RFR: JDK-8304054: Linux: NullPointerException from FontConfiguration.getVersion in case no fonts are installed

[Lutz Schmidt]

On Wed, 15 Mar 2023 16:02:36 GMT, Matthias Baesken <mbaesken at openjdk.org> wrote:

> On Linux Alpine we were running in the jtreg awt tests into a lot of NPEs like this :
> 
> java.lang.InternalError: java.lang.reflect.InvocationTargetException
> at java.desktop/sun.font.FontManagerFactory$1.run(FontManagerFactory.java:87)
> at java.base/java.security.AccessController.doPrivileged(AccessController.java:318)
> at java.desktop/sun.font.FontManagerFactory.getInstance(FontManagerFactory.java:75)
> at java.desktop/java.awt.Font.getFont2D(Font.java:526)
> at java.desktop/java.awt.Font$FontAccessImpl.getFont2D(Font.java:265)
> at java.desktop/sun.font.FontUtilities.getFont2D(FontUtilities.java:148)
> at java.desktop/sun.font.GlyphLayout$SDCache.<init>(GlyphLayout.java:254)
> at java.desktop/sun.font.GlyphLayout$SDCache.get(GlyphLayout.java:328)
> at java.desktop/sun.font.GlyphLayout.layout(GlyphLayout.java:375)
> at java.desktop/java.awt.Font.layoutGlyphVector(Font.java:2858)
> at FontLayoutStressTest.doLayout(FontLayoutStressTest.java:51)
> at FontLayoutStressTest.main(FontLayoutStressTest.java:57)
> at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
> at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:77)
> at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
> at java.base/java.lang.reflect.Method.invoke(Method.java:568)
> at com.sun.javatest.regtest.agent.MainWrapper$MainThread.run(MainWrapper.java:127)
> at java.base/java.lang.Thread.run(Thread.java:833)
> Caused by: java.lang.reflect.InvocationTargetException
> at java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
> at java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:77)
> at java.base/jdk.internal.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
> at java.base/java.lang.reflect.Constructor.newInstanceWithCaller(Constructor.java:499)
> at java.base/java.lang.reflect.Constructor.newInstance(Constructor.java:480)
> at java.desktop/sun.font.FontManagerFactory$1.run(FontManagerFactory.java:85)
> ... 17 more
> Caused by: java.lang.NullPointerException: Cannot load from short array because "sun.awt.FontConfiguration.head" is null
> at java.desktop/sun.awt.FontConfiguration.getVersion(FontConfiguration.java:1264)
> at java.desktop/sun.awt.FontConfiguration.readFontConfigFile(FontConfiguration.java:224)
> at java.desktop/sun.awt.FontConfiguration.init(FontConfiguration.java:106)
> at java.desktop/sun.awt.X11FontManager.createFontConfiguration(X11FontManager.java:706)
> at java.desktop/sun.font.SunFontManager$2.run(SunFontManager.java:358)
> at java.desktop/sun.font.SunFontManager$2.run(SunFontManager.java:315)
> at java.base/java.security.AccessController.doPrivileged(AccessController.java:318)
> at java.desktop/sun.font.SunFontManager.<init>(SunFontManager.java:315)
> at java.desktop/sun.awt.FcFontManager.<init>(FcFontManager.java:35)
> at java.desktop/sun.awt.X11FontManager.<init>(X11FontManager.java:56)
> ... 23 more
> 
> Seems this was caused because no fonts were installed on the machine.
> Probably 'head' in FontConfiguration.getVersion() should be checked for null and a specific exception like "Check your fonts or fonts configuration"
> should be throw.

Changes look good to me. 
This is a required fix, even more so because "default fonts" are not even visible on the horizon.
Thanks for fixing.

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Marked as reviewed by lucy (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/13045#pullrequestreview-1381272271