There should only be one write buffer at a time in QFile
[qt-netbsd.git] / src / corelib / io / qfile.cpp
blobd4077bcb23f73f74a71598edaebc04abb37cfe3d
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42 #include "qplatformdefs.h"
43 #include "qdebug.h"
44 #include "qfile.h"
45 #include "qfsfileengine.h"
46 #include "qtemporaryfile.h"
47 #include "qlist.h"
48 #include "qfileinfo.h"
49 #include "private/qiodevice_p.h"
50 #include "private/qfile_p.h"
51 #if defined(QT_BUILD_CORE_LIB)
52 # include "qcoreapplication.h"
53 #endif
55 #ifdef QT_NO_QOBJECT
56 #define tr(X) QString::fromLatin1(X)
57 #endif
59 QT_BEGIN_NAMESPACE
61 static const int QFILE_WRITEBUFFER_SIZE = 16384;
63 static QByteArray locale_encode(const QString &f)
65 #ifndef Q_OS_DARWIN
66 return f.toLocal8Bit();
67 #else
68 // Mac always expects UTF-8... and decomposed...
69 return f.normalized(QString::NormalizationForm_D).toUtf8();
70 #endif
73 static QString locale_decode(const QByteArray &f)
75 #ifndef Q_OS_DARWIN
76 return QString::fromLocal8Bit(f);
77 #else
78 // Mac always gives us UTF-8 and decomposed, we want that composed...
79 return QString::fromUtf8(f).normalized(QString::NormalizationForm_C);
80 #endif
83 //************* QFilePrivate
84 QFile::EncoderFn QFilePrivate::encoder = locale_encode;
85 QFile::DecoderFn QFilePrivate::decoder = locale_decode;
87 QFilePrivate::QFilePrivate()
88 : fileEngine(0), lastWasWrite(false),
89 writeBuffer(QFILE_WRITEBUFFER_SIZE), error(QFile::NoError)
93 QFilePrivate::~QFilePrivate()
95 delete fileEngine;
96 fileEngine = 0;
99 bool
100 QFilePrivate::openExternalFile(int flags, int fd)
102 #ifdef QT_NO_FSFILEENGINE
103 Q_UNUSED(flags);
104 Q_UNUSED(fd);
105 return false;
106 #else
107 delete fileEngine;
108 fileEngine = 0;
109 QFSFileEngine *fe = new QFSFileEngine;
110 fe->setFileName(fileName);
111 fileEngine = fe;
112 return fe->open(QIODevice::OpenMode(flags), fd);
113 #endif
116 bool
117 QFilePrivate::openExternalFile(int flags, FILE *fh)
119 #ifdef QT_NO_FSFILEENGINE
120 Q_UNUSED(flags);
121 Q_UNUSED(fh);
122 return false;
123 #else
124 delete fileEngine;
125 fileEngine = 0;
126 QFSFileEngine *fe = new QFSFileEngine;
127 fe->setFileName(fileName);
128 fileEngine = fe;
129 return fe->open(QIODevice::OpenMode(flags), fh);
130 #endif
133 inline bool QFilePrivate::ensureFlushed() const
135 // This function ensures that the write buffer has been flushed (const
136 // because certain const functions need to call it.
137 if (lastWasWrite) {
138 const_cast<QFilePrivate *>(this)->lastWasWrite = false;
139 if (!const_cast<QFile *>(q_func())->flush())
140 return false;
142 return true;
145 void
146 QFilePrivate::setError(QFile::FileError err)
148 error = err;
149 errorString.clear();
152 void
153 QFilePrivate::setError(QFile::FileError err, const QString &errStr)
155 error = err;
156 errorString = errStr;
159 void
160 QFilePrivate::setError(QFile::FileError err, int errNum)
162 error = err;
163 errorString = qt_error_string(errNum);
166 //************* QFile
169 \class QFile
170 \brief The QFile class provides an interface for reading from and writing to files.
172 \ingroup io
174 \reentrant
176 QFile is an I/O device for reading and writing text and binary
177 files and \l{The Qt Resource System}{resources}. A QFile may be
178 used by itself or, more conveniently, with a QTextStream or
179 QDataStream.
181 The file name is usually passed in the constructor, but it can be
182 set at any time using setFileName(). QFile expects the file
183 separator to be '/' regardless of operating system. The use of
184 other separators (e.g., '\\') is not supported.
186 You can check for a file's existence using exists(), and remove a
187 file using remove(). (More advanced file system related operations
188 are provided by QFileInfo and QDir.)
190 The file is opened with open(), closed with close(), and flushed
191 with flush(). Data is usually read and written using QDataStream
192 or QTextStream, but you can also call the QIODevice-inherited
193 functions read(), readLine(), readAll(), write(). QFile also
194 inherits getChar(), putChar(), and ungetChar(), which work one
195 character at a time.
197 The size of the file is returned by size(). You can get the
198 current file position using pos(), or move to a new file position
199 using seek(). If you've reached the end of the file, atEnd()
200 returns true.
202 \section1 Reading Files Directly
204 The following example reads a text file line by line:
206 \snippet doc/src/snippets/file/file.cpp 0
208 The QIODevice::Text flag passed to open() tells Qt to convert
209 Windows-style line terminators ("\\r\\n") into C++-style
210 terminators ("\\n"). By default, QFile assumes binary, i.e. it
211 doesn't perform any conversion on the bytes stored in the file.
213 \section1 Using Streams to Read Files
215 The next example uses QTextStream to read a text file
216 line by line:
218 \snippet doc/src/snippets/file/file.cpp 1
220 QTextStream takes care of converting the 8-bit data stored on
221 disk into a 16-bit Unicode QString. By default, it assumes that
222 the user system's local 8-bit encoding is used (e.g., ISO 8859-1
223 for most of Europe; see QTextCodec::codecForLocale() for
224 details). This can be changed using setCodec().
226 To write text, we can use operator<<(), which is overloaded to
227 take a QTextStream on the left and various data types (including
228 QString) on the right:
230 \snippet doc/src/snippets/file/file.cpp 2
232 QDataStream is similar, in that you can use operator<<() to write
233 data and operator>>() to read it back. See the class
234 documentation for details.
236 When you use QFile, QFileInfo, and QDir to access the file system
237 with Qt, you can use Unicode file names. On Unix, these file
238 names are converted to an 8-bit encoding. If you want to use
239 standard C++ APIs (\c <cstdio> or \c <iostream>) or
240 platform-specific APIs to access files instead of QFile, you can
241 use the encodeName() and decodeName() functions to convert
242 between Unicode file names and 8-bit file names.
244 On Unix, there are some special system files (e.g. in \c /proc) for which
245 size() will always return 0, yet you may still be able to read more data
246 from such a file; the data is generated in direct response to you calling
247 read(). In this case, however, you cannot use atEnd() to determine if
248 there is more data to read (since atEnd() will return true for a file that
249 claims to have size 0). Instead, you should either call readAll(), or call
250 read() or readLine() repeatedly until no more data can be read. The next
251 example uses QTextStream to read \c /proc/modules line by line:
253 \snippet doc/src/snippets/file/file.cpp 3
255 \section1 Signals
257 Unlike other QIODevice implementations, such as QTcpSocket, QFile does not
258 emit the aboutToClose(), bytesWritten(), or readyRead() signals. This
259 implementation detail means that QFile is not suitable for reading and
260 writing certain types of files, such as device files on Unix platforms.
262 \section1 Platform Specific Issues
264 File permissions are handled differently on Linux/Mac OS X and
265 Windows. In a non \l{QIODevice::isWritable()}{writable}
266 directory on Linux, files cannot be created. This is not always
267 the case on Windows, where, for instance, the 'My Documents'
268 directory usually is not writable, but it is still possible to
269 create files in it.
271 \sa QTextStream, QDataStream, QFileInfo, QDir, {The Qt Resource System}
275 \enum QFile::FileError
277 This enum describes the errors that may be returned by the error()
278 function.
280 \value NoError No error occurred.
281 \value ReadError An error occurred when reading from the file.
282 \value WriteError An error occurred when writing to the file.
283 \value FatalError A fatal error occurred.
284 \value ResourceError
285 \value OpenError The file could not be opened.
286 \value AbortError The operation was aborted.
287 \value TimeOutError A timeout occurred.
288 \value UnspecifiedError An unspecified error occurred.
289 \value RemoveError The file could not be removed.
290 \value RenameError The file could not be renamed.
291 \value PositionError The position in the file could not be changed.
292 \value ResizeError The file could not be resized.
293 \value PermissionsError The file could not be accessed.
294 \value CopyError The file could not be copied.
296 \omitvalue ConnectError
300 \enum QFile::Permission
302 This enum is used by the permission() function to report the
303 permissions and ownership of a file. The values may be OR-ed
304 together to test multiple permissions and ownership values.
306 \value ReadOwner The file is readable by the owner of the file.
307 \value WriteOwner The file is writable by the owner of the file.
308 \value ExeOwner The file is executable by the owner of the file.
309 \value ReadUser The file is readable by the user.
310 \value WriteUser The file is writable by the user.
311 \value ExeUser The file is executable by the user.
312 \value ReadGroup The file is readable by the group.
313 \value WriteGroup The file is writable by the group.
314 \value ExeGroup The file is executable by the group.
315 \value ReadOther The file is readable by anyone.
316 \value WriteOther The file is writable by anyone.
317 \value ExeOther The file is executable by anyone.
319 \warning Because of differences in the platforms supported by Qt,
320 the semantics of ReadUser, WriteUser and ExeUser are
321 platform-dependent: On Unix, the rights of the owner of the file
322 are returned and on Windows the rights of the current user are
323 returned. This behavior might change in a future Qt version.
325 Note that Qt does not by default check for permissions on NTFS
326 file systems, as this may decrease the performance of file
327 handling considerably. It is possible to force permission checking
328 on NTFS by including the following code in your source:
330 \snippet doc/src/snippets/ntfsp.cpp 0
332 Permission checking is then turned on and off by incrementing and
333 decrementing \c qt_ntfs_permission_lookup by 1.
335 \snippet doc/src/snippets/ntfsp.cpp 1
338 #ifdef QT3_SUPPORT
340 \typedef QFile::PermissionSpec
342 Use QFile::Permission instead.
344 #endif
346 #ifdef QT_NO_QOBJECT
347 QFile::QFile()
348 : QIODevice(*new QFilePrivate)
351 QFile::QFile(const QString &name)
352 : QIODevice(*new QFilePrivate)
354 d_func()->fileName = name;
356 QFile::QFile(QFilePrivate &dd)
357 : QIODevice(dd)
360 #else
362 \internal
364 QFile::QFile()
365 : QIODevice(*new QFilePrivate, 0)
369 Constructs a new file object with the given \a parent.
371 QFile::QFile(QObject *parent)
372 : QIODevice(*new QFilePrivate, parent)
376 Constructs a new file object to represent the file with the given \a name.
378 QFile::QFile(const QString &name)
379 : QIODevice(*new QFilePrivate, 0)
381 Q_D(QFile);
382 d->fileName = name;
385 Constructs a new file object with the given \a parent to represent the
386 file with the specified \a name.
388 QFile::QFile(const QString &name, QObject *parent)
389 : QIODevice(*new QFilePrivate, parent)
391 Q_D(QFile);
392 d->fileName = name;
395 \internal
397 QFile::QFile(QFilePrivate &dd, QObject *parent)
398 : QIODevice(dd, parent)
401 #endif
404 Destroys the file object, closing it if necessary.
406 QFile::~QFile()
408 close();
412 Returns the name set by setFileName() or to the QFile
413 constructors.
415 \sa setFileName(), QFileInfo::fileName()
417 QString QFile::fileName() const
419 return fileEngine()->fileName(QAbstractFileEngine::DefaultName);
423 Sets the \a name of the file. The name can have no path, a
424 relative path, or an absolute path.
426 Do not call this function if the file has already been opened.
428 If the file name has no path or a relative path, the path used
429 will be the application's current directory path
430 \e{at the time of the open()} call.
432 Example:
433 \snippet doc/src/snippets/code/src_corelib_io_qfile.cpp 0
435 Note that the directory separator "/" works for all operating
436 systems supported by Qt.
438 \sa fileName(), QFileInfo, QDir
440 void
441 QFile::setFileName(const QString &name)
443 Q_D(QFile);
444 if (isOpen()) {
445 qWarning("QFile::setFileName: File (%s) is already opened",
446 qPrintable(fileName()));
447 close();
449 if(d->fileEngine) { //get a new file engine later
450 delete d->fileEngine;
451 d->fileEngine = 0;
453 d->fileName = name;
457 \fn QString QFile::decodeName(const char *localFileName)
459 \overload
461 Returns the Unicode version of the given \a localFileName. See
462 encodeName() for details.
466 By default, this function converts \a fileName to the local 8-bit
467 encoding determined by the user's locale. This is sufficient for
468 file names that the user chooses. File names hard-coded into the
469 application should only use 7-bit ASCII filename characters.
471 \sa decodeName() setEncodingFunction()
474 QByteArray
475 QFile::encodeName(const QString &fileName)
477 return (*QFilePrivate::encoder)(fileName);
481 \typedef QFile::EncoderFn
483 This is a typedef for a pointer to a function with the following
484 signature:
486 \snippet doc/src/snippets/code/src_corelib_io_qfile.cpp 1
488 \sa setEncodingFunction(), encodeName()
492 This does the reverse of QFile::encodeName() using \a localFileName.
494 \sa setDecodingFunction(), encodeName()
497 QString
498 QFile::decodeName(const QByteArray &localFileName)
500 return (*QFilePrivate::decoder)(localFileName);
504 \fn void QFile::setEncodingFunction(EncoderFn function)
506 \nonreentrant
508 Sets the \a function for encoding Unicode file names. The
509 default encodes in the locale-specific 8-bit encoding.
511 \sa encodeName(), setDecodingFunction()
514 void
515 QFile::setEncodingFunction(EncoderFn f)
517 if (!f)
518 f = locale_encode;
519 QFilePrivate::encoder = f;
523 \typedef QFile::DecoderFn
525 This is a typedef for a pointer to a function with the following
526 signature:
528 \snippet doc/src/snippets/code/src_corelib_io_qfile.cpp 2
530 \sa setDecodingFunction()
534 \fn void QFile::setDecodingFunction(DecoderFn function)
536 \nonreentrant
538 Sets the \a function for decoding 8-bit file names. The
539 default uses the locale-specific 8-bit encoding.
541 \sa setEncodingFunction(), decodeName()
544 void
545 QFile::setDecodingFunction(DecoderFn f)
547 if (!f)
548 f = locale_decode;
549 QFilePrivate::decoder = f;
553 \overload
555 Returns true if the file specified by fileName() exists; otherwise
556 returns false.
558 \sa fileName(), setFileName()
561 bool
562 QFile::exists() const
564 // 0x1000000 = QAbstractFileEngine::Refresh, forcing an update
565 return (fileEngine()->fileFlags(QAbstractFileEngine::FlagsMask
566 | QAbstractFileEngine::FileFlag(0x1000000)) & QAbstractFileEngine::ExistsFlag);
570 Returns true if the file specified by \a fileName exists; otherwise
571 returns false.
574 bool
575 QFile::exists(const QString &fileName)
577 return QFileInfo(fileName).exists();
581 \fn QString QFile::symLinkTarget() const
582 \since 4.2
583 \overload
585 Returns the absolute path of the file or directory a symlink (or shortcut
586 on Windows) points to, or a an empty string if the object isn't a symbolic
587 link.
589 This name may not represent an existing file; it is only a string.
590 QFile::exists() returns true if the symlink points to an existing file.
592 \sa fileName() setFileName()
596 \obsolete
598 Use symLinkTarget() instead.
600 QString
601 QFile::readLink() const
603 return fileEngine()->fileName(QAbstractFileEngine::LinkName);
607 \fn static QString QFile::symLinkTarget(const QString &fileName)
608 \since 4.2
610 Returns the absolute path of the file or directory referred to by the
611 symlink (or shortcut on Windows) specified by \a fileName, or returns an
612 empty string if the \a fileName does not correspond to a symbolic link.
614 This name may not represent an existing file; it is only a string.
615 QFile::exists() returns true if the symlink points to an existing file.
619 \obsolete
621 Use symLinkTarget() instead.
623 QString
624 QFile::readLink(const QString &fileName)
626 return QFileInfo(fileName).readLink();
630 Removes the file specified by fileName(). Returns true if successful;
631 otherwise returns false.
633 The file is closed before it is removed.
635 \sa setFileName()
638 bool
639 QFile::remove()
641 Q_D(QFile);
642 if (d->fileName.isEmpty()) {
643 qWarning("QFile::remove: Empty or null file name");
644 return false;
646 close();
647 if(error() == QFile::NoError) {
648 if(fileEngine()->remove()) {
649 unsetError();
650 return true;
652 d->setError(QFile::RemoveError, fileEngine()->errorString());
654 return false;
658 \overload
660 Removes the file specified by the \a fileName given.
662 Returns true if successful; otherwise returns false.
664 \sa remove()
667 bool
668 QFile::remove(const QString &fileName)
670 return QFile(fileName).remove();
674 Renames the file currently specified by fileName() to \a newName.
675 Returns true if successful; otherwise returns false.
677 If a file with the name \a newName already exists, rename() returns false
678 (i.e., QFile will not overwrite it).
680 The file is closed before it is renamed.
682 \sa setFileName()
685 bool
686 QFile::rename(const QString &newName)
688 Q_D(QFile);
689 if (d->fileName.isEmpty()) {
690 qWarning("QFile::rename: Empty or null file name");
691 return false;
693 if (QFile(newName).exists()) {
694 // ### Race condition. If a file is moved in after this, it /will/ be
695 // overwritten. On Unix, the proper solution is to use hardlinks:
696 // return ::link(old, new) && ::remove(old);
697 d->setError(QFile::RenameError, tr("Destination file exists"));
698 return false;
700 unsetError();
701 close();
702 if(error() == QFile::NoError) {
703 if (fileEngine()->rename(newName)) {
704 unsetError();
705 // engine was able to handle the new name so we just reset it
706 fileEngine()->setFileName(newName);
707 d->fileName = newName;
708 return true;
711 if (isSequential()) {
712 d->setError(QFile::RenameError, tr("Will not rename sequential file using block copy"));
713 return false;
716 QFile out(newName);
717 if (open(QIODevice::ReadOnly)) {
718 if (out.open(QIODevice::WriteOnly | QIODevice::Truncate)) {
719 bool error = false;
720 char block[4096];
721 qint64 bytes;
722 while ((bytes = read(block, sizeof(block))) > 0) {
723 if (bytes != out.write(block, bytes)) {
724 d->setError(QFile::RenameError, out.errorString());
725 error = true;
726 break;
729 if (bytes == -1) {
730 d->setError(QFile::RenameError, errorString());
731 error = true;
733 if(!error) {
734 if (!remove()) {
735 d->setError(QFile::RenameError, tr("Cannot remove source file"));
736 error = true;
739 if (error) {
740 out.remove();
741 } else {
742 fileEngine()->setFileName(newName);
743 setPermissions(permissions());
744 unsetError();
745 setFileName(newName);
747 close();
748 return !error;
750 close();
752 d->setError(QFile::RenameError, out.isOpen() ? errorString() : out.errorString());
754 return false;
758 \overload
760 Renames the file \a oldName to \a newName. Returns true if
761 successful; otherwise returns false.
763 If a file with the name \a newName already exists, rename() returns false
764 (i.e., QFile will not overwrite it).
766 \sa rename()
769 bool
770 QFile::rename(const QString &oldName, const QString &newName)
772 return QFile(oldName).rename(newName);
777 Creates a link named \a linkName that points to the file currently specified by
778 fileName(). What a link is depends on the underlying filesystem (be it a
779 shortcut on Windows or a symbolic link on Unix). Returns true if successful;
780 otherwise returns false.
782 This function will not overwrite an already existing entity in the file system;
783 in this case, \c link() will return false and set \l{QFile::}{error()} to
784 return \l{QFile::}{RenameError}.
786 \note To create a valid link on Windows, \a linkName must have a \c{.lnk} file extension.
788 \note On Symbian, no link is created and false is returned if fileName()
789 currently specifies a directory.
791 \sa setFileName()
794 bool
795 QFile::link(const QString &linkName)
797 Q_D(QFile);
798 if (d->fileName.isEmpty()) {
799 qWarning("QFile::link: Empty or null file name");
800 return false;
802 QFileInfo fi(linkName);
803 if(fileEngine()->link(fi.absoluteFilePath())) {
804 unsetError();
805 return true;
807 d->setError(QFile::RenameError, fileEngine()->errorString());
808 return false;
812 \overload
814 Creates a link named \a linkName that points to the file \a fileName. What a link is
815 depends on the underlying filesystem (be it a shortcut on Windows
816 or a symbolic link on Unix). Returns true if successful; otherwise
817 returns false.
819 \sa link()
822 bool
823 QFile::link(const QString &fileName, const QString &linkName)
825 return QFile(fileName).link(linkName);
829 Copies the file currently specified by fileName() to a file called
830 \a newName. Returns true if successful; otherwise returns false.
832 Note that if a file with the name \a newName already exists,
833 copy() returns false (i.e. QFile will not overwrite it).
835 The source file is closed before it is copied.
837 \sa setFileName()
840 bool
841 QFile::copy(const QString &newName)
843 Q_D(QFile);
844 if (d->fileName.isEmpty()) {
845 qWarning("QFile::copy: Empty or null file name");
846 return false;
848 if (QFile(newName).exists()) {
849 // ### Race condition. If a file is moved in after this, it /will/ be
850 // overwritten. On Unix, the proper solution is to use hardlinks:
851 // return ::link(old, new) && ::remove(old); See also rename().
852 d->setError(QFile::CopyError, tr("Destination file exists"));
853 return false;
855 unsetError();
856 close();
857 if(error() == QFile::NoError) {
858 if(fileEngine()->copy(newName)) {
859 unsetError();
860 return true;
861 } else {
862 bool error = false;
863 if(!open(QFile::ReadOnly)) {
864 error = true;
865 d->setError(QFile::CopyError, tr("Cannot open %1 for input").arg(d->fileName));
866 } else {
867 QString fileTemplate = QLatin1String("%1/qt_temp.XXXXXX");
868 #ifdef QT_NO_TEMPORARYFILE
869 QFile out(fileTemplate.arg(QFileInfo(newName).path()));
870 if (!out.open(QIODevice::ReadWrite))
871 error = true;
872 #else
873 QTemporaryFile out(fileTemplate.arg(QFileInfo(newName).path()));
874 if (!out.open()) {
875 out.setFileTemplate(fileTemplate.arg(QDir::tempPath()));
876 if (!out.open())
877 error = true;
879 #endif
880 if (error) {
881 out.close();
882 d->setError(QFile::CopyError, tr("Cannot open for output"));
883 } else {
884 char block[4096];
885 qint64 totalRead = 0;
886 while(!atEnd()) {
887 qint64 in = read(block, sizeof(block));
888 if (in <= 0)
889 break;
890 totalRead += in;
891 if(in != out.write(block, in)) {
892 d->setError(QFile::CopyError, tr("Failure to write block"));
893 error = true;
894 break;
898 if (totalRead != size()) {
899 // Unable to read from the source. The error string is
900 // already set from read().
901 error = true;
903 if (!error && !out.rename(newName)) {
904 error = true;
905 d->setError(QFile::CopyError, tr("Cannot create %1 for output").arg(newName));
907 #ifdef QT_NO_TEMPORARYFILE
908 if (error)
909 out.remove();
910 #else
911 if (!error)
912 out.setAutoRemove(false);
913 #endif
915 close();
917 if(!error) {
918 QFile::setPermissions(newName, permissions());
919 unsetError();
920 return true;
924 return false;
928 \overload
930 Copies the file \a fileName to \a newName. Returns true if successful;
931 otherwise returns false.
933 If a file with the name \a newName already exists, copy() returns false
934 (i.e., QFile will not overwrite it).
936 \sa rename()
939 bool
940 QFile::copy(const QString &fileName, const QString &newName)
942 return QFile(fileName).copy(newName);
946 Returns true if the file can only be manipulated sequentially;
947 otherwise returns false.
949 Most files support random-access, but some special files may not.
951 \sa QIODevice::isSequential()
953 bool QFile::isSequential() const
955 Q_D(const QFile);
956 return d->fileEngine && d->fileEngine->isSequential();
960 Opens the file using OpenMode \a mode, returning true if successful;
961 otherwise false.
963 The \a mode must be QIODevice::ReadOnly, QIODevice::WriteOnly, or
964 QIODevice::ReadWrite. It may also have additional flags, such as
965 QIODevice::Text and QIODevice::Unbuffered.
967 \note In \l{QIODevice::}{WriteOnly} or \l{QIODevice::}{ReadWrite}
968 mode, if the relevant file does not already exist, this function
969 will try to create a new file before opening it.
971 \note Because of limitations in the native API, QFile ignores the
972 Unbuffered flag on Windows.
974 \sa QIODevice::OpenMode, setFileName()
976 bool QFile::open(OpenMode mode)
978 Q_D(QFile);
979 if (isOpen()) {
980 qWarning("QFile::open: File (%s) already open", qPrintable(fileName()));
981 return false;
983 if (mode & Append)
984 mode |= WriteOnly;
986 unsetError();
987 if ((mode & (ReadOnly | WriteOnly)) == 0) {
988 qWarning("QIODevice::open: File access not specified");
989 return false;
991 if (fileEngine()->open(mode)) {
992 QIODevice::open(mode);
993 if (mode & Append)
994 seek(size());
995 return true;
997 QFile::FileError err = fileEngine()->error();
998 if(err == QFile::UnspecifiedError)
999 err = QFile::OpenError;
1000 d->setError(err, fileEngine()->errorString());
1001 return false;
1004 /*! \fn QFile::open(OpenMode, FILE*)
1006 Use open(FILE *, OpenMode) instead.
1010 \overload
1012 Opens the existing file handle \a fh in the given \a mode.
1013 Returns true if successful; otherwise returns false.
1015 Example:
1016 \snippet doc/src/snippets/code/src_corelib_io_qfile.cpp 3
1018 When a QFile is opened using this function, close() does not actually
1019 close the file, but only flushes it.
1021 \bold{Warning:}
1022 \list 1
1023 \o If \a fh does not refer to a regular file, e.g., it is \c stdin,
1024 \c stdout, or \c stderr, you may not be able to seek(). size()
1025 returns \c 0 in those cases. See QIODevice::isSequential() for
1026 more information.
1027 \o Since this function opens the file without specifying the file name,
1028 you cannot use this QFile with a QFileInfo.
1029 \endlist
1031 \note For Windows CE you may not be able to call resize().
1033 \sa close(), {qmake Variable Reference#CONFIG}{qmake Variable Reference}
1035 \bold{Note for the Windows Platform}
1037 \a fh must be opened in binary mode (i.e., the mode string must contain
1038 'b', as in "rb" or "wb") when accessing files and other random-access
1039 devices. Qt will translate the end-of-line characters if you pass
1040 QIODevice::Text to \a mode. Sequential devices, such as stdin and stdout,
1041 are unaffected by this limitation.
1043 You need to enable support for console applications in order to use the
1044 stdin, stdout and stderr streams at the console. To do this, add the
1045 following declaration to your application's project file:
1047 \snippet doc/src/snippets/code/src_corelib_io_qfile.cpp 4
1049 bool QFile::open(FILE *fh, OpenMode mode)
1051 Q_D(QFile);
1052 if (isOpen()) {
1053 qWarning("QFile::open: File (%s) already open", qPrintable(fileName()));
1054 return false;
1056 if (mode & Append)
1057 mode |= WriteOnly;
1058 unsetError();
1059 if ((mode & (ReadOnly | WriteOnly)) == 0) {
1060 qWarning("QFile::open: File access not specified");
1061 return false;
1063 if(d->openExternalFile(mode, fh)) {
1064 QIODevice::open(mode);
1065 if (mode & Append) {
1066 seek(size());
1067 } else {
1068 qint64 pos = (qint64)QT_FTELL(fh);
1069 if (pos != -1)
1070 seek(pos);
1072 return true;
1074 return false;
1077 /*! \fn QFile::open(OpenMode, int)
1079 Use open(int, OpenMode) instead.
1083 \overload
1085 Opens the existing file descriptor \a fd in the given \a mode.
1086 Returns true if successful; otherwise returns false.
1088 When a QFile is opened using this function, close() does not
1089 actually close the file.
1091 The QFile that is opened using this function is automatically set
1092 to be in raw mode; this means that the file input/output functions
1093 are slow. If you run into performance issues, you should try to
1094 use one of the other open functions.
1096 \warning If \a fd is not a regular file, e.g, it is 0 (\c stdin),
1097 1 (\c stdout), or 2 (\c stderr), you may not be able to seek(). In
1098 those cases, size() returns \c 0. See QIODevice::isSequential()
1099 for more information.
1101 \warning For Windows CE you may not be able to call seek(), setSize(),
1102 fileTime(). size() returns \c 0.
1104 \warning Since this function opens the file without specifying the file name,
1105 you cannot use this QFile with a QFileInfo.
1107 \sa close()
1109 bool QFile::open(int fd, OpenMode mode)
1111 Q_D(QFile);
1112 if (isOpen()) {
1113 qWarning("QFile::open: File (%s) already open", qPrintable(fileName()));
1114 return false;
1116 if (mode & Append)
1117 mode |= WriteOnly;
1118 unsetError();
1119 if ((mode & (ReadOnly | WriteOnly)) == 0) {
1120 qWarning("QFile::open: File access not specified");
1121 return false;
1123 if(d->openExternalFile(mode, fd)) {
1124 QIODevice::open(mode);
1125 if (mode & Append) {
1126 seek(size());
1127 } else {
1128 qint64 pos = (qint64)QT_LSEEK(fd, QT_OFF_T(0), SEEK_CUR);
1129 if (pos != -1)
1130 seek(pos);
1132 return true;
1134 return false;
1138 Returns the file handle of the file.
1140 This is a small positive integer, suitable for use with C library
1141 functions such as fdopen() and fcntl(). On systems that use file
1142 descriptors for sockets (i.e. Unix systems, but not Windows) the handle
1143 can be used with QSocketNotifier as well.
1145 If the file is not open, or there is an error, handle() returns -1.
1147 This function is not supported on Windows CE.
1149 \sa QSocketNotifier
1153 QFile::handle() const
1155 if (!isOpen())
1156 return -1;
1158 if (QAbstractFileEngine *engine = fileEngine())
1159 return engine->handle();
1160 return -1;
1164 \enum QFile::MemoryMapFlags
1165 \since 4.4
1167 This enum describes special options that may be used by the map()
1168 function.
1170 \value NoOptions No options.
1174 \since 4.4
1175 Maps \a size bytes of the file into memory starting at \a offset. A file
1176 should be open for a map to succeed but the file does not need to stay
1177 open after the memory has been mapped. When the QFile is destroyed
1178 or a new file is opened with this object, any maps that have not been
1179 unmapped will automatically be unmapped.
1181 Any mapping options can be passed through \a flags.
1183 Returns a pointer to the memory or 0 if there is an error.
1185 \note On Windows CE 5.0 the file will be closed before mapping occurs.
1187 \sa unmap(), QAbstractFileEngine::supportsExtension()
1189 uchar *QFile::map(qint64 offset, qint64 size, MemoryMapFlags flags)
1191 Q_D(QFile);
1192 QAbstractFileEngine *engine = fileEngine();
1193 if (engine
1194 && engine->supportsExtension(QAbstractFileEngine::MapExtension)) {
1195 unsetError();
1196 uchar *address = engine->map(offset, size, flags);
1197 if (address == 0)
1198 d->setError(engine->error(), engine->errorString());
1199 return address;
1201 return 0;
1205 \since 4.4
1206 Unmaps the memory \a address.
1208 Returns true if the unmap succeeds; false otherwise.
1210 \sa map(), QAbstractFileEngine::supportsExtension()
1212 bool QFile::unmap(uchar *address)
1214 Q_D(QFile);
1215 QAbstractFileEngine *engine = fileEngine();
1216 if (engine
1217 && engine->supportsExtension(QAbstractFileEngine::UnMapExtension)) {
1218 unsetError();
1219 bool success = engine->unmap(address);
1220 if (!success)
1221 d->setError(engine->error(), engine->errorString());
1222 return success;
1224 return false;
1228 \fn QString QFile::name() const
1230 Use fileName() instead.
1234 \fn void QFile::setName(const QString &name)
1236 Use setFileName() instead.
1240 Sets the file size (in bytes) \a sz. Returns true if the file if the
1241 resize succeeds; false otherwise. If \a sz is larger than the file
1242 currently is the new bytes will be set to 0, if \a sz is smaller the
1243 file is simply truncated.
1245 \sa size(), setFileName()
1248 bool
1249 QFile::resize(qint64 sz)
1251 Q_D(QFile);
1252 if (!d->ensureFlushed())
1253 return false;
1254 if (isOpen() && fileEngine()->pos() > sz)
1255 seek(sz);
1256 if(fileEngine()->setSize(sz)) {
1257 unsetError();
1258 return true;
1260 d->setError(QFile::ResizeError, fileEngine()->errorString());
1261 return false;
1265 \overload
1267 Sets \a fileName to size (in bytes) \a sz. Returns true if the file if
1268 the resize succeeds; false otherwise. If \a sz is larger than \a
1269 fileName currently is the new bytes will be set to 0, if \a sz is
1270 smaller the file is simply truncated.
1272 \sa resize()
1275 bool
1276 QFile::resize(const QString &fileName, qint64 sz)
1278 return QFile(fileName).resize(sz);
1282 Returns the complete OR-ed together combination of
1283 QFile::Permission for the file.
1285 \sa setPermissions(), setFileName()
1288 QFile::Permissions
1289 QFile::permissions() const
1291 QAbstractFileEngine::FileFlags perms = fileEngine()->fileFlags(QAbstractFileEngine::PermsMask) & QAbstractFileEngine::PermsMask;
1292 return QFile::Permissions((int)perms); //ewww
1296 \overload
1298 Returns the complete OR-ed together combination of
1299 QFile::Permission for \a fileName.
1302 QFile::Permissions
1303 QFile::permissions(const QString &fileName)
1305 return QFile(fileName).permissions();
1309 Sets the permissions for the file to the \a permissions specified.
1310 Returns true if successful, or false if the permissions cannot be
1311 modified.
1313 \sa permissions(), setFileName()
1316 bool
1317 QFile::setPermissions(Permissions permissions)
1319 Q_D(QFile);
1320 if(fileEngine()->setPermissions(permissions)) {
1321 unsetError();
1322 return true;
1324 d->setError(QFile::PermissionsError, fileEngine()->errorString());
1325 return false;
1329 \overload
1331 Sets the permissions for \a fileName file to \a permissions.
1334 bool
1335 QFile::setPermissions(const QString &fileName, Permissions permissions)
1337 return QFile(fileName).setPermissions(permissions);
1340 static inline qint64 _qfile_writeData(QAbstractFileEngine *engine, QRingBuffer *buffer)
1342 qint64 ret = engine->write(buffer->readPointer(), buffer->nextDataBlockSize());
1343 if (ret > 0)
1344 buffer->free(ret);
1345 return ret;
1349 Flushes any buffered data to the file. Returns true if successful;
1350 otherwise returns false.
1353 bool
1354 QFile::flush()
1356 Q_D(QFile);
1357 if (!d->writeBuffer.isEmpty()) {
1358 qint64 size = d->writeBuffer.size();
1359 if (_qfile_writeData(d->fileEngine ? d->fileEngine : fileEngine(),
1360 &d->writeBuffer) != size) {
1361 QFile::FileError err = fileEngine()->error();
1362 if(err == QFile::UnspecifiedError)
1363 err = QFile::WriteError;
1364 d->setError(err, fileEngine()->errorString());
1365 return false;
1369 if (!fileEngine()->flush()) {
1370 QFile::FileError err = fileEngine()->error();
1371 if(err == QFile::UnspecifiedError)
1372 err = QFile::WriteError;
1373 d->setError(err, fileEngine()->errorString());
1374 return false;
1376 return true;
1380 Calls QFile::flush() and closes the file. Errors from flush are ignored.
1382 \sa QIODevice::close()
1384 void
1385 QFile::close()
1387 Q_D(QFile);
1388 if(!isOpen())
1389 return;
1390 flush();
1391 QIODevice::close();
1393 unsetError();
1394 if(!fileEngine()->close())
1395 d->setError(fileEngine()->error(), fileEngine()->errorString());
1399 Returns the size of the file.
1401 For regular empty files on Unix (e.g. those in \c /proc), this function
1402 returns 0; the contents of such a file are generated on demand in response
1403 to you calling read().
1406 qint64 QFile::size() const
1408 Q_D(const QFile);
1409 if (!d->ensureFlushed())
1410 return 0;
1411 return fileEngine()->size();
1415 \reimp
1418 qint64 QFile::pos() const
1420 return QIODevice::pos();
1424 Returns true if the end of the file has been reached; otherwise returns
1425 false.
1427 For regular empty files on Unix (e.g. those in \c /proc), this function
1428 returns true, since the file system reports that the size of such a file is
1429 0. Therefore, you should not depend on atEnd() when reading data from such a
1430 file, but rather call read() until no more data can be read.
1433 bool QFile::atEnd() const
1435 Q_D(const QFile);
1437 if (!isOpen())
1438 return true;
1440 if (!d->ensureFlushed())
1441 return false;
1443 // If there's buffered data left, we're not at the end.
1444 if (!d->buffer.isEmpty())
1445 return false;
1447 // If the file engine knows best, say what it says.
1448 if (fileEngine()->supportsExtension(QAbstractFileEngine::AtEndExtension)) {
1449 // Check if the file engine supports AtEndExtension, and if it does,
1450 // check if the file engine claims to be at the end.
1451 return fileEngine()->atEnd();
1454 // Fall back to checking how much is available (will stat files).
1455 return bytesAvailable() == 0;
1459 \reimp
1462 bool QFile::seek(qint64 off)
1464 Q_D(QFile);
1465 if (!isOpen()) {
1466 qWarning("QFile::seek: IODevice is not open");
1467 return false;
1470 if (!d->ensureFlushed())
1471 return false;
1473 if (!fileEngine()->seek(off) || !QIODevice::seek(off)) {
1474 QFile::FileError err = fileEngine()->error();
1475 if(err == QFile::UnspecifiedError)
1476 err = QFile::PositionError;
1477 d->setError(err, fileEngine()->errorString());
1478 return false;
1480 unsetError();
1481 return true;
1485 \reimp
1487 qint64 QFile::readLineData(char *data, qint64 maxlen)
1489 Q_D(QFile);
1490 if (!d->ensureFlushed())
1491 return -1;
1493 if (fileEngine()->supportsExtension(QAbstractFileEngine::FastReadLineExtension))
1494 return fileEngine()->readLine(data, maxlen);
1496 // Fall back to QIODevice's readLine implementation if the engine
1497 // cannot do it faster.
1498 return QIODevice::readLineData(data, maxlen);
1502 \reimp
1505 qint64 QFile::readData(char *data, qint64 len)
1507 Q_D(QFile);
1508 unsetError();
1509 if (!d->ensureFlushed())
1510 return -1;
1512 qint64 ret = -1;
1513 qint64 read = fileEngine()->read(data, len);
1514 if (read != -1)
1515 ret = read;
1517 if(ret < 0) {
1518 QFile::FileError err = fileEngine()->error();
1519 if(err == QFile::UnspecifiedError)
1520 err = QFile::ReadError;
1521 d->setError(err, fileEngine()->errorString());
1523 return ret;
1527 \internal
1529 bool QFilePrivate::putCharHelper(char c)
1531 #ifdef QT_NO_QOBJECT
1532 return QIODevicePrivate::putCharHelper(c);
1533 #else
1535 // Cutoff for code that doesn't only touch the buffer.
1536 int writeBufferSize = writeBuffer.size();
1537 if ((openMode & QIODevice::Unbuffered) || writeBufferSize + 1 >= QFILE_WRITEBUFFER_SIZE
1538 #ifdef Q_OS_WIN
1539 || ((openMode & QIODevice::Text) && c == '\n' && writeBufferSize + 2 >= QFILE_WRITEBUFFER_SIZE)
1540 #endif
1542 return QIODevicePrivate::putCharHelper(c);
1545 if (!(openMode & QIODevice::WriteOnly)) {
1546 if (openMode == QIODevice::NotOpen)
1547 qWarning("QIODevice::putChar: Closed device");
1548 else
1549 qWarning("QIODevice::putChar: ReadOnly device");
1550 return false;
1553 // Make sure the device is positioned correctly.
1554 const bool sequential = isSequential();
1555 if (pos != devicePos && !sequential && !q_func()->seek(pos))
1556 return false;
1558 lastWasWrite = true;
1560 int len = 1;
1561 #ifdef Q_OS_WIN
1562 if ((openMode & QIODevice::Text) && c == '\n') {
1563 ++len;
1564 *writeBuffer.reserve(1) = '\r';
1566 #endif
1568 // Write to buffer.
1569 *writeBuffer.reserve(1) = c;
1571 if (!sequential) {
1572 pos += len;
1573 devicePos += len;
1574 if (!buffer.isEmpty())
1575 buffer.skip(len);
1578 return true;
1579 #endif
1583 \reimp
1586 qint64
1587 QFile::writeData(const char *data, qint64 len)
1589 Q_D(QFile);
1590 unsetError();
1591 d->lastWasWrite = true;
1592 bool buffered = !(d->openMode & Unbuffered);
1594 // Flush buffered data if this read will overflow.
1595 if (buffered && (d->writeBuffer.size() + len) > QFILE_WRITEBUFFER_SIZE) {
1596 if (!flush())
1597 return -1;
1600 // Write directly to the engine if the block size is larger than
1601 // the write buffer size.
1602 if (!buffered || len > QFILE_WRITEBUFFER_SIZE) {
1603 QAbstractFileEngine *fe = d->fileEngine ? d->fileEngine : fileEngine();
1604 qint64 ret = fe->write(data, len);
1605 if(ret < 0) {
1606 QFile::FileError err = fileEngine()->error();
1607 if(err == QFile::UnspecifiedError)
1608 err = QFile::WriteError;
1609 d->setError(err, fileEngine()->errorString());
1611 return ret;
1614 // Write to the buffer.
1615 char *writePointer = d->writeBuffer.reserve(len);
1616 if (len == 1)
1617 *writePointer = *data;
1618 else
1619 ::memcpy(writePointer, data, len);
1620 return len;
1624 \internal
1625 Returns the QIOEngine for this QFile object.
1627 QAbstractFileEngine *QFile::fileEngine() const
1629 Q_D(const QFile);
1630 if(!d->fileEngine)
1631 d->fileEngine = QAbstractFileEngine::create(d->fileName);
1632 return d->fileEngine;
1636 Returns the file error status.
1638 The I/O device status returns an error code. For example, if open()
1639 returns false, or a read/write operation returns -1, this function can
1640 be called to find out the reason why the operation failed.
1642 \sa unsetError()
1645 QFile::FileError
1646 QFile::error() const
1648 Q_D(const QFile);
1649 return d->error;
1653 Sets the file's error to QFile::NoError.
1655 \sa error()
1657 void
1658 QFile::unsetError()
1660 Q_D(QFile);
1661 d->setError(QFile::NoError);
1664 QT_END_NAMESPACE