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max file upload size

Last Modified: 2013-11-05
Just read this php doc about limiting a posted file's size in the form. It says to do this:

    <!-- MAX_FILE_SIZE must precede the file input field -->
    <input type="hidden" name="MAX_FILE_SIZE" value="30000" />

Now does 'name' have to be 'MAX_FILE_SIZE'?

Also I have two file input fields - so can there only be one size limit - or can I have two hitten limit fields, one for each file input field with specific different sizes?

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i.g. you cannot limit the file size in the form, the client (browser) can always change or ignore it. Never trust client data.
The web server is the only true place for such a limitation, even PHP is behind that.


that is really sad, ideally there would be a way to control the file size limit per file field. Now I guess the only thing I can do is the following:

1) Set one global max file upload size via php.
2) Let the user upload whatever size file they want, so long as it doesn't violate #1.
3) Check individual uploaded files after they're already on my server to see if they violated individual file size limits I've set.

it just doesn't look nice, but that's all we have right?

Well even if you could specify upload limits in your HTML the third step you listed there is essential anyway. A user can always take your HTML and edit it to change the contents of a form, be it upload limits or field lengths. You should never trust input from a form to match what you are expecting, it always needs to be checked that it matches the type of infomation and any sensible bounds before being acted on.

Unfortunately without additional plugins the HTTP file uploads are a bit primitive, they weren't really designed with the modern internet in mind, you can't do very much to a file input with javascript as browsers nowadays disallow programmatic access to them to prevent people having files stolen.

You might want to take a look at SWFUpload, a flash based file uploader


and JUpload and Java based file uploader


although these may be overkill.
the only reliable choice is 3)

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