finding current file pointer

foyleman

I've been trying to figure out how to determine my current file pointer in a file that is being read but can't seem to do it.

I am writing a script that will download a file and alert me when the download process is cancelled or complete. I can do this so far.

Now, I want to try and calculate the amount of time left for the download to complete. I want to do this by determining how much of the file has been sent (or read) and running my math from there.

I thought I could use ftell(), but that doesn't output anything for me.

Any other suggestions?

Here is my code for reference:

<?php

Ignore_User_Abort(True); // finish the script after it starts running
$start_time = time();

$filename = "files/cod/suppliments/Allied_AI.zip";
$ext = substr( $filename,-3 );
if( $filename == "" ) {
echo "<html><body>ERROR: Empty file to download. USE download.php?file=[file path]</body></html>";
exit;
} elseif ( ! file_exists( $filename ) ) {
echo "<html><body>ERROR: File not found. USE download.php?file=[file path]</body></html>";
exit;
};
switch( $ext ){
case "pdf": $ctype="application/pdf"; break;
case "exe": $ctype="application/octet-stream"; break;
case "zip": $ctype="application/zip"; break;
case "doc": $ctype="application/msword"; break;
case "xls": $ctype="application/vnd.ms-excel"; break;
case "ppt": $ctype="application/vnd.ms-powerpoint"; break;
case "gif": $ctype="image/gif"; break;
case "png": $ctype="image/png"; break;
case "jpg": $ctype="image/jpg"; break;
default: $ctype="application/force-download";
}
header("Pragma: public");
header("Expires: 0");
header("Cache-Control: must-revalidate, post-check=0, pre-check=0");
header("Content-Type: $ctype");
$user_agent = strtolower ($_SERVER["HTTP_USER_AGENT"]);
if ((is_integer (strpos($user_agent, "msie"))) && (is_integer (strpos($user_agent, "win")))) {
header( "Content-Disposition: filename=".basename($filename).";" );
} else {
header( "Content-Disposition: attachment; filename=".basename($filename).";" );
}
header("Content-Transfer-Encoding: binary");
header("Content-Length: ".filesize($filename));

// write the results to a file
$fo = fopen("stream_result.txt", "wb");
fwrite($fo, "started file size = ".filesize($filename)."\n");
fclose($fo);

While(!Connection_Aborted()) {
$handle = fread($filename, filesize($filename));
$read = ftell($handle); // not working
print($handle); // send the file being read
flush();
}

// write the results to a file
if(connection_status() != 0) {
$fo = fopen("stream_result.txt", "ab");
fwrite($fo, "stopped after ".(time() - $start_time)." seconds at byte $read");
fclose($fo);
}

?>

stream_result.txt ends up reading:
"started file size = 53121688
stopped after 6 seconds at byte "

As you can see there is no ftell and I can't find another way to find my current pointer.

swr

Originally posted by foyleman
While(!Connection_Aborted()) {
$handle = fread($filename, filesize($filename));
$read = ftell($handle); // not working
print($handle); // send the file being read
flush();
}

I'm pretty sure the $handle = fread($filename ...) bit is wrong.

You need to do this instead:

$handle = fopen($filename, "rb");
$data = fread($handle, filesize($filename))
$read = ftell($handle);

I think what you're trying to do isn't going to work though. fread will block until it has read all the data, then when you do ftell it is going to be equal to filesize($filename).

foyleman

You are correct, on both accounts.

I ended up with code that looked like this:

Ignore_User_Abort(True); // finish the script after it starts running
$start_time = time();

$filename = "files/cod/maps/portvillage.zip";

$ext = substr( $filename,-3 );
if( $filename == "" ) {
   echo "<html><body>ERROR: Empty file</body></html>";
   exit;
} elseif ( ! file_exists( $filename ) ) {
   echo "<html><body>ERROR: File not found</body></html>";
   exit;
};
switch( $ext ){
   case "pdf": $ctype="application/pdf";              break;
   case "exe": $ctype="application/octet-stream";      break;
   case "zip": $ctype="application/zip";              break;
   case "doc": $ctype="application/msword";            break;
   case "xls": $ctype="application/vnd.ms-excel";      break;
   case "ppt": $ctype="application/vnd.ms-powerpoint"; break;
   case "gif": $ctype="image/gif";                    break;
   case "png": $ctype="image/png";                    break;
   case "jpg": $ctype="image/jpg";                    break;
   default:    $ctype="application/force-download";
}
header("Pragma: public");
header("Expires: 0");
header("Cache-Control: must-revalidate, post-check=0, pre-check=0");
header("Content-Type: $ctype");
$user_agent = strtolower ($_SERVER["HTTP_USER_AGENT"]);
if ((is_integer (strpos($user_agent, "msie"))) && (is_integer (strpos($user_agent, "win")))) {
   header( "Content-Disposition: filename=".basename($filename).";" );
} else {
   header( "Content-Disposition: attachment; filename=".basename($filename).";" );
}
header("Content-Transfer-Encoding: binary");
header("Content-Length: ".filesize($filename));

// write the results to a file
$fo = fopen("stream_result.txt", "wb");
fwrite($fo, "started file size = ".filesize($filename)."\n");
fclose($fo);

$fr = fopen($filename, 'rb');

while(!feof($fr)) {
	$handle = fread($fr, filesize($filename));
	print($handle); // send the file being read
	flush();
	}

// write the results to a file
if(connection_status() != 0) {
	$fo = fopen("stream_result.txt", "ab");
	fwrite($fo, "stopped after ".(time() - $start_time)." seconds\n\n");
	fclose($fo);
	} else {
	$fo = fopen("stream_result.txt", "ab");
	fwrite($fo, "completed after ".(time() - $start_time)." seconds\n\n");
	fclose($fo);
	}

fclose($fr);

I was getting missing data without the fopen.

And also the fopen opens the entire file so I never have an accurate file pointer.

I tried experimenting with opening the file in packets where I would only read so much of the file out to the browser before going back for more. But I couldn't get this to read correctly either.

I can very nicely download a file and log if the file is complete or cancelled.. I just can't estimate the time to completion since I can't determine how much of the file is complete or any other stats during the download process.

I really hate the idea of estimating a general download time for a file since that can often be very inaccurate, but I may be stuck.

Thanks for your input.

swr

When you do fread($handle, filesize($filename) the filesize($filename) part is telling fread to read the entire file. If you use something smaller, like 10000 or something, you'll not read the entire file all at once.

But I'm wondering how you expect to report progress when the browser connection will be tied up with the download...?

foyleman

Exactly one of my problems. I can't retrieve download status if I cannot determine how much of the file has actually been read by the user.

I was trying to figure that out.

I thought I could figure out how to feed the download to the user in packets, retrieve confirmation or something that the packet has been sent, and then send another packet until the entire file has been sent.

I wanted to read the file in packets using fseek to place the file pointer based on the last packet read/sent. Then when I hit feof(), I would send the next batch.

The problem, as you have been pointing out to me, is that I cannot confirm that the user has completed the receipt of the packet since it's all stored in a cache (I think) for the user downloading it at a speed separate from how fast I feed it to them.

I don't expect to find an answer using php anymore, but I'm not ready to give up quite yet.