1686437 - Office Open XML file extensions

Status: RESOLVED INCOMPLETE

(Firefox :: File Handling, defect)

Description

[Damien Goor]

Attachment: xml-xlsx.JPG

User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/87.0.4280.141 Safari/537.36

Steps to reproduce:

PHP generates a spreadsheet in openXml format with the following headers:
Content-type: application/vnd.openxmlformats-officedocument.spreadsheetml.sheet;
File extension set to '.xml', still Firefox replaces the '.xml' extension with '*.xlsx' extension which prevents the file to correctly open in Excel as xlsx is not the expected format.

Comment 1

[Tom S. (please needinfo tschuster)]

I don't understand how .xlsx is not the correct extension for that MIME type for that file. Looking at https://www.iana.org/assignments/media-types/media-types.xhtml you probably meant application/vnd.openxmlformats-officedocument.spreadsheetml.sheet.main+xml (Note the trialing +xml) ?

Comment 2

[Tom S. (please needinfo tschuster)]

Maybe the mapping from application/vnd.openxmlformats-officedocument.spreadsheetml.sheet is indeed not completely correct. Or there are multiple file extensions? https://www.iana.org/assignments/media-types/application/vnd.openxmlformats-officedocument.spreadsheetml.sheet lists .xltx. https://en.wikipedia.org/wiki/Office_Open_XML lists both .xlsx and .xlsm.

Comment 3

[BugBot [:suhaib / :marco/ :calixte]]

Bugbug thinks this bug should belong to this component, but please revert this change in case of error.

Comment 4

[Tom S. (please needinfo tschuster)]

Seems like we either need to stop enforcing file extensions for OOXML or make sure we definitely have all the right extensions listed. Adding .xml seems problematic, but maybe that case was actually an issue with the reporter's code.

Comment 5

[:Gijs (he/him)]

Can you provide a testcase?

Comment 6

[:Gijs (he/him)]

(In reply to Tom Schuster [:evilpie] from comment #4)

Seems like we either need to stop enforcing file extensions for OOXML or make sure we definitely have all the right extensions listed. Adding .xml seems problematic, but maybe that case was actually an issue with the reporter's code.

Yeah, I don't really understand what is going on here. Unless we list XML I don't think the original case is going to be fixed...

Maybe we just end up having to drop all the non-media types. :-\

Comment 7

[:Gijs (he/him)]

Without more information about the specifics, we can't do much here.

Comment 8

[jscher2000]

Hi Damien, did Firefox 85 fix this for you (via the bug 1684183 patch)?

Comment 9

[Damien Goor]

Attachment: sql416045.xlsx

Attached, sample of exported file.
File is correct but Firefox changes the file extension to ".xlsx" while extension is explicitly set to ".xml" in PHP code.

PHP code that exports the data to the browser:

header("Content-type: application/vnd.openxmlformats-officedocument.spreadsheetml.sheet; charset=utf-8");
header("Content-Disposition: attachment; filename=".$settings['file'].rand(1001,1000000).".xml");
header("Pragma: no-cache");
header("Expires: 0");
print $data;

Comment 10

[Damien Goor]

Nope Sorry, I missed previous emails. tested with FF 85.0.2=> result is the same

Comment 11

[Tom S. (please needinfo tschuster)]

Changing your code to

header("Content-Type: application/vnd.openxmlformats-officedocument.spreadsheetml.sheet.main+xml");

would fix this.

Comment 12

[Tom S. (please needinfo tschuster)]

Actually just application/xml might be better. Seems like sheet.main+xml is for something else

This subtype is intended for an OPC part of an OOXML document rather
than an entire OOXML document.

https://www.iana.org/assignments/media-types/application/vnd.openxmlformats-officedocument.spreadsheetml.sheet.main+xml