Re: Settings to Allow Precise File Upload Bytes

Dee Ayy <[email protected]> Fri, 20 Jan 2012 14:18:06 -0600
Newsgroups	gmane.comp.php.database,gmane.comp.php.general
Message-ID	<CAFXM-azKocYG1Ead3aOqMx-TGf-4_nwNNR9MES1LFX2q2dhxtg@mail.gmail.com>
Obviously I don't want a Flash/Gears solution.

FYI: Your #6 should be:
The server uploads...

Even though I do not want a Flash/Gears solution, I would be happy
with your #8 stating:
I won't fail silently, I'll report the problem to the user.

Do you know the correct settings on any applicable LAMP/AJAX stack to
get the error you claim is available in your step #8 and where to look
for this error?  Is $_FILES['attachment'] supposed to be set and
hopefully something is in $_FILES['attachment']['error']?
I decided to post here instead of trying various permutations.

MySQL max_allowed_packet was mentioned because even if you correct #8,
MySQL can choke on what Apache allowed through, and I included the DB
list.

I never claimed I want to know the file size before upload, just that
some solutions may do this.


On Fri, Jan 20, 2012 at 11:50 AM, Maciek Sokolewicz
<[email protected]> wrote:
> 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
>
>

-- 
PHP Database Mailing List (http://www.php.net/)
To unsubscribe, visit: http://www.php.net/unsub.php