132713 - xpconnect should allow nsIException in places where it requires nsIXPCException

Status: VERIFIED FIXED

(Core :: XPConnect, defect)

Description

[John Bandhauer]

When nsIXPCException was factored out into nsIException to allow for generic
exceptions, some places in xpconnect were not updated to reference the base
nsIException interface as they should have been. This breaks the case where
non-nsIXPCException wrapped native nsIExceptions are passed through xpconnect.
XPConnect should correctly unwrap them (for error reporting and the like).
Instead, it fails to QI them to nsIXPCException and so it thinks they are just
plain nsISupports objects - even though they are perfectly useful implmenttions
of nsIException.

This problem bit rayw's SOAP code. I've also heard reports of other problems
with unrecognised exceptions that I think resolve to this problem.

I see that another place where we should have converted to nsIException is in
the code that handles JS code like: "if(foo instanceof Components.Exception)..."

I'll attach a patch that should fix both of these problems.

The following is from an email from rayw that illustrates the problem he had
with getting a useless error report where his very helpful error report should
have been emitted....

1.  I have code in SOAP for throwing exception objects with long descriptions on
many SOAP errors to help the JS writer.  This calls SetCurrentException on a
fairly-well-implemented nsIException, which has the appropriate class info and
works fine in most JS code, but when it is called from a callback such as the
SOAP responseHandler, instead of reporting the nice error, it gets strange.  I
am sure I should have reported this as a bug, and I will file a bug soon, but
I'd like to get an idea of what is wrong.

The latest version of the soapisprimenumber.html test relies on
soapisprimeproxy.js in the same directory.  If I go to line 22 and change the
word "boolean" to float", I get the error:

Error: [Exception... "'Javascript component threw a native object that is not an
exception' when calling method: [nsISOAPResponseListener::handleResponse]"
nsresult "0x8057001b (NS_ERROR_XPC_JS_THREW_NATIVE_OBJECT)" location "<unknown>"
data: yes]

If I eliminate the oncompletion argument on line 35 of the same file to make the
call synchronous instead of asynchronous, then I get the proper error message
that the user should get:

Error: uncaught exception: SOAP_TYPE_SUBCLASS: The type of the element or
xsi:type must be a subclass of the required type, called by JS frame ::
file:///home/rayw/mozilla/extensions/xmlextras/tests/soapisprimeproxy.js ::
anonymous :: line 30

Comment 1

[John Bandhauer]

Attachment: proposed fix

Comment 2

[Johnny Stenback (:jst)]

Comment on attachment 75519 [details] [diff] [review]
proposed fix

sr=jst

Comment 3

[Ray Whitmer]

*** Bug 132753 has been marked as a duplicate of this bug. ***

Comment 4

[Ray Whitmer]

The patch works as advertised.  It causes SOAP to display the correct messages.
 I assume that nsIXPCEception is still needed for internal use, which is why
there are still a few references to it in this directory (but nowhere else)
after the patch is applied.

Comment 5

[David Bradley]

Comment on attachment 75519 [details] [diff] [review]
proposed fix

r=dbradley

Looks good to me. From what I saw the remaining instances are correct.

Comment 6

[Scott Collins]

Comment on attachment 75519 [details] [diff] [review]
proposed fix

a=scc

Comment 7

[John Bandhauer]

Fix checked in. Thanks for the quick review approval and testing.

Comment 8

[Phil Schwartau]

Marking Verified -