Stop a PHP Curl Download - php

Question

I am trying to find a way to stop an active PHP Curl download. I am downloading large files from a remote server and sometimes I would like to cancel the download after it has started. I have tried returning false within CURLOPT_PROGRESSFUNCTION, however that did not work. I also tried deleting the file that was being downloaded, and that did not work either (web stats showed the download was continuing).
The below code is triggered via a quick ajax call:
$ch = curl_init( $file->url );
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_NOPROGRESS, false );
curl_setopt($ch, CURLOPT_FILE, $targetFile); //save the file to here
curl_setopt( $ch, CURLOPT_PROGRESSFUNCTION, function($resource, $download_size, $downloaded_size, $upload_size, $uploaded_size) use ($download_id) {
if ( $download_size == 0 ) {
$progress = 0;
} else {
$progress = round( $downloaded_size * 100 / $download_size );
}
// if download complete trigger completed function
if($progress == 100) {
self::DownloadCompleted($download_id);
}
});
$curl = curl_exec($ch);

Answer 1

Solution was to return a non-zero value in the CURLOPT_PROGRESSFUNCTION function, as per drew010 in the comment.
To get this done I added a check within the function to see if a file exists, if it does the function returns 1 and aborts. I just create a file in the directory with the same name as the download ID when I want to cancel the download. It works well for me.
$ch = curl_init( $file->url );
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_NOPROGRESS, false );
curl_setopt($ch, CURLOPT_FILE, $targetFile); //save the file to here
curl_setopt( $ch, CURLOPT_PROGRESSFUNCTION, function($resource, $download_size, $downloaded_size, $upload_size, $uploaded_size) use ($download_id) {
//if the file exists, the download is aborted
if(file_exists('path/to/directory/cancel.'.$download_id)) {
Self::CleanupCancelledDownload; //function to clean up the partially downloaded file, etc.
return 1; //returning a non-zero value cancels the CURL download.
}
});
$curl = curl_exec($ch);