Image upload handler with random filename generator and postprocessing

I have a function to handle image uploads. Originally, it contained a goto:

restartA:
$name = $this->random_name() . $ext;
if(file_exists($this->img_path . $name)){
    unset($name);
    goto restartA; 
}

It seems pretty clear to me what the code does, and I think anyone who reads it would immediately understand what's happening. On the other hand, goto is considered evil, so I rewrote it like this:

while(true){
    $name = $this->random_name() . $ext;
    if(file_exists($this->img_path . $name)){
        unset($name);
    }else{
        break;  //weve got a unique name
    }
}

Here's the context in which the code excerpt above appears. In place of some code which I am not allowed to post, I have substituted an array of 3 static sizes.

public function original_img_upload()
{
    $img_name = 'original_image';
    $image_name = $_FILES[$img_name]['name'];
    $image_temp = $_FILES[$img_name]['tmp_name'];
    $image_type = $_FILES[$img_name]['type'];
    $image_info = getimagesize($image_temp);
    $valid = ['.jpg', '.jpeg', '.gif', '.png'];
    $exif = [IMAGETYPE_GIF,IMAGETYPE_JPEG,IMAGETYPE_PNG];
    $ext = strtolower(strrchr($image_name, "."));
    $names_to_return = []; //image names to return to main scope
    $sizes = [
        [1000,608],
        [657,400],
        [329,200]
    ]; //image target sizes

    if( !is_uploaded_file($_FILES[$img_name]['tmp_name']) ){
        $this->e('bad file input');
    }
    if( !in_array(exif_imagetype($image_temp),$exif) && in_array($ext,$valid) ){
        $this->e('file type not allowed');
    }
    if( !$image_info ){
        $this->e('invalid image size.');
    }

    switch($image_type){
        case 'image/png': 
            $image_res = imagecreatefrompng($image_temp); 
        break;
        case 'image/gif': 
            $image_res = imagecreatefromgif($image_temp);
        break;           
        case 'image/jpeg': 
        case 'image/pjpeg': 
            $image_res = imagecreatefromjpeg($image_temp); 
        break;
        default:$this->e('bad file input');
    }

    for($i=0;$i <3; $i++){
        $canvas = imagecreatetruecolor($sizes[$i][0],$sizes[$i][1]);//width + height
        //( resource $dst_image , resource $src_image , int $dst_x , int $dst_y , int $src_x , int $src_y , int $dst_w , int $dst_h , int $src_w , int $src_h )
        imagecopyresampled(
            $canvas,
            $image_res,
            0,0,0,0,
            $sizes[$i][0],
            $sizes[$i][1],
            $image_info[0],
            $image_info[1]
        );

        //create random destination file name
        while(true){
            $name = $this->random_name() . $ext;
            if(file_exists($this->img_path . $name)){
                unset($name);
            }else{
                break;  //weve got a unique name
            }
        }

        $destination = $this->img_path . $name;

        //write image
        switch(strtolower($image_type))
        {
            case 'image/png':
                imagepng($canvas,$destination);
                break;
            case 'image/gif':
                imagegif($canvas,$destination);
                break;          
            case 'image/jpeg':
            case 'image/pjpeg':
                imagejpeg($canvas,$destination,100);
                break;
        }

        //push image name to return images
        array_push($names_to_return,$this->args['base_url'].'img/'. $name);
        //unset resources and free memory
        unset($canvas,$name,$destination);
    }
    return $names_to_return;
}