Changes to a plugin interface might cause recursion

[Sidnei da Silva]

If a plugin declared and was activated for a specific interface, and then suddenly stops providing that interface and removes the method from its implementation, PAS might end up acquiring the method from itself and recursing.

An example:

  - LDAPMultiPlugins used to provide and implement ICredentialsUpdate

  - An instance of LDAPMultiPlugins exists inside the database, activated to ICredentialsUpdate

  - LDAPMultiPlugins then removed the updateCredentials method and stopped declaring the ICredentialsUpdate interface.

  - Existing sites get a recursion error on login, because PAS tries to call <ldapmultiplugin-object>.updateCredentials(), but the method is acquired from PAS.

A proposed fix is attached, just checks that the object actually provides the interface it's declared for when doing listPlugins.

[Sidnei da Silva (sidnei)]

FWIW, the patch is for PluginRegistry.

[Tres Seaver (tseaver)]

Status: Pending => Resolved

Thanks for the patch! Checked in, with a test, on the trunk:

  http://svn.zope.org/PluginRegistry/trunk/?view=rev&rev=74716

and will be in the upcoming 1.1.2 release.