qfile_unix.cpp

doxygen(一个自动从源代码生成文档的工具)的源代码

/****************************************************************************
** $Id: qt/src/tools/qfile_unix.cpp   2.2.3   edited 2000-10-20 $
**
** Implementation of QFileInfo class
**
** Created : 950628
**
** Copyright (C) 1992-2000 Trolltech AS.  All rights reserved.
**
** This file is part of the tools module of the Qt GUI Toolkit.
**
** This file may be distributed under the terms of the Q Public License
** as defined by Trolltech AS of Norway and appearing in the file
** LICENSE.QPL included in the packaging of this file.
**
** This file may be distributed and/or modified under the terms of the
** GNU General Public License version 2 as published by the Free Software
** Foundation and appearing in the file LICENSE.GPL included in the
** packaging of this file.
**
** Licensees holding valid Qt Enterprise Edition or Qt Professional Edition
** licenses for Unix/X11 or for Qt/Embedded may use this file in accordance
** with the Qt Commercial License Agreement provided with the Software.
**
** This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
** WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
**
** See http://www.trolltech.com/pricing.html or email [e-mail] for
**   information about Qt Commercial License Agreements.
** See http://www.trolltech.com/qpl/ for QPL licensing information.
** See http://www.trolltech.com/gpl/ for GPL licensing information.
**
** Contact [e-mail] if any conditions of this licensing are
** not clear to you.
**
**********************************************************************/

#include "qglobal.h"

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

bool qt_file_access( const QString& fn, int t )
{
    if ( fn.isEmpty() )
	return FALSE;
    return ACCESS( QFile::encodeName(fn), t ) == 0;
}

/*!
  Removes the file \a fileName.
  Returns TRUE if successful, otherwise FALSE.
*/

bool QFile::remove( const QString &fileName )
{
    if ( fileName.isEmpty() ) {
#if defined(CHECK_NULL)
	qWarning( "QFile::remove: Empty or null file name" );
#endif
	return FALSE;
    }
    return unlink( QFile::encodeName(fileName) ) == 0;	
    // unlink more common in UNIX
}

#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

/*!
  Opens the file specified by the file name currently set, using the mode \e m.
  Returns TRUE if successful, otherwise FALSE.

  The mode parameter \e m must be a combination of the following flags:
  <ul>
  <li>\c IO_Raw specified raw (non-buffered) file access.
  <li>\c IO_ReadOnly opens the file in read-only mode.
  <li>\c IO_WriteOnly opens the file in write-only mode (and truncates).
  <li>\c IO_ReadWrite opens the file in read/write mode, equivalent to
  \c (IO_ReadOnly|IO_WriteOnly).
  <li>\c IO_Append opens the file in append mode. This mode is very useful
  when you want to write something to a log file. The file index is set to
  the end of the file. Note that the result is undefined if you position the
  file index manually using at() in append mode.
  <li>\c IO_Truncate truncates the file.
  <li>\c IO_Translate enables carriage returns and linefeed translation
  for text files under MS-DOS, Windows and OS/2.
  </ul>

  The raw access mode is best when I/O is block-operated using 4kB block size
  or greater. Buffered access works better when reading small portions of
  data at a time.

  <strong>Important:</strong> When working with buffered files, data may
  not be written to the file at once. Call \link flush() flush\endlink
  to make sure the data is really written.

  \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.

  If the file does not exist and \c IO_WriteOnly or \c IO_ReadWrite is
  specified, it is created.

  Example:
  \code
    QFile f1( "/tmp/data.bin" );
    QFile f2( "readme.txt" );
    f1.open( IO_Raw | IO_ReadWrite | IO_Append );
    f2.open( IO_ReadOnly | IO_Translate );
  \endcode

  \sa name(), close(), isOpen(), flush()
*/

bool QFile::open( int m )
{
    if ( isOpen() ) {				// file already open
#if defined(CHECK_STATE)
	qWarning( "QFile::open: File already open" );
#endif
	return FALSE;
    }
    if ( fn.isNull() ) {			// no file name defined
#if defined(CHECK_NULL)
	qWarning( "QFile::open: No file name specified" );
#endif
	return FALSE;
    }
    init();					// reset params
    setMode( m );
    if ( !(isReadable() || isWritable()) ) {
#if defined(CHECK_RANGE)
	qWarning( "QFile::open: File access not specified" );
#endif
	return FALSE;
    }
    bool ok = TRUE;
    STATBUF st;
    if ( isRaw() ) {				// raw file I/O
	int oflags = OPEN_RDONLY;
	if ( isReadable() && isWritable() )
	    oflags = OPEN_RDWR;
	else if ( isWritable() )
	    oflags = OPEN_WRONLY;
	if ( flags() & IO_Append ) {		// append to end of file?
	    if ( flags() & IO_Truncate )
		oflags |= (OPEN_CREAT | OPEN_TRUNC);
	    else
		oflags |= (OPEN_APPEND | OPEN_CREAT);
	    setFlags( flags() | IO_WriteOnly ); // append implies write
	} else if ( isWritable() ) {		// create/trunc if writable
	    if ( flags() & IO_Truncate )
		oflags |= (OPEN_CREAT | OPEN_TRUNC);
	    else
		oflags |= OPEN_CREAT;
	}
#if defined(HAS_TEXT_FILEMODE)
	if ( isTranslated() )
	    oflags |= OPEN_TEXT;
	else
	    oflags |= OPEN_BINARY;
#endif
#if defined(HAS_ASYNC_FILEMODE)
	if ( isAsynchronous() )
	    oflags |= OPEN_ASYNC;
#endif
	fd = OPEN( QFile::encodeName(fn), oflags, 0666 );

	if ( fd != -1 ) {			// open successful
	    FSTAT( fd, &st ); // get the stat for later usage
	} else {
	    ok = FALSE;
	}
    } else {					// buffered file I/O
	QCString perm;
	char perm2[4];
	bool try_create = FALSE;
	if ( flags() & IO_Append ) {		// append to end of file?
	    setFlags( flags() | IO_WriteOnly ); // append implies write
	    perm = isReadable() ? "a+" : "a";
	} else {
	    if ( isReadWrite() ) {
		if ( flags() & IO_Truncate ) {
		    perm = "w+";
		} else {
		    perm = "r+";
		    try_create = TRUE;		// try to create if not exists
		}
	    } else if ( isReadable() ) {
		perm = "r";
	    } else if ( isWritable() ) {
		perm = "w";
	    }
	}
	qstrcpy( perm2, perm );
#if defined(HAS_TEXT_FILEMODE)
	if ( isTranslated() )
	    strcat( perm2, "t" );
	else
	    strcat( perm2, "b" );
#endif
	while (1) { // At most twice

	    fh = fopen( QFile::encodeName(fn), perm2 );

	    if ( !fh && try_create ) {
		perm2[0] = 'w';			// try "w+" instead of "r+"
		try_create = FALSE;
	    } else {
		break;
	    }
	}
	if ( fh ) {
	    FSTAT( FILENO(fh), &st ); // get the stat for later usage
	} else {
	    ok = FALSE;
	}
    }
    if ( ok ) {
	setState( IO_Open );
	// on successful open the file stat was got; now test what type
	// of file we have
	if ( (st.st_mode & STAT_MASK) != STAT_REG ) {
	    // non-seekable
	    setType( IO_Sequential );
	    length = INT_MAX;
	    ioIndex  = (flags() & IO_Append) == 0 ? 0 : length;
	} else {
	    length = (int)st.st_size;
	    ioIndex  = (flags() & IO_Append) == 0 ? 0 : length;
	    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;
		}
	    }
	}
    } else {
	init();
	if ( errno == EMFILE )			// no more file handles/descrs
	    setStatus( IO_ResourceError );
	else
	    setStatus( IO_OpenError );
    }
    return ok;
}

/*!
  Opens a file in the mode \e m using an existing file handle \e f.
  Returns TRUE if successful, otherwise FALSE.

  Example:
  \code
    #include <stdio.h>

    void printError( const char* msg )
    {
	QFile f;
	f.open( IO_WriteOnly, stderr );
	f.writeBlock( msg, qstrlen(msg) );	// write to stderr
	f.close();
    }
  \endcode

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

  \warning If \e f is \c stdin, \c stdout, \c stderr, you may not
  be able to seek.  See QIODevice::isSequentialAccess() for more
  information.

  \sa close()
*/

bool QFile::open( int m, FILE *f )
{
    if ( isOpen() ) {
#if defined(CHECK_RANGE)
	qWarning( "QFile::open: File already open" );
#endif
	return FALSE;
    }
    init();
    setMode( m &~IO_Raw );
    setState( IO_Open );
    fh = f;
    ext_f = TRUE;
    STATBUF st;
    FSTAT( FILENO(fh), &st );
    ioIndex = (int)ftell( fh );
    if ( (st.st_mode & STAT_MASK) != STAT_REG || f == stdin ) { //stdin is non seekable
	// non-seekable
	setType( IO_Sequential );
	length = INT_MAX;
    } else {
	length = (int)st.st_size;