qfile.cpp

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/****************************************************************************
** 
**
** Implementation of QFile class
**
** Created : 930812
**
** Copyright (C) 1992-2000 Trolltech AS.  All rights reserved.
**
** This file is part of the tools module of the Qt GUI Toolkit.
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** as defined by Trolltech AS of Norway and appearing in the file
** LICENSE.QPL included in the packaging of this file.
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** This file may be distributed and/or modified under the terms of the
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** Foundation and appearing in the file LICENSE.GPL included in the
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#include "qglobal.h"
#if defined(_OS_WIN32_)
#ifdef UNICODE
#ifndef _UNICODE
#define _UNICODE
#endif
#endif
#endif

#include "qfile.h"
#include "qfiledefs_p.h"

extern bool qt_file_access( const QString& fn, int t );

// NOT REVISED
/*!
  \class QFile qfile.h
  \brief The QFile class is an I/O device that operates on files.

  \ingroup io

  QFile is an I/O device for reading and writing binary and text files. A
  QFile may be used by itself (readBlock and writeBlock) or by more
  conveniently using QDataStream or QTextStream.

  Here is a code fragment that uses QTextStream to read a text
  file line by line. It prints each line with a line number.
  \code
    QFile f("file.txt");
    if ( f.open(IO_ReadOnly) ) {    // file opened successfully
        QTextStream t( &f );        // use a text stream
        QString s;
        int n = 1;
        while ( !t.eof() ) {        // until end of file...
            s = t.readLine();       // line of text excluding '\n'
            printf( "%3d: %s\n", n++, (const char *)s );
        }
        f.close();
    }
  \endcode

  The QFileInfo class holds detailed information about a file, such as
  access permissions, file dates and file types.

  The QDir class manages directories and lists of file names.

  \sa QDataStream, QTextStream
*/


/*!
  Constructs a QFile with no name.
*/

QFile::QFile()
{
    init();
}

/*!
  Constructs a QFile with a file name \e name.
  \sa setName()
*/

QFile::QFile( const QString &name )
    : fn(name)
{
    init();
}


/*!
  Destructs a QFile.  Calls close().
*/

QFile::~QFile()
{
    close();
}


/*!
  \internal
  Initialize internal data.
*/

void QFile::init()
{
    setFlags( IO_Direct );
    setStatus( IO_Ok );
    fh     = 0;
    fd     = 0;
    length = 0;
    ioIndex = 0;
    ext_f  = FALSE;                             // not an external file handle
}


/*!
  \fn QString QFile::name() const
  Returns the name set by setName().
  \sa setName(), QFileInfo::fileName()
*/

/*!
  Sets the name of the file. The name can include an absolute directory
  path or it can be a name or a path relative to the current directory.

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

  Note that if the name is relative QFile does not associate it with the
  current directory.  If you change directory before calling open(), open
  uses the new current directory.

  Example:
  \code
     QFile f;
     QDir::setCurrent( "/tmp" );
     f.setName( "readme.txt" );
     QDir::setCurrent( "/home" );
     f.open( IO_ReadOnly );        // opens "/home/readme.txt" under UNIX
  \endcode

  Also note that the directory separator '/' works for all operating
  systems supported by Qt.

  \sa name(), QFileInfo, QDir
*/

void QFile::setName( const QString &name )
{
    if ( isOpen() ) {
#if defined(CHECK_STATE)
        qWarning( "QFile::setName: File is open" );
#endif
        close();
    }
    fn = name;
}

/*!
  Returns TRUE if this file exists, otherwise FALSE.
  \sa name()
*/

bool QFile::exists() const
{
    return qt_file_access( fn, F_OK );
}

/*!
  Returns TRUE if the file given by \e fileName exists, otherwise FALSE.
*/

bool QFile::exists( const QString &fileName )
{
    return qt_file_access( fileName, F_OK );
}


/*!
  Removes the file specified by the file name currently set.
  Returns TRUE if successful, otherwise FALSE.

  The file is closed before it is removed.
*/

bool QFile::remove()
{
    close();
    return remove( fn );
}

#if defined(_OS_MAC_) || defined(_OS_MSDOS_) || defined(_OS_WIN32_) || defined(_OS_OS2_) || defined(_OS_CYGWIN_)
# define HAS_TEXT_FILEMODE                      // has translate/text filemode
#endif
#if defined(O_NONBLOCK)
# define HAS_ASYNC_FILEMODE
# define OPEN_ASYNC O_NONBLOCK
#elif defined(O_NDELAY)
# define HAS_ASYNC_FILEMODE
# define OPEN_ASYNC O_NDELAY
#endif

/*!
  Flushes the file buffer to the disk.

  close() also flushes the file buffer.
*/

void QFile::flush()
{
    if ( isOpen() && fh )                       // can only flush open/buffered
        fflush( fh );                           //   file
}

/*!
  Returns TRUE if the end of file has been reached, otherwise FALSE.
  \sa size()
*/

bool QFile::atEnd() const
{
    if ( !isOpen() ) {
#if defined(CHECK_STATE)
        qWarning( "QFile::atEnd: File is not open" );
#endif
        return FALSE;
    }
    if ( isDirectAccess() && !isTranslated() ) {
        if ( at() < length )
            return FALSE;
    }
    return QIODevice::atEnd();
}

/*!
  Reads a line of text.

  Reads bytes from the file until end-of-line is reached, or up to \a
  maxlen bytes, and returns the number of bytes read, or -1 in case of
  error.  The terminating newline is not stripped.

  This function is efficient only for buffered files.  Avoid
  readLine() for files that have been opened with the \c IO_Raw
  flag.

  \sa readBlock(), QTextStream::readLine()
*/

int QFile::readLine( char *p, uint maxlen )
{
    if ( maxlen == 0 )                          // application bug?
        return 0;
#if defined(CHECK_STATE)
    CHECK_PTR( p );
    if ( !isOpen() ) {                          // file not open
        qWarning( "QFile::readLine: File not open" );
        return -1;
    }
    if ( !isReadable() ) {                      // reading not permitted
        qWarning( "QFile::readLine: Read operation not permitted" );
        return -1;
    }
#endif
    int nread;                                  // number of bytes read
    if ( isRaw() ) {                            // raw file
        nread = QIODevice::readLine( p, maxlen );
    } else {                                    // buffered file
        p = fgets( p, maxlen, fh );
        if ( p ) {
            nread = qstrlen( p );
            ioIndex += nread;
        } else {
            nread = -1;
            setStatus(IO_ReadError);
        }
    }
    return nread;
}


/*!
  Reads a line of text.

  Reads bytes from the file until end-of-line is reached, or up to \a
  maxlen bytes, and returns the number of bytes read, or -1 in case of
  error.  The terminating newline is not stripped.

  This function is efficient only for buffered files.  Avoid
  readLine() for files that have been opened with the \c IO_Raw
  flag.

  Note that the string is read as plain Latin1 bytes, not Unicode.

  \sa readBlock(), QTextStream::readLine()
*/

int QFile::readLine( QString& s, uint maxlen )
{
    QByteArray ba(maxlen);
    int l = readLine(ba.data(),maxlen);
    if ( l >= 0 ) {
        ba.truncate(l);
        s = QString(ba);
    }
    return l;
}


/*!
  Reads a single byte/character from the file.

  Returns the byte/character read, or -1 if the end of the file has been
  reached.

  \sa putch(), ungetch()
*/

int QFile::getch()
{
#if defined(CHECK_STATE)
    if ( !isOpen() ) {                          // file not open
        qWarning( "QFile::getch: File not open" );
        return EOF;
    }
    if ( !isReadable() ) {                      // reading not permitted
        qWarning( "QFile::getch: Read operation not permitted" );
        return EOF;
    }
#endif

    int ch;

    if ( !ungetchBuffer.isEmpty() ) {
        int len = ungetchBuffer.length();
        ch = ungetchBuffer[ len-1 ];
        ungetchBuffer.truncate( len - 1 );
        return ch;
    }

    if ( isRaw() ) {                            // raw file (inefficient)
        char buf[1];
        ch = readBlock( buf, 1 ) == 1 ? buf[0] : EOF;
    } else {                                    // buffered file
        if ( (ch = getc( fh )) != EOF )
            ioIndex++;
        else
            setStatus(IO_ReadError);
    }
    return ch;
}

/*!
  \fn int QFile::writeBlock( const QByteArray& data )
  \reimp
  \internal
  Should be removed in 3.0
*/

/*!
  Writes the character \e ch to the file.

  Returns \e ch, or -1 if some error occurred.

  \sa getch(), ungetch()
*/

int QFile::putch( int ch )
{
#if defined(CHECK_STATE)
    if ( !isOpen() ) {                          // file not open
        qWarning( "QFile::putch: File not open" );
        return EOF;
    }
    if ( !isWritable() ) {                      // writing not permitted
        qWarning( "QFile::putch: Write operation not permitted" );
        return EOF;
    }
#endif
    if ( isRaw() ) {                            // raw file (inefficient)
        char buf[1];
        buf[0] = ch;
        ch = writeBlock( buf, 1 ) == 1 ? ch : EOF;
    } else {                                    // buffered file
        if ( (ch = putc( ch, fh )) != EOF ) {
            ioIndex++;
            if ( ioIndex > length )             // update file length
                length = ioIndex;
        } else {
            setStatus(IO_WriteError);
        }
    }
    return ch;
}

/*!
  Puts the character \e ch back into the file and decrements the index if it
  is not zero.

  This function is normally called to "undo" a getch() operation.

  Returns \e ch, or -1 if some error occurred.

  \sa getch(), putch()
*/

int QFile::ungetch( int ch )
{
#if defined(CHECK_STATE)
    if ( !isOpen() ) {                          // file not open
        qWarning( "QFile::ungetch: File not open" );
        return EOF;
    }
    if ( !isReadable() ) {                      // reading not permitted
        qWarning( "QFile::ungetch: Read operation not permitted" );
        return EOF;
    }
#endif
    if ( ch == EOF )                            // cannot unget EOF
        return ch;

    if ( isSequentialAccess() && !fh) {
        // pipe or similar => we cannot ungetch, so do it manually
        ungetchBuffer +=ch;
        return ch;
    }

    if ( isRaw() ) {                            // raw file (very inefficient)
        char buf[1];
        at( ioIndex-1 );
        buf[0] = ch;
        if ( writeBlock(buf, 1) == 1 )
            at ( ioIndex-1 );
        else
            ch = EOF;
    } else {                                    // buffered file
        if ( (ch = ungetc(ch, fh)) != EOF )
            ioIndex--;
        else
            setStatus( IO_ReadError );
    }
    return ch;
}


static QCString locale_encoder( const QString &fileName )
{
    return fileName.local8Bit();
}


static QFile::EncoderFn encoder = locale_encoder;

/*!
  When you use QFile, QFileInfo, and QDir to access the filesystem
  with Qt, you can use Unicode filenames.  On Unix, these filenames
  are converted to an 8-bit encoding.  If you want to do your own
  file I/O on Unix, you should convert the filename using this
  function.  On Windows NT, Unicode filenames are supported directly
  in the filesystem and this function should be avoided. On Windows 95,
  non-Latin1 locales are not supported at this time.

  By default, this function converts to the local 8-bit encoding
  determined by the user's locale.  This is sufficient for
  filenames that the user chooses.  Filenames hard-coded into the
  application should only use 7-bit ASCII filename characters.

  The conversion scheme can be changed using setEncodingFunction().
  This might be useful if you wish to give the user an option to
  store in filenames in UTF-8, etc., but beware that such filenames
  would probably then be unrecognizable when seen by other programs.

  \sa decodeName()
*/

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

/*!
  \enum QFile::EncoderFn

  This is used by QFile::setEncodingFunction().
*/

/*!
  Sets the function for encoding Unicode filenames.
  The default encodes in the locale-specific 8-bit encoding.

  \sa encodeName()
*/
void QFile::setEncodingFunction( EncoderFn f )
{
    encoder = f;
}

static
QString locale_decoder( const QCString &localFileName )
{
    return QString::fromLocal8Bit(localFileName);
}

static QFile::DecoderFn decoder = locale_decoder;

/*!
  This does the reverse of QFile::encodeName().

  \sa setDecodingFunction()
*/
QString QFile::decodeName( const QCString &localFileName )
{
    return (*decoder)(localFileName);
}

/*!
  \enum QFile::DecoderFn

  This is used by QFile::setDecodingFunction().
*/

/*!
  Sets the function for decoding 8-bit filenames.
  The default uses the locale-specific 8-bit encoding.

  \sa encodeName(), decodeName()
*/

void QFile::setDecodingFunction( DecoderFn f )
{
    decoder = f;
}