Question

Thanks for all your help – see blow original question, and my edit following the two line rules (I cannot yet answer my own questions as a new user..).

I’ve looked around and question (here) almost meets the aims of my question:

For example, I’m creating a user data directory for each user on a web application; the folder of-course must be unique but also abstract for security (using their user id for example, would not be appropriate.

So far I’ve created the following function; it generates a unique folder name, checks to make sure it doesn’t already exist and assigns it to a variable. It then loops back if the dir already exists:

function generate_unique_userDirectory(){
    $userDirectory = md5(uniqid($uid)); //Generate a unique folder name.
    if (is_dir($userDirectory)) {
        return FALSE; //If the dir exists, report so
    } else {
        return $userDirectory; //Return unique foldername
    }
}

While loop is used to keep going until an unused folder name is found.

while (!$userDirectory = generate_unique_userDirectory()) {
    echo 'folder exists...loop back try another';
    //Try another:
    $userDirectory = generate_unique_userDirectory();
}

Is there a better way of doing this, my main concern is whether I’m over-complicating the procedure?

Many thanks for your time.

---

My findings thanks to all that contributed!

Thanks @Veger, and everyone else; your assistance was brilliant; I’ve since re-worked the function based on your advice:

function generate_unique_userDirectory($uid){

        $userDirectory = md5(uniqid($uid));             

            while (is_dir(BASE_URI . "$userDirectory")){

                $userDirectory = md5(uniqid($uid));
            }

            return $userDirectory;

        }//End of generate_unique_userDirectory funcation decleration.

            //Example call to function:
        $userDirectory = generate_unique_userDirectory($uid);

            echo "The generated user directory is: $userDirectory";

As suggested, I’ve put the folder name generation while loop within the function which now makes the function call much simpler.

In response to your second bullet point @Veger, it is my understanding that as I’ve fed the ‘uniqid’ function to the md5 function this will result in a new string each time (though I may have misunderstood).

The purpose of passing the $uid to generate_unique_userDirectory() is to further ‘salt’ the generated string, however, I may be taking it a step too far!

Many thanks to all- a great first time on stackoverflow…

Answer 1

Some of my thoughts on your design:

• As Wesley already commented generate_unique_userDirectory() suggests that the returned directory is unique. So you should not need to check after calling whether its result is a unique directory or not…
• Calling the function a second time results in the same failure, as $uid is not changed for the new user.
• If it does change, why not put your while loop inside the function? So it always returns a unique directory.
• By calling the function in the while-statement and in the loop itself, results in it being called twice after failure. First call in the loop which is overridden by the call in the statement.