Fix a crashier in CPDFSDK_Document::GetPageView()

Fix a crashier in CPDFSDK_Document::GetPageView()

BUG=pdfium:369
R=tsepez@chromium.org

Committed: https://pdfium.googlesource.com/pdfium/+/54537d1bb5f6bddd37ed4ca28cd4d5cfb4e95942

[jun_fang, 2016-02-03 10:30:31]

jun_fang@foxitsoftware.com changed reviewers:
+ thestig@chromium.org, tsepez@chromium.org

[jun_fang, 2016-02-03 10:30:31]

Hi Tom and Lei,

Please review this CL. I submitted another patch in
https://codereview.chromium.org/1652883002/ the day before yersterday. It didn't
pass embedder tests.

[Tom Sepez, 2016-02-03 18:02:50]

https://codereview.chromium.org/1667643002/diff/1/fpdfsdk/src/fpdfxfa/fpdfxfa...
File fpdfsdk/src/fpdfxfa/fpdfxfa_doc.cpp (right):

https://codereview.chromium.org/1667643002/diff/1/fpdfsdk/src/fpdfxfa/fpdfxfa...
fpdfsdk/src/fpdfxfa/fpdfxfa_doc.cpp:57: m_pXFADoc = nullptr;
These are always worrisome; if the correct operation relies on this being null,
then some other routine (as called from the dtor) is accessing the object after
the dtor has been invoked (sometimes it's the dtor itself being re-entered).
Either way, it points out a design problem. Which is why we remove these
wherever possible, so that if we see one, we know that there's a reentrancy
issue and we must tread carefully.

Do we need this assignment and the one for m_pSDKDoc below?

[jun_fang, 2016-02-04 06:15:10]

https://codereview.chromium.org/1667643002/diff/20001/fpdfsdk/src/fpdfxfa/fpd...
File fpdfsdk/src/fpdfxfa/fpdfxfa_doc.cpp (left):

https://codereview.chromium.org/1667643002/diff/20001/fpdfsdk/src/fpdfxfa/fpd...
fpdfsdk/src/fpdfxfa/fpdfxfa_doc.cpp:493:
m_pSDKDoc->GetPageView(pPage)->ClearFXAnnots();
When a XFA page is deleted, it doesn't need to clear annotations
on this page.
That's because a XFA page is dynamically created by layout process. 
A XFA page is a virtual and dynamic page. Annotations will be mapped
to a new XFA page during performing layout.

[jun_fang, 2016-02-04 16:10:07]

On 2016/02/03 18:02:50, Tom Sepez wrote:
>
https://codereview.chromium.org/1667643002/diff/1/fpdfsdk/src/fpdfxfa/fpdfxfa...
> File fpdfsdk/src/fpdfxfa/fpdfxfa_doc.cpp (right):
> 
>
https://codereview.chromium.org/1667643002/diff/1/fpdfsdk/src/fpdfxfa/fpdfxfa...
> fpdfsdk/src/fpdfxfa/fpdfxfa_doc.cpp:57: m_pXFADoc = nullptr;
> These are always worrisome; if the correct operation relies on this being
null,
> then some other routine (as called from the dtor) is accessing the object
after
> the dtor has been invoked (sometimes it's the dtor itself being re-entered).
> Either way, it points out a design problem. Which is why we remove these
> wherever possible, so that if we see one, we know that there's a reentrancy
> issue and we must tread carefully.
> 
> Do we need this assignment and the one for m_pSDKDoc below?

It doesn't need these two assignments if we release docs in right order.
I removed them from the patch 2. Please doule check. Thanks!

[Tom Sepez, 2016-02-04 17:29:05]

lgtm

[jun_fang, 2016-02-05 01:29:41]

Description was changed from

==========
Fix a crashier in CPDFSDK_Document::GetPageView()

BUG=pdfium:369
==========

to

==========
Fix a crashier in CPDFSDK_Document::GetPageView()

BUG=pdfium:369
R=tsepez@chromium.org

Committed:
https://pdfium.googlesource.com/pdfium/+/54537d1bb5f6bddd37ed4ca28cd4d5cfb4e9...
==========

[jun_fang, 2016-02-05 01:29:45]

Committed patchset #2 (id:20001) manually as
54537d1bb5f6bddd37ed4ca28cd4d5cfb4e95942 (presubmit successful).

[Lei Zhang, 2016-02-05 01:49:01]

BTW, you need to land this on master.

[jun_fang, 2016-02-05 01:50:38]

On 2016/02/05 01:49:01, Lei Zhang wrote:
> BTW, you need to land this on master.

Yes. I did that.