/* Function used for read (to handle iflag=fullblock parameter).  */
static ssize_t (*iread_fnc) (int fd, char *buf, size_t size);

/* A longest symbol in the struct symbol_values tables below.  */
#define LONGEST_SYMBOL "fdatasync"

/* A symbol and the corresponding integer value.  */
struct symbol_value
{
  char symbol[sizeof LONGEST_SYMBOL];
  int value;
};

/* Conversion symbols, for conv="...".  */
static struct symbol_value const conversions[] =
{
  {"ascii", C_ASCII | C_TWOBUFS},	/* EBCDIC to ASCII. */
  {"ebcdic", C_EBCDIC | C_TWOBUFS},	/* ASCII to EBCDIC. */
  {"ibm", C_IBM | C_TWOBUFS},	/* Slightly different ASCII to EBCDIC. */
  {"block", C_BLOCK | C_TWOBUFS},	/* Variable to fixed length records. */
  {"unblock", C_UNBLOCK | C_TWOBUFS},	/* Fixed to variable length records. */
  {"lcase", C_LCASE | C_TWOBUFS},	/* Translate upper to lower case. */
  {"ucase", C_UCASE | C_TWOBUFS},	/* Translate lower to upper case. */
  {"swab", C_SWAB | C_TWOBUFS},	/* Swap bytes of input. */
  {"noerror", C_NOERROR},	/* Ignore i/o errors. */
  {"nocreat", C_NOCREAT},	/* Do not create output file.  */
  {"excl", C_EXCL},		/* Fail if the output file already exists.  */
  {"notrunc", C_NOTRUNC},	/* Do not truncate output file. */
  {"sync", C_SYNC},		/* Pad input records to ibs with NULs. */
  {"fdatasync", C_FDATASYNC},	/* Synchronize output data before finishing.  */
  {"fsync", C_FSYNC},		/* Also synchronize output metadata.  */
  {"", 0}
};

enum
  {
    /* Compute a value that's bitwise disjoint from the union
       of all O_ values.  */
    v = ~(0
          | O_APPEND
          | O_BINARY
          | O_CIO
          | O_DIRECT
          | O_DIRECTORY
          | O_DSYNC
          | O_NOATIME
          | O_NOCTTY
          | O_NOFOLLOW
          | O_NOLINKS
          | O_NONBLOCK
          | O_SYNC
          | O_TEXT
          ),
    /* Use its lowest bit.  */
    O_FULLBLOCK = v ^ (v & (v - 1))
  };

/* Ensure that we got something.  */
verify (O_FULLBLOCK != 0);

#define MULTIPLE_BITS_SET(i) (((i) & ((i) - 1)) != 0)

/* Ensure that this is a single-bit value.  */
verify ( ! MULTIPLE_BITS_SET (O_FULLBLOCK));

/* Flags, for iflag="..." and oflag="...".  */
static struct symbol_value const flags[] =
{
  {"append",	O_APPEND},
  {"binary",	O_BINARY},
  {"cio",	O_CIO},
  {"direct",	O_DIRECT},
  {"directory",	O_DIRECTORY},
  {"dsync",	O_DSYNC},
  {"noatime",	O_NOATIME},
  {"noctty",	O_NOCTTY},
  {"nofollow",	HAVE_WORKING_O_NOFOLLOW ? O_NOFOLLOW : 0},
  {"nolinks",	O_NOLINKS},
  {"nonblock",	O_NONBLOCK},
  {"sync",	O_SYNC},
  {"text",	O_TEXT},
  {"fullblock", O_FULLBLOCK}, /* Accumulate full blocks from input.  */
  {"",		0}
};

/* Status, for status="...".  */
static struct symbol_value const statuses[] =
{
  {"noxfer",	STATUS_NOXFER},
  {"",		0}
};

/* Translation table formed by applying successive transformations. */
static unsigned char trans_table[256];

static char const ascii_to_ebcdic[] =
{
  '\000', '\001', '\002', '\003', '\067', '\055', '\056', '\057',
  '\026', '\005', '\045', '\013', '\014', '\015', '\016', '\017',
  '\020', '\021', '\022', '\023', '\074', '\075', '\062', '\046',
  '\030', '\031', '\077', '\047', '\034', '\035', '\036', '\037',
  '\100', '\117', '\177', '\173', '\133', '\154', '\120', '\175',
  '\115', '\135', '\134', '\116', '\153', '\140', '\113', '\141',
  '\360', '\361', '\362', '\363', '\364', '\365', '\366', '\367',
  '\370', '\371', '\172', '\136', '\114', '\176', '\156', '\157',
  '\174', '\301', '\302', '\303', '\304', '\305', '\306', '\307',
  '\310', '\311', '\321', '\322', '\323', '\324', '\325', '\326',
  '\327', '\330', '\331', '\342', '\343', '\344', '\345', '\346',
  '\347', '\350', '\351', '\112', '\340', '\132', '\137', '\155',
  '\171', '\201', '\202', '\203', '\204', '\205', '\206', '\207',
  '\210', '\211', '\221', '\222', '\223', '\224', '\225', '\226',
  '\227', '\230', '\231', '\242', '\243', '\244', '\245', '\246',
  '\247', '\250', '\251', '\300', '\152', '\320', '\241', '\007',
  '\040', '\041', '\042', '\043', '\044', '\025', '\006', '\027',
  '\050', '\051', '\052', '\053', '\054', '\011', '\012', '\033',
  '\060', '\061', '\032', '\063', '\064', '\065', '\066', '\010',
  '\070', '\071', '\072', '\073', '\004', '\024', '\076', '\341',
  '\101', '\102', '\103', '\104', '\105', '\106', '\107', '\110',
  '\111', '\121', '\122', '\123', '\124', '\125', '\126', '\127',
  '\130', '\131', '\142', '\143', '\144', '\145', '\146', '\147',
  '\150', '\151', '\160', '\161', '\162', '\163', '\164', '\165',
  '\166', '\167', '\170', '\200', '\212', '\213', '\214', '\215',
  '\216', '\217', '\220', '\232', '\233', '\234', '\235', '\236',
  '\237', '\240', '\252', '\253', '\254', '\255', '\256', '\257',
  '\260', '\261', '\262', '\263', '\264', '\265', '\266', '\267',
  '\270', '\271', '\272', '\273', '\274', '\275', '\276', '\277',
  '\312', '\313', '\314', '\315', '\316', '\317', '\332', '\333',
  '\334', '\335', '\336', '\337', '\352', '\353', '\354', '\355',
  '\356', '\357', '\372', '\373', '\374', '\375', '\376', '\377'
};

static char const ascii_to_ibm[] =
{
  '\000', '\001', '\002', '\003', '\067', '\055', '\056', '\057',
  '\026', '\005', '\045', '\013', '\014', '\015', '\016', '\017',
  '\020', '\021', '\022', '\023', '\074', '\075', '\062', '\046',
  '\030', '\031', '\077', '\047', '\034', '\035', '\036', '\037',
  '\100', '\132', '\177', '\173', '\133', '\154', '\120', '\175',
  '\115', '\135', '\134', '\116', '\153', '\140', '\113', '\141',
  '\360', '\361', '\362', '\363', '\364', '\365', '\366', '\367',
  '\370', '\371', '\172', '\136', '\114', '\176', '\156', '\157',
  '\174', '\301', '\302', '\303', '\304', '\305', '\306', '\307',
  '\310', '\311', '\321', '\322', '\323', '\324', '\325', '\326',
  '\327', '\330', '\331', '\342', '\343', '\344', '\345', '\346',
  '\347', '\350', '\351', '\255', '\340', '\275', '\137', '\155',
  '\171', '\201', '\202', '\203', '\204', '\205', '\206', '\207',
  '\210', '\211', '\221', '\222', '\223', '\224', '\225', '\226',
  '\227', '\230', '\231', '\242', '\243', '\244', '\245', '\246',
  '\247', '\250', '\251', '\300', '\117', '\320', '\241', '\007',
  '\040', '\041', '\042', '\043', '\044', '\025', '\006', '\027',
  '\050', '\051', '\052', '\053', '\054', '\011', '\012', '\033',
  '\060', '\061', '\032', '\063', '\064', '\065', '\066', '\010',
  '\070', '\071', '\072', '\073', '\004', '\024', '\076', '\341',
  '\101', '\102', '\103', '\104', '\105', '\106', '\107', '\110',
  '\111', '\121', '\122', '\123', '\124', '\125', '\126', '\127',
  '\130', '\131', '\142', '\143', '\144', '\145', '\146', '\147',
  '\150', '\151', '\160', '\161', '\162', '\163', '\164', '\165',
  '\166', '\167', '\170', '\200', '\212', '\213', '\214', '\215',
  '\216', '\217', '\220', '\232', '\233', '\234', '\235', '\236',
  '\237', '\240', '\252', '\253', '\254', '\255', '\256', '\257',
  '\260', '\261', '\262', '\263', '\264', '\265', '\266', '\267',
  '\270', '\271', '\272', '\273', '\274', '\275', '\276', '\277',
  '\312', '\313', '\314', '\315', '\316', '\317', '\332', '\333',
  '\334', '\335', '\336', '\337', '\352', '\353', '\354', '\355',
  '\356', '\357', '\372', '\373', '\374', '\375', '\376', '\377'
};

static char const ebcdic_to_ascii[] =
{
  '\000', '\001', '\002', '\003', '\234', '\011', '\206', '\177',
  '\227', '\215', '\216', '\013', '\014', '\015', '\016', '\017',
  '\020', '\021', '\022', '\023', '\235', '\205', '\010', '\207',
  '\030', '\031', '\222', '\217', '\034', '\035', '\036', '\037',
  '\200', '\201', '\202', '\203', '\204', '\012', '\027', '\033',
  '\210', '\211', '\212', '\213', '\214', '\005', '\006', '\007',
  '\220', '\221', '\026', '\223', '\224', '\225', '\226', '\004',
  '\230', '\231', '\232', '\233', '\024', '\025', '\236', '\032',
  '\040', '\240', '\241', '\242', '\243', '\244', '\245', '\246',
  '\247', '\250', '\133', '\056', '\074', '\050', '\053', '\041',
  '\046', '\251', '\252', '\253', '\254', '\255', '\256', '\257',
  '\260', '\261', '\135', '\044', '\052', '\051', '\073', '\136',
  '\055', '\057', '\262', '\263', '\264', '\265', '\266', '\267',
  '\270', '\271', '\174', '\054', '\045', '\137', '\076', '\077',
  '\272', '\273', '\274', '\275', '\276', '\277', '\300', '\301',
  '\302', '\140', '\072', '\043', '\100', '\047', '\075', '\042',
  '\303', '\141', '\142', '\143', '\144', '\145', '\146', '\147',
  '\150', '\151', '\304', '\305', '\306', '\307', '\310', '\311',
  '\312', '\152', '\153', '\154', '\155', '\156', '\157', '\160',
  '\161', '\162', '\313', '\314', '\315', '\316', '\317', '\320',
  '\321', '\176', '\163', '\164', '\165', '\166', '\167', '\170',
  '\171', '\172', '\322', '\323', '\324', '\325', '\326', '\327',
  '\330', '\331', '\332', '\333', '\334', '\335', '\336', '\337',
  '\340', '\341', '\342', '\343', '\344', '\345', '\346', '\347',
  '\173', '\101', '\102', '\103', '\104', '\105', '\106', '\107',
  '\110', '\111', '\350', '\351', '\352', '\353', '\354', '\355',
  '\175', '\112', '\113', '\114', '\115', '\116', '\117', '\120',
  '\121', '\122', '\356', '\357', '\360', '\361', '\362', '\363',
  '\134', '\237', '\123', '\124', '\125', '\126', '\127', '\130',
  '\131', '\132', '\364', '\365', '\366', '\367', '\370', '\371',
  '\060', '\061', '\062', '\063', '\064', '\065', '\066', '\067',
  '\070', '\071', '\372', '\373', '\374', '\375', '\376', '\377'
};

/* True if we need to close the standard output *stream*.  */
static bool close_stdout_required = true;

/* The only reason to close the standard output *stream* is if
   parse_long_options fails (as it does for --help or --version).
   In any other case, dd uses only the STDOUT_FILENO file descriptor,
   and the "cleanup" function calls "close (STDOUT_FILENO)".
   Closing the file descriptor and then letting the usual atexit-run
   close_stdout function call "fclose (stdout)" would result in a
   harmless failure of the close syscall (with errno EBADF).
   This function serves solely to avoid the unnecessary close_stdout
   call, once parse_long_options has succeeded.  */
static void
maybe_close_stdout (void)
{
  if (close_stdout_required)
    close_stdout ();
}

void
usage (int status)
{
  if (status != EXIT_SUCCESS)
    fprintf (stderr, _("Try `%s --help' for more information.\n"),
	     program_name);
  else
    {
      printf (_("\
Usage: %s [OPERAND]...\n\
  or:  %s OPTION\n\
"),
	      program_name, program_name);
      fputs (_("\
Copy a file, converting and formatting according to the operands.\n\
\n\
  bs=BYTES        read and write BYTES bytes at a time (also see ibs=,obs=)\n\
  cbs=BYTES       convert BYTES bytes at a time\n\
  conv=CONVS      convert the file as per the comma separated symbol list\n\
  count=BLOCKS    copy only BLOCKS input blocks\n\
  ibs=BYTES       read BYTES bytes at a time (default: 512)\n\
"), stdout);
      fputs (_("\
  if=FILE         read from FILE instead of stdin\n\
  iflag=FLAGS     read as per the comma separated symbol list\n\
  obs=BYTES       write BYTES bytes at a time (default: 512)\n\
  of=FILE         write to FILE instead of stdout\n\
  oflag=FLAGS     write as per the comma separated symbol list\n\
  seek=BLOCKS     skip BLOCKS obs-sized blocks at start of output\n\
  skip=BLOCKS     skip BLOCKS ibs-sized blocks at start of input\n\
  status=noxfer   suppress transfer statistics\n\
"), stdout);
      fputs (_("\
\n\
BLOCKS and BYTES may be followed by the following multiplicative suffixes:\n\
c =1, w =2, b =512, kB =1000, K =1024, MB =1000*1000, M =1024*1024, xM =M\n\
GB =1000*1000*1000, G =1024*1024*1024, and so on for T, P, E, Z, Y.\n\
\n\
Each CONV symbol may be:\n\
\n\
"), stdout);
      fputs (_("\
  ascii     from EBCDIC to ASCII\n\
  ebcdic    from ASCII to EBCDIC\n\
  ibm       from ASCII to alternate EBCDIC\n\
  block     pad newline-terminated records with spaces to cbs-size\n\
  unblock   replace trailing spaces in cbs-size records with newline\n\
  lcase     change upper case to lower case\n\
"), stdout);
      fputs (_("\
  nocreat   do not create the output file\n\
  excl      fail if the output file already exists\n\
  notrunc   do not truncate the output file\n\
  ucase     change lower case to upper case\n\
  swab      swap every pair of input bytes\n\
"), stdout);
      fputs (_("\
  noerror   continue after read errors\n\
  sync      pad every input block with NULs to ibs-size; when used\n\
            with block or unblock, pad with spaces rather than NULs\n\
  fdatasync  physically write output file data before finishing\n\
  fsync     likewise, but also write metadata\n\
"), stdout);
      fputs (_("\
\n\
Each FLAG symbol may be:\n\
\n\
  append    append mode (makes sense only for output; conv=notrunc suggested)\n\
"), stdout);
      if (O_CIO)
	fputs (_("  cio       use concurrent I/O for data\n"), stdout);
      if (O_DIRECT)
	fputs (_("  direct    use direct I/O for data\n"), stdout);
      if (O_DIRECTORY)
	fputs (_("  directory  fail unless a directory\n"), stdout);
      if (O_DSYNC)
	fputs (_("  dsync     use synchronized I/O for data\n"), stdout);
      if (O_SYNC)
	fputs (_("  sync      likewise, but also for metadata\n"), stdout);
      fputs (_("  fullblock  accumulate full blocks of input (iflag only)\n"),
	     stdout);
      if (O_NONBLOCK)
	fputs (_("  nonblock  use non-blocking I/O\n"), stdout);
      if (O_NOATIME)
	fputs (_("  noatime   do not update access time\n"), stdout);
      if (O_NOCTTY)
	fputs (_("  noctty    do not assign controlling terminal from file\n"),
	       stdout);
      if (HAVE_WORKING_O_NOFOLLOW)
	fputs (_("  nofollow  do not follow symlinks\n"), stdout);
      if (O_NOLINKS)
	fputs (_("  nolinks   fail if multiply-linked\n"), stdout);
      if (O_BINARY)
	fputs (_("  binary    use binary I/O for data\n"), stdout);
      if (O_TEXT)
	fputs (_("  text      use text I/O for data\n"), stdout);

      {
	char const *siginfo_name = (SIGINFO == SIGUSR1 ? "USR1" : "INFO");
	printf (_("\
\n\
Sending a %s signal to a running `dd' process makes it\n\
print I/O statistics to standard error and then resume copying.\n\
\n\
  $ dd if=/dev/zero of=/dev/null& pid=$!\n\
  $ kill -%s $pid; sleep 1; kill $pid\n\
  18335302+0 records in\n\
  18335302+0 records out\n\
  9387674624 bytes (9.4 GB) copied, 34.6279 seconds, 271 MB/s\n\
\n\
Options are:\n\
\n\
"),
		siginfo_name, siginfo_name);
      }

      fputs (HELP_OPTION_DESCRIPTION, stdout);
      fputs (VERSION_OPTION_DESCRIPTION, stdout);
      emit_bug_reporting_address ();
    }
  exit (status);
}

static void
translate_charset (char const *new_trans)
{
  int i;

  for (i = 0; i < 256; i++)
    trans_table[i] = new_trans[trans_table[i]];
  translation_needed = true;
}

/* Return true if I has more than one bit set.  I must be nonnegative.  */

static inline bool
multiple_bits_set (int i)
{
  return MULTIPLE_BITS_SET (i);
}

/* Print transfer statistics.  */

static void
print_stats (void)
{
  xtime_t now = gethrxtime ();
  char hbuf[LONGEST_HUMAN_READABLE + 1];
  int human_opts =
    (human_autoscale | human_round_to_nearest
     | human_space_before_unit | human_SI | human_B);
  double delta_s;
  char const *bytes_per_second;

  fprintf (stderr,
	   _("%"PRIuMAX"+%"PRIuMAX" records in\n"
	     "%"PRIuMAX"+%"PRIuMAX" records out\n"),
	   r_full, r_partial, w_full, w_partial);

  if (r_truncate != 0)
    fprintf (stderr,
	     ngettext ("%"PRIuMAX" truncated record\n",
		       "%"PRIuMAX" truncated records\n",
		       select_plural (r_truncate)),
	     r_truncate);

  if (status_flags & STATUS_NOXFER)
    return;

  /* Use integer arithmetic to compute the transfer rate,
     since that makes it easy to use SI abbreviations.  */

  fprintf (stderr,
	   ngettext ("%"PRIuMAX" byte (%s) copied",
		     "%"PRIuMAX" bytes (%s) copied",
		     select_plural (w_bytes)),
	   w_bytes,
	   human_readable (w_bytes, hbuf, human_opts, 1, 1));

  if (start_time < now)
    {
      double XTIME_PRECISIONe0 = XTIME_PRECISION;
      uintmax_t delta_xtime = now;
      delta_xtime -= start_time;
      delta_s = delta_xtime / XTIME_PRECISIONe0;
      bytes_per_second = human_readable (w_bytes, hbuf, human_opts,
					 XTIME_PRECISION, delta_xtime);
    }
  else
    {
      delta_s = 0;
      bytes_per_second = _("Infinity B");
    }

  /* TRANSLATORS: The two instances of "s" in this string are the SI
     symbol "s" (meaning second), and should not be translated.

     This format used to be:

     ngettext (", %g second, %s/s\n", ", %g seconds, %s/s\n", delta_s == 1)

     but that was incorrect for languages like Polish.  To fix this
     bug we now use SI symbols even though they're a bit more
     confusing in English.  */
  fprintf (stderr, _(", %g s, %s/s\n"), delta_s, bytes_per_second);
}

static void
cleanup (void)
{
  if (close (STDIN_FILENO) < 0)
    error (EXIT_FAILURE, errno,
	   _("closing input file %s"), quote (input_file));

  /* Don't remove this call to close, even though close_stdout
     closes standard output.  This close is necessary when cleanup
     is called as part of a signal handler.  */
  if (close (STDOUT_FILENO) < 0)
    error (EXIT_FAILURE, errno,
	   _("closing output file %s"), quote (output_file));
}

static void ATTRIBUTE_NORETURN
quit (int code)
{
  cleanup ();
  print_stats ();
  process_signals ();
  exit (code);
}

/* An ordinary signal was received; arrange for the program to exit.  */

static void
interrupt_handler (int sig)
{
  if (! SA_RESETHAND)
    signal (sig, SIG_DFL);
  interrupt_signal = sig;
}

/* An info signal was received; arrange for the program to print status.  */

static void
siginfo_handler (int sig)
{
  if (! SA_NOCLDSTOP)
    signal (sig, siginfo_handler);
  info_signal_count++;
}

/* Install the signal handlers.  */

static void
install_signal_handlers (void)
{
  bool catch_siginfo = ! (SIGINFO == SIGUSR1 && getenv ("POSIXLY_CORRECT"));

#if SA_NOCLDSTOP

  struct sigaction act;
  sigemptyset (&caught_signals);
  if (catch_siginfo)
    {
      sigaction (SIGINFO, NULL, &act);
      if (act.sa_handler != SIG_IGN)
	sigaddset (&caught_signals, SIGINFO);
    }
  sigaction (SIGINT, NULL, &act);
  if (act.sa_handler != SIG_IGN)
    sigaddset (&caught_signals, SIGINT);
  act.sa_mask = caught_signals;

  if (sigismember (&caught_signals, SIGINFO))
    {
      act.sa_handler = siginfo_handler;
      act.sa_flags = 0;
      sigaction (SIGINFO, &act, NULL);
    }

  if (sigismember (&caught_signals, SIGINT))
    {
      /* POSIX 1003.1-2001 says SA_RESETHAND implies SA_NODEFER,
	 but this is not true on Solaris 8 at least.  It doesn't
	 hurt to use SA_NODEFER here, so leave it in.  */
      act.sa_handler = interrupt_handler;
      act.sa_flags = SA_NODEFER | SA_RESETHAND;
      sigaction (SIGINT, &act, NULL);
    }

#else

  if (catch_siginfo && signal (SIGINFO, SIG_IGN) != SIG_IGN)
    {
      signal (SIGINFO, siginfo_handler);
      siginterrupt (SIGINFO, 1);
    }
  if (signal (SIGINT, SIG_IGN) != SIG_IGN)
    {
      signal (SIGINT, interrupt_handler);
      siginterrupt (SIGINT, 1);
    }
#endif
}

/* Process any pending signals.  If signals are caught, this function
   should be called periodically.  Ideally there should never be an
   unbounded amount of time when signals are not being processed.  */

static void
process_signals (void)
{
  while (interrupt_signal | info_signal_count)
    {
      int interrupt;
      int infos;
      sigset_t oldset;

      sigprocmask (SIG_BLOCK, &caught_signals, &oldset);

      /* Reload interrupt_signal and info_signal_count, in case a new
	 signal was handled before sigprocmask took effect.  */
      interrupt = interrupt_signal;
      infos = info_signal_count;

      if (infos)
	info_signal_count = infos - 1;

      sigprocmask (SIG_SETMASK, &oldset, NULL);

      if (interrupt)
	cleanup ();
      print_stats ();
      if (interrupt)
	raise (interrupt);
    }
}

/* Read from FD into the buffer BUF of size SIZE, processing any
   signals that arrive before bytes are read.  Return the number of
   bytes read if successful, -1 (setting errno) on failure.  */

static ssize_t
iread (int fd, char *buf, size_t size)
{
  for (;;)
    {
      ssize_t nread;
      process_signals ();
      nread = read (fd, buf, size);
      if (! (nread < 0 && errno == EINTR))
	return nread;
    }
}

/* Wrapper around iread function to accumulate full blocks.  */
static ssize_t
iread_fullblock (int fd, char *buf, size_t size)
{
  ssize_t nread = 0;

  while (0 < size)
    {
      ssize_t ncurr = iread (fd, buf, size);
      if (ncurr < 0)
	return ncurr;
      if (ncurr == 0)
	break;
      nread += ncurr;
      buf   += ncurr;
      size  -= ncurr;
    }

  return nread;
}

/* Write to FD the buffer BUF of size SIZE, processing any signals
   that arrive.  Return the number of bytes written, setting errno if
   this is less than SIZE.  Keep trying if there are partial
   writes.  */

static size_t
iwrite (int fd, char const *buf, size_t size)
{
  size_t total_written = 0;

  while (total_written < size)
    {
      ssize_t nwritten;
      process_signals ();
      nwritten = write (fd, buf + total_written, size - total_written);
      if (nwritten < 0)
	{
	  if (errno != EINTR)
	    break;
	}
      else if (nwritten == 0)
	{
	  /* Some buggy drivers return 0 when one tries to write beyond
	     a device's end.  (Example: Linux kernel 1.2.13 on /dev/fd0.)
	     Set errno to ENOSPC so they get a sensible diagnostic.  */
	  errno = ENOSPC;
	  break;
	}
      else
	total_written += nwritten;
    }

  return total_written;
}

/* Write, then empty, the output buffer `obuf'. */

static void
write_output (void)
{
  size_t nwritten = iwrite (STDOUT_FILENO, obuf, output_blocksize);
  w_bytes += nwritten;
  if (nwritten != output_blocksize)
    {
      error (0, errno, _("writing to %s"), quote (output_file));
      if (nwritten != 0)
	w_partial++;
      quit (EXIT_FAILURE);
    }
  else
    w_full++;
  oc = 0;
}

/* Return true if STR is of the form "PATTERN" or "PATTERNDELIM...".  */

static bool
operand_matches (char const *str, char const *pattern, char delim)
{
  while (*pattern)
    if (*str++ != *pattern++)
      return false;
  return !*str || *str == delim;
}

/* Interpret one "conv=..." or similar operand STR according to the
   symbols in TABLE, returning the flags specified.  If the operand
   cannot be parsed, use ERROR_MSGID to generate a diagnostic.  */

static int
parse_symbols (char const *str, struct symbol_value const *table,
	       char const *error_msgid)
{
  int value = 0;

  for (;;)
    {
      char const *strcomma = strchr (str, ',');
      struct symbol_value const *entry;

      for (entry = table;
	   ! (operand_matches (str, entry->symbol, ',') && entry->value);
	   entry++)
	{
	  if (! entry->symbol[0])
	    {
	      size_t slen = strcomma ? strcomma - str : strlen (str);
	      error (0, 0, "%s: %s", _(error_msgid),
		     quotearg_n_style_mem (0, locale_quoting_style, str, slen));
	      usage (EXIT_FAILURE);
	    }
	}

      value |= entry->value;
      if (!strcomma)
	break;
      str = strcomma + 1;
    }

  return value;
}

/* Return the value of STR, interpreted as a non-negative decimal integer,
   optionally multiplied by various values.
   Set *INVALID if STR does not represent a number in this format.  */

static uintmax_t
parse_integer (const char *str, bool *invalid)
{
  uintmax_t n;
  char *suffix;
  enum strtol_error e = xstrtoumax (str, &suffix, 10, &n, "bcEGkKMPTwYZ0");

  if (e == LONGINT_INVALID_SUFFIX_CHAR && *suffix == 'x')
    {
      uintmax_t multiplier = parse_integer (suffix + 1, invalid);

      if (multiplier != 0 && n * multiplier / multiplier != n)
	{
	  *invalid = true;
	  return 0;
	}

      n *= multiplier;
    }
  else if (e != LONGINT_OK)
    {
      *invalid = true;
      return 0;
    }

  return n;
}

/* OPERAND is of the form "X=...".  Return true if X is NAME.  */

static bool
operand_is (char const *operand, char const *name)
{
  return operand_matches (operand, name, '=');
}

static void
scanargs (int argc, char *const *argv)
{
  int i;
  size_t blocksize = 0;

  for (i = optind; i < argc; i++)
    {
      char const *name = argv[i];
      char const *val = strchr (name, '=');

      if (val == NULL)
	{
	  error (0, 0, _("unrecognized operand %s"), quote (name));
	  usage (EXIT_FAILURE);
	}
      val++;

      if (operand_is (name, "if"))
	input_file = val;
      else if (operand_is (name, "of"))
	output_file = val;
      else if (operand_is (name, "conv"))
	conversions_mask |= parse_symbols (val, conversions,
					   N_("invalid conversion"));
      else if (operand_is (name, "iflag"))
	input_flags |= parse_symbols (val, flags,
				      N_("invalid input flag"));
      else if (operand_is (name, "oflag"))
	output_flags |= parse_symbols (val, flags,
				       N_("invalid output flag"));
      else if (operand_is (name, "status"))
	status_flags |= parse_symbols (val, statuses,
				       N_("invalid status flag"));
      else
	{
	  bool invalid = false;
	  uintmax_t n = parse_integer (val, &invalid);

	  if (operand_is (name, "ibs"))
	    {
	      invalid |= ! (0 < n && n <= MAX_BLOCKSIZE (INPUT_BLOCK_SLOP));
	      input_blocksize = n;
	    }
	  else if (operand_is (name, "obs"))
	    {
	      invalid |= ! (0 < n && n <= MAX_BLOCKSIZE (OUTPUT_BLOCK_SLOP));
	      output_blocksize = n;
	    }
	  else if (operand_is (name, "bs"))
	    {
	      invalid |= ! (0 < n && n <= MAX_BLOCKSIZE (INPUT_BLOCK_SLOP));
	      blocksize = n;
	    }
	  else if (operand_is (name, "cbs"))
	    {
	      invalid |= ! (0 < n && n <= SIZE_MAX);
	      conversion_blocksize = n;
	    }
	  else if (operand_is (name, "skip"))
	    skip_records = n;
	  else if (operand_is (name, "seek"))
	    seek_records = n;
	  else if (operand_is (name, "count"))
	    max_records = n;
	  else
	    {
	      error (0, 0, _("unrecognized operand %s"), quote (name));
	      usage (EXIT_FAILURE);
	    }

	  if (invalid)
	    error (EXIT_FAILURE, 0, _("invalid number %s"), quote (val));
	}
    }

  if (blocksize)
    input_blocksize = output_blocksize = blocksize;
  else
    {
      /* POSIX says dd aggregates short reads into
	 output_blocksize if bs= is not specified.  */
      conversions_mask |= C_TWOBUFS;
    }

  if (input_blocksize == 0)
    input_blocksize = DEFAULT_BLOCKSIZE;
  if (output_blocksize == 0)
    output_blocksize = DEFAULT_BLOCKSIZE;
  if (conversion_blocksize == 0)
    conversions_mask &= ~(C_BLOCK | C_UNBLOCK);

  if (input_flags & (O_DSYNC | O_SYNC))
    input_flags |= O_RSYNC;

  if (output_flags & O_FULLBLOCK)
    {
      error (0, 0, "%s: %s", _("invalid output flag"), "'fullblock'");
      usage (EXIT_FAILURE);
    }
  iread_fnc = ((input_flags & O_FULLBLOCK)
	       ? iread_fullblock
	       : iread);
  input_flags &= ~O_FULLBLOCK;

  if (multiple_bits_set (conversions_mask & (C_ASCII | C_EBCDIC | C_IBM)))
    error (EXIT_FAILURE, 0, _("cannot combine any two of {ascii,ebcdic,ibm}"));
  if (multiple_bits_set (conversions_mask & (C_BLOCK | C_UNBLOCK)))
    error (EXIT_FAILURE, 0, _("cannot combine block and unblock"));
  if (multiple_bits_set (conversions_mask & (C_LCASE | C_UCASE)))
    error (EXIT_FAILURE, 0, _("cannot combine lcase and ucase"));
  if (multiple_bits_set (conversions_mask & (C_EXCL | C_NOCREAT)))
    error (EXIT_FAILURE, 0, _("cannot combine excl and nocreat"));
}

/* Fix up translation table. */

static void
apply_translations (void)
{
  int i;

  if (conversions_mask & C_ASCII)
    translate_charset (ebcdic_to_ascii);

  if (conversions_mask & C_UCASE)
    {
      for (i = 0; i < 256; i++)
	trans_table[i] = toupper (trans_table[i]);
      translation_needed = true;
    }
  else if (conversions_mask & C_LCASE)
    {
      for (i = 0; i < 256; i++)
	trans_table[i] = tolower (trans_table[i]);
      translation_needed = true;
    }

  if (conversions_mask & C_EBCDIC)
    {
      translate_charset (ascii_to_ebcdic);
      newline_character = ascii_to_ebcdic['\n'];
      space_character = ascii_to_ebcdic[' '];
    }
  else if (conversions_mask & C_IBM)
    {
      translate_charset (ascii_to_ibm);
      newline_character = ascii_to_ibm['\n'];
      space_character = ascii_to_ibm[' '];
    }
}

/* Apply the character-set translations specified by the user
   to the NREAD bytes in BUF.  */

static void
translate_buffer (char *buf, size_t nread)
{
  char *cp;
  size_t i;

  for (i = nread, cp = buf; i; i--, cp++)
    *cp = trans_table[to_uchar (*cp)];
}

/* If true, the last char from the previous call to `swab_buffer'
   is saved in `saved_char'.  */
static bool char_is_saved = false;

/* Odd char from previous call.  */
static char saved_char;

/* Swap NREAD bytes in BUF, plus possibly an initial char from the
   previous call.  If NREAD is odd, save the last char for the
   next call.   Return the new start of the BUF buffer.  */

static char *
swab_buffer (char *buf, size_t *nread)
{
  char *bufstart = buf;
  char *cp;
  size_t i;

  /* Is a char left from last time?  */
  if (char_is_saved)
    {
      *--bufstart = saved_char;
      (*nread)++;
      char_is_saved = false;
    }

  if (*nread & 1)
    {
      /* An odd number of chars are in the buffer.  */
      saved_char = bufstart[--*nread];
      char_is_saved = true;
    }

  /* Do the byte-swapping by moving every second character two
     positions toward the end, working from the end of the buffer
     toward the beginning.  This way we only move half of the data.  */

  cp = bufstart + *nread;	/* Start one char past the last.  */
  for (i = *nread / 2; i; i--, cp -= 2)
    *cp = *(cp - 2);

  return ++bufstart;
}

/* Add OFFSET to the input offset, setting the overflow flag if
   necessary.  */

static void
advance_input_offset (uintmax_t offset)
{
  input_offset += offset;
  if (input_offset < offset)
    input_offset_overflow = true;
}

/* This is a wrapper for lseek.  It detects and warns about a kernel
   bug that makes lseek a no-op for tape devices, even though the kernel
   lseek return value suggests that the function succeeded.

   The parameters are the same as those of the lseek function, but
   with the addition of FILENAME, the name of the file associated with
   descriptor FDESC.  The file name is used solely in the warning that's
   printed when the bug is detected.  Return the same value that lseek
   would have returned, but when the lseek bug is detected, return -1
   to indicate that lseek failed.

   The offending behavior has been confirmed with an Exabyte SCSI tape
   drive accessed via /dev/nst0 on both Linux 2.2.17 and 2.4.16 kernels.  */

#ifdef __linux__

# include <sys/mtio.h>

# define MT_SAME_POSITION(P, Q) \
   ((P).mt_resid == (Q).mt_resid \
    && (P).mt_fileno == (Q).mt_fileno \
    && (P).mt_blkno == (Q).mt_blkno)

static off_t
skip_via_lseek (char const *filename, int fdesc, off_t offset, int whence)
{
  struct mtget s1;
  struct mtget s2;
  bool got_original_tape_position = (ioctl (fdesc, MTIOCGET, &s1) == 0);
  /* known bad device type */
  /* && s.mt_type == MT_ISSCSI2 */

  off_t new_position = lseek (fdesc, offset, whence);
  if (0 <= new_position
      && got_original_tape_position
      && ioctl (fdesc, MTIOCGET, &s2) == 0
      && MT_SAME_POSITION (s1, s2))
    {
      error (0, 0, _("warning: working around lseek kernel bug for file (%s)\n\
  of mt_type=0x%0lx -- see <sys/mtio.h> for the list of types"),
	     filename, s2.mt_type);
      errno = 0;
      new_position = -1;
    }

  return new_position;
}
#else
# define skip_via_lseek(Filename, Fd, Offset, Whence) lseek (Fd, Offset, Whence)
#endif

/* Throw away RECORDS blocks of BLOCKSIZE bytes on file descriptor FDESC,
   which is open with read permission for FILE.  Store up to BLOCKSIZE
   bytes of the data at a time in BUF, if necessary.  RECORDS must be
   nonzero.  If fdesc is STDIN_FILENO, advance the input offset.
   Return the number of records remaining, i.e., that were not skipped
   because EOF was reached.  */

static uintmax_t
skip (int fdesc, char const *file, uintmax_t records, size_t blocksize,
      char *buf)
{
  uintmax_t offset = records * blocksize;

  /* Try lseek and if an error indicates it was an inappropriate operation --
     or if the file offset is not representable as an off_t --
     fall back on using read.  */

  errno = 0;
  if (records <= OFF_T_MAX / blocksize
      && 0 <= skip_via_lseek (file, fdesc, offset, SEEK_CUR))
    {
      if (fdesc == STDIN_FILENO)
        {
	   struct stat st;
	   if (fstat (STDIN_FILENO, &st) != 0)
	     error (EXIT_FAILURE, errno, _("cannot fstat %s"), quote (file));
	   if (S_ISREG (st.st_mode) && st.st_size < (input_offset + offset))
	     {
	       /* When skipping past EOF, return the number of _full_ blocks
		* that are not skipped, and set offset to EOF, so the caller
		* can determine the requested skip was not satisfied.  */
	       records = ( offset - st.st_size ) / blocksize;
	       offset = st.st_size - input_offset;
	     }
	   else
	     records = 0;
	   advance_input_offset (offset);
        }
      else
        records = 0;
      return records;
    }
  else
    {
      int lseek_errno = errno;
      off_t soffset;

      /* The seek request may have failed above if it was too big
         (> device size, > max file size, etc.)
         Or it may not have been done at all (> OFF_T_MAX).
         Therefore try to seek to the end of the file,
         to avoid redundant reading.  */
      if ((soffset = skip_via_lseek (file, fdesc, 0, SEEK_END)) >= 0)
	{
	  /* File is seekable, and we're at the end of it, and
	     size <= OFF_T_MAX. So there's no point using read to advance.  */

	  if (!lseek_errno)
	    {
	      /* The original seek was not attempted as offset > OFF_T_MAX.
		 We should error for write as can't get to the desired
		 location, even if OFF_T_MAX < max file size.
		 For read we're not going to read any data anyway,
		 so we should error for consistency.
		 It would be nice to not error for /dev/{zero,null}
		 for any offset, but that's not a significant issue.  */
	      lseek_errno = EOVERFLOW;
	    }

	  if (fdesc == STDIN_FILENO)
	    error (0, lseek_errno, _("%s: cannot skip"), quote (file));
	  else
	    error (0, lseek_errno, _("%s: cannot seek"), quote (file));
	  /* If the file has a specific size and we've asked
	     to skip/seek beyond the max allowable, then quit.  */
	  quit (EXIT_FAILURE);
	}
      /* else file_size && offset > OFF_T_MAX or file ! seekable */

      do
	{
	  ssize_t nread = iread_fnc (fdesc, buf, blocksize);
	  if (nread < 0)
	    {
	      if (fdesc == STDIN_FILENO)
		{
		  error (0, errno, _("reading %s"), quote (file));
		  if (conversions_mask & C_NOERROR)
		    {
		      print_stats ();
		      continue;
		    }
		}
	      else
		error (0, lseek_errno, _("%s: cannot seek"), quote (file));
	      quit (EXIT_FAILURE);
	    }

	  if (nread == 0)
	    break;
	  if (fdesc == STDIN_FILENO)
	    advance_input_offset (nread);
	}
      while (--records != 0);

      return records;
    }
}

/* Advance the input by NBYTES if possible, after a read error.
   The input file offset may or may not have advanced after the failed
   read; adjust it to point just after the bad record regardless.
   Return true if successful, or if the input is already known to not
   be seekable.  */

static bool
advance_input_after_read_error (size_t nbytes)
{
  if (! input_seekable)
    {
      if (input_seek_errno == ESPIPE)
	return true;
      errno = input_seek_errno;
    }
  else
    {
      off_t offset;
      advance_input_offset (nbytes);
      input_offset_overflow |= (OFF_T_MAX < input_offset);
      if (input_offset_overflow)
	{
	  error (0, 0, _("offset overflow while reading file %s"),
		 quote (input_file));
	  return false;
	}
      offset = lseek (STDIN_FILENO, 0, SEEK_CUR);
      if (0 <= offset)
	{
	  off_t diff;
	  if (offset == input_offset)
	    return true;
	  diff = input_offset - offset;
	  if (! (0 <= diff && diff <= nbytes))
	    error (0, 0, _("warning: invalid file offset after failed read"));
	  if (0 <= skip_via_lseek (input_file, STDIN_FILENO, diff, SEEK_CUR))
	    return true;
	  if (errno == 0)
	    error (0, 0, _("cannot work around kernel bug after all"));
	}
    }

  error (0, errno, _("%s: cannot seek"), quote (input_file));
  return false;
}

/* Copy NREAD bytes of BUF, with no conversions.  */

static void
copy_simple (char const *buf, size_t nread)
{
  const char *start = buf;	/* First uncopied char in BUF.  */

  do
    {
      size_t nfree = MIN (nread, output_blocksize - oc);

      memcpy (obuf + oc, start, nfree);

      nread -= nfree;		/* Update the number of bytes left to copy. */
      start += nfree;
      oc += nfree;
      if (oc >= output_blocksize)
	write_output ();
    }
  while (nread != 0);
}

/* Copy NREAD bytes of BUF, doing conv=block
   (pad newline-terminated records to `conversion_blocksize',
   replacing the newline with trailing spaces).  */

static void
copy_with_block (char const *buf, size_t nread)
{
  size_t i;

  for (i = nread; i; i--, buf++)
    {
      if (*buf == newline_character)
	{
	  if (col < conversion_blocksize)
	    {
	      size_t j;
	      for (j = col; j < conversion_blocksize; j++)
		output_char (space_character);
	    }
	  col = 0;
	}
      else
	{
	  if (col == conversion_blocksize)
	    r_truncate++;
	  else if (col < conversion_blocksize)
	    output_char (*buf);
	  col++;
	}
    }
}

/* Copy NREAD bytes of BUF, doing conv=unblock
   (replace trailing spaces in `conversion_blocksize'-sized records
   with a newline).  */

static void
copy_with_unblock (char const *buf, size_t nread)
{
  size_t i;
  char c;
  static size_t pending_spaces = 0;

  for (i = 0; i < nread; i++)
    {
      c = buf[i];

      if (col++ >= conversion_blocksize)
	{
	  col = pending_spaces = 0; /* Wipe out any pending spaces.  */
	  i--;			/* Push the char back; get it later. */
	  output_char (newline_character);
	}
      else if (c == space_character)
	pending_spaces++;
      else
	{
	  /* `c' is the character after a run of spaces that were not
	     at the end of the conversion buffer.  Output them.  */
	  while (pending_spaces)
	    {
	      output_char (space_character);
	      --pending_spaces;
	    }
	  output_char (c);
	}
    }
}

/* Set the file descriptor flags for FD that correspond to the nonzero bits
   in ADD_FLAGS.  The file's name is NAME.  */

static void
set_fd_flags (int fd, int add_flags, char const *name)
{
  /* Ignore file creation flags that are no-ops on file descriptors.  */
  add_flags &= ~ (O_NOCTTY | O_NOFOLLOW);

  if (add_flags)
    {
      int old_flags = fcntl (fd, F_GETFL);
      int new_flags = old_flags | add_flags;
      bool ok = true;
      if (old_flags < 0)
	ok = false;
      else if (old_flags != new_flags)
	{
	  if (new_flags & (O_DIRECTORY | O_NOLINKS))
	    {
	      /* NEW_FLAGS contains at least one file creation flag that
		 requires some checking of the open file descriptor.  */
	      struct stat st;
	      if (fstat (fd, &st) != 0)
		ok = false;
	      else if ((new_flags & O_DIRECTORY) && ! S_ISDIR (st.st_mode))
		{
		  errno = ENOTDIR;
		  ok = false;
		}
	      else if ((new_flags & O_NOLINKS) && 1 < st.st_nlink)
		{
		  errno = EMLINK;
		  ok = false;
		}
	      new_flags &= ~ (O_DIRECTORY | O_NOLINKS);
	    }

	  if (ok && old_flags != new_flags
	      && fcntl (fd, F_SETFL, new_flags) == -1)
	    ok = false;
	}

      if (!ok)
	error (EXIT_FAILURE, errno, _("setting flags for %s"), quote (name));
    }
}

/* The main loop.  */

static int
dd_copy (void)
{
  char *ibuf, *bufstart;	/* Input buffer. */
  /* These are declared static so that even though we don't free the
     buffers, valgrind will recognize that there is no "real" leak.  */
  static char *real_buf;	/* real buffer address before alignment */
  static char *real_obuf;
  ssize_t nread;		/* Bytes read in the current block.  */

  /* If nonzero, then the previously read block was partial and
     PARTREAD was its size.  */
  size_t partread = 0;

  int exit_status = EXIT_SUCCESS;
  size_t n_bytes_read;

  /* Leave at least one extra byte at the beginning and end of `ibuf'
     for conv=swab, but keep the buffer address even.  But some peculiar
     device drivers work only with word-aligned buffers, so leave an
     extra two bytes.  */

  /* Some devices require alignment on a sector or page boundary
     (e.g. character disk devices).  Align the input buffer to a
     page boundary to cover all bases.  Note that due to the swab
     algorithm, we must have at least one byte in the page before
     the input buffer;  thus we allocate 2 pages of slop in the
     real buffer.  8k above the blocksize shouldn't bother anyone.

     The page alignment is necessary on any Linux kernel that supports
     either the SGI raw I/O patch or Steven Tweedies raw I/O patch.
     It is necessary when accessing raw (i.e. character special) disk
     devices on Unixware or other SVR4-derived system.  */

  real_buf = xmalloc (input_blocksize + INPUT_BLOCK_SLOP);
  ibuf = real_buf;
  ibuf += SWAB_ALIGN_OFFSET;	/* allow space for swab */

  ibuf = ptr_align (ibuf, page_size);

  if (conversions_mask & C_TWOBUFS)
    {
      /* Page-align the output buffer, too.  */
      real_obuf = xmalloc (output_blocksize + OUTPUT_BLOCK_SLOP);
      obuf = ptr_align (real_obuf, page_size);
    }
  else
    {
      real_obuf = NULL;
      obuf = ibuf;
    }

  if (skip_records != 0)
    {
      uintmax_t us_bytes = input_offset + (skip_records * input_blocksize);
      uintmax_t us_blocks = skip (STDIN_FILENO, input_file,
				  skip_records, input_blocksize, ibuf);
      us_bytes -= input_offset;

      /* POSIX doesn't say what to do when dd detects it has been
	 asked to skip past EOF, so I assume it's non-fatal.
	 There are 3 reasons why there might be unskipped blocks/bytes:
	     1. file is too small
	     2. pipe has not enough data
	     3. short reads  */
      if (us_blocks || (!input_offset_overflow && us_bytes))
	{
	  error (0, 0,
		 _("%s: cannot skip to specified offset"), quote (input_file));
	}
    }

  if (seek_records != 0)
    {
      uintmax_t write_records = skip (STDOUT_FILENO, output_file,
				      seek_records, output_blocksize, obuf);

      if (write_records != 0)
	{
	  memset (obuf, 0, output_blocksize);

	  do
	    if (iwrite (STDOUT_FILENO, obuf, output_blocksize)
		!= output_blocksize)
	      {
		error (0, errno, _("writing to %s"), quote (output_file));
		quit (EXIT_FAILURE);
	      }
	  while (--write_records != 0);
	}
    }

  if (max_records == 0)
    return exit_status;

  while (1)
    {
      if (r_partial + r_full >= max_records)
	break;

      /* Zero the buffer before reading, so that if we get a read error,
	 whatever data we are able to read is followed by zeros.
	 This minimizes data loss. */
      if ((conversions_mask & C_SYNC) && (conversions_mask & C_NOERROR))
	memset (ibuf,
		(conversions_mask & (C_BLOCK | C_UNBLOCK)) ? ' ' : '\0',
		input_blocksize);

      nread = iread_fnc (STDIN_FILENO, ibuf, input_blocksize);

      if (nread == 0)
	break;			/* EOF.  */

      if (nread < 0)
	{
	  error (0, errno, _("reading %s"), quote (input_file));
	  if (conversions_mask & C_NOERROR)
	    {
	      print_stats ();
	      /* Seek past the bad block if possible. */
	      if (!advance_input_after_read_error (input_blocksize - partread))
		{
		  exit_status = EXIT_FAILURE;

		  /* Suppress duplicate diagnostics.  */
		  input_seekable = false;
		  input_seek_errno = ESPIPE;
		}
	      if ((conversions_mask & C_SYNC) && !partread)
		/* Replace the missing input with null bytes and
		   proceed normally.  */
		nread = 0;
	      else
		continue;
	    }
	  else
	    {
	      /* Write any partial block. */
	      exit_status = EXIT_FAILURE;
	      break;
	    }
	}

      n_bytes_read = nread;
      advance_input_offset (nread);

      if (n_bytes_read < input_blocksize)
	{
	  r_partial++;
	  partread = n_bytes_read;
	  if (conversions_mask & C_SYNC)
	    {
	      if (!(conversions_mask & C_NOERROR))
		/* If C_NOERROR, we zeroed the block before reading. */
		memset (ibuf + n_bytes_read,
			(conversions_mask & (C_BLOCK | C_UNBLOCK)) ? ' ' : '\0',
			input_blocksize - n_bytes_read);
	      n_bytes_read = input_blocksize;
	    }
	}
      else
	{
	  r_full++;
	  partread = 0;
	}

      if (ibuf == obuf)		/* If not C_TWOBUFS. */
	{
	  size_t nwritten = iwrite (STDOUT_FILENO, obuf, n_bytes_read);
	  w_bytes += nwritten;
	  if (nwritten != n_bytes_read)
	    {
	      error (0, errno, _("writing %s"), quote (output_file));
	      return EXIT_FAILURE;
	    }
	  else if (n_bytes_read == input_blocksize)
	    w_full++;
	  else
	    w_partial++;
	  continue;
	}

      /* Do any translations on the whole buffer at once.  */

      if (translation_needed)
	translate_buffer (ibuf, n_bytes_read);

      if (conversions_mask & C_SWAB)
	bufstart = swab_buffer (ibuf, &n_bytes_read);
      else
	bufstart = ibuf;

      if (conversions_mask & C_BLOCK)
        copy_with_block (bufstart, n_bytes_read);
      else if (conversions_mask & C_UNBLOCK)
	copy_with_unblock (bufstart, n_bytes_read);
      else
	copy_simple (bufstart, n_bytes_read);
    }

  /* If we have a char left as a result of conv=swab, output it.  */
  if (char_is_saved)
    {
      if (conversions_mask & C_BLOCK)
        copy_with_block (&saved_char, 1);
      else if (conversions_mask & C_UNBLOCK)
	copy_with_unblock (&saved_char, 1);
      else
	output_char (saved_char);
    }

  if ((conversions_mask & C_BLOCK) && col > 0)
    {
      /* If the final input line didn't end with a '\n', pad
	 the output block to `conversion_blocksize' chars.  */
      size_t i;
      for (i = col; i < conversion_blocksize; i++)
	output_char (space_character);
    }

  if ((conversions_mask & C_UNBLOCK) && col == conversion_blocksize)
    /* Add a final '\n' if there are exactly `conversion_blocksize'
       characters in the final record. */
    output_char (newline_character);

  /* Write out the last block. */
  if (oc != 0)
    {
      size_t nwritten = iwrite (STDOUT_FILENO, obuf, oc);
      w_bytes += nwritten;
      if (nwritten != 0)
	w_partial++;
      if (nwritten != oc)
	{
	  error (0, errno, _("writing %s"), quote (output_file));
	  return EXIT_FAILURE;
	}
    }

  if ((conversions_mask & C_FDATASYNC) && fdatasync (STDOUT_FILENO) != 0)
    {
      if (errno != ENOSYS && errno != EINVAL)
	{
	  error (0, errno, _("fdatasync failed for %s"), quote (output_file));
	  exit_status = EXIT_FAILURE;
	}
      conversions_mask |= C_FSYNC;
    }

  if (conversions_mask & C_FSYNC)
    while (fsync (STDOUT_FILENO) != 0)
      if (errno != EINTR)
	{
	  error (0, errno, _("fsync failed for %s"), quote (output_file));
	  return EXIT_FAILURE;
	}

  return exit_status;
}

int
main (int argc, char **argv)
{
  int i;
  int exit_status;
  off_t offset;

  initialize_main (&argc, &argv);
  set_program_name (argv[0]);
  setlocale (LC_ALL, "");
  bindtextdomain (PACKAGE, LOCALEDIR);
  textdomain (PACKAGE);

  /* Arrange to close stdout if parse_long_options exits.  */
  atexit (maybe_close_stdout);

  page_size = getpagesize ();

  parse_long_options (argc, argv, PROGRAM_NAME, PACKAGE, Version,
		      usage, AUTHORS, (char const *) NULL);
  close_stdout_required = false;

  if (getopt_long (argc, argv, "", NULL, NULL) != -1)
    usage (EXIT_FAILURE);

  /* Initialize translation table to identity translation. */
  for (i = 0; i < 256; i++)
    trans_table[i] = i;

  /* Decode arguments. */
  scanargs (argc, argv);

  apply_translations ();

  if (input_file == NULL)
    {
      input_file = _("standard input");
      set_fd_flags (STDIN_FILENO, input_flags, input_file);
    }
  else
    {
      if (fd_reopen (STDIN_FILENO, input_file, O_RDONLY | input_flags, 0) < 0)
	error (EXIT_FAILURE, errno, _("opening %s"), quote (input_file));
    }

  offset = lseek (STDIN_FILENO, 0, SEEK_CUR);
  input_seekable = (0 <= offset);
  input_offset = MAX(0, offset);
  input_seek_errno = errno;

  if (output_file == NULL)
    {
      output_file = _("standard output");
      set_fd_flags (STDOUT_FILENO, output_flags, output_file);
    }
  else
    {
      mode_t perms = S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP | S_IROTH | S_IWOTH;
      int opts
	= (output_flags
	   | (conversions_mask & C_NOCREAT ? 0 : O_CREAT)
	   | (conversions_mask & C_EXCL ? O_EXCL : 0)
	   | (seek_records || (conversions_mask & C_NOTRUNC) ? 0 : O_TRUNC));

      /* Open the output file with *read* access only if we might
	 need to read to satisfy a `seek=' request.  If we can't read
	 the file, go ahead with write-only access; it might work.  */
      if ((! seek_records
	   || fd_reopen (STDOUT_FILENO, output_file, O_RDWR | opts, perms) < 0)
	  && (fd_reopen (STDOUT_FILENO, output_file, O_WRONLY | opts, perms)
	      < 0))
	error (EXIT_FAILURE, errno, _("opening %s"), quote (output_file));

#if HAVE_FTRUNCATE
      if (seek_records != 0 && !(conversions_mask & C_NOTRUNC))
	{
	  uintmax_t size = seek_records * output_blocksize;
	  unsigned long int obs = output_blocksize;

	  if (OFF_T_MAX / output_blocksize < seek_records)
	    error (EXIT_FAILURE, 0,
		   _("offset too large: "
		     "cannot truncate to a length of seek=%"PRIuMAX""
		     " (%lu-byte) blocks"),
		   seek_records, obs);

	  if (ftruncate (STDOUT_FILENO, size) != 0)
	    {
	      /* Complain only when ftruncate fails on a regular file, a
		 directory, or a shared memory object, as POSIX 1003.1-2004
		 specifies ftruncate's behavior only for these file types.
		 For example, do not complain when Linux kernel 2.4 ftruncate
		 fails on /dev/fd0.  */
	      int ftruncate_errno = errno;
	      struct stat stdout_stat;
	      if (fstat (STDOUT_FILENO, &stdout_stat) != 0)
		error (EXIT_FAILURE, errno, _("cannot fstat %s"),
		       quote (output_file));
	      if (S_ISREG (stdout_stat.st_mode)
		  || S_ISDIR (stdout_stat.st_mode)
		  || S_TYPEISSHM (&stdout_stat))
		error (EXIT_FAILURE, ftruncate_errno,
		       _("truncating at %"PRIuMAX" bytes in output file %s"),
		       size, quote (output_file));
	    }
	}
#endif
    }

  install_signal_handlers ();

  start_time = gethrxtime ();

  exit_status = dd_copy ();

  quit (exit_status);
}