Validating Uploaded File Size in eForm Before Accepting the File

File uploads become much safer when the form rejects oversized files before the rest of the workflow continues. In eForm, a lightweight way to do that is to add a custom validation callback and inspect $_FILES directly.

The original pattern looked like this:

[!validatefilesize!]
[!eForm? ... &eFormOnValidate=`validatefilesize`!]

With a file field such as:

<input type="file" name="testfile" eform=":file:0">

And a validator similar to:

function validatefilesize($fields,&$vMsg,&$rMsg){
    if ($_FILES['testfile']['size'] > 1024) {
        $vMsg[]='File is too large';
    }
}

The real value here is not the exact threshold, but the pattern itself: use the standard eForm validation flow, keep the rule close to the form, and fail early before later hooks try to process an invalid upload.

In real projects you would normally compare against a more realistic limit, validate MIME type as well, and keep the error message editor-friendly. But this remains a solid foundation for safer upload workflows in Evolution CMS.