254280 - NPAPI GetProperty() never gets called

Status: RESOLVED DUPLICATE of bug 257191

(Core Graveyard :: Plug-ins, defect)

Description

[Vlad Alexander]

User-Agent:       Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.6) Gecko/20040115
Build Identifier: 2004080309 Mozilla 1.8a3

Developing a plugin using NPAPI. Unable to call a property from script. Suspect
this is a bug.

Reproducible: Always
Steps to Reproduce:
1.
2.
3.

Comment 1

[Christian :Biesinger (don't email me, ping me on IRC)]

you mean http://www.mozilla.org/projects/plugins/npruntime.html#NPN_GetProperty ?

Comment 2

[Vlad Alexander]

Attachment: C++ source files

The method is SPO_GetProperty(). See attached C++ source files.

Comment 3

[Christian :Biesinger (don't email me, ping me on IRC)]

is that the entire plugin source code? because if so, this is missing functions
like NP_Initialize.

it is also missing a RemoveProperty function.

Comment 4

[Vlad Alexander]

Attachment: Sample VC++ project

Attached is the entire project. There is a property called Foo that does not
work when you try to call it from script. By the way, the latest nightly build
of Mozilla crashes loading this plugin. Last week's builds were okay.

Comment 5

[Vlad Alexander]

Hi Guys,

We are in the process of developing the first plugin to use this new API but we
reached a dead end because we are not able to get properties to work. If this is
a bug, please, let's get this fixed. If we are not using properties correctly,
please give us some examples of correct usage. We have a lot of users who are
waiting to use this plugin in Mozilla/Firefox. Thanks.

Comment 6

[Heikki Toivonen (remove -bugzilla when emailing directly)]

Vlad, haven't looked at your code, but here's a resource you might find useful:
http://www.mozilla.org/projects/plugins/npruntime.html

Comment 7

[Vlad Alexander]

Properties do not work if they are called by "document.getElementById". Methods
do work if they are called in this manner.

If the plug-in adds a representation of itself to the "document" object,
properties do work. For example: alert(pluginobj.bar);  However, this is not the
preferred method for interacting with scriptable plug-ins. Plug-in IDs need to
be assigned through the "id" attribute on the <object> tag.

Example:
<object id="abc" type="application/mozilla-npruntime-scriptable-plugin"
width="600" height="40" />

<!-- this does not work -->
<input type=button value="Call Property"
onclick="alert(document.getElementById('abc').Bar)" />

<!-- this does work -->
<input type=button value="Call Method"
onclick="alert(document.getElementById('abc').Foo())" />

Also, there appears to be a memory leak when a property returns a value. If the
property is a string, the plug-in alloc some memory for that string and returns
it to script engine. It appears that the script engine does not release it. The
same thing happens to the Invoke function. We were able to identify this by
debugging our plug-in. Every time the browser is closed, the VC++ debug
environment reports that there is a memory leak. For example, the GetProperty
function malloc memory to the return value but it appears that it never gets
released.

bool
ScriptablePluginObjectBase::GetProperty(NPIdentifier name, NPVariant
*result)
{
  if (name == sBar_id) {
    STRINGZ_TO_NPVARIANT(strdup("Hi, I'm bar"), *result);
    return true;
  }
  VOID_TO_NPVARIANT(*result);
  return false;
}

Comment 8

[Johnny Stenback (:jst)]

This will be fixed by the patch in bug 257191. Duping, just to keep my sanity
here...

*** This bug has been marked as a duplicate of 257191 ***