C++ Renaming Files with Qt causes SIGSEGV - c++

Question

I just copied all my cds to my computer with a program called "Sound Juicer". It works fine, it creates for each artist a folder and it it for each album another folder. And of course in these folders the mp3 files.
The problem is I want the Tracknumber, the Artist and then the Tracktitle as name for my songs. What Sound Juicer does is adding d1t in front of the file which stands for "Disk 1 Title".
I'm a programmer so I used this problem to practice a little bit. This works :
void MainWindow::rename( const QString & text )
{
static int _files = 0;
QDir dir( text );
QFileInfoList a = dir.entryInfoList( QDir::Files | QDir::Dirs );
for( int i = 2; i < a.size(); i++ )
{
static QDir tmp;
if( a.at( i ).isDir() )
rename( a.at( i ).absoluteFilePath() );
if( a.at( i ).fileName().startsWith( "d1t" ) || a.at( i ).fileName().startsWith( "d2t" ) )
{
QString newFile = a.at( i ).fileName().remove(0,3);
tmp = a.at( i ).dir();
if( !tmp.rename( a.at( i ).fileName(), newFile ) )
qDebug() << "Failed";
_files++;
}
}
}
It checks a directory, selects the first file or directory and checks what it is. If it is a directory it calls itself (recursion) and starts again until he finds some files or no more directories exist. If a file is found, it renames it and adds 1 to the file counter.
However, it only renamed all files in the first 2 or 3 directories. After that it caused a SIGSEGV. Does anyone knows whats wrong?
Example of my directories :
1 Directory ("Sum 41") -> 1 Subdirectory ("All Killer No Filler") ->
Files "d1t01. Sum 41 - Introduction to Destruction.mp3" etc. ...
2 Subdirectory ("Blah Blah") -> Files ...
2 Directory ("Shinedown") -> 1 Subdirectory ("Sound of Madness") ->
Files d1t01. Shinedown - Devour.mp3 etc...
3 Directory ("Guns N’ Roses") -> Subdirectory ("Blah Blah") -> files ...
Subdirectory ("Blah ") -> files ...

Answer 1

With static you try to tell the compiler you want only one instance in the whole program, yet you put it in a for loop. That is not really clean. In this situation static is useless. Static can also cause problems due to the static initialization chaos problem. So if you dont really need static initialization, drop it and make it a local or a class variable.
Rewriting your method, to be able to read it better, i saw that you call the method recursively and that could cause an infinite loop.
Another problem is your files variable, what is the purpose of it?
void MainWindow::rename( const QString & text ) {
int files = 0;
QDir dir(text); // does QDir also accept wrong paths?
QFileInfoList list = dir.entryInfoList(QDir::Files|QDir::Dirs); // does it return a list in all cases?
foreach (QFileInfo entry, list) {
if (entry.isDir()) {
//is everything always ok when doing this?
// POTENTIAL infinite loop
rename(entry.absoluteFilePath());
}
else {
QString fileName = entry.fileName();
if(fileName.startsWith("d1t") || fileName.startsWith("d2t")) {
if (!entry.dir().rename(fileName, fileName.remove(0,3))) qDebug() << "Failed";
files++;
}
}
}
}

Answer 2

I have with the help of fonZ and Frank Osterfeld somehow fixed it. I finally created a GUI to select just a single path. However, I have done it. This piece of code looks up all directories without causing an infinite loop or an overflow (so far). The problem was something with QDir's and QFileInfo's functions to get the path. I played a while with it and this came out :
void MainWindow::rename( const QString& path )
{
//If invalid path return
if( path.isEmpty() || ( !QDir( path ).exists() ) )
return;
//entryInfoList( QDir::NoDotAndDotDot ) doesn't work.
QFileInfoList fileList = QDir( path ).entryInfoList();
foreach (QFileInfo entry, fileList ) {
//Eliminating wrong paths
if( entry.isDir() ){
if( entry.filePath().endsWith(".") )
continue;
//Start function again with new directory
rename( entry.filePath() );
}
else{
QString fileName = entry.fileName();
if( fileName.startsWith( "d1t" ) || fileName.startsWith( "d2t" ) ){
//Remove those characters
fileName.remove( 0, 3 );
//If renaming is successful, increment the successful files
//If not, increment the failed files and print an error
if( entry.dir().rename( entry.fileName(), fileName ) )
files++;
else{
addError( "Could not rename " + entry.fileName() + " to " + fileName );
filesFailed++;
}
}
}
}
}