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

[Alexey Ivanov]

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.

src/java.desktop/share/classes/sun/awt/FontConfiguration.java line 1255:

> 1253:     public String getExtraFontPath() {
> 1254:         if (head == null) {
> 1255:             throw new RuntimeException("Fontconfig head is null, check your fonts or fonts configuration");

Does it make sense to create a String constant for the error message?

I understand that there's only one instance of the message in the class file, it's more to avoid duplication and to avoid having different error messages in case someone updates only one of them.

Other than that, it looks good to me.

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PR Review Comment: https://git.openjdk.org/jdk/pull/13045#discussion_r1165983401