qfile_unix.cpp

Trolltech公司发布的图形界面操作系统。可在qt-embedded-2.3.10平台上编译为嵌入式图形界面操作系统。

	ioIndex = 0;
    } else {
	length = (Offset)st.st_size;
	if ( !(flags()&IO_Truncate) && length == 0 && isReadable() ) {
	    // try if you can read from it (if you can, it's a sequential
	    // device; e.g. a file in the /proc filesystem)
	    int c = getch();
	    if ( c != -1 ) {
		ungetch(c);
		setType( IO_Sequential );
		length = INT_MAX;
		ioIndex = 0;
	    }
	    resetStatus();
	}
    }
    return TRUE;
}

/*!
    \overload
  Opens a file in the mode \a m using an existing file descriptor \a f.
  Returns TRUE if successful, otherwise 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 f is one of 0 (stdin), 1 (stdout) or 2 (stderr), you may not
  be able to seek. size() is set to \c INT_MAX (in limits.h).

  \sa close()
*/


bool QFile::open( int m, int f )
{
    if ( isOpen() ) {
#if defined(QT_CHECK_RANGE)
	qWarning( "QFile::open: File already open" );
#endif
	return FALSE;
    }
    init();
    setMode( m |IO_Raw );
    setState( IO_Open );
    fd = f;
    ext_f = TRUE;
    struct stat st;
    ::fstat( fd, &st );
    ioIndex = (Offset)::lseek(fd, 0, SEEK_CUR);
    if ( (st.st_mode & S_IFMT) != S_IFREG || f == 0 ) { // stdin is not seekable...
	// non-seekable
	setType( IO_Sequential );
	length = INT_MAX;
	ioIndex = 0;
    } else {
	length = (Offset)st.st_size;
	if ( length == 0 && isReadable() ) {
	    // try if you can read from it (if you can, it's a sequential
	    // device; e.g. a file in the /proc filesystem)
	    int c = getch();
	    if ( c != -1 ) {
		ungetch(c);
		setType( IO_Sequential );
		length = INT_MAX;
		ioIndex = 0;
	    }
	    resetStatus();
	}
    }
    return TRUE;
}

/*!
  Returns the file size.
  \sa at()
*/

QIODevice::Offset QFile::size() const
{
    struct stat st;
    int ret = 0;
    if ( isOpen() ) {
	ret = ::fstat( fh ? fileno(fh) : fd, &st );
    } else {
	ret = ::stat( QFile::encodeName(fn), &st );
    }
    if ( ret == -1 )
	return 0;
#if defined(QT_LARGEFILE_SUPPORT) && !defined(QT_ABI_64BITOFFSET)
    return (uint)st.st_size > UINT_MAX ? UINT_MAX : (QIODevice::Offset)st.st_size;
#else
    return st.st_size;
#endif
}


/*!
    \overload

    Sets the file index to \a pos. Returns TRUE if successful;
    otherwise returns FALSE.

    Example:
    \code
    QFile f( "data.bin" );
    f.open( IO_ReadOnly );  // index set to 0
    f.at( 100 );	    // set index to 100
    f.at( f.at()+50 );	    // set index to 150
    f.at( f.size()-80 );    // set index to 80 before EOF
    f.close();
    \endcode

    Use \c at() without arguments to retrieve the file offset.

    \warning The result is undefined if the file was open()'ed using
    the \c IO_Append specifier.

    \sa size(), open()
*/

bool QFile::at( Offset pos )
{
    if ( !isOpen() ) {
#if defined(QT_CHECK_STATE)
	qWarning( "QFile::at: File is not open" );
#endif
	return FALSE;
    }
    if ( isSequentialAccess() )
	return FALSE;
    bool ok;
    if ( isRaw() ) {
	off_t l = ::lseek( fd, pos, SEEK_SET );
	ok = ( l != -1 );
	pos = (Offset)l;
    } else {					// buffered file
#if defined(QT_LARGEFILE_SUPPORT)
	ok = ( ::fseeko(fh, pos, SEEK_SET) == 0 );
#else
	ok = ( ::fseek(fh, pos, SEEK_SET) == 0 );
#endif
    }
    if ( ok )
	ioIndex = pos;
#if defined(QT_CHECK_RANGE)
    else
#if defined(QT_LARGEFILE_SUPPORT) && defined(QT_ABI_64BITOFFSET)
	qWarning( "QFile::at: Cannot set file position %llu", pos );
#else
	qWarning( "QFile::at: Cannot set file position %lu", pos );
#endif
#endif
    return ok;
}

/*!
  \reimp

  \warning We have experienced problems with some C libraries when a buffered
  file is opened for both reading and writing. If a read operation takes place
  immediately after a write operation, the read buffer contains garbage data.
  Worse, the same garbage is written to the file. Calling flush() before
  readBlock() solved this problem.
*/

Q_LONG QFile::readBlock( char *p, Q_ULONG len )
{
    if ( !len ) // nothing to do
	return 0;

#if defined(QT_CHECK_NULL)
    if ( !p )
	qWarning( "QFile::readBlock: Null pointer error" );
#endif
#if defined(QT_CHECK_STATE)
    if ( !isOpen() ) {
	qWarning( "QFile::readBlock: File not open" );
	return -1;
    }
    if ( !isReadable() ) {
	qWarning( "QFile::readBlock: Read operation not permitted" );
	return -1;
    }
#endif
    Q_ULONG nread = 0;					// number of bytes read
    if ( !ungetchBuffer.isEmpty() ) {
	// need to add these to the returned string.
	uint l = ungetchBuffer.length();
	while( nread < l ) {
	    *p = ungetchBuffer.at( l - nread - 1 );
	    p++;
	    nread++;
	}
	ungetchBuffer.truncate( l - nread );
    }

    if ( nread < len ) {
	if ( isRaw() ) {				// raw file
	    nread += ::read( fd, p, len-nread );
	    if ( len && nread <= 0 ) {
		nread = 0;
		setStatus(IO_ReadError);
		setErrorStringErrno( errno );
	    }
	} else {					// buffered file
	    nread += fread( p, 1, len-nread, fh );
	    if ( (uint)nread != len ) {
		if ( ferror( fh ) || nread==0 ) {
		    setStatus(IO_ReadError);
		    setErrorString( qt_fileerr_read );
		}
	    }
	}
    }
    if ( !isSequentialAccess() )
	ioIndex += nread;
    return nread;
}


/*! \reimp

  Writes \a len bytes from \a p to the file and returns the number of
  bytes actually written.

  Returns -1 if a serious error occurred.

  \warning When working with buffered files, data may not be written
  to the file at once. Call flush() to make sure the data is really
  written.

  \sa readBlock()
*/

Q_LONG QFile::writeBlock( const char *p, Q_ULONG len )
{
    if ( !len ) // nothing to do
	return 0;

#if defined(QT_CHECK_NULL)
    if ( p == 0 && len != 0 )
	qWarning( "QFile::writeBlock: Null pointer error" );
#endif
#if defined(QT_CHECK_STATE)
    if ( !isOpen() ) {				// file not open
	qWarning( "QFile::writeBlock: File not open" );
	return -1;
    }
    if ( !isWritable() ) {			// writing not permitted
	qWarning( "QFile::writeBlock: Write operation not permitted" );
	return -1;
    }
#endif
    Q_ULONG nwritten;				// number of bytes written
    if ( isRaw() )				// raw file
	nwritten = ::write( fd, (void *)p, len );
    else					// buffered file
	nwritten = fwrite( p, 1, len, fh );
    if ( nwritten != len ) {		// write error
	if ( errno == ENOSPC )			// disk is full
	    setStatus( IO_ResourceError );
	else
	    setStatus( IO_WriteError );
	setErrorStringErrno( errno );
	if ( !isSequentialAccess() ) {
	    if ( isRaw() )			// recalc file position
		ioIndex = (Offset)::lseek( fd, 0, SEEK_CUR );
	    else
#if defined(QT_LARGEFILE_SUPPORT)
		ioIndex = (Offset)::fseeko( fh, 0, SEEK_CUR );
#else
		ioIndex = (Offset)::fseek( fh, 0, SEEK_CUR );
#endif
	}
    } else {
	if ( !isSequentialAccess() )
	    ioIndex += nwritten;
    }
    if ( ioIndex > length )			// update file length
	length = ioIndex;
    return nwritten;
}

/*!
  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 (ie. 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.

  \sa QSocketNotifier
*/

int QFile::handle() const
{
    if ( !isOpen() )
	return -1;
    else if ( fh )
	return fileno( fh );
    else
	return fd;
}

/*!
  Closes an open file.

  The file is not closed if it was opened with an existing file handle.
  If the existing file handle is a \c FILE*, the file is flushed.
  If the existing file handle is an \c int file descriptor, nothing
  is done to the file.

  Some "write-behind" filesystems may report an unspecified error on
  closing the file. These errors only indicate that something may
  have gone wrong since the previous open(). In such a case status()
  reports IO_UnspecifiedError after close(), otherwise IO_Ok.

  \sa open(), flush()
*/


void QFile::close()
{
    bool ok = FALSE;
    if ( isOpen() ) {				// file is not open
	if ( fh ) {				// buffered file
	    if ( ext_f )
		ok = fflush( fh ) != -1;	// flush instead of closing
	    else
		ok = fclose( fh ) != -1;
	} else {				// raw file
	    if ( ext_f )
		ok = TRUE;			// cannot close
	    else
		ok = ::close( fd ) != -1;
	}
	init();					// restore internal state
    }
    if (!ok) {
	setStatus( IO_UnspecifiedError );
	setErrorStringErrno( errno );
    }
}