Your problem here is the fact that you do not seem to grasp what is
hapenning when a file is being uploaded, hence your question. So let me
explain:
1. A user goes to your page by entering it into the browser.
2. The page is downloaded to the client, and the connection is closed.
3. The user chooses to upload a file via an HTML control (ie. an HTML
input element of type="file".
4. The user submits the form
5. The browser makes a connection to the server containing a header
saying "the following data is a file".
6. The server downloads all of the data from the user
7. The server parses the data, finds the header stating that the content
is a file
8. The server invokes your PHP script, which decides "whoa! wait a
minute, that file is too large" and shows an error.
9. The server removes the file from memory / temporary storage
10. The server sends back the error to the client, and closes the
connection.
The point I am trying to make here is the fact that the server does not
know the size of the file, until it has fully downloaded it, since it is
not given in any way. Good browsers let the server know what size to
*expect*, but even then, you can't rely on it.
All checking of how large a file is has to happen client-side. Due to
security reasons, languages such as javascript are not allowed to view
any details about files on your disk, and thus can't be used to
determine the filesize before sending anything to the server.
The reason flash and gears can do this, is because these are designed
differently and actually form a separate program inside your browser,
which is not limited in its activity, as javascript (and vbscript in IE)
are.
So... you can use Flash and Gears to prevent upload of a too large file
to your server. But not plain HTML and/or javascript. Since the server
does not check the size until AFTER it has fully downloaded the file,
there is no setting in Apache, PHP, MySQL (which has absolutely nothing
to do with uploading at all), etc. Which are all server-side and ran
after the upload has finished.
In other words: use the Flash/Gears solution, or just decide you don't
mind if a large file is uploaded. In the last case you can always reject
the file afterwards.
- Tul
On 20-01-2012 18:15, Dee Ayy wrote:
Please advise the proper settings (Apache/PHP/HTML/MySQL/Anything else
I missed) to allow a specific byte size upload and to deny 1 byte over
with error reporting in LAMP/AJAX. I've heard of Flash and Gears
solutions, but these require additional installs for the user -- just
to know the file size before an upload.
The server is Apache 2.
PHP is 5.1.6
HTML has
<!DOCTYPE html>
<input type="hidden" name="MAX_FILE_SIZE" value="1030000" />
<input type="file" name="attachment" />
PHP ini :
file_uploads On On
upload_max_filesize 2M 2M
post_max_size 8M 8M
I believe MySQL max_allowed_packet 1,048,576 was affecting the MySQL
INSERT, so I changed MAX_FILE_SIZE to 1030000 above.
Now I am seeing cases where
if(isset($_FILES['attachment'])&& $_FILES['attachment']['size']> 0){
evaluates to FALSE
How can I know that a file upload was attempted yet failed or will fail?
My last test case had the web page still claiming it was busy, yet I
noticed that the above condition must have evaluated to FALSE, failing
silently due to missing error reporting on my part (or the system's
part).
I am willing to make 2 requests:
1) just to find out if the attempted upload will fail and inform the user.
2) for the actual upload if it should succeed.
TIA
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