aboutsummaryrefslogtreecommitdiff
path: root/src/util/disk.c
blob: 2d5e353c810eb67af2689669a78e46f7358ea629 (plain) (blame)
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
/*
     This file is part of GNUnet.
     Copyright (C) 2001--2013, 2016, 2018 GNUnet e.V.

     GNUnet is free software: you can redistribute it and/or modify it
     under the terms of the GNU Affero General Public License as published
     by the Free Software Foundation, either version 3 of the License,
     or (at your option) any later version.

     GNUnet 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
     Affero General Public License for more details.

     You should have received a copy of the GNU Affero General Public License
     along with this program.  If not, see <http://www.gnu.org/licenses/>.

     SPDX-License-Identifier: AGPL3.0-or-later
 */
/**
 * @file util/disk.c
 * @brief disk IO convenience methods
 * @author Christian Grothoff
 * @author Nils Durner
 */
#include "platform.h"
#include "disk.h"
#include "gnunet_strings_lib.h"
#include "gnunet_disk_lib.h"

#define LOG(kind, ...) GNUNET_log_from (kind, "util-disk", __VA_ARGS__)

#define LOG_STRERROR(kind, syscall) \
  GNUNET_log_from_strerror (kind, "util-disk", syscall)

#define LOG_STRERROR_FILE(kind, syscall, filename) \
  GNUNET_log_from_strerror_file (kind, "util-disk", syscall, filename)

/**
 * Block size for IO for copying files.
 */
#define COPY_BLK_SIZE 65536

#include <sys/types.h>
#if HAVE_SYS_VFS_H
#include <sys/vfs.h>
#endif
#if HAVE_SYS_PARAM_H
#include <sys/param.h>
#endif
#if HAVE_SYS_MOUNT_H
#include <sys/mount.h>
#endif
#if HAVE_SYS_STATVFS_H
#include <sys/statvfs.h>
#endif

#ifndef S_ISLNK
#define _IFMT 0170000 /* type of file */
#define _IFLNK 0120000 /* symbolic link */
#define S_ISLNK(m) (((m) & _IFMT) == _IFLNK)
#endif


/**
 * Handle used to manage a pipe.
 */
struct GNUNET_DISK_PipeHandle
{
  /**
   * File descriptors for the pipe.
   * One or both of them could be NULL.
   */
  struct GNUNET_DISK_FileHandle *fd[2];
};


/**
 * Closure for the recursion to determine the file size
 * of a directory.
 */
struct GetFileSizeData
{
  /**
   * Set to the total file size.
   */
  uint64_t total;

  /**
   * GNUNET_YES if symbolic links should be included.
   */
  int include_sym_links;

  /**
   * GNUNET_YES if mode is file-only (return total == -1 for directories).
   */
  int single_file_mode;
};


/**
 * Translate GNUnet-internal permission bitmap to UNIX file
 * access permission bitmap.
 *
 * @param perm file permissions, GNUnet style
 * @return file permissions, UNIX style
 */
static int
translate_unix_perms (enum GNUNET_DISK_AccessPermissions perm)
{
  int mode;

  mode = 0;
  if (perm & GNUNET_DISK_PERM_USER_READ)
    mode |= S_IRUSR;
  if (perm & GNUNET_DISK_PERM_USER_WRITE)
    mode |= S_IWUSR;
  if (perm & GNUNET_DISK_PERM_USER_EXEC)
    mode |= S_IXUSR;
  if (perm & GNUNET_DISK_PERM_GROUP_READ)
    mode |= S_IRGRP;
  if (perm & GNUNET_DISK_PERM_GROUP_WRITE)
    mode |= S_IWGRP;
  if (perm & GNUNET_DISK_PERM_GROUP_EXEC)
    mode |= S_IXGRP;
  if (perm & GNUNET_DISK_PERM_OTHER_READ)
    mode |= S_IROTH;
  if (perm & GNUNET_DISK_PERM_OTHER_WRITE)
    mode |= S_IWOTH;
  if (perm & GNUNET_DISK_PERM_OTHER_EXEC)
    mode |= S_IXOTH;

  return mode;
}


/**
 * Iterate over all files in the given directory and
 * accumulate their size.
 *
 * @param cls closure of type `struct GetFileSizeData`
 * @param fn current filename we are looking at
 * @return #GNUNET_SYSERR on serious errors, otherwise #GNUNET_OK
 */
static int
getSizeRec (void *cls, const char *fn)
{
  struct GetFileSizeData *gfsd = cls;

#if defined(HAVE_STAT64) && \
  ! (defined(_FILE_OFFSET_BITS) && _FILE_OFFSET_BITS == 64)
  struct stat64 buf;

  if (0 != stat64 (fn, &buf))
  {
    LOG_STRERROR_FILE (GNUNET_ERROR_TYPE_DEBUG, "stat64", fn);
    return GNUNET_SYSERR;
  }
#else
  struct stat buf;

  if (0 != stat (fn, &buf))
  {
    LOG_STRERROR_FILE (GNUNET_ERROR_TYPE_DEBUG, "stat", fn);
    return GNUNET_SYSERR;
  }
#endif
  if ((S_ISDIR (buf.st_mode)) && (gfsd->single_file_mode == GNUNET_YES))
  {
    errno = EISDIR;
    return GNUNET_SYSERR;
  }
  if ((! S_ISLNK (buf.st_mode)) || (gfsd->include_sym_links == GNUNET_YES))
    gfsd->total += buf.st_size;
  if ((S_ISDIR (buf.st_mode)) && (0 == access (fn, X_OK)) &&
      ((! S_ISLNK (buf.st_mode)) || (gfsd->include_sym_links == GNUNET_YES)))
  {
    if (GNUNET_SYSERR == GNUNET_DISK_directory_scan (fn, &getSizeRec, gfsd))
      return GNUNET_SYSERR;
  }
  return GNUNET_OK;
}


/**
 * Checks whether a handle is invalid
 *
 * @param h handle to check
 * @return #GNUNET_YES if invalid, #GNUNET_NO if valid
 */
int
GNUNET_DISK_handle_invalid (const struct GNUNET_DISK_FileHandle *h)
{
  return ((! h) || (h->fd == -1)) ? GNUNET_YES : GNUNET_NO;
}


/**
 * Get the size of an open file.
 *
 * @param fh open file handle
 * @param size where to write size of the file
 * @return #GNUNET_OK on success, #GNUNET_SYSERR on error
 */
int
GNUNET_DISK_file_handle_size (struct GNUNET_DISK_FileHandle *fh, off_t *size)
{
  struct stat sbuf;

  if (0 != fstat (fh->fd, &sbuf))
    return GNUNET_SYSERR;
  *size = sbuf.st_size;
  return GNUNET_OK;
}


/**
 * Move the read/write pointer in a file
 *
 * @param h handle of an open file
 * @param offset position to move to
 * @param whence specification to which position the offset parameter relates to
 * @return the new position on success, #GNUNET_SYSERR otherwise
 */
off_t
GNUNET_DISK_file_seek (const struct GNUNET_DISK_FileHandle *h,
                       off_t offset,
                       enum GNUNET_DISK_Seek whence)
{
  if (h == NULL)
  {
    errno = EINVAL;
    return GNUNET_SYSERR;
  }

  static int t[] = { SEEK_SET, SEEK_CUR, SEEK_END };

  return lseek (h->fd, offset, t[whence]);
}


/**
 * Get the size of the file (or directory) of the given file (in
 * bytes).
 *
 * @param filename name of the file or directory
 * @param size set to the size of the file (or,
 *             in the case of directories, the sum
 *             of all sizes of files in the directory)
 * @param include_symbolic_links should symbolic links be
 *        included?
 * @param single_file_mode #GNUNET_YES to only get size of one file
 *        and return #GNUNET_SYSERR for directories.
 * @return #GNUNET_SYSERR on error, #GNUNET_OK on success
 */
int
GNUNET_DISK_file_size (const char *filename,
                       uint64_t *size,
                       int include_symbolic_links,
                       int single_file_mode)
{
  struct GetFileSizeData gfsd;
  int ret;

  GNUNET_assert (size != NULL);
  gfsd.total = 0;
  gfsd.include_sym_links = include_symbolic_links;
  gfsd.single_file_mode = single_file_mode;
  ret = getSizeRec (&gfsd, filename);
  *size = gfsd.total;
  return ret;
}


/**
 * Obtain some unique identifiers for the given file
 * that can be used to identify it in the local system.
 * This function is used between GNUnet processes to
 * quickly check if two files with the same absolute path
 * are actually identical.  The two processes represent
 * the same peer but may communicate over the network
 * (and the file may be on an NFS volume).  This function
 * may not be supported on all operating systems.
 *
 * @param filename name of the file
 * @param dev set to the device ID
 * @param ino set to the inode ID
 * @return #GNUNET_OK on success
 */
int
GNUNET_DISK_file_get_identifiers (const char *filename,
                                  uint64_t *dev,
                                  uint64_t *ino)
{
#if HAVE_STAT
  {
    struct stat sbuf;

    if (0 != stat (filename, &sbuf))
    {
      return GNUNET_SYSERR;
    }
    *ino = (uint64_t) sbuf.st_ino;
  }
#else
  *ino = 0;
#endif
#if HAVE_STATVFS
  {
    struct statvfs fbuf;

    if (0 != statvfs (filename, &fbuf))
    {
      return GNUNET_SYSERR;
    }
    *dev = (uint64_t) fbuf.f_fsid;
  }
#elif HAVE_STATFS
  {
    struct statfs fbuf;

    if (0 != statfs (filename, &fbuf))
    {
      return GNUNET_SYSERR;
    }
    *dev =
      ((uint64_t) fbuf.f_fsid.val[0]) << 32 || ((uint64_t) fbuf.f_fsid.val[1]);
  }
#else
  *dev = 0;
#endif
  return GNUNET_OK;
}


/**
 * Create the name for a temporary file or directory from a template.
 *
 * @param t template (without XXXXX or "/tmp/")
 * @return name ready for passing to 'mktemp' or 'mkdtemp', NULL on error
 */
static char *
mktemp_name (const char *t)
{
  const char *tmpdir;
  char *tmpl;
  char *fn;

  if ((t[0] != '/') && (t[0] != '\\'))
  {
    /* FIXME: This uses system codepage on W32, not UTF-8 */
    tmpdir = getenv ("TMPDIR");
    if (NULL == tmpdir)
      tmpdir = getenv ("TMP");
    if (NULL == tmpdir)
      tmpdir = getenv ("TEMP");
    if (NULL == tmpdir)
      tmpdir = "/tmp";
    GNUNET_asprintf (&tmpl, "%s/%s%s", tmpdir, t, "XXXXXX");
  }
  else
  {
    GNUNET_asprintf (&tmpl, "%s%s", t, "XXXXXX");
  }
  fn = tmpl;
  return fn;
}


/**
 * Update POSIX permissions mask of a file on disk.  If both argumets
 * are #GNUNET_NO, the file is made world-read-write-executable (777).
 *
 * @param fn name of the file to update
 * @param require_uid_match #GNUNET_YES means 700
 * @param require_gid_match #GNUNET_YES means 770 unless @a require_uid_match is set
 */
void
GNUNET_DISK_fix_permissions (const char *fn,
                             int require_uid_match,
                             int require_gid_match)
{
  mode_t mode;

  if (GNUNET_YES == require_uid_match)
    mode = S_IRUSR | S_IWUSR | S_IXUSR;
  else if (GNUNET_YES == require_gid_match)
    mode = S_IRUSR | S_IWUSR | S_IXUSR | S_IRGRP | S_IWGRP | S_IXGRP;
  else
    mode = S_IRUSR | S_IWUSR | S_IXUSR | S_IRGRP | S_IWGRP | S_IXGRP | S_IROTH
           | S_IWOTH | S_IXOTH;
  if (0 != chmod (fn, mode))
    GNUNET_log_strerror_file (GNUNET_ERROR_TYPE_WARNING, "chmod", fn);
}


/**
 * Create an (empty) temporary directory on disk.  If the given name is not
 * an absolute path, the current 'TMPDIR' will be prepended.  In any case,
 * 6 random characters will be appended to the name to create a unique
 * filename.
 *
 * @param t component to use for the name;
 *        does NOT contain "XXXXXX" or "/tmp/".
 * @return NULL on error, otherwise name of fresh
 *         file on disk in directory for temporary files
 */
char *
GNUNET_DISK_mkdtemp (const char *t)
{
  char *fn;
  mode_t omask;

  omask = umask (S_IWGRP | S_IWOTH | S_IRGRP | S_IROTH);
  fn = mktemp_name (t);
  if (fn != mkdtemp (fn))
  {
    LOG_STRERROR_FILE (GNUNET_ERROR_TYPE_ERROR, "mkdtemp", fn);
    GNUNET_free (fn);
    umask (omask);
    return NULL;
  }
  umask (omask);
  return fn;
}


/**
 * Move a file out of the way (create a backup) by
 * renaming it to "orig.NUM~" where NUM is the smallest
 * number that is not used yet.
 *
 * @param fil name of the file to back up
 */
void
GNUNET_DISK_file_backup (const char *fil)
{
  size_t slen;
  char *target;
  unsigned int num;

  slen = strlen (fil) + 20;
  target = GNUNET_malloc (slen);
  num = 0;
  do
  {
    GNUNET_snprintf (target, slen, "%s.%u~", fil, num++);
  }
  while (0 == access (target, F_OK));
  if (0 != rename (fil, target))
    GNUNET_log_strerror_file (GNUNET_ERROR_TYPE_ERROR, "rename", fil);
  GNUNET_free (target);
}


/**
 * Create an (empty) temporary file on disk.  If the given name is not
 * an absolute path, the current 'TMPDIR' will be prepended.  In any case,
 * 6 random characters will be appended to the name to create a unique
 * filename.
 *
 * @param t component to use for the name;
 *        does NOT contain "XXXXXX" or "/tmp/".
 * @return NULL on error, otherwise name of fresh
 *         file on disk in directory for temporary files
 */
char *
GNUNET_DISK_mktemp (const char *t)
{
  int fd;
  char *fn;
  mode_t omask;

  omask = umask (S_IWGRP | S_IWOTH | S_IRGRP | S_IROTH);
  fn = mktemp_name (t);
  if (-1 == (fd = mkstemp (fn)))
  {
    LOG_STRERROR_FILE (GNUNET_ERROR_TYPE_ERROR, "mkstemp", fn);
    GNUNET_free (fn);
    umask (omask);
    return NULL;
  }
  umask (omask);
  if (0 != close (fd))
    LOG_STRERROR_FILE (GNUNET_ERROR_TYPE_WARNING, "close", fn);
  return fn;
}


/**
 * Test if @a fil is a directory and listable. Optionally, also check if the
 * directory is readable.  Will not print an error message if the directory does
 * not exist.  Will log errors if #GNUNET_SYSERR is returned (i.e., a file exists
 * with the same name).
 *
 * @param fil filename to test
 * @param is_readable #GNUNET_YES to additionally check if @a fil is readable;
 *          #GNUNET_NO to disable this check
 * @return #GNUNET_YES if yes, #GNUNET_NO if not; #GNUNET_SYSERR if it
 *           does not exist or stat'ed
 */
int
GNUNET_DISK_directory_test (const char *fil, int is_readable)
{
  struct stat filestat;
  int ret;

  ret = stat (fil, &filestat);
  if (ret != 0)
  {
    if (errno != ENOENT)
      LOG_STRERROR_FILE (GNUNET_ERROR_TYPE_WARNING, "stat", fil);
    return GNUNET_SYSERR;
  }
  if (! S_ISDIR (filestat.st_mode))
  {
    LOG (GNUNET_ERROR_TYPE_INFO,
         "A file already exits with the same name %s\n",
         fil);
    return GNUNET_NO;
  }
  if (GNUNET_YES == is_readable)
    ret = access (fil, R_OK | X_OK);
  else
    ret = access (fil, X_OK);
  if (ret < 0)
  {
    LOG_STRERROR_FILE (GNUNET_ERROR_TYPE_WARNING, "access", fil);
    return GNUNET_NO;
  }
  return GNUNET_YES;
}


/**
 * Check that fil corresponds to a filename
 * (of a file that exists and that is not a directory).
 *
 * @param fil filename to check
 * @return #GNUNET_YES if yes, #GNUNET_NO if not a file, #GNUNET_SYSERR if something
 * else (will print an error message in that case, too).
 */
int
GNUNET_DISK_file_test (const char *fil)
{
  struct stat filestat;
  int ret;
  char *rdir;

  rdir = GNUNET_STRINGS_filename_expand (fil);
  if (rdir == NULL)
    return GNUNET_SYSERR;

  ret = stat (rdir, &filestat);
  if (ret != 0)
  {
    if (errno != ENOENT)
    {
      LOG_STRERROR_FILE (GNUNET_ERROR_TYPE_WARNING, "stat", rdir);
      GNUNET_free (rdir);
      return GNUNET_SYSERR;
    }
    GNUNET_free (rdir);
    return GNUNET_NO;
  }
  if (! S_ISREG (filestat.st_mode))
  {
    GNUNET_free (rdir);
    return GNUNET_NO;
  }
  if (access (rdir, F_OK) < 0)
  {
    LOG_STRERROR_FILE (GNUNET_ERROR_TYPE_WARNING, "access", rdir);
    GNUNET_free (rdir);
    return GNUNET_SYSERR;
  }
  GNUNET_free (rdir);
  return GNUNET_YES;
}


/**
 * Implementation of "mkdir -p"
 *
 * @param dir the directory to create
 * @return #GNUNET_OK on success, #GNUNET_SYSERR on failure
 */
int
GNUNET_DISK_directory_create (const char *dir)
{
  char *rdir;
  unsigned int len;
  unsigned int pos;
  unsigned int pos2;
  int ret = GNUNET_OK;

  rdir = GNUNET_STRINGS_filename_expand (dir);
  if (rdir == NULL)
  {
    GNUNET_break (0);
    return GNUNET_SYSERR;
  }

  len = strlen (rdir);

  pos = 1; /* skip heading '/' */

  /* Check which low level directories already exist */
  pos2 = len;
  rdir[len] = DIR_SEPARATOR;
  while (pos <= pos2)
  {
    if (DIR_SEPARATOR == rdir[pos2])
    {
      rdir[pos2] = '\0';
      ret = GNUNET_DISK_directory_test (rdir, GNUNET_NO);
      if (GNUNET_NO == ret)
      {
        GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
                    "Creating directory `%s' failed",
                    rdir);
        GNUNET_free (rdir);
        return GNUNET_SYSERR;
      }
      rdir[pos2] = DIR_SEPARATOR;
      if (GNUNET_YES == ret)
      {
        pos2++;
        break;
      }
    }
    pos2--;
  }
  rdir[len] = '\0';
  if (pos < pos2)
    pos = pos2;
  /* Start creating directories */
  while (pos <= len)
  {
    if ((rdir[pos] == DIR_SEPARATOR) || (pos == len))
    {
      rdir[pos] = '\0';
      ret = GNUNET_DISK_directory_test (rdir, GNUNET_NO);
      if (GNUNET_NO == ret)
      {
        GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
                    "Creating directory `%s' failed",
                    rdir);
        GNUNET_free (rdir);
        return GNUNET_SYSERR;
      }
      if (GNUNET_SYSERR == ret)
      {
        ret = mkdir (rdir,
                     S_IRUSR | S_IWUSR | S_IXUSR | S_IRGRP | S_IXGRP | S_IROTH
                     | S_IXOTH);    /* 755 */

        if ((ret != 0) && (errno != EEXIST))
        {
          LOG_STRERROR_FILE (GNUNET_ERROR_TYPE_ERROR, "mkdir", rdir);
          GNUNET_free (rdir);
          return GNUNET_SYSERR;
        }
      }
      rdir[pos] = DIR_SEPARATOR;
    }
    pos++;
  }
  GNUNET_free (rdir);
  return GNUNET_OK;
}


/**
 * Create the directory structure for storing a file.
 *
 * @param filename name of a file in the directory
 * @returns #GNUNET_OK on success,
 *          #GNUNET_SYSERR on failure,
 *          #GNUNET_NO if the directory
 *          exists but is not writeable for us
 */
int
GNUNET_DISK_directory_create_for_file (const char *filename)
{
  char *rdir;
  size_t len;
  int ret;
  int eno;

  rdir = GNUNET_STRINGS_filename_expand (filename);
  if (NULL == rdir)
  {
    errno = EINVAL;
    return GNUNET_SYSERR;
  }
  if (0 == access (rdir, W_OK))
  {
    GNUNET_free (rdir);
    return GNUNET_OK;
  }

  len = strlen (rdir);
  while ((len > 0) && (rdir[len] != DIR_SEPARATOR))
    len--;
  rdir[len] = '\0';
  /* The empty path is invalid and in this case refers to / */
  if (0 == len)
  {
    GNUNET_free (rdir);
    rdir = GNUNET_strdup ("/");
  }
  ret = GNUNET_DISK_directory_create (rdir);
  if ((GNUNET_OK == ret) && (0 != access (rdir, W_OK)))
    ret = GNUNET_NO;
  eno = errno;
  GNUNET_free (rdir);
  errno = eno;
  return ret;
}


/**
 * Read the contents of a binary file into a buffer.
 *
 * @param h handle to an open file
 * @param result the buffer to write the result to
 * @param len the maximum number of bytes to read
 * @return the number of bytes read on success, #GNUNET_SYSERR on failure
 */
ssize_t
GNUNET_DISK_file_read (const struct GNUNET_DISK_FileHandle *h,
                       void *result,
                       size_t len)
{
  if (NULL == h)
  {
    errno = EINVAL;
    return GNUNET_SYSERR;
  }

  return read (h->fd, result, len);
}


/**
 * Read the contents of a binary file into a buffer.
 * Guarantees not to block (returns GNUNET_SYSERR and sets errno to EAGAIN
 * when no data can be read).
 *
 * @param h handle to an open file
 * @param result the buffer to write the result to
 * @param len the maximum number of bytes to read
 * @return the number of bytes read on success, #GNUNET_SYSERR on failure
 */
ssize_t
GNUNET_DISK_file_read_non_blocking (const struct GNUNET_DISK_FileHandle *h,
                                    void *result,
                                    size_t len)
{
  if (NULL == h)
  {
    errno = EINVAL;
    return GNUNET_SYSERR;
  }

  int flags;
  ssize_t ret;

  /* set to non-blocking, read, then set back */
  flags = fcntl (h->fd, F_GETFL);
  if (0 == (flags & O_NONBLOCK))
    (void) fcntl (h->fd, F_SETFL, flags | O_NONBLOCK);
  ret = read (h->fd, result, len);
  if (0 == (flags & O_NONBLOCK))
  {
    int eno = errno;
    (void) fcntl (h->fd, F_SETFL, flags);
    errno = eno;
  }
  return ret;
}


/**
 * Read the contents of a binary file into a buffer.
 *
 * @param fn file name
 * @param result the buffer to write the result to
 * @param len the maximum number of bytes to read
 * @return number of bytes read, #GNUNET_SYSERR on failure
 */
ssize_t
GNUNET_DISK_fn_read (const char *fn, void *result, size_t len)
{
  struct GNUNET_DISK_FileHandle *fh;
  ssize_t ret;
  int eno;

  fh = GNUNET_DISK_file_open (fn, GNUNET_DISK_OPEN_READ, GNUNET_DISK_PERM_NONE);
  if (NULL == fh)
    return GNUNET_SYSERR;
  ret = GNUNET_DISK_file_read (fh, result, len);
  eno = errno;
  GNUNET_assert (GNUNET_OK == GNUNET_DISK_file_close (fh));
  errno = eno;
  return ret;
}


/**
 * Write a buffer to a file.
 *
 * @param h handle to open file
 * @param buffer the data to write
 * @param n number of bytes to write
 * @return number of bytes written on success, #GNUNET_SYSERR on error
 */
ssize_t
GNUNET_DISK_file_write (const struct GNUNET_DISK_FileHandle *h,
                        const void *buffer,
                        size_t n)
{
  if (NULL == h)
  {
    errno = EINVAL;
    return GNUNET_SYSERR;
  }


  return write (h->fd, buffer, n);
}


/**
 * Write a buffer to a file, blocking, if necessary.
 *
 * @param h handle to open file
 * @param buffer the data to write
 * @param n number of bytes to write
 * @return number of bytes written on success, #GNUNET_SYSERR on error
 */
ssize_t
GNUNET_DISK_file_write_blocking (const struct GNUNET_DISK_FileHandle *h,
                                 const void *buffer,
                                 size_t n)
{
  if (NULL == h)
  {
    errno = EINVAL;
    return GNUNET_SYSERR;
  }


  int flags;
  ssize_t ret;

  /* set to blocking, write, then set back */
  flags = fcntl (h->fd, F_GETFL);
  if (0 != (flags & O_NONBLOCK))
    (void) fcntl (h->fd, F_SETFL, flags - O_NONBLOCK);
  ret = write (h->fd, buffer, n);
  if (0 == (flags & O_NONBLOCK))
    (void) fcntl (h->fd, F_SETFL, flags);
  return ret;
}


/**
 * Write a buffer to a file.  If the file is longer than the
 * number of bytes that will be written, it will be truncated.
 *
 * @param fn file name
 * @param buffer the data to write
 * @param n number of bytes to write
 * @param mode file permissions
 * @return number of bytes written on success, #GNUNET_SYSERR on error
 */
ssize_t
GNUNET_DISK_fn_write (const char *fn,
                      const void *buffer,
                      size_t n,
                      enum GNUNET_DISK_AccessPermissions mode)
{
  struct GNUNET_DISK_FileHandle *fh;
  ssize_t ret;

  fh =
    GNUNET_DISK_file_open (fn,
                           GNUNET_DISK_OPEN_WRITE | GNUNET_DISK_OPEN_TRUNCATE
                           | GNUNET_DISK_OPEN_CREATE,
                           mode);
  if (! fh)
    return GNUNET_SYSERR;
  ret = GNUNET_DISK_file_write (fh, buffer, n);
  GNUNET_assert (GNUNET_OK == GNUNET_DISK_file_close (fh));
  return ret;
}


/**
 * Scan a directory for files.
 *
 * @param dir_name the name of the directory
 * @param callback the method to call for each file,
 *        can be NULL, in that case, we only count
 * @param callback_cls closure for @a callback
 * @return the number of files found, #GNUNET_SYSERR on error or
 *         ieration aborted by callback returning #GNUNET_SYSERR
 */
int
GNUNET_DISK_directory_scan (const char *dir_name,
                            GNUNET_FileNameCallback callback,
                            void *callback_cls)
{
  DIR *dinfo;
  struct dirent *finfo;
  struct stat istat;
  int count = 0;
  int ret;
  char *name;
  char *dname;
  unsigned int name_len;
  unsigned int n_size;

  GNUNET_assert (NULL != dir_name);
  dname = GNUNET_STRINGS_filename_expand (dir_name);
  if (NULL == dname)
    return GNUNET_SYSERR;
  while ((strlen (dname) > 0) && (dname[strlen (dname) - 1] == DIR_SEPARATOR))
    dname[strlen (dname) - 1] = '\0';
  if (0 != stat (dname, &istat))
  {
    LOG_STRERROR_FILE (GNUNET_ERROR_TYPE_WARNING, "stat", dname);
    GNUNET_free (dname);
    return GNUNET_SYSERR;
  }
  if (! S_ISDIR (istat.st_mode))
  {
    LOG (GNUNET_ERROR_TYPE_WARNING,
         _ ("Expected `%s' to be a directory!\n"),
         dir_name);
    GNUNET_free (dname);
    return GNUNET_SYSERR;
  }
  errno = 0;
  dinfo = opendir (dname);
  if ((EACCES == errno) || (NULL == dinfo))
  {
    LOG_STRERROR_FILE (GNUNET_ERROR_TYPE_WARNING, "opendir", dname);
    if (NULL != dinfo)
      closedir (dinfo);
    GNUNET_free (dname);
    return GNUNET_SYSERR;
  }
  name_len = 256;
  n_size = strlen (dname) + name_len + strlen (DIR_SEPARATOR_STR) + 1;
  name = GNUNET_malloc (n_size);
  while (NULL != (finfo = readdir (dinfo)))
  {
    if ((0 == strcmp (finfo->d_name, ".")) ||
        (0 == strcmp (finfo->d_name, "..")))
      continue;
    if (NULL != callback)
    {
      if (name_len < strlen (finfo->d_name))
      {
        GNUNET_free (name);
        name_len = strlen (finfo->d_name);
        n_size = strlen (dname) + name_len + strlen (DIR_SEPARATOR_STR) + 1;
        name = GNUNET_malloc (n_size);
      }
      /* dname can end in "/" only if dname == "/";
       * if dname does not end in "/", we need to add
       * a "/" (otherwise, we must not!) */
      GNUNET_snprintf (name,
                       n_size,
                       "%s%s%s",
                       dname,
                       (0 == strcmp (dname, DIR_SEPARATOR_STR))
                       ? ""
                       : DIR_SEPARATOR_STR,
                       finfo->d_name);
      ret = callback (callback_cls, name);
      if (GNUNET_OK != ret)
      {
        closedir (dinfo);
        GNUNET_free (name);
        GNUNET_free (dname);
        if (GNUNET_NO == ret)
          return count;
        return GNUNET_SYSERR;
      }
    }
    count++;
  }
  closedir (dinfo);
  GNUNET_free (name);
  GNUNET_free (dname);
  return count;
}


/**
 * Function that removes the given directory by calling
 * #GNUNET_DISK_directory_remove().
 *
 * @param unused not used
 * @param fn directory to remove
 * @return #GNUNET_OK
 */
static int
remove_helper (void *unused, const char *fn)
{
  (void) unused;
  (void) GNUNET_DISK_directory_remove (fn);
  return GNUNET_OK;
}


/**
 * Remove all files in a directory (rm -r). Call with
 * caution.
 *
 * @param filename the file to remove
 * @return #GNUNET_OK on success, #GNUNET_SYSERR on error
 */
int
GNUNET_DISK_directory_remove (const char *filename)
{
  struct stat istat;

  if (NULL == filename)
  {
    GNUNET_break (0);
    return GNUNET_SYSERR;
  }
  if (0 != lstat (filename, &istat))
    return GNUNET_NO; /* file may not exist... */
  (void) chmod (filename, S_IWUSR | S_IRUSR | S_IXUSR);
  if (0 == unlink (filename))
    return GNUNET_OK;
  if ((errno != EISDIR) &&
      /* EISDIR is not sufficient in all cases, e.g.
      * sticky /tmp directory may result in EPERM on BSD.
      * So we also explicitly check "isDirectory" */
      (GNUNET_YES != GNUNET_DISK_directory_test (filename, GNUNET_YES)))
  {
    LOG_STRERROR_FILE (GNUNET_ERROR_TYPE_WARNING, "rmdir", filename);
    return GNUNET_SYSERR;
  }
  if (GNUNET_SYSERR ==
      GNUNET_DISK_directory_scan (filename, &remove_helper, NULL))
    return GNUNET_SYSERR;
  if (0 != rmdir (filename))
  {
    LOG_STRERROR_FILE (GNUNET_ERROR_TYPE_WARNING, "rmdir", filename);
    return GNUNET_SYSERR;
  }
  return GNUNET_OK;
}


/**
 * Copy a file.
 *
 * @param src file to copy
 * @param dst destination file name
 * @return #GNUNET_OK on success, #GNUNET_SYSERR on error
 */
int
GNUNET_DISK_file_copy (const char *src, const char *dst)
{
  char *buf;
  uint64_t pos;
  uint64_t size;
  size_t len;
  ssize_t sret;
  struct GNUNET_DISK_FileHandle *in;
  struct GNUNET_DISK_FileHandle *out;

  if (GNUNET_OK != GNUNET_DISK_file_size (src, &size, GNUNET_YES, GNUNET_YES))
  {
    GNUNET_log_strerror_file (GNUNET_ERROR_TYPE_ERROR, "stat", src);
    return GNUNET_SYSERR;
  }
  pos = 0;
  in =
    GNUNET_DISK_file_open (src, GNUNET_DISK_OPEN_READ, GNUNET_DISK_PERM_NONE);
  if (! in)
  {
    GNUNET_log_strerror_file (GNUNET_ERROR_TYPE_ERROR, "open", src);
    return GNUNET_SYSERR;
  }
  out =
    GNUNET_DISK_file_open (dst,
                           GNUNET_DISK_OPEN_WRITE | GNUNET_DISK_OPEN_CREATE
                           | GNUNET_DISK_OPEN_FAILIFEXISTS,
                           GNUNET_DISK_PERM_USER_READ
                           | GNUNET_DISK_PERM_USER_WRITE
                           | GNUNET_DISK_PERM_GROUP_READ
                           | GNUNET_DISK_PERM_GROUP_WRITE);
  if (! out)
  {
    GNUNET_log_strerror_file (GNUNET_ERROR_TYPE_ERROR, "open", dst);
    GNUNET_DISK_file_close (in);
    return GNUNET_SYSERR;
  }
  buf = GNUNET_malloc (COPY_BLK_SIZE);
  while (pos < size)
  {
    len = COPY_BLK_SIZE;
    if (len > size - pos)
      len = size - pos;
    sret = GNUNET_DISK_file_read (in, buf, len);
    if ((sret < 0) || (len != (size_t) sret))
      goto FAIL;
    sret = GNUNET_DISK_file_write (out, buf, len);
    if ((sret < 0) || (len != (size_t) sret))
      goto FAIL;
    pos += len;
  }
  GNUNET_free (buf);
  GNUNET_DISK_file_close (in);
  GNUNET_DISK_file_close (out);
  return GNUNET_OK;
FAIL:
  GNUNET_free (buf);
  GNUNET_DISK_file_close (in);
  GNUNET_DISK_file_close (out);
  return GNUNET_SYSERR;
}


/**
 * @brief Removes special characters as ':' from a filename.
 * @param fn the filename to canonicalize
 */
void
GNUNET_DISK_filename_canonicalize (char *fn)
{
  char *idx;
  char c;

  for (idx = fn; *idx; idx++)
  {
    c = *idx;

    if ((c == '/') || (c == '\\') || (c == ':') || (c == '*') || (c == '?') ||
        (c ==
         '"')
        ||
        (c == '<') || (c == '>') || (c == '|') )
    {
      *idx = '_';
    }
  }
}


/**
 * @brief Change owner of a file
 *
 * @param filename name of file to change the owner of
 * @param user name of the new owner
 * @return #GNUNET_OK on success, #GNUNET_SYSERR on failure
 */
int
GNUNET_DISK_file_change_owner (const char *filename, const char *user)
{
  struct passwd *pws;

  pws = getpwnam (user);
  if (NULL == pws)
  {
    LOG (GNUNET_ERROR_TYPE_ERROR,
         _ ("Cannot obtain information about user `%s': %s\n"),
         user,
         strerror (errno));
    return GNUNET_SYSERR;
  }
  if (0 != chown (filename, pws->pw_uid, pws->pw_gid))
  {
    LOG_STRERROR_FILE (GNUNET_ERROR_TYPE_WARNING, "chown", filename);
    return GNUNET_SYSERR;
  }
  return GNUNET_OK;
}


/**
 * Lock a part of a file
 *
 * @param fh file handle
 * @param lock_start absolute position from where to lock
 * @param lock_end absolute position until where to lock
 * @param excl #GNUNET_YES for an exclusive lock
 * @return #GNUNET_OK on success, #GNUNET_SYSERR on error
 */
int
GNUNET_DISK_file_lock (struct GNUNET_DISK_FileHandle *fh,
                       off_t lock_start,
                       off_t lock_end,
                       int excl)
{
  if (fh == NULL)
  {
    errno = EINVAL;
    return GNUNET_SYSERR;
  }

  struct flock fl;

  memset (&fl, 0, sizeof(struct flock));
  fl.l_type = excl ? F_WRLCK : F_RDLCK;
  fl.l_whence = SEEK_SET;
  fl.l_start = lock_start;
  fl.l_len = lock_end;

  return fcntl (fh->fd, F_SETLK, &fl) != 0 ? GNUNET_SYSERR : GNUNET_OK;
}


/**
 * Unlock a part of a file
 *
 * @param fh file handle
 * @param unlock_start absolute position from where to unlock
 * @param unlock_end absolute position until where to unlock
 * @return #GNUNET_OK on success, #GNUNET_SYSERR on error
 */
int
GNUNET_DISK_file_unlock (struct GNUNET_DISK_FileHandle *fh,
                         off_t unlock_start,
                         off_t unlock_end)
{
  if (fh == NULL)
  {
    errno = EINVAL;
    return GNUNET_SYSERR;
  }

  struct flock fl;

  memset (&fl, 0, sizeof(struct flock));
  fl.l_type = F_UNLCK;
  fl.l_whence = SEEK_SET;
  fl.l_start = unlock_start;
  fl.l_len = unlock_end;

  return fcntl (fh->fd, F_SETLK, &fl) != 0 ? GNUNET_SYSERR : GNUNET_OK;
}


/**
 * Open a file.  Note that the access permissions will only be
 * used if a new file is created and if the underlying operating
 * system supports the given permissions.
 *
 * @param fn file name to be opened
 * @param flags opening flags, a combination of GNUNET_DISK_OPEN_xxx bit flags
 * @param perm permissions for the newly created file, use
 *             #GNUNET_DISK_PERM_NONE if a file could not be created by this
 *             call (because of flags)
 * @return IO handle on success, NULL on error
 */
struct GNUNET_DISK_FileHandle *
GNUNET_DISK_file_open (const char *fn,
                       enum GNUNET_DISK_OpenFlags flags,
                       enum GNUNET_DISK_AccessPermissions perm)
{
  char *expfn;
  struct GNUNET_DISK_FileHandle *ret;

  int oflags;
  int mode;
  int fd;

  expfn = GNUNET_STRINGS_filename_expand (fn);
  if (NULL == expfn)
    return NULL;

  mode = 0;
  if (GNUNET_DISK_OPEN_READWRITE == (flags & GNUNET_DISK_OPEN_READWRITE))
    oflags = O_RDWR; /* note: O_RDWR is NOT always O_RDONLY | O_WRONLY */
  else if (flags & GNUNET_DISK_OPEN_READ)
    oflags = O_RDONLY;
  else if (flags & GNUNET_DISK_OPEN_WRITE)
    oflags = O_WRONLY;
  else
  {
    GNUNET_break (0);
    GNUNET_free (expfn);
    return NULL;
  }
  if (flags & GNUNET_DISK_OPEN_FAILIFEXISTS)
    oflags |= (O_CREAT | O_EXCL);
  if (flags & GNUNET_DISK_OPEN_TRUNCATE)
    oflags |= O_TRUNC;
  if (flags & GNUNET_DISK_OPEN_APPEND)
    oflags |= O_APPEND;
  if (GNUNET_NO == GNUNET_DISK_file_test (fn))
  {
    if (flags & GNUNET_DISK_OPEN_CREATE)
    {
      (void) GNUNET_DISK_directory_create_for_file (expfn);
      oflags |= O_CREAT;
      mode = translate_unix_perms (perm);
    }
  }

  fd = open (expfn,
             oflags
#if O_CLOEXEC
             | O_CLOEXEC
#endif
             | O_LARGEFILE,
             mode);
  if (fd == -1)
  {
    if (0 == (flags & GNUNET_DISK_OPEN_FAILIFEXISTS))
      LOG_STRERROR_FILE (GNUNET_ERROR_TYPE_WARNING, "open", expfn);
    else
      LOG_STRERROR_FILE (GNUNET_ERROR_TYPE_DEBUG, "open", expfn);
    GNUNET_free (expfn);
    return NULL;
  }

  ret = GNUNET_new (struct GNUNET_DISK_FileHandle);

  ret->fd = fd;

  GNUNET_free (expfn);
  return ret;
}


/**
 * Close an open file.
 *
 * @param h file handle
 * @return #GNUNET_OK on success, #GNUNET_SYSERR otherwise
 */
int
GNUNET_DISK_file_close (struct GNUNET_DISK_FileHandle *h)
{
  int ret;

  if (h == NULL)
  {
    errno = EINVAL;
    return GNUNET_SYSERR;
  }

  ret = GNUNET_OK;

  if (close (h->fd) != 0)
  {
    LOG_STRERROR (GNUNET_ERROR_TYPE_WARNING, "close");
    ret = GNUNET_SYSERR;
  }

  GNUNET_free (h);
  return ret;
}


/**
 * Get a handle from a native integer FD.
 *
 * @param fno native integer file descriptor
 * @return file handle corresponding to the descriptor, NULL on error
 */
struct GNUNET_DISK_FileHandle *
GNUNET_DISK_get_handle_from_int_fd (int fno)
{
  struct GNUNET_DISK_FileHandle *fh;

  if ((((off_t) -1) == lseek (fno, 0, SEEK_CUR)) && (EBADF == errno))
    return NULL; /* invalid FD */

  fh = GNUNET_new (struct GNUNET_DISK_FileHandle);

  fh->fd = fno;

  return fh;
}


/**
 * Get a handle from a native streaming FD.
 *
 * @param fd native streaming file descriptor
 * @return file handle corresponding to the descriptor
 */
struct GNUNET_DISK_FileHandle *
GNUNET_DISK_get_handle_from_native (FILE *fd)
{
  int fno;

  fno = fileno (fd);
  if (-1 == fno)
    return NULL;

  return GNUNET_DISK_get_handle_from_int_fd (fno);
}


/**
 * Handle for a memory-mapping operation.
 */
struct GNUNET_DISK_MapHandle
{
  /**
   * Address where the map is in memory.
   */
  void *addr;

  /**
   * Number of bytes mapped.
   */
  size_t len;
};


#ifndef MAP_FAILED
#define MAP_FAILED ((void *) -1)
#endif

/**
 * Map a file into memory
 *
 * @param h open file handle
 * @param m handle to the new mapping
 * @param access access specification, GNUNET_DISK_MAP_TYPE_xxx
 * @param len size of the mapping
 * @return pointer to the mapped memory region, NULL on failure
 */
void *
GNUNET_DISK_file_map (const struct GNUNET_DISK_FileHandle *h,
                      struct GNUNET_DISK_MapHandle **m,
                      enum GNUNET_DISK_MapType access,
                      size_t len)
{
  if (NULL == h)
  {
    errno = EINVAL;
    return NULL;
  }

  int prot;

  prot = 0;
  if (access & GNUNET_DISK_MAP_TYPE_READ)
    prot = PROT_READ;
  if (access & GNUNET_DISK_MAP_TYPE_WRITE)
    prot |= PROT_WRITE;
  *m = GNUNET_new (struct GNUNET_DISK_MapHandle);
  (*m)->addr = mmap (NULL, len, prot, MAP_SHARED, h->fd, 0);
  GNUNET_assert (NULL != (*m)->addr);
  if (MAP_FAILED == (*m)->addr)
  {
    GNUNET_free (*m);
    return NULL;
  }
  (*m)->len = len;
  return (*m)->addr;
}


/**
 * Unmap a file
 * @param h mapping handle
 * @return GNUNET_OK on success, GNUNET_SYSERR otherwise
 */
int
GNUNET_DISK_file_unmap (struct GNUNET_DISK_MapHandle *h)
{
  int ret;

  if (h == NULL)
  {
    errno = EINVAL;
    return GNUNET_SYSERR;
  }

  ret = munmap (h->addr, h->len) != -1 ? GNUNET_OK : GNUNET_SYSERR;

  GNUNET_free (h);
  return ret;
}


/**
 * Write file changes to disk
 * @param h handle to an open file
 * @return GNUNET_OK on success, GNUNET_SYSERR otherwise
 */
int
GNUNET_DISK_file_sync (const struct GNUNET_DISK_FileHandle *h)
{
  if (h == NULL)
  {
    errno = EINVAL;
    return GNUNET_SYSERR;
  }

#if ! defined(__linux__) || ! defined(GNU)
  return fsync (h->fd) == -1 ? GNUNET_SYSERR : GNUNET_OK;
#else
  return fdatasync (h->fd) == -1 ? GNUNET_SYSERR : GNUNET_OK;
#endif
}


/**
 * Creates an interprocess channel
 *
 * @param blocking_read creates an asynchronous pipe for reading if set to GNUNET_NO
 * @param blocking_write creates an asynchronous pipe for writing if set to GNUNET_NO
 * @param inherit_read inherit the parent processes stdin (only for windows)
 * @param inherit_write inherit the parent processes stdout (only for windows)
 * @return handle to the new pipe, NULL on error
 */
struct GNUNET_DISK_PipeHandle *
GNUNET_DISK_pipe (int blocking_read,
                  int blocking_write,
                  int inherit_read,
                  int inherit_write)
{
  int fd[2];
  int ret;
  int eno;

  (void) inherit_read;
  (void) inherit_write;
  ret = pipe (fd);
  if (ret == -1)
  {
    eno = errno;
    LOG_STRERROR (GNUNET_ERROR_TYPE_ERROR, "pipe");
    errno = eno;
    return NULL;
  }
  return GNUNET_DISK_pipe_from_fd (blocking_read, blocking_write, fd);
}


/**
 * Creates a pipe object from a couple of file descriptors.
 * Useful for wrapping existing pipe FDs.
 *
 * @param blocking_read creates an asynchronous pipe for reading if set to GNUNET_NO
 * @param blocking_write creates an asynchronous pipe for writing if set to GNUNET_NO
 * @param fd an array of two fd values. One of them may be -1 for read-only or write-only pipes
 *
 * @return handle to the new pipe, NULL on error
 */
struct GNUNET_DISK_PipeHandle *
GNUNET_DISK_pipe_from_fd (int blocking_read, int blocking_write, int fd[2])
{
  struct GNUNET_DISK_PipeHandle *p;

  p = GNUNET_new (struct GNUNET_DISK_PipeHandle);

  int ret;
  int flags;
  int eno = 0; /* make gcc happy */

  ret = 0;
  if (fd[0] >= 0)
  {
    p->fd[0] = GNUNET_new (struct GNUNET_DISK_FileHandle);
    p->fd[0]->fd = fd[0];
    if (! blocking_read)
    {
      flags = fcntl (fd[0], F_GETFL);
      flags |= O_NONBLOCK;
      if (0 > fcntl (fd[0], F_SETFL, flags))
      {
        ret = -1;
        eno = errno;
      }
    }
    flags = fcntl (fd[0], F_GETFD);
    flags |= FD_CLOEXEC;
    if (0 > fcntl (fd[0], F_SETFD, flags))
    {
      ret = -1;
      eno = errno;
    }
  }

  if (fd[1] >= 0)
  {
    p->fd[1] = GNUNET_new (struct GNUNET_DISK_FileHandle);
    p->fd[1]->fd = fd[1];
    if (! blocking_write)
    {
      flags = fcntl (fd[1], F_GETFL);
      flags |= O_NONBLOCK;
      if (0 > fcntl (fd[1], F_SETFL, flags))
      {
        ret = -1;
        eno = errno;
      }
    }
    flags = fcntl (fd[1], F_GETFD);
    flags |= FD_CLOEXEC;
    if (0 > fcntl (fd[1], F_SETFD, flags))
    {
      ret = -1;
      eno = errno;
    }
  }
  if (ret == -1)
  {
    errno = eno;
    LOG_STRERROR (GNUNET_ERROR_TYPE_ERROR, "fcntl");
    if (p->fd[0]->fd >= 0)
      GNUNET_break (0 == close (p->fd[0]->fd));
    if (p->fd[1]->fd >= 0)
      GNUNET_break (0 == close (p->fd[1]->fd));
    GNUNET_free_non_null (p->fd[0]);
    GNUNET_free_non_null (p->fd[1]);
    GNUNET_free (p);
    errno = eno;
    return NULL;
  }

  return p;
}


/**
 * Closes an interprocess channel
 *
 * @param p pipe to close
 * @param end which end of the pipe to close
 * @return GNUNET_OK on success, GNUNET_SYSERR otherwise
 */
int
GNUNET_DISK_pipe_close_end (struct GNUNET_DISK_PipeHandle *p,
                            enum GNUNET_DISK_PipeEnd end)
{
  int ret = GNUNET_OK;

  if (end == GNUNET_DISK_PIPE_END_READ)
  {
    if (p->fd[0])
    {
      ret = GNUNET_DISK_file_close (p->fd[0]);
      p->fd[0] = NULL;
    }
  }
  else if (end == GNUNET_DISK_PIPE_END_WRITE)
  {
    if (p->fd[1])
    {
      ret = GNUNET_DISK_file_close (p->fd[1]);
      p->fd[1] = NULL;
    }
  }

  return ret;
}


/**
 * Detaches one of the ends from the pipe.
 * Detached end is a fully-functional FileHandle, it will
 * not be affected by anything you do with the pipe afterwards.
 * Each end of a pipe can only be detched from it once (i.e.
 * it is not duplicated).
 *
 * @param p pipe to detach an end from
 * @param end which end of the pipe to detach
 * @return Detached end on success, NULL on failure
 * (or if that end is not present or is closed).
 */
struct GNUNET_DISK_FileHandle *
GNUNET_DISK_pipe_detach_end (struct GNUNET_DISK_PipeHandle *p,
                             enum GNUNET_DISK_PipeEnd end)
{
  struct GNUNET_DISK_FileHandle *ret = NULL;

  if (end == GNUNET_DISK_PIPE_END_READ)
  {
    if (p->fd[0])
    {
      ret = p->fd[0];
      p->fd[0] = NULL;
    }
  }
  else if (end == GNUNET_DISK_PIPE_END_WRITE)
  {
    if (p->fd[1])
    {
      ret = p->fd[1];
      p->fd[1] = NULL;
    }
  }

  return ret;
}


/**
 * Closes an interprocess channel
 *
 * @param p pipe to close
 * @return GNUNET_OK on success, GNUNET_SYSERR otherwise
 */
int
GNUNET_DISK_pipe_close (struct GNUNET_DISK_PipeHandle *p)
{
  int ret = GNUNET_OK;

  int read_end_close;
  int write_end_close;
  int read_end_close_errno;
  int write_end_close_errno;

  read_end_close = GNUNET_DISK_pipe_close_end (p, GNUNET_DISK_PIPE_END_READ);
  read_end_close_errno = errno;
  write_end_close = GNUNET_DISK_pipe_close_end (p, GNUNET_DISK_PIPE_END_WRITE);
  write_end_close_errno = errno;
  GNUNET_free (p);

  if (GNUNET_OK != read_end_close)
  {
    errno = read_end_close_errno;
    ret = read_end_close;
  }
  else if (GNUNET_OK != write_end_close)
  {
    errno = write_end_close_errno;
    ret = write_end_close;
  }

  return ret;
}


/**
 * Get the handle to a particular pipe end
 *
 * @param p pipe
 * @param n end to access
 * @return handle for the respective end
 */
const struct GNUNET_DISK_FileHandle *
GNUNET_DISK_pipe_handle (const struct GNUNET_DISK_PipeHandle *p,
                         enum GNUNET_DISK_PipeEnd n)
{
  switch (n)
  {
  case GNUNET_DISK_PIPE_END_READ:
  case GNUNET_DISK_PIPE_END_WRITE:
    return p->fd[n];

  default:
    GNUNET_break (0);
    return NULL;
  }
}


/**
 * Retrieve OS file handle
 * @internal
 * @param fh GNUnet file descriptor
 * @param dst destination buffer
 * @param dst_len length of dst
 * @return #GNUNET_OK on success, #GNUNET_SYSERR otherwise
 */
int
GNUNET_DISK_internal_file_handle_ (const struct GNUNET_DISK_FileHandle *fh,
                                   void *dst,
                                   size_t dst_len)
{
  if (NULL == fh)
    return GNUNET_SYSERR;

  if (dst_len < sizeof(int))
    return GNUNET_SYSERR;
  *((int *) dst) = fh->fd;

  return GNUNET_OK;
}


/**
 * Helper function for #GNUNET_DISK_purge_cfg_dir.
 *
 * @param cls a `const char *` with the option to purge
 * @param cfg our configuration
 * @return #GNUNET_OK on success
 */
static int
purge_cfg_dir (void *cls, const struct GNUNET_CONFIGURATION_Handle *cfg)
{
  const char *option = cls;
  char *tmpname;

  if (GNUNET_OK !=
      GNUNET_CONFIGURATION_get_value_filename (cfg, "PATHS", option, &tmpname))
  {
    GNUNET_log_config_missing (GNUNET_ERROR_TYPE_ERROR, "PATHS", option);
    return GNUNET_NO;
  }
  if (GNUNET_SYSERR == GNUNET_DISK_directory_remove (tmpname))
  {
    GNUNET_log_strerror_file (GNUNET_ERROR_TYPE_ERROR, "remove", tmpname);
    GNUNET_free (tmpname);
    return GNUNET_OK;
  }
  GNUNET_free (tmpname);
  return GNUNET_OK;
}


/**
 * Remove the directory given under @a option in
 * section [PATHS] in configuration under @a cfg_filename
 *
 * @param cfg_filename configuration file to parse
 * @param option option with the dir name to purge
 */
void
GNUNET_DISK_purge_cfg_dir (const char *cfg_filename, const char *option)
{
  GNUNET_break (GNUNET_OK ==
                GNUNET_CONFIGURATION_parse_and_run (cfg_filename,
                                                    &purge_cfg_dir,
                                                    (void *) option));
}


/* end of disk.c */