summaryrefslogtreecommitdiffstats
path: root/src/corelib/io/qfile.cpp
blob: 85e78a604876d31c665bfc6a89c9edb3d5b1e9fd (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
/****************************************************************************
**
** Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies).
** All rights reserved.
** Contact: Nokia Corporation (qt-info@nokia.com)
**
** This file is part of the QtCore module of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL$
** No Commercial Usage
** This file contains pre-release code and may not be distributed.
** You may use this file in accordance with the terms and conditions
** contained in the Technology Preview License Agreement accompanying
** this package.
**
** GNU Lesser General Public License Usage
** Alternatively, this file may be used under the terms of the GNU Lesser
** General Public License version 2.1 as published by the Free Software
** Foundation and appearing in the file LICENSE.LGPL included in the
** packaging of this file.  Please review the following information to
** ensure the GNU Lesser General Public License version 2.1 requirements
** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
**
** In addition, as a special exception, Nokia gives you certain additional
** rights.  These rights are described in the Nokia Qt LGPL Exception
** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
**
** If you have questions regarding the use of this file, please contact
** Nokia at qt-info@nokia.com.
**
**
**
**
**
**
**
**
** $QT_END_LICENSE$
**
****************************************************************************/

#include "qplatformdefs.h"
#include "qdebug.h"
#include "qfile.h"
#include "qfsfileengine.h"
#include "qtemporaryfile.h"
#include "qlist.h"
#include "qfileinfo.h"
#include "private/qiodevice_p.h"
#include "private/qfile_p.h"
#include "private/qsystemerror_p.h"
#if defined(QT_BUILD_CORE_LIB)
# include "qcoreapplication.h"
#endif

#ifdef QT_NO_QOBJECT
#define tr(X) QString::fromLatin1(X)
#endif

QT_BEGIN_NAMESPACE

static const int QFILE_WRITEBUFFER_SIZE = 16384;

static QByteArray locale_encode(const QString &f)
{
#if defined(Q_OS_DARWIN)
    // Mac always expects UTF-8... and decomposed...
    return f.normalized(QString::NormalizationForm_D).toUtf8();
#elif defined(Q_OS_SYMBIAN)
    return f.toUtf8();
#else
    return f.toLocal8Bit();
#endif
}

static QString locale_decode(const QByteArray &f)
{
#if defined(Q_OS_DARWIN)
    // Mac always gives us UTF-8 and decomposed, we want that composed...
    return QString::fromUtf8(f).normalized(QString::NormalizationForm_C);
#elif defined(Q_OS_SYMBIAN)
    return QString::fromUtf8(f);
#else
    return QString::fromLocal8Bit(f);
#endif
}

//************* QFilePrivate
QFile::EncoderFn QFilePrivate::encoder = locale_encode;
QFile::DecoderFn QFilePrivate::decoder = locale_decode;

QFilePrivate::QFilePrivate()
    : fileEngine(0), lastWasWrite(false),
      writeBuffer(QFILE_WRITEBUFFER_SIZE), error(QFile::NoError),
      cachedSize(0)
{
}

QFilePrivate::~QFilePrivate()
{
    delete fileEngine;
    fileEngine = 0;
}

bool
QFilePrivate::openExternalFile(int flags, int fd)
{
#ifdef QT_NO_FSFILEENGINE
    Q_UNUSED(flags);
    Q_UNUSED(fd);
    return false;
#else
    delete fileEngine;
    fileEngine = 0;
    QFSFileEngine *fe = new QFSFileEngine;
    fe->setFileName(fileName);
    fileEngine = fe;
    return fe->open(QIODevice::OpenMode(flags), fd);
#endif
}

bool
QFilePrivate::openExternalFile(int flags, FILE *fh)
{
#ifdef QT_NO_FSFILEENGINE
    Q_UNUSED(flags);
    Q_UNUSED(fh);
    return false;
#else
    delete fileEngine;
    fileEngine = 0;
    QFSFileEngine *fe = new QFSFileEngine;
    fe->setFileName(fileName);
    fileEngine = fe;
    return fe->open(QIODevice::OpenMode(flags), fh);
#endif
}

inline bool QFilePrivate::ensureFlushed() const
{
    // This function ensures that the write buffer has been flushed (const
    // because certain const functions need to call it.
    if (lastWasWrite) {
        const_cast<QFilePrivate *>(this)->lastWasWrite = false;
        if (!const_cast<QFile *>(q_func())->flush())
            return false;
    }
    return true;
}

void
QFilePrivate::setError(QFile::FileError err)
{
    error = err;
    errorString.clear();
}

void
QFilePrivate::setError(QFile::FileError err, const QString &errStr)
{
    error = err;
    errorString = errStr;
}

void
QFilePrivate::setError(QFile::FileError err, int errNum)
{
    error = err;
    errorString = qt_error_string(errNum);
}

//************* QFile

/*!
    \class QFile
    \brief The QFile class provides an interface for reading from and writing to files.

    \ingroup io

    \reentrant

    QFile is an I/O device for reading and writing text and binary
    files and \l{The Qt Resource System}{resources}. A QFile may be
    used by itself or, more conveniently, with a QTextStream or
    QDataStream.

    The file name is usually passed in the constructor, but it can be
    set at any time using setFileName(). QFile expects the file
    separator to be '/' regardless of operating system. The use of
    other separators (e.g., '\\') is not supported.

    You can check for a file's existence using exists(), and remove a
    file using remove(). (More advanced file system related operations
    are provided by QFileInfo and QDir.)

    The file is opened with open(), closed with close(), and flushed
    with flush(). Data is usually read and written using QDataStream
    or QTextStream, but you can also call the QIODevice-inherited
    functions read(), readLine(), readAll(), write(). QFile also
    inherits getChar(), putChar(), and ungetChar(), which work one
    character at a time.

    The size of the file is returned by size(). You can get the
    current file position using pos(), or move to a new file position
    using seek(). If you've reached the end of the file, atEnd()
    returns true.

    \section1 Reading Files Directly

    The following example reads a text file line by line:

    \snippet doc/src/snippets/file/file.cpp 0

    The QIODevice::Text flag passed to open() tells Qt to convert
    Windows-style line terminators ("\\r\\n") into C++-style
    terminators ("\\n"). By default, QFile assumes binary, i.e. it
    doesn't perform any conversion on the bytes stored in the file.

    \section1 Using Streams to Read Files

    The next example uses QTextStream to read a text file
    line by line:

    \snippet doc/src/snippets/file/file.cpp 1

    QTextStream takes care of converting the 8-bit data stored on
    disk into a 16-bit Unicode QString. By default, it assumes that
    the user system's local 8-bit encoding is used (e.g., ISO 8859-1
    for most of Europe; see QTextCodec::codecForLocale() for
    details). This can be changed using setCodec().

    To write text, we can use operator<<(), which is overloaded to
    take a QTextStream on the left and various data types (including
    QString) on the right:

    \snippet doc/src/snippets/file/file.cpp 2

    QDataStream is similar, in that you can use operator<<() to write
    data and operator>>() to read it back. See the class
    documentation for details.

    When you use QFile, QFileInfo, and QDir to access the file system
    with Qt, you can use Unicode file names. On Unix, these file
    names are converted to an 8-bit encoding. If you want to use
    standard C++ APIs (\c <cstdio> or \c <iostream>) or
    platform-specific APIs to access files instead of QFile, you can
    use the encodeName() and decodeName() functions to convert
    between Unicode file names and 8-bit file names.

    On Unix, there are some special system files (e.g. in \c /proc) for which
    size() will always return 0, yet you may still be able to read more data
    from such a file; the data is generated in direct response to you calling
    read(). In this case, however, you cannot use atEnd() to determine if
    there is more data to read (since atEnd() will return true for a file that
    claims to have size 0). Instead, you should either call readAll(), or call
    read() or readLine() repeatedly until no more data can be read. The next
    example uses QTextStream to read \c /proc/modules line by line:

    \snippet doc/src/snippets/file/file.cpp 3

    \section1 Signals

    Unlike other QIODevice implementations, such as QTcpSocket, QFile does not
    emit the aboutToClose(), bytesWritten(), or readyRead() signals. This
    implementation detail means that QFile is not suitable for reading and
    writing certain types of files, such as device files on Unix platforms.

    \section1 Platform Specific Issues

    File permissions are handled differently on Linux/Mac OS X and
    Windows.  In a non \l{QIODevice::isWritable()}{writable}
    directory on Linux, files cannot be created. This is not always
    the case on Windows, where, for instance, the 'My Documents'
    directory usually is not writable, but it is still possible to
    create files in it.

    \sa QTextStream, QDataStream, QFileInfo, QDir, {The Qt Resource System}
*/

/*!
    \enum QFile::FileError

    This enum describes the errors that may be returned by the error()
    function.

    \value NoError          No error occurred.
    \value ReadError        An error occurred when reading from the file.
    \value WriteError       An error occurred when writing to the file.
    \value FatalError       A fatal error occurred.
    \value ResourceError
    \value OpenError        The file could not be opened.
    \value AbortError       The operation was aborted.
    \value TimeOutError     A timeout occurred.
    \value UnspecifiedError An unspecified error occurred.
    \value RemoveError      The file could not be removed.
    \value RenameError      The file could not be renamed.
    \value PositionError    The position in the file could not be changed.
    \value ResizeError      The file could not be resized.
    \value PermissionsError The file could not be accessed.
    \value CopyError        The file could not be copied.

    \omitvalue ConnectError
*/

/*!
    \enum QFile::Permission

    This enum is used by the permission() function to report the
    permissions and ownership of a file. The values may be OR-ed
    together to test multiple permissions and ownership values.

    \value ReadOwner The file is readable by the owner of the file.
    \value WriteOwner The file is writable by the owner of the file.
    \value ExeOwner The file is executable by the owner of the file.
    \value ReadUser The file is readable by the user.
    \value WriteUser The file is writable by the user.
    \value ExeUser The file is executable by the user.
    \value ReadGroup The file is readable by the group.
    \value WriteGroup The file is writable by the group.
    \value ExeGroup The file is executable by the group.
    \value ReadOther The file is readable by anyone.
    \value WriteOther The file is writable by anyone.
    \value ExeOther The file is executable by anyone.

    \warning Because of differences in the platforms supported by Qt,
    the semantics of ReadUser, WriteUser and ExeUser are
    platform-dependent: On Unix, the rights of the owner of the file
    are returned and on Windows the rights of the current user are
    returned. This behavior might change in a future Qt version.

    Note that Qt does not by default check for permissions on NTFS
    file systems, as this may decrease the performance of file
    handling considerably. It is possible to force permission checking
    on NTFS by including the following code in your source:

    \snippet doc/src/snippets/ntfsp.cpp 0

    Permission checking is then turned on and off by incrementing and
    decrementing \c qt_ntfs_permission_lookup by 1.

    \snippet doc/src/snippets/ntfsp.cpp 1
*/

#ifdef QT3_SUPPORT
/*!
    \typedef QFile::PermissionSpec

    Use QFile::Permission instead.
*/
#endif

#ifdef QT_NO_QOBJECT
QFile::QFile()
    : QIODevice(*new QFilePrivate)
{
}
QFile::QFile(const QString &name)
    : QIODevice(*new QFilePrivate)
{
    d_func()->fileName = name;
}
QFile::QFile(QFilePrivate &dd)
    : QIODevice(dd)
{
}
#else
/*!
    \internal
*/
QFile::QFile()
    : QIODevice(*new QFilePrivate, 0)
{
}
/*!
    Constructs a new file object with the given \a parent.
*/
QFile::QFile(QObject *parent)
    : QIODevice(*new QFilePrivate, parent)
{
}
/*!
    Constructs a new file object to represent the file with the given \a name.
*/
QFile::QFile(const QString &name)
    : QIODevice(*new QFilePrivate, 0)
{
    Q_D(QFile);
    d->fileName = name;
}
/*!
    Constructs a new file object with the given \a parent to represent the
    file with the specified \a name.
*/
QFile::QFile(const QString &name, QObject *parent)
    : QIODevice(*new QFilePrivate, parent)
{
    Q_D(QFile);
    d->fileName = name;
}
/*!
    \internal
*/
QFile::QFile(QFilePrivate &dd, QObject *parent)
    : QIODevice(dd, parent)
{
}
#endif

/*!
    Destroys the file object, closing it if necessary.
*/
QFile::~QFile()
{
    close();
}

/*!
    Returns the name set by setFileName() or to the QFile
    constructors.

    \sa setFileName(), QFileInfo::fileName()
*/
QString QFile::fileName() const
{
    return fileEngine()->fileName(QAbstractFileEngine::DefaultName);
}

/*!
    Sets the \a name of the file. The name can have no path, a
    relative path, or an absolute path.

    Do not call this function if the file has already been opened.

    If the file name has no path or a relative path, the path used
    will be the application's current directory path
    \e{at the time of the open()} call.

    Example:
    \snippet doc/src/snippets/code/src_corelib_io_qfile.cpp 0

    Note that the directory separator "/" works for all operating
    systems supported by Qt.

    \sa fileName(), QFileInfo, QDir
*/
void
QFile::setFileName(const QString &name)
{
    Q_D(QFile);
    if (isOpen()) {
        qWarning("QFile::setFileName: File (%s) is already opened",
                 qPrintable(fileName()));
        close();
    }
    if(d->fileEngine) { //get a new file engine later
        delete d->fileEngine;
        d->fileEngine = 0;
    }
    d->fileName = name;
}

/*!
    \fn QString QFile::decodeName(const char *localFileName)

    \overload

    Returns the Unicode version of the given \a localFileName. See
    encodeName() for details.
*/

/*!
    By default, this function converts \a fileName to the local 8-bit
    encoding determined by the user's locale. This is sufficient for
    file names that the user chooses. File names hard-coded into the
    application should only use 7-bit ASCII filename characters.

    \sa decodeName() setEncodingFunction()
*/

QByteArray
QFile::encodeName(const QString &fileName)
{
    return (*QFilePrivate::encoder)(fileName);
}

/*!
    \typedef QFile::EncoderFn

    This is a typedef for a pointer to a function with the following
    signature:

    \snippet doc/src/snippets/code/src_corelib_io_qfile.cpp 1

    \sa setEncodingFunction(), encodeName()
*/

/*!
    This does the reverse of QFile::encodeName() using \a localFileName.

    \sa setDecodingFunction(), encodeName()
*/

QString
QFile::decodeName(const QByteArray &localFileName)
{
    return (*QFilePrivate::decoder)(localFileName);
}

/*!
    \fn void QFile::setEncodingFunction(EncoderFn function)

    \nonreentrant

    Sets the \a function for encoding Unicode file names. The
    default encodes in the locale-specific 8-bit encoding.

    \sa encodeName(), setDecodingFunction()
*/

void
QFile::setEncodingFunction(EncoderFn f)
{
    if (!f)
        f = locale_encode;
    QFilePrivate::encoder = f;
}

/*!
    \typedef QFile::DecoderFn

    This is a typedef for a pointer to a function with the following
    signature:

    \snippet doc/src/snippets/code/src_corelib_io_qfile.cpp 2

    \sa setDecodingFunction()
*/

/*!
    \fn void QFile::setDecodingFunction(DecoderFn function)

    \nonreentrant

    Sets the \a function for decoding 8-bit file names. The
    default uses the locale-specific 8-bit encoding.

    \sa setEncodingFunction(), decodeName()
*/

void
QFile::setDecodingFunction(DecoderFn f)
{
    if (!f)
        f = locale_decode;
    QFilePrivate::decoder = f;
}

/*!
    \overload

    Returns true if the file specified by fileName() exists; otherwise
    returns false.

    \sa fileName(), setFileName()
*/

bool
QFile::exists() const
{
    // 0x1000000 = QAbstractFileEngine::Refresh, forcing an update
    return (fileEngine()->fileFlags(QAbstractFileEngine::FlagsMask
                                    | QAbstractFileEngine::FileFlag(0x1000000)) & QAbstractFileEngine::ExistsFlag);
}

/*!
    Returns true if the file specified by \a fileName exists; otherwise
    returns false.
*/

bool
QFile::exists(const QString &fileName)
{
    return QFileInfo(fileName).exists();
}

/*!
    \fn QString QFile::symLinkTarget() const
    \since 4.2
    \overload

    Returns the absolute path of the file or directory a symlink (or shortcut
    on Windows) points to, or a an empty string if the object isn't a symbolic
    link.

    This name may not represent an existing file; it is only a string.
    QFile::exists() returns true if the symlink points to an existing file.

    \sa fileName() setFileName()
*/

/*!
    \obsolete

    Use symLinkTarget() instead.
*/
QString
QFile::readLink() const
{
    return fileEngine()->fileName(QAbstractFileEngine::LinkName);
}

/*!
    \fn static QString QFile::symLinkTarget(const QString &fileName)
    \since 4.2

    Returns the absolute path of the file or directory referred to by the
    symlink (or shortcut on Windows) specified by \a fileName, or returns an
    empty string if the \a fileName does not correspond to a symbolic link.

    This name may not represent an existing file; it is only a string.
    QFile::exists() returns true if the symlink points to an existing file.
*/

/*!
    \obsolete

    Use symLinkTarget() instead.
*/
QString
QFile::readLink(const QString &fileName)
{
    return QFileInfo(fileName).readLink();
}

/*!
    Removes the file specified by fileName(). Returns true if successful;
    otherwise returns false.

    The file is closed before it is removed.

    \sa setFileName()
*/

bool
QFile::remove()
{
    Q_D(QFile);
    if (d->fileName.isEmpty()) {
        qWarning("QFile::remove: Empty or null file name");
        return false;
    }
    unsetError();
    close();
    if(error() == QFile::NoError) {
        if(fileEngine()->remove()) {
            unsetError();
            return true;
        }
        d->setError(QFile::RemoveError, d->fileEngine->errorString());
    }
    return false;
}

/*!
    \overload

    Removes the file specified by the \a fileName given.

    Returns true if successful; otherwise returns false.

    \sa remove()
*/

bool
QFile::remove(const QString &fileName)
{
    return QFile(fileName).remove();
}

/*!
    Renames the file currently specified by fileName() to \a newName.
    Returns true if successful; otherwise returns false.

    If a file with the name \a newName already exists, rename() returns false
    (i.e., QFile will not overwrite it).

    The file is closed before it is renamed.

    \sa setFileName()
*/

bool
QFile::rename(const QString &newName)
{
    Q_D(QFile);
    if (d->fileName.isEmpty()) {
        qWarning("QFile::rename: Empty or null file name");
        return false;
    }
    if (QFile(newName).exists()) {
        // ### Race condition. If a file is moved in after this, it /will/ be
        // overwritten. On Unix, the proper solution is to use hardlinks:
        // return ::link(old, new) && ::remove(old);
        d->setError(QFile::RenameError, tr("Destination file exists"));
        return false;
    }
    unsetError();
    close();
    if(error() == QFile::NoError) {
        if (fileEngine()->rename(newName)) {
            unsetError();
            // engine was able to handle the new name so we just reset it
            d->fileEngine->setFileName(newName);
            d->fileName = newName;
            return true;
        }

        if (isSequential()) {
            d->setError(QFile::RenameError, tr("Will not rename sequential file using block copy"));
            return false;
        }

        QFile out(newName);
        if (open(QIODevice::ReadOnly)) {
            if (out.open(QIODevice::WriteOnly | QIODevice::Truncate)) {
                bool error = false;
                char block[4096];
                qint64 bytes;
                while ((bytes = read(block, sizeof(block))) > 0) {
                    if (bytes != out.write(block, bytes)) {
                        d->setError(QFile::RenameError, out.errorString());
                        error = true;
                        break;
                    }
                }
                if (bytes == -1) {
                    d->setError(QFile::RenameError, errorString());
                    error = true;
                }
                if(!error) {
                    if (!remove()) {
                        d->setError(QFile::RenameError, tr("Cannot remove source file"));
                        error = true;
                    }
                }
                if (error) {
                    out.remove();
                } else {
                    d->fileEngine->setFileName(newName);
                    setPermissions(permissions());
                    unsetError();
                    setFileName(newName);
                }
                close();
                return !error;
            }
            close();
        }
        d->setError(QFile::RenameError, out.isOpen() ? errorString() : out.errorString());
    }
    return false;
}

/*!
    \overload

    Renames the file \a oldName to \a newName. Returns true if
    successful; otherwise returns false.

    If a file with the name \a newName already exists, rename() returns false
    (i.e., QFile will not overwrite it).

    \sa rename()
*/

bool
QFile::rename(const QString &oldName, const QString &newName)
{
    return QFile(oldName).rename(newName);
}

/*!

    Creates a link named \a linkName that points to the file currently specified by
    fileName().  What a link is depends on the underlying filesystem (be it a
    shortcut on Windows or a symbolic link on Unix). Returns true if successful;
    otherwise returns false.

    This function will not overwrite an already existing entity in the file system;
    in this case, \c link() will return false and set \l{QFile::}{error()} to
    return \l{QFile::}{RenameError}.

    \note To create a valid link on Windows, \a linkName must have a \c{.lnk} file extension.

    \note On Symbian, no link is created and false is returned if fileName()
    currently specifies a directory.

    \sa setFileName()
*/

bool
QFile::link(const QString &linkName)
{
    Q_D(QFile);
    if (d->fileName.isEmpty()) {
        qWarning("QFile::link: Empty or null file name");
        return false;
    }
    QFileInfo fi(linkName);
    if(fileEngine()->link(fi.absoluteFilePath())) {
        unsetError();
        return true;
    }
    d->setError(QFile::RenameError, d->fileEngine->errorString());
    return false;
}

/*!
    \overload

    Creates a link named \a linkName that points to the file \a fileName. What a link is
    depends on the underlying filesystem (be it a shortcut on Windows
    or a symbolic link on Unix). Returns true if successful; otherwise
    returns false.

    \sa link()
*/

bool
QFile::link(const QString &fileName, const QString &linkName)
{
    return QFile(fileName).link(linkName);
}

/*!
    Copies the file currently specified by fileName() to a file called
    \a newName.  Returns true if successful; otherwise returns false.

    Note that if a file with the name \a newName already exists,
    copy() returns false (i.e. QFile will not overwrite it).

    The source file is closed before it is copied.

    \sa setFileName()
*/

bool
QFile::copy(const QString &newName)
{
    Q_D(QFile);
    if (d->fileName.isEmpty()) {
        qWarning("QFile::copy: Empty or null file name");
        return false;
    }
    if (QFile(newName).exists()) {
        // ### Race condition. If a file is moved in after this, it /will/ be
        // overwritten. On Unix, the proper solution is to use hardlinks:
        // return ::link(old, new) && ::remove(old); See also rename().
        d->setError(QFile::CopyError, tr("Destination file exists"));
        return false;
    }
    unsetError();
    close();
    if(error() == QFile::NoError) {
        if(fileEngine()->copy(newName)) {
            unsetError();
            return true;
        } else {
            bool error = false;
            if(!open(QFile::ReadOnly)) {
                error = true;
                d->setError(QFile::CopyError, tr("Cannot open %1 for input").arg(d->fileName));
            } else {
                QString fileTemplate = QLatin1String("%1/qt_temp.XXXXXX");
#ifdef QT_NO_TEMPORARYFILE
                QFile out(fileTemplate.arg(QFileInfo(newName).path()));
                if (!out.open(QIODevice::ReadWrite))
                    error = true;
#else
                QTemporaryFile out(fileTemplate.arg(QFileInfo(newName).path()));
                if (!out.open()) {
                    out.setFileTemplate(fileTemplate.arg(QDir::tempPath()));
                    if (!out.open())
                        error = true;
                }
#endif
                if (error) {
                    out.close();
                    d->setError(QFile::CopyError, tr("Cannot open for output"));
                } else {
                    char block[4096];
                    qint64 totalRead = 0;
                    while(!atEnd()) {
                        qint64 in = read(block, sizeof(block));
                        if (in <= 0)
                            break;
                        totalRead += in;
                        if(in != out.write(block, in)) {
                            d->setError(QFile::CopyError, tr("Failure to write block"));
                            error = true;
                            break;
                        }
                    }

                    if (totalRead != size()) {
                        // Unable to read from the source. The error string is
                        // already set from read().
                        error = true;
                    }
                    if (!error && !out.rename(newName)) {
                        error = true;
                        d->setError(QFile::CopyError, tr("Cannot create %1 for output").arg(newName));
                    }
#ifdef QT_NO_TEMPORARYFILE
                    if (error)
                        out.remove();
#else
                    if (!error)
                        out.setAutoRemove(false);
#endif
                }
                close();
            }
            if(!error) {
                QFile::setPermissions(newName, permissions());
                unsetError();
                return true;
            }
        }
    }
    return false;
}

/*!
    \overload

    Copies the file \a fileName to \a newName. Returns true if successful;
    otherwise returns false.

    If a file with the name \a newName already exists, copy() returns false
    (i.e., QFile will not overwrite it).

    \sa rename()
*/

bool
QFile::copy(const QString &fileName, const QString &newName)
{
    return QFile(fileName).copy(newName);
}

/*!
    Returns true if the file can only be manipulated sequentially;
    otherwise returns false.

    Most files support random-access, but some special files may not.

    \sa QIODevice::isSequential()
*/
bool QFile::isSequential() const
{
    Q_D(const QFile);
    return d->fileEngine && d->fileEngine->isSequential();
}

/*!
    Opens the file using OpenMode \a mode, returning true if successful;
    otherwise false.

    The \a mode must be QIODevice::ReadOnly, QIODevice::WriteOnly, or
    QIODevice::ReadWrite. It may also have additional flags, such as
    QIODevice::Text and QIODevice::Unbuffered.

    \note In \l{QIODevice::}{WriteOnly} or \l{QIODevice::}{ReadWrite}
    mode, if the relevant file does not already exist, this function
    will try to create a new file before opening it.

    \sa QIODevice::OpenMode, setFileName()
*/
bool QFile::open(OpenMode mode)
{
    Q_D(QFile);
    if (isOpen()) {
        qWarning("QFile::open: File (%s) already open", qPrintable(fileName()));
        return false;
    }
    if (mode & Append)
        mode |= WriteOnly;

    unsetError();
    if ((mode & (ReadOnly | WriteOnly)) == 0) {
        qWarning("QIODevice::open: File access not specified");
        return false;
    }

#ifdef Q_OS_SYMBIAN
    // For symbian, the unbuffered flag is used to control write-behind cache behaviour
    if (fileEngine()->open(mode))
#else
    // QIODevice provides the buffering, so there's no need to request it from the file engine.
    if (fileEngine()->open(mode | QIODevice::Unbuffered))
#endif
    {
        QIODevice::open(mode);
        if (mode & Append)
            seek(size());
        return true;
    }
    QFile::FileError err = d->fileEngine->error();
    if(err == QFile::UnspecifiedError)
        err = QFile::OpenError;
    d->setError(err, d->fileEngine->errorString());
    return false;
}

/*! \fn QFile::open(OpenMode, FILE*)

    Use open(FILE *, OpenMode) instead.
*/

/*!
    \overload

    Opens the existing file handle \a fh in the given \a mode.
    Returns true if successful; otherwise returns false.

    Example:
    \snippet doc/src/snippets/code/src_corelib_io_qfile.cpp 3

    When a QFile is opened using this function, close() does not actually
    close the file, but only flushes it.

    \bold{Warning:}
    \list 1
        \o If \a fh does not refer to a regular file, e.g., it is \c stdin,
           \c stdout, or \c stderr, you may not be able to seek(). size()
           returns \c 0 in those cases. See QIODevice::isSequential() for
           more information.
        \o Since this function opens the file without specifying the file name,
           you cannot use this QFile with a QFileInfo.
    \endlist

    \note For Windows CE you may not be able to call resize().

    \sa close(), {qmake Variable Reference#CONFIG}{qmake Variable Reference}

    \bold{Note for the Windows Platform}

    \a fh must be opened in binary mode (i.e., the mode string must contain
    'b', as in "rb" or "wb") when accessing files and other random-access
    devices. Qt will translate the end-of-line characters if you pass
    QIODevice::Text to \a mode. Sequential devices, such as stdin and stdout,
    are unaffected by this limitation.

    You need to enable support for console applications in order to use the
    stdin, stdout and stderr streams at the console. To do this, add the
    following declaration to your application's project file:

    \snippet doc/src/snippets/code/src_corelib_io_qfile.cpp 4
*/
bool QFile::open(FILE *fh, OpenMode mode)
{
    Q_D(QFile);
    if (isOpen()) {
        qWarning("QFile::open: File (%s) already open", qPrintable(fileName()));
        return false;
    }
    if (mode & Append)
        mode |= WriteOnly;
    unsetError();
    if ((mode & (ReadOnly | WriteOnly)) == 0) {
        qWarning("QFile::open: File access not specified");
        return false;
    }
    if(d->openExternalFile(mode, fh)) {
        QIODevice::open(mode);
        if (mode & Append) {
            seek(size());
        } else {
            qint64 pos = (qint64)QT_FTELL(fh);
            if (pos != -1)
                seek(pos);
        }
        return true;
    }
    return false;
}

/*! \fn QFile::open(OpenMode, int)

    Use open(int, OpenMode) instead.
*/

/*!
    \overload

    Opens the existing file descriptor \a fd in the given \a mode.
    Returns true if successful; otherwise returns false.

    When a QFile is opened using this function, close() does not
    actually close the file.

    The QFile that is opened using this function is automatically set
    to be in raw mode; this means that the file input/output functions
    are slow. If you run into performance issues, you should try to
    use one of the other open functions.

    \warning If \a fd is not a regular file, e.g, it is 0 (\c stdin),
    1 (\c stdout), or 2 (\c stderr), you may not be able to seek(). In
    those cases, size() returns \c 0.  See QIODevice::isSequential()
    for more information.

    \warning For Windows CE you may not be able to call seek(), setSize(),
    fileTime(). size() returns \c 0.

    \warning Since this function opens the file without specifying the file name,
             you cannot use this QFile with a QFileInfo.

    \sa close()
*/
bool QFile::open(int fd, OpenMode mode)
{
    Q_D(QFile);
    if (isOpen()) {
        qWarning("QFile::open: File (%s) already open", qPrintable(fileName()));
        return false;
    }
    if (mode & Append)
        mode |= WriteOnly;
    unsetError();
    if ((mode & (ReadOnly | WriteOnly)) == 0) {
        qWarning("QFile::open: File access not specified");
        return false;
    }
    if(d->openExternalFile(mode, fd)) {
        QIODevice::open(mode);
        if (mode & Append) {
            seek(size());
        } else {
            qint64 pos = (qint64)QT_LSEEK(fd, QT_OFF_T(0), SEEK_CUR);
            if (pos != -1)
                seek(pos);
        }
        return true;
    }
    return false;
}

/*!
  Returns the file handle of the file.

  This is a small positive integer, suitable for use with C library
  functions such as fdopen() and fcntl(). On systems that use file
  descriptors for sockets (i.e. Unix systems, but not Windows) the handle
  can be used with QSocketNotifier as well.

  If the file is not open, or there is an error, handle() returns -1.

  This function is not supported on Windows CE.

  \sa QSocketNotifier
*/

int
QFile::handle() const
{
    Q_D(const QFile);
    if (!isOpen() || !d->fileEngine)
        return -1;

    return d->fileEngine->handle();
}

/*!
    \enum QFile::MemoryMapFlags
    \since 4.4

    This enum describes special options that may be used by the map()
    function.

    \value NoOptions        No options.
*/

/*!
    \since 4.4
    Maps \a size bytes of the file into memory starting at \a offset.  A file
    should be open for a map to succeed but the file does not need to stay
    open after the memory has been mapped.  When the QFile is destroyed
    or a new file is opened with this object, any maps that have not been
    unmapped will automatically be unmapped.

    Any mapping options can be passed through \a flags.

    Returns a pointer to the memory or 0 if there is an error.

    \note On Windows CE 5.0 the file will be closed before mapping occurs.

    \sa unmap(), QAbstractFileEngine::supportsExtension()
 */
uchar *QFile::map(qint64 offset, qint64 size, MemoryMapFlags flags)
{
    Q_D(QFile);
    if (fileEngine()
            && d->fileEngine->supportsExtension(QAbstractFileEngine::MapExtension)) {
        unsetError();
        uchar *address = d->fileEngine->map(offset, size, flags);
        if (address == 0)
            d->setError(d->fileEngine->error(), d->fileEngine->errorString());
        return address;
    }
    return 0;
}

/*!
    \since 4.4
    Unmaps the memory \a address.

    Returns true if the unmap succeeds; false otherwise.

    \sa map(), QAbstractFileEngine::supportsExtension()
 */
bool QFile::unmap(uchar *address)
{
    Q_D(QFile);
    if (fileEngine()
        && d->fileEngine->supportsExtension(QAbstractFileEngine::UnMapExtension)) {
        unsetError();
        bool success = d->fileEngine->unmap(address);
        if (!success)
            d->setError(d->fileEngine->error(), d->fileEngine->errorString());
        return success;
    }
    d->setError(PermissionsError, tr("No file engine available or engine does not support UnMapExtension"));
    return false;
}

/*!
    \fn QString QFile::name() const

    Use fileName() instead.
*/

/*!
    \fn void QFile::setName(const QString &name)

    Use setFileName() instead.
*/

/*!
    Sets the file size (in bytes) \a sz. Returns true if the file if the
    resize succeeds; false otherwise. If \a sz is larger than the file
    currently is the new bytes will be set to 0, if \a sz is smaller the
    file is simply truncated.

    \sa size(), setFileName()
*/

bool
QFile::resize(qint64 sz)
{
    Q_D(QFile);
    if (!d->ensureFlushed())
        return false;
    fileEngine();
    if (isOpen() && d->fileEngine->pos() > sz)
        seek(sz);
    if(d->fileEngine->setSize(sz)) {
        unsetError();
        d->cachedSize = sz;
        return true;
    }
    d->cachedSize = 0;
    d->setError(QFile::ResizeError, d->fileEngine->errorString());
    return false;
}

/*!
    \overload

    Sets \a fileName to size (in bytes) \a sz. Returns true if the file if
    the resize succeeds; false otherwise. If \a sz is larger than \a
    fileName currently is the new bytes will be set to 0, if \a sz is
    smaller the file is simply truncated.

    \sa resize()
*/

bool
QFile::resize(const QString &fileName, qint64 sz)
{
    return QFile(fileName).resize(sz);
}

/*!
    Returns the complete OR-ed together combination of
    QFile::Permission for the file.

    \sa setPermissions(), setFileName()
*/

QFile::Permissions
QFile::permissions() const
{
    QAbstractFileEngine::FileFlags perms = fileEngine()->fileFlags(QAbstractFileEngine::PermsMask) & QAbstractFileEngine::PermsMask;
    return QFile::Permissions((int)perms); //ewww
}

/*!
    \overload

    Returns the complete OR-ed together combination of
    QFile::Permission for \a fileName.
*/

QFile::Permissions
QFile::permissions(const QString &fileName)
{
    return QFile(fileName).permissions();
}

/*!
    Sets the permissions for the file to the \a permissions specified.
    Returns true if successful, or false if the permissions cannot be
    modified.

    \sa permissions(), setFileName()
*/

bool
QFile::setPermissions(Permissions permissions)
{
    Q_D(QFile);
    if(fileEngine()->setPermissions(permissions)) {
        unsetError();
        return true;
    }
    d->setError(QFile::PermissionsError, d->fileEngine->errorString());
    return false;
}

/*!
    \overload

    Sets the permissions for \a fileName file to \a permissions.
*/

bool
QFile::setPermissions(const QString &fileName, Permissions permissions)
{
    return QFile(fileName).setPermissions(permissions);
}

static inline qint64 _qfile_writeData(QAbstractFileEngine *engine, QRingBuffer *buffer)
{
    qint64 ret = engine->write(buffer->readPointer(), buffer->nextDataBlockSize());
    if (ret > 0)
        buffer->free(ret);
    return ret;
}

/*!
    Flushes any buffered data to the file. Returns true if successful;
    otherwise returns false.
*/

bool
QFile::flush()
{
    Q_D(QFile);
    if (!d->fileEngine) {
        qWarning("QFile::flush: No file engine. Is IODevice open?");
        return false;
    }

    if (!d->writeBuffer.isEmpty()) {
        qint64 size = d->writeBuffer.size();
        if (_qfile_writeData(d->fileEngine, &d->writeBuffer) != size) {
            QFile::FileError err = d->fileEngine->error();
            if(err == QFile::UnspecifiedError)
                err = QFile::WriteError;
            d->setError(err, d->fileEngine->errorString());
            return false;
        }
    }

    if (!d->fileEngine->flush()) {
        QFile::FileError err = d->fileEngine->error();
        if(err == QFile::UnspecifiedError)
            err = QFile::WriteError;
        d->setError(err, d->fileEngine->errorString());
        return false;
    }
    return true;
}

/*!
  Calls QFile::flush() and closes the file. Errors from flush are ignored.

  \sa QIODevice::close()
*/
void
QFile::close()
{
    Q_D(QFile);
    if(!isOpen())
        return;
    bool flushed = flush();
    QIODevice::close();

    // reset write buffer
    d->lastWasWrite = false;
    d->writeBuffer.clear();

    // keep earlier error from flush
    if (d->fileEngine->close() && flushed)
        unsetError();
    else if (flushed)
        d->setError(d->fileEngine->error(), d->fileEngine->errorString());
}

/*!
  Returns the size of the file.

  For regular empty files on Unix (e.g. those in \c /proc), this function
  returns 0; the contents of such a file are generated on demand in response
  to you calling read().
*/

qint64 QFile::size() const
{
    Q_D(const QFile);
    if (!d->ensureFlushed())
        return 0;
    d->cachedSize = fileEngine()->size();
    return d->cachedSize;
}

/*!
  \reimp
*/

qint64 QFile::pos() const
{
    return QIODevice::pos();
}

/*!
  Returns true if the end of the file has been reached; otherwise returns
  false.

  For regular empty files on Unix (e.g. those in \c /proc), this function
  returns true, since the file system reports that the size of such a file is
  0. Therefore, you should not depend on atEnd() when reading data from such a
  file, but rather call read() until no more data can be read.
*/

bool QFile::atEnd() const
{
    Q_D(const QFile);

    // If there's buffered data left, we're not at the end.
    if (!d->buffer.isEmpty())
        return false;

    if (!isOpen())
        return true;

    if (!d->ensureFlushed())
        return false;

    // If the file engine knows best, say what it says.
    if (d->fileEngine->supportsExtension(QAbstractFileEngine::AtEndExtension)) {
        // Check if the file engine supports AtEndExtension, and if it does,
        // check if the file engine claims to be at the end.
        return d->fileEngine->atEnd();
    }

    // if it looks like we are at the end, or if size is not cached,
    // fall through to bytesAvailable() to make sure.
    if (pos() < d->cachedSize)
        return false;

    // Fall back to checking how much is available (will stat files).
    return bytesAvailable() == 0;
}

/*!
    For random-access devices, this function sets the current position
    to \a pos, returning true on success, or false if an error occurred.
    For sequential devices, the default behavior is to do nothing and
    return false.

    Seeking beyond the end of a file:
    If the position is beyond the end of a file, then seek() shall not
    immediately extend the file. If a write is performed at this position,
    then the file shall be extended. The content of the file between the
    previous end of file and the newly written data is UNDEFINED and
    varies between platforms and file systems.
*/

bool QFile::seek(qint64 off)
{
    Q_D(QFile);
    if (!isOpen()) {
        qWarning("QFile::seek: IODevice is not open");
        return false;
    }

    if (!d->ensureFlushed())
        return false;

    if (!d->fileEngine->seek(off) || !QIODevice::seek(off)) {
        QFile::FileError err = d->fileEngine->error();
        if(err == QFile::UnspecifiedError)
            err = QFile::PositionError;
        d->setError(err, d->fileEngine->errorString());
        return false;
    }
    unsetError();
    return true;
}

/*!
  \reimp
*/
qint64 QFile::readLineData(char *data, qint64 maxlen)
{
    Q_D(QFile);
    if (!d->ensureFlushed())
        return -1;

    qint64 read;
    if (d->fileEngine->supportsExtension(QAbstractFileEngine::FastReadLineExtension)) {
        read = d->fileEngine->readLine(data, maxlen);
    } else {
        // Fall back to QIODevice's readLine implementation if the engine
        // cannot do it faster.
        read = QIODevice::readLineData(data, maxlen);
    }

    if (read < maxlen) {
        // failed to read all requested, may be at the end of file, stop caching size so that it's rechecked
        d->cachedSize = 0;
    }

    return read;
}

/*!
  \reimp
*/

qint64 QFile::readData(char *data, qint64 len)
{
    Q_D(QFile);
    unsetError();
    if (!d->ensureFlushed())
        return -1;

    qint64 read = d->fileEngine->read(data, len);
    if(read < 0) {
        QFile::FileError err = d->fileEngine->error();
        if(err == QFile::UnspecifiedError)
            err = QFile::ReadError;
        d->setError(err, d->fileEngine->errorString());
    }

    if (read < len) {
        // failed to read all requested, may be at the end of file, stop caching size so that it's rechecked
        d->cachedSize = 0;
    }

    return read;
}

/*!
    \internal
*/
bool QFilePrivate::putCharHelper(char c)
{
#ifdef QT_NO_QOBJECT
    return QIODevicePrivate::putCharHelper(c);
#else

    // Cutoff for code that doesn't only touch the buffer.
    int writeBufferSize = writeBuffer.size();
    if ((openMode & QIODevice::Unbuffered) || writeBufferSize + 1 >= QFILE_WRITEBUFFER_SIZE
#ifdef Q_OS_WIN
        || ((openMode & QIODevice::Text) && c == '\n' && writeBufferSize + 2 >= QFILE_WRITEBUFFER_SIZE)
#endif
        ) {
        return QIODevicePrivate::putCharHelper(c);
    }

    if (!(openMode & QIODevice::WriteOnly)) {
        if (openMode == QIODevice::NotOpen)
            qWarning("QIODevice::putChar: Closed device");
        else
            qWarning("QIODevice::putChar: ReadOnly device");
        return false;
    }

    // Make sure the device is positioned correctly.
    const bool sequential = isSequential();
    if (pos != devicePos && !sequential && !q_func()->seek(pos))
        return false;

    lastWasWrite = true;

    int len = 1;
#ifdef Q_OS_WIN
    if ((openMode & QIODevice::Text) && c == '\n') {
        ++len;
        *writeBuffer.reserve(1) = '\r';
    }
#endif

    // Write to buffer.
    *writeBuffer.reserve(1) = c;

    if (!sequential) {
        pos += len;
        devicePos += len;
        if (!buffer.isEmpty())
            buffer.skip(len);
    }

    return true;
#endif
}

/*!
  \reimp
*/

qint64
QFile::writeData(const char *data, qint64 len)
{
    Q_D(QFile);
    unsetError();
    d->lastWasWrite = true;
    bool buffered = !(d->openMode & Unbuffered);

    // Flush buffered data if this read will overflow.
    if (buffered && (d->writeBuffer.size() + len) > QFILE_WRITEBUFFER_SIZE) {
        if (!flush())
            return -1;
    }

    // Write directly to the engine if the block size is larger than
    // the write buffer size.
    if (!buffered || len > QFILE_WRITEBUFFER_SIZE) {
        qint64 ret = d->fileEngine->write(data, len);
        if(ret < 0) {
            QFile::FileError err = d->fileEngine->error();
            if(err == QFile::UnspecifiedError)
                err = QFile::WriteError;
            d->setError(err, d->fileEngine->errorString());
        }
        return ret;
    }

    // Write to the buffer.
    char *writePointer = d->writeBuffer.reserve(len);
    if (len == 1)
        *writePointer = *data;
    else
        ::memcpy(writePointer, data, len);
    return len;
}

/*!
    \internal
    Returns the QIOEngine for this QFile object.
*/
QAbstractFileEngine *QFile::fileEngine() const
{
    Q_D(const QFile);
    if(!d->fileEngine)
        d->fileEngine = QAbstractFileEngine::create(d->fileName);
    return d->fileEngine;
}

/*!
    Returns the file error status.

    The I/O device status returns an error code. For example, if open()
    returns false, or a read/write operation returns -1, this function can
    be called to find out the reason why the operation failed.

    \sa unsetError()
*/

QFile::FileError
QFile::error() const
{
    Q_D(const QFile);
    return d->error;
}

/*!
    Sets the file's error to QFile::NoError.

    \sa error()
*/
void
QFile::unsetError()
{
    Q_D(QFile);
    d->setError(QFile::NoError);
}

QT_END_NAMESPACE