Bug 36815 – [Qt] [Gtk] Plug-ins having upper case in mime type are failing to load

• Component: WebKitGTK
• Status: RESOLVED FIXED

[Paanky]

WebKit can not load Mozilla Plug-ins having uppercase in their mime type description string. For example a HelloWorld plug-in with mime type as "application/sample-helloworld" is loaded successfully but when the mime type string becomes "application/Sample-HelloWorld" it fails to load. Where as Mozilla Firefox browser loads it properly.

With a little debugging I found that WebKit converts the mime type strings to lower case explicitly, before searching for the plug-ins in plug-in directories. Is there any special reason behind that? If not, I think, they should not be converted to lower case.

The files and functions where they are converted to lower case are as below
1. In the file "WebCore/html/HTMLObjectElement.cpp", in the function 
   "void HTMLObjectElement::parseMappedAttribute(MappedAttribute *attr)"
   the line "m_serviceType = val.lower();"
2. In the file "WebCore/plugins/PluginDatabase.cpp", in the function 
   "PluginPackage* PluginDatabase::pluginForMIMEType(const String& mimeType)"
   the line "String key = mimeType.lower();"
3. In the file "WebCore/plugins/PluginDatabase.cpp", in the function 
   "void PluginDatabase::setPreferredPluginForMIMEType(const String& mimeType, PluginPackage* plugin)"
   the line "m_preferredPlugins.set(mimeType.lower(), plugin);"

[Alexey Proskuryakov]

RFC 2045 says that matching of media types should be case insensitive. Whether it's correct to change attribute value case is a separate question.

I don't think we have such problem on Mac, because WebBasePluginPackage lowercases MIME strings it gets from plug-ins.

[Paanky]

The plug-in library, I have created, is for Scriptable plug-in objects. Though the case-insensitivity holds good, still WebKit does not load it, where as Firefox Mozilla loads it properly and invoke it for the the properties and methods of the Scriptable objects.

Note: When I change the above statements, such as, not to convert the mime-type to lower case, it works fine.

[Paanky]

WebKit converts all the characters in the Mime-Type string mentioned in the type="application/Sample-HelloWorld" attribute of the <object> tag to lower case as "application/sample-helloworld" and give it to the NPP_New() call.

So, even though in the HTML page object tag has type="application/Sample-HelloWorld" and I return "application/sample-helloworld" as mime-type from my Plug-in then it loads fine. But in Firefox this scenario does not work.

I could not find any where the reason of converting the attribute values to lower case explicitly. 

I don't think that this problem is only for [Qt] or [Gtk] ports. This problem will be there if upper-cases MIME strings are returned from plug-ins in [Mac] port also.

Since RFC 2045 says that matching of media types should be case insensitive, So Plug-ins can have upper-case in their Mime-type strings.

[Paanky]

Another solution to this problem is as below.
---------------------------------------------

As said above the string comparison of mime-types should be case insensitve but I guess here in the below code it goes wrong.

When pluginForMIMEType() is called from findPlugin(), the mime-type string is in lower cases. But the mimeToDescriptions() for PluginPackage have upper case characters as recieved from the plugin library.
Since, mimeToDescriptions().contains(key) will do a case sensitive comparison so the PluginPackage will not be identified for that mime-type.


Code Changes:
-------------
1. In the file "WebCore/plugins/PluginDatabase.cpp", in the function
   "PluginPackage* PluginDatabase::pluginForMIMEType(const String& mimeType)"
   the lines 

   "if (plugin->mimeToDescriptions().contains(key))
            pluginChoices.append(plugin);"

   can be replaced with

   "MIMEToDescriptionsMap::const_iterator map_it = (*it)->mimeToDescriptions().begin();
        MIMEToDescriptionsMap::const_iterator map_end = (*it)->mimeToDescriptions().end();
        for (; map_it != map_end; ++map_it){
            if (equalIgnoringCase(map_it->first, key)){
                pluginChoices.append(plugin);
                continue;
            }
        }

[Robert Hogan]

Created attachment 72455 [details]
Patch

[Antonio Gomes]

Comment on attachment 72455 [details]
Patch

No way to test this?
Do mac and win port do the same?

[Robert Hogan]

(In reply to comment #6)
> (From update of attachment 72455 [details])
> No way to test this?
> Do mac and win port do the same?

The change to the casing of the mime-type returned by the test plugin tests it.

[WebKit Review Bot]

Attachment 72455 [details] did not build on gtk:
Build output: http://queues.webkit.org/results/4865086

[Robert Hogan]

(In reply to comment #6)
> Do mac and win port do the same?
Looking at PluginPackage::fetchInfo() for Mac and Win, yes it does.

[Antonio Gomes]

Comment on attachment 72455 [details]
Patch

r=me, with the Gtk build fixed.

[Robert Hogan]

Created attachment 72460 [details]
Patch

[Robert Hogan]

Created attachment 72461 [details]
Patch

[WebKit Commit Bot]

Comment on attachment 72461 [details]
Patch

Clearing flags on attachment: 72461

Committed r71006: <http://trac.webkit.org/changeset/71006>

[WebKit Commit Bot]

All reviewed patches have been landed.  Closing bug.