unable to skip unreadable directories with RecursiveDirectoryIterator

Introduction

The main issue with your code is using CHILD_FIRST

FROM PHP DOC

Optional mode. Possible values are

• RecursiveIteratorIterator::LEAVES_ONLY - The default. Lists only leaves in iteration.
• RecursiveIteratorIterator::SELF_FIRST - Lists leaves and parents in iteration with parents coming first.
• RecursiveIteratorIterator::CHILD_FIRST - Lists leaves and parents in iteration with leaves coming first.

What you should use is SELF_FIRST so that the current directory is included. You also forgot to add optional parameters RecursiveIteratorIterator::CATCH_GET_CHILD

FROM PHP DOC

Optional flag. Possible values are RecursiveIteratorIterator::CATCH_GET_CHILD which will then ignore exceptions thrown in calls to RecursiveIteratorIterator::getChildren().

Your CODE Revisited

foreach (new RecursiveIteratorIterator(
        new RecursiveDirectoryIterator($path,RecursiveDirectoryIterator::KEY_AS_PATHNAME),
        RecursiveIteratorIterator::SELF_FIRST, RecursiveIteratorIterator::CATCH_GET_CHILD) as $file => $info)
{
    if ($info->isDir())
    {
        echo $file . '<br>';
    }
}

You really want CHILD_FIRST

If you really want to maintain the CHILD_FIRST structure then i suggest you use ReadableDirectoryIterator

Example

foreach ( new RecursiveIteratorIterator(
        new ReadableDirectoryIterator($path),RecursiveIteratorIterator::CHILD_FIRST) as $file ) {
    echo $file . '<br>';
}

Class Used

class ReadableDirectoryIterator extends RecursiveFilterIterator {
    function __construct($path) {
        if (!$path instanceof RecursiveDirectoryIterator) {
            if (! is_readable($path) || ! is_dir($path))
                throw new InvalidArgumentException("$path is not a valid directory or not readable");
            $path = new RecursiveDirectoryIterator($path, RecursiveDirectoryIterator::SKIP_DOTS);
        }
        parent::__construct($path);
    }

    public function accept() {
        return $this->current()->isReadable() && $this->current()->isDir();
    }
}

function dirScan($dir, $fullpath = false){

    $ignore = array(".","..");
    if (isset($dir) && is_readable($dir)){
        $dlist = array();
        $dir = realpath($dir);
        $objects = new RecursiveIteratorIterator(new RecursiveDirectoryIterator($dir,RecursiveDirectoryIterator::KEY_AS_PATHNAME),RecursiveIteratorIterator::SELF_FIRST, RecursiveIteratorIterator::CATCH_GET_CHILD);

        foreach($objects as $entry){    
                    if(!in_array(basename($entry), $ignore)){
                        if (!$fullpath){
                            $entry = str_replace($dir, '', $entry);
                        }           
                            $dlist[] = $entry;
                    }                        
        }       
        return $dlist;
    }

}

This code works 100%...

You can simply use this function in order to scan for files and folders in your desired directory or drive. You just need to pass the path of the desired directory into the function. The second parameter of the function is to show full-path of the scanned files and folder. False value of the second parameter means not to show full-path.

The array $ignore is used to exclude any desired filename or foldername from the listing.

The function returns the array containing list of files and folders.

This function skips the files and folders that are unreadable while recursion.