[RESOLVED] I need help understanding this php code

[kikki]

Hi guys,
I have little piece of code, I need to understand the code better. If any of you guys can add comments each line, it would be really helpful to understand the code better to proceed..

Thanks 🙂

if($freakshow)
{
 //do blah!
}
else
{
//starts from here------------------------------------------------>

$handle = fopen('stuff/'.$_GET['info_hash'], 'rb+');
flock($handle, LOCK_EX);
$length = filesize('stuff/'.$_GET['info_hash']);

if ($length)
{
	$peer_num = $length / 19;
	$data = fread($handle, $length);

	for ($i=0; $i<$peer_num; $i++)
	{

		if ($peer_ip == substr($data, $i * 19 + 1, 6))
		{
			$updated = true;

			if ($_GET['event'] == 'stopped')
			{
				$peer_num--;
			}
			else
			{
				$peers[] = $time.$peer_ip.$peer_details;
			}
		}
		else
		{
			$t_peer_seed = implode('', unpack('C', substr($data, $i * 19, 1)));	

			if ($t_peer_seed >= 128)
			{
				$t_time = $t_peer_seed - 128;
			}
			else
			{
				$t_time = $t_peer_seed;
			}


			$peers[] = substr($data, $i * 19, 19);

		}
	}
}
}

if ($updated == false)
{
	$peers[] = $time.$peer_ip.$peer_details;
	$peer_num++;
}

rewind($handle);
ftruncate($handle, 0);
fwrite($handle, implode('', $peers), $peer_num * 19);
flock($handle, LOCK_UN);
fclose($handle);

[bpat1434]

//starts from here------------------------------------------------>

  // Opens the file for reading, byte safe
    $handle = fopen('stuff/'.$_GET['info_hash'], 'rb+');
  // EXCLUSIVELY locks the file
    flock($handle, LOCK_EX);
  // Determins file length / size
    $length = filesize('stuff/'.$_GET['info_hash']);

  // If there is a length (i.e. previous call didn't fail)
    if ($length)
    {
      // Divides length by 19 (not sure why)
        $peer_num = $length / 19;
      // Reads the contents of the file into a string
        $data = fread($handle, $length);

 // Loops through $peer_num (19) times
    for ($i=0; $i<$peer_num; $i++)
    {

     // If $peer_ip is equal to an extractaed part of data
        if ($peer_ip == substr($data, $i * 19 + 1, 6))
        {

          // Set updated to true
            $updated = true;

         // If event is "stopped"
            if ($_GET['event'] == 'stopped')
            {
             // Decrement the $peer_num by 1
                $peer_num--;
            }
            else
            {
              // Otherwise add the peer details to an array
                $peers[] = $time.$peer_ip.$peer_details;
            }
        }
        else
        {
          // unpack into an array the data, then implode it back on itself
            $t_peer_seed = implode('', unpack('C', substr($data, $i * 19, 1)));    

          // If the value of $t_peer_seed is > = 128, subtract 128 
            if ($t_peer_seed >= 128)
            {
                $t_time = $t_peer_seed - 128;
            }
            else
            {
              // Otherwise, make time the value from above
                $t_time = $t_peer_seed;
            }

           // Add information to $peers[] array
            $peers[] = substr($data, $i * 19, 19);

        }
    }
}
}

// If we didn't update any of the items
if ($updated == false)
{
  // Add info to the peers array, increment the $peer_num
    $peers[] = $time.$peer_ip.$peer_details;
    $peer_num++;
}

// Set the pointer to beginning of file
rewind($handle);
// Truncate the file to 0 length
ftruncate($handle, 0);
// Write the new contents
fwrite($handle, implode('', $peers), $peer_num * 19);
// Unlock the file
flock($handle, LOCK_UN);
// Close the file
fclose($handle);

Help?

[kikki]

thanks for the reply bpat1434, appreciate it,
It's nicely commented... I didn't want this code to use any files to write/read files in "stuff" folder.... thought to do that process with mysql database.. I really needed to know whats going on.. because the output of this piece of code is.. êÕ‹£[á , I thought I could make it readable or to output in mysql table to make things faster(insert/update)... or something to make things more clear.. but it's still remaining as mystery..