Check input file size using Flash

I have a multipart html form with a file input element and wou开发者_StackOverflow社区ld like to check the size of the selected file before uploading. I can access the file path using the value attribute, however is it possible to pass that path to a swf and have the swf return the file size or is this blocked by the flash sandbox? Are there any existing projects that already do this? I'd like to avoid replacing my file input element with a flash uploader if possible.

Passing file names and accessing it via Flash is security risk. Flash does support a FileReference API, but it requires user input in order to work.