validation - DOCX File type in PHP finfo_file is application/zip

Question

hello I'm trying to validate an uploaded file type by finfo_file function.

But when a .docx file is sent, the file type is:

application/zip

instead of:

application/vnd.openxmlformats-officedocument.wordprocessingml.document

how can I change this behavior?

Answer 1

As far as I now the vendor specific file types (vnd.) are not standardized (by any RFC) and therefore not covered by file_info(). .docx is a zipped xml-format and thats the reason, why file_info() returns application_zip (what is completely right). You may unzip the file and test the mime-type of the result, but that will lead to xml (what is completely correct too) and other files, that are used by the document. To differ between different XML formats file_info() had to analyze its content and it must know, how it looks, what goes just to far.