PHP - Renaming a file to disallow duplicates - php

Question

So I am using this script to upload a file to a directory and show it live.
<?php
function UploadImage($settings = false)
{
// Input allows you to change where your file is coming from so you can port this code easily
$inputname = (isset($settings['input']) && !empty($settings['input']))? $settings['input'] : "fileToUpload";
// Sets your document root for easy uploading reference
$root_dir = (isset($settings['root']) && !empty($settings['root']))? $settings['root'] : $_SERVER['DOCUMENT_ROOT'];
// Allows you to set a folder where your file will be dropped, good for porting elsewhere
$target_dir = (isset($settings['dir']) && !empty($settings['dir']))? $settings['dir'] : "/uploads/";
// Check the file is not empty (if you want to change the name of the file are uploading)
if(isset($settings['filename']) && !empty($settings['filename']))
$filename = $settings['filename'] . "sss";
// Use the default upload name
else
$filename = preg_replace('/[^a-zA-Z0-9\.\_\-]/',"",$_FILES[$inputname]["name"]);
// If empty name, just return false and end the process
if(empty($filename))
return false;
// Check if the upload spot is a real folder
if(!is_dir($root_dir.$target_dir))
// If not, create the folder recursively
mkdir($root_dir.$target_dir,0755,true);
// Create a root-based upload path
$target_file = $root_dir.$target_dir.$filename;
// If the file is uploaded successfully...
if(move_uploaded_file($_FILES[$inputname]["tmp_name"],$target_file)) {
// Save out all the stats of the upload
$stats['filename'] = $filename;
$stats['fullpath'] = $target_file;
$stats['localpath'] = $target_dir.$filename;
$stats['filesize'] = filesize($target_file);
// Return the stats
return $stats;
}
// Return false
return false;
}
?>
<?php
// Make sure the above function is included...
// Check file is uploaded
if(isset($_FILES["fileToUpload"]["name"]) && !empty($_FILES["fileToUpload"]["name"])) {
// Process and return results
$file = UploadImage();
// If success, show image
if($file != false) { ?>
<img src="<?php echo $file['localpath']; ?>" />
<?php
}
}
?>
The thing I am worried about is that if a person uploads a file with the same name as another person, it will overwrite it. How would I go along scraping the filename from the url and just adding a random string in place of the file name.
Explanation: When someone uploads a picture, it currently shows up as
www.example.com/%filename%.png.
I would like it to show up as
www.example.com/randomstring.png
to make it almost impossible for images to overwrite each other.
Thank you for the help,
A php noob

Answer 1

As contributed in the comments, I added a timestamp to the end of the filename like so:
if(isset($settings['filename']) && !empty($settings['filename']))
$filename = $settings['filename'] . "sss";
// Use the default upload name
else
$filename = preg_replace('/[^a-zA-Z0-9\.\_\-]/',"",$_FILES[$inputname]["name"]) . date('YmdHis');
Thank you for the help