PHP readfile() and large files

Question

When using readfile() -- using PHP on Apache -- is the file immediately read into Apache\'s output buffer and the PHP script execution completed, or does the PHP script exec

Answer 1

The script will be running until the user finishes downloading the file. The simplest, most efficient and surely working solution is to redirect the user:

header("Location: /real/path/to/file");
exit;

But this may reveal the location of the files. It's a good idea to password-protect the files that may not be downloaded by everyone anyway with an .htaccess file, but perhaps you use a database to detemine access and this is no option.

Another possible solution is setting the maximum execution time of PHP to 0, which disables the limit:

set_time_limit(0);

Your host may disallow this, though. Also PHP reads the file into the memory first, then goes through Apache's output buffer, and finally makes it to the network. Making users download the file directly is much more efficient, and does not have PHP's limitations like the maximum execution time.

Edit: The reason you get this complaint a lot from iPhone users is probably that they have a slower connection (e.g. 3G).