RFR: 8284680: sun.font.FontConfigManager.getFontConfig() leaks charset

[Zhengyu Gu]

On Fri, 15 Apr 2022 18:43:27 GMT, Phil Race <prr at openjdk.org> wrote:

>> Please review this small patch that releases temporary charsets to avoid memory leak.
>> 
>> Test:
>> 
>> - [x] jdk_2d
>
> src/java.desktop/unix/native/common/awt/fontpath.c line 1112:
> 
>> 1110:                     if (currentUnionSet != charset) {
>> 1111:                         (*FcCharSetDestroy)(currentUnionSet);
>> 1112:                     }
> 
> Hmm. I worry that you may be replacing a leak with a crash.
> The original "charset" was returned from FcPatternGetCharSet() and I don't think it was a copy and will be freed when the pattern is destroyed.
> So that should not be freed here.

Right, that is why I have `if (currentUnionSet != charset)` check to prevent from freeing original `charset`.

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PR: https://git.openjdk.java.net/jdk/pull/8187