Do you already have some kind of sessioning set up?
If you have:
  • Write the PID ($$) of the script processing the upload to the session
  • Point your Cancel-button to another CGI script which reads the PID of the upload-script from the session and kill's it
    kill 15,$Upload_PID; # Hard-kill and risk half-uploaded temp-files on 
+disk, if you write them
kill 10,$Upload_PID; # Send SIGUSR1 to the upload-script

    [download]
  • When using SIGUSR1 (second line above), you could clean up before aborting the upload script, for example:
    $SIG{USR1} = sub { unlink $Temp_File; exit; };

    [download]

    • If you don't have any sessioning, add a hidden field with some unique token to the upload form. A lovely thing could be:

    my $Token = unpack('H*',pack('L',time).pack('S',$$));

    [download]
    Your upload script makes itself findable using the token it received from the form (a good idea would be adding the token as GET parameter for early parsing), for example:
    $0 .= '('.$Token.')';

    [download]
    or
    open my $ID_File,'>/dev/shm/tokenfiles/'.$Token;
print $ID_File $$;
close $ID_File;

    [download]
    (You should verify the incoming token for matching /^\da-f$/ for security reasons for both solutions! Don't forget to clean up the file after the upload has finished when using a ID-file.)
    Feed the same token from the form to your cancel-script and let it find the PID of the upload process by searching the process table or looking at /dev/shm/tokenfiles/$Token. The rest is the same as above: Now as you know the PID, you could send a cancel signal to the process.

    In reply to Re: Cancelling a cgi file transfer by Sewi
    in thread Cancelling a cgi file transfer by Rogue

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