DOCX File type in PHP finfo
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?
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.
This works on debian. Add this to /etc/magic:
#------------------------------------------------------------------------------
# $File: msooxml,v 1.1 2011/01/25 18:36:19 christos Exp $
# msooxml: file(1) magic for Microsoft Office XML
# From: Ralf Brown <ralf.brown@gmail.com>
# .docx, .pptx, and .xlsx are XML plus other files inside a ZIP
# archive. The first member file is normally "[Content_Types].xml".
# Since MSOOXML doesn't have anything like the uncompressed "mimetype"
# file of ePub or OpenDocument, we'll have to scan for a filename
# which can distinguish between the three types
# start by checking for ZIP local file header signature
0 string PK 03 04
# make sure the first file is correct
>0x1E string [Content_Types].xml
# skip to the second local file header
# since some documents include a 520-byte extra field following the file
# header, we need to scan for the next header
>>(18.l+49) search/2000 PK 03 04
# now skip to the *third* local file header; again, we need to scan due to a
# 520-byte extra field following the file header
>>>&26 search/1000 PK 03 04
# and check the subdirectory name to determine which type of OOXML
# file we have
>>>>&26 string word/ Microsoft Word 2007+
!:mime application/msword
>>>>&26 string ppt/ Microsoft PowerPoint 2007+
!:mime application/vnd.ms-powerpoint
>>>>&26 string xl/ Microsoft Excel 2007+
!:mime application/vnd.ms-excel
>>>>&26 default x Microsoft OOXML
!:strength +10
Then, tell php to use /etc/magic as it's database:
$finfo = finfo_open(FILEINFO_MIME,"/etc/magic");
This is because a DOCX is a ZIP file:
An Office Open XML file is a ZIP-compatible OPC package containing XML documents and other resources.
Like Open Office files, the documents are ZIPs containing various resources in a structured and well-defined manner. So when you try to identify the file content, you first see that it is a ZIP file. You would then need to look inside the ZIP to decide whether it's a DOCX or OpenOffice file.
As an alternative, you could have a look at the file extension: if you identify the file to be a ZIP and the extension happens to be .doc or .docx then you can assume it to be an OOXML file.