Fix regression in JBIG2 decoding from commit ce37d73.

Fix regression in JBIG2 decoding from commit ce37d73.

many callers can tolerate CJBig2_ArithIntDecoder::decode() OOB failure.

BUG=539749, pdfium:209
R=tsepez@chromium.org

Committed: https://pdfium.googlesource.com/pdfium/+/35902e725aa6cc83a317c3b6fdd1926b81b8e44b

[Lei Zhang, 2015-10-06 05:42:40]

Patchset #1 (id:1) has been deleted

[Lei Zhang, 2015-10-06 05:47:56]

thestig@chromium.org changed reviewers:
+ dml@google.com, tsepez@chromium.org

[Lei Zhang, 2015-10-06 05:47:56]

Given:
- original code
- broken code (my CL that caused bug 209)
- new code (this CL)

In the original code, most callers checked for the -1 return value, and a few
callers checked for the 1 return value. The decode function never returned -1,
so I should have changed it to the new code. Instead, I incorrectly turned the
original -1 checks into checks for the orignal 1 return value. (Confusingly,
false in the broken code maps to 1 in the original code.)

In the previous CL, I changed 5 call sites in Sdd and 9 in Trd. I've updated
those call sites to not check the return value. In the 2 call sites that
actually checked for OOB, they now check for false.

[Tom Sepez, 2015-10-06 05:58:37]

LGTM.  I didn't verify that the new code matches the old semantics, though.

https://codereview.chromium.org/1384663007/diff/20001/core/src/fxcodec/jbig2/...
File core/src/fxcodec/jbig2/JBig2_ArithIntDecoder.h (right):

https://codereview.chromium.org/1384663007/diff/20001/core/src/fxcodec/jbig2/...
core/src/fxcodec/jbig2/JBig2_ArithIntDecoder.h:21: // callers can tolerate OOB
and does not check the return value.
nit: do not

[Lei Zhang, 2015-10-06 06:01:23]

I temporarily changed the return type to void to flush out all the callers.
Otherwise I would have never noticed the ones that checked for JBIG2_OOB.
Previously when I changed it from int to bool, I only noticed the checks for -1.
I've verified that the known affected PDFs render correctly again.

https://codereview.chromium.org/1384663007/diff/20001/core/src/fxcodec/jbig2/...
File core/src/fxcodec/jbig2/JBig2_ArithIntDecoder.h (right):

https://codereview.chromium.org/1384663007/diff/20001/core/src/fxcodec/jbig2/...
core/src/fxcodec/jbig2/JBig2_ArithIntDecoder.h:21: // callers can tolerate OOB
and does not check the return value.
On 2015/10/06 05:58:37, Tom Sepez wrote:
> nit: do not

Done.

[Lei Zhang, 2015-10-06 06:02:30]

Committed patchset #2 (id:40001) manually as
35902e725aa6cc83a317c3b6fdd1926b81b8e44b (presubmit successful).

[Lei Zhang, 2015-10-06 06:03:31]

And we'll have a regression test for this, hopefully tomorrow.