Bug 246131

Summary:	Accept image/jpg for compatibility reasons
Product:	WebKit	Reporter:	Karl Dubost <karlcow>
Component:	Images	Assignee:	Chris Dumez <cdumez>
Status:	RESOLVED FIXED
Severity:	Normal	CC:	annevk, cdumez, marcosc, sabouhallawa, webkit-bug-importer
Priority:	P2	Keywords:	BrowserCompat, InRadar
Version:	Safari Technology Preview
Hardware:	Unspecified
OS:	Unspecified
See Also:	https://bugs.webkit.org/show_bug.cgi?id=13154

Description Karl Dubost 2022-10-05 19:32:43 PDT

Some servers seems to send JPEG images as `image/jpg`
The correct Content Type is `image/jpeg` per RFC.
https://www.iana.org/assignments/media-types/media-types.xhtml#image
https://www.rfc-editor.org/rfc/rfc2046.html

It may create web compatibility breakages. 
It would be good to assess the level of breakages it creates.

* Both Firefox and Chrome accepts `image/jpg` for displaying JPEG images.
* Safari is downloading the image.

Comment 1 Radar WebKit Bug Importer 2022-10-05 20:10:09 PDT

<rdar://problem/100835192>

Comment 2 Karl Dubost 2022-10-06 02:16:21 PDT

There is history into this:

It seems to be available already on iOS.
https://searchfox.org/wubkat/rev/e8e9be7353991aee7df45aa62f0e0148f16e6f9f/Source/WebCore/platform/MIMETypeRegistry.cpp#74-93

Comment 3 Karl Dubost 2022-10-06 02:17:09 PDT

Forgotten
https://searchfox.org/wubkat/rev/e8e9be7353991aee7df45aa62f0e0148f16e6f9f/Source/WebCore/platform/MIMETypeRegistry.cpp#108-112

Comment 4 Anne van Kesteren 2022-10-06 09:09:13 PDT

I'm actually surprised we don't resort to sniffing here, but I suppose that's because we're given a MIME type? In that case we probably want to claim support for this MIME type even if it's non-standard. HTML could probably be more specific about the MIME types here. It currently has "A supported image, video, or audio type" in the navigate algorithm which isn't great. (Separately it suggests `image/*` are image MIME types for a different algorithm, but claiming all of them might also not be what we want for navigate or what other browsers implement.)

https://github.com/web-platform-tests/wpt/pull/30403 has some work-in-progress tests for sniffing-related cases where there's also download-vs-display differences.

https://github.com/whatwg/html/issues/7420 discusses a similar issue for XML MIME types.

Comment 5 Chris Dumez 2022-10-06 12:25:07 PDT

Pull request: https://github.com/WebKit/WebKit/pull/5100

Comment 6 EWS 2022-10-07 07:37:59 PDT

Committed 255268@main (0d17dc0c310f): <https://commits.webkit.org/255268@main>

Reviewed commits have been landed. Closing PR #5100 and removing active labels.