Why QFile::exists return true value on three dots path (“…”)

Stramonium

Hello!

Today I found that when checking file existence, QFile::exists always return true value on three dots path ("...").

Does three dot's have some special meaning?

BlastDV

What Operating System are you using?

If you run
@cd ...
@
on Windows it will leave you on the same directory you are.
If you do it on Linux it will move you 2 directories up on the directory tree. And one more every extra dot you put.

QFile::exists() may be returning true on ("...") because as far as I know, directories are a special type of file, at least on UNIX based systems (which I think Linux and Mac OS are based on).

So asking for ("...") file should always return true.

p3c0

I'm using Qt 5.3.1 on Ubuntu 13.04 and QFile::exists("...") returns false.

[quote author="BlastDV" date="1407075374"]What Operating System are you using?

If you run
@cd ...
@
on Windows it will leave you on the same directory you are.
If you do it on Linux it will move you 2 directories up on the directory tree. And one more every extra dot you put.

QFile::exists() may be returning true on ("...") because as far as I know, directories are a special type of file, at least on UNIX based systems (which I think Linux and Mac OS are based on).

So asking for ("...") file should always return true.[/quote]

AFAIK, using cd ... wont work on Linux systems.

BlastDV

You are absolutely right p3c0, "cd ..." won't work on Linux.

I said that because I misread an article about defining alias for directories in order to run them on the terminal as if they were commands. This is the "link":http://www.thegeekstuff.com/2008/10/6-awesome-linux-cd-command-hacks-productivity-tip3-for-geeks/ for that.

p3c0

Hmm with alias anything is possible.
That makes me think for the original question.

bq. Why QFile::exists return true value on three dots path (“…”)

Do you have a file named ... ? It would be a hidden file. May be the file is created accidently or it may be a symbolic link to another file ?

Stramonium

I use Win7 x64. No such file exists.

http://i62.tinypic.com/15ogpdy.jpg

I read for a while and I think the only the first dot does matter, because file from string "." also exists. So I suppose that qt just checks if current directory exists and returns true.

hskoglund

On Win98SE and WinME cd ... did work :-) i.e. you stepped up two directories

andreyc

What is result of QFileInfo::exists("...") ?
Is it possible that you have a link that is named "..." ?

The code below returns false for ... on Linux
@
#include <QCoreApplication>
#include <QFile>
#include <QDebug>
#include <QFileInfo>

int main(int argc, char *argv[])
{
QCoreApplication a(argc, argv);

QStringList fileNames;
fileNames << "...." << "..." << ".." << ".";
QFile file;
foreach (QString fileName, fileNames) {
    file.setFileName(fileName);
    qDebug() << file.fileName()
             << file.exists()
             << QFile::exists(fileName)
             << QFileInfo::exists(fileName);
}

return 0;

}
@