[OpenJDK 2D-Dev] RFR(S): 8171248: Minor HarfBuzz fixes to pacify Coverity code scan

[Phil Race]

I have created a bug on the upgrade 
https://bugs.openjdk.java.net/browse/JDK-8171456

I don't expect to get to this until January as I'll be out until then 
and there is
some internal process to be navigated. And of course Behdad needs to make
the release too.

So if you can't wait until then I don't object to it being pushed but it
also isn't all that critical/urgent either ..

-phil.

On 12/19/2016 12:31 AM, Volker Simonis wrote:
> Thanks Behdad!
>
> @Phil: what do you think, can I push this now that it was committed
> upstream? Or should I wait until you pull in a new HarfBuzz release?
> In that case, do you already have a bug open for that task such that I
> can link it to the current issue?
>
> Thank you and best regards,
> Volker
>
>
> On Sun, Dec 18, 2016 at 8:23 AM, Behdad Esfahbod <behdad at google.com> wrote:
>> Thanks Volker.  Fixed upstream.  I'll make a release in the next couple of
>> days.
>>
>> On Wed, Dec 14, 2016 at 1:15 PM, Volker Simonis <volker.simonis at gmail.com>
>> wrote:
>>> Hi,
>>>
>>> can I please have a review for the following small changes which fix
>>> some Coverity code scan issues in the Harfbuzz library:
>>>
>>> https://bugs.openjdk.java.net/browse/JDK-8171248
>>> http://cr.openjdk.java.net/~simonis/webrevs/2016/8171248/
>>>
>>> These changes only make sense if they are also accepted in the
>>> upstream HarfBuzz repository. I've therefore send out a pull request
>>> with the same changes and kindly requested Behdad to accept them
>>> upstream:
>>>
>>> https://github.com/behdad/harfbuzz/pull/377
>>>
>>> Following are the details of the fix:
>>>
>>> we regularly run Coverity code scans on the OpenJDK sources and
>>> recently discovered two issues with HarfBuzz. While the discovered
>>> issues are not real errors, we think that fixing them my be
>>> nevertheless worthwile in order to increase the readability of the
>>> source code.
>>>
>>> We just wanted to ask, if you are willing to accept these changes in
>>> the upstream HarfBuzz repository because only then it would make sense
>>> to also fix them in the OpenJDK copy of HarfBuzz.
>>>
>>> The first issue found by Coverity is the last of the following four
>>> lines from src/hb-ot-font.cc:
>>>
>>>      if (!subtable) subtable = cmap->find_subtable (0, 2);
>>>      if (!subtable) subtable = cmap->find_subtable (0, 1);
>>>      if (!subtable) subtable = cmap->find_subtable (0, 0);
>>>      if (!subtable)(subtable = cmap->find_subtable (3, 0)) && (symbol =
>>> true);
>>>
>>>  From the whole context it really took me some time to understand that
>>> 'symbol' should only be set to true if 'subtable' is set from
>>> 'cmap->find_subtable (3, 0)'. Coverity reports an "assignment instead
>>> of compare" which is a false positive, but we think the could would be
>>> much more readable if changed to look as follows:
>>>
>>>      if (!subtable)
>>>      {
>>>        subtable = cmap->find_subtable (3, 0);
>>>        if (subtable) symbol = true;
>>>      }
>>>
>>> The second issue is related to the following definition in
>>> src/hb-ot-layout-gpos-table.hh:
>>>
>>>    ValueFormat  valueFormat1;           /* Defines the types of data in
>>>                                          * ValueRecord1--for the first
>>> glyph
>>>                                          * in the pair--may be zero (0) */
>>>    ValueFormat  valueFormat2;           /* Defines the types of data in
>>>                                          * ValueRecord2--for the second
>>> glyph
>>>                                          * in the pair--may be zero (0) */
>>>
>>> Throughout hb-ot-layout-gpos-table.hh, '&valueFormat1' is used as if
>>> it were an array of two ValueFormat objects. While extremely unlikely,
>>> a compiler could theoretically insert padding between 'valueFormat1'
>>> and 'valueFormat2' which would make the code incorrect. We would
>>> therefore propose to simply change the previous definiton into a real
>>> array:
>>>
>>>    ValueFormat  valueFormat[2];         /* [0] Defines the types of data in
>>>                                          * ValueRecord1--for the first
>>> glyph
>>>                                          * in the pair--may be zero (0) */
>>>                                         /* [1] Defines the types of data in
>>>                                          * ValueRecord2--for the second
>>> glyph
>>>                                          * in the pair--may be zero (0) */
>>>
>>> and change the code which uses 'valueFormat' accordingly.
>>>
>>> Thank youand best regards,
>>> Volker
>>