Description:
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php corrupts with the following error log:
[Sun Dec 15 23:37:29.394166 2019] [core:notice] [pid 5439] AH00094: Command line: '/usr/sbin/apache2'
[Sun Dec 15 23:45:59.115631 2019] [core:notice] [pid 5439] AH00052: child pid 5444 exit signal Segmentation fault (11)
[Sun Dec 15 23:45:59.115799 2019] [core:notice] [pid 5439] AH00052: child pid 5457 exit signal Segmentation fault (11)
[Sun Dec 15 23:45:59.115901 2019] [mpm_prefork:notice] [pid 5439] AH00169: caught SIGTERM, shutting down
[Sun Dec 15 23:45:59.280035 2019] [mpm_prefork:notice] [pid 5615] AH00163: Apache/2.4.38 (Debian) configured -- resuming normal operations
[Sun Dec 15 23:45:59.280156 2019] [core:notice] [pid 5615] AH00094: Command line: '/usr/sbin/apache2'

This error happens when I test the video stream function and print the buffer read from a local media file. If client closes the internet connection for example by disconnecting wifi while the video is still playing and data is still downloading, print function will cause a segmentation fault.

The code comes originally from http://infinityquest.com/php-tutorials/program-http-range-in-php/ and the critical line number is #148. If we use echo instead of print, problem is then solved.


Test script:
---------------
// Move the proper place in the file
// And print out the requested piece in chunks
function send_range($handle, $start, $end) {
    $line_length = 4096; // magic number

    if (fseek($handle, $start) === -1) {
        error_log("Error: fseek() fail.");
    }

    $left_to_read = $end - $start + 1;
    do {
        $length = min($line_length, $left_to_read);
        if (($buffer = fread($handle, $length)) !== false) {
            // print $buffer;   // ***** BUG if use print *****
            echo $buffer;       // ***** ok *****
        } else {
            error_log("Error: fread() fail.");
        }
    } while ($left_to_read -= $length);
}