check if file was downloaded

[Hendri Adriaens]

Hi,

I use the following code to offer a download:

header("Content-Type:$mimetype" );
header("Content-Disposition: attachment; filename=$filen ame");
header("Cache-Control:must-revalidate,post-check=0,pre-check=0");
header("Content-Length:".filesi ze($temp_filena me));
readfile_chunke d($temp_filenam e);

(readfile_chunk ed comes from
http://nl2.php.net/manual/nl/function.readfile.php)

My question: how can I check if the file was downloaded and saved? I want to
make an automatic removal possible after download.

The function seems to exit when the user clicks cancel and doesn't download
the file, so all following commands will not get executed. That's perfect.

However, it doesn't when the file is small enough to fit in a chunk. php's
readfile seems to have the same behaviour. So, in that case, all following
commands do get executed, even if cancel was clicked (and in my application,
the file then gets removed, which shouldn't happen of course).

Also checking the bytes sent doesn't help. If the function exists, it always
returns the complete filesize for the small files that fit in a single
chunk, even if cancel was clicked.

So, is there any working way to determine if a file was downloaded and
opened/saved instead of cancel being clicked in the download dialog?

Thanks in advance, best regards,
-Hendri Adriaens.

[Hendri Adriaens]

Well, not really, somewhat slower, but mainly somewhat headvier on the

server.

Ok, thanks. So, a chunksize of 1 byte should be optimal for my purpose. I
will
test the load differences for the server.

Nope, it's in the browser itself, the cancelling of a download isn't a
HTTP feature. You can add a dialogue on the page, or possibly something
with javascript, it will not help: the browser dialogue will still come
into play in the end.

Bad luck.

There may be a possibility to load the file into a hidden frame or
something, and to check that with javascript. This will not help your php
script, but javascript could fire a request on succes, ans you only delete
the file on that second request. It would mean nothing get's deleted with
javascript disabled, and I'm a little bit fuzzy on the details...

Ok, no problem, me neither.

Then again: I do not know what the exact purpose of you script is in
general, maybe it's OK to keep the small files and delete them
periodically after a check with filemtime()?

I just wanted to offer users of a sharing environment to remove the file
from
the server automatically after the file was downloaded. So a period clean up
is not really what I want. I don't want to remove files that shouldn't be
removed.

But thanks for your help and answers! But if you find any other ideas than
chunksize=1, I will be more than happy to test them :)

Best regards,
-Hendri.

[Hendri Adriaens]

Ok, thanks. So, a chunksize of 1 byte should be optimal for my purpose. I

will
test the load differences for the server.

Strangely enough, this doesn't work either...

I have 3 files:
a 19.4 MB
b 159 KB
c 1.03KB

With the previous chunksize (1*1024*1024 bytes), the script continued even
when cancel was clicked for files b and c, but not for a. With a chunksize
of 1 byte, it doens't continue for a and b, but still does for c. So the
script would still conclude that it was downloaded even if cancel was
clicked.

If anyone has an idea how this works and how I could get a script to
correctly report whether a file was actually downloaded or not, please let
me know.

Thanks, best regards,
-Hendri.