FileUpload - PreCheck

[Eric_Bartels]

Is there any possibility to pre-check if a file is bigger than the upload_max_filesize defined in the php.ini?
It seems that php first tries to upload the file and then checks if it is too big.

[dgrinberg]

I dont think so.

You can only check a files size, using PHP, when the file is on the actual server. That means the file needs to be uploaded.

What are you actually trying to acheive??

If you have control over it, you could increase the max_upload_size and then check the file once it has been uploaded (deleting it if it is too big).

Another option would be using Javascript. I am pretty sure that it has functions for that sort of thing.

[gutlass]

PHP will copy the file to a TMP directory then it will be able to check for the file_size. If it's too big, or bigger than you want then don't copy the file to the server.

If it's good to go. Then copy it.

So it doesn't copy it to your destination until you tell it to.
But you still have to wait for the TMP process to complete.

As far as I know you can't check the size before you upload any type of file.

🙁

[dgrinberg]

I dont think that PHP will copy it to the tmp folder if the file is bigger that max_upload_size, not so that you would be able to do any checking anyway.

If a file is bigger than max_upload_size then the upload will fail.

I think that is why Eric wants to check it before it gets uploaded.

[mmilano]

yeah, check out how vbulletin does it. try to attach a big file in a post. it will start to do it, but when it fails, it will give you a nice little notice that the file is too big. since php runs server-side, it is impossible for it to verify before you start uploading.

is there a way with javascript to do it? i wonder.

[undertow]

Well, if you're getting a popup then it's most likely a JavaScript thing. The hard part about figuring out how vB JavaScript stuff works (and I know this from experience) is that most of the code used is in separate .js files on the server that get included with <script language="javascript" src="../js/myfuncs.js"> And then it's hard to find what you're looking for because those files contain other stuff that might not even be used on the page you're trying to figure out.

I remember seeing on PHP's documentation for file uploads that seemed to suggest that you can use a hidden form value to contain the maximum size. Supposedly, then your browser wouldn't let you select a file that's larger. Kind of like the JavaScript way, except it doesn't require the client to be using JavaScript. However, it would still be possible for someone that wants to fill your server's HD with useless stuff to rewrite the form in a separate HTML file on his machine without the hidden value but still have its action point to your source. The same is true with JavaScript.

That's about all I know. I have file uploads completely disabled on my server because I never use them.

[dgrinberg]

Yeah,

I too have read about the hidden form field.

<input type="hidden" name="MAX_FILE_SIZE" value="1000">

This is the form field that is supposed to limit file sizes (the value is in bytes). However from what I have been told this is not a required feature in the specifications so I am not sure which browsers it would work on.

There has to be a Javascript solution, just finding one is the hard part.

[undertow]

JavaScript is almost never the solutions in cases like these, because the can be circumvented by just disabled JS on the client side or copying the HTML file and removing the JS.