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

Alexey Ivanov aivanov at openjdk.org
Thu Apr 13 20:13:34 UTC 2023 

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.

I reproduced this exception on a system where FontConfig library is installed yet no fonts are present.

It looks like Java can't or doesn't create its own `fontconfig.properties` file in such a case, which results in the exception from the PR description. Yet if I pass a dummy `fontconfig.properties` with `-Dsun.awt.fontconfig=/path/fontconfig.properties`, the exception isn't thrown.

For example,

$ fc-list

$ ./jdk-17.0.6/bin/java ListFonts
Exception in thread "main" java.lang.InternalError: java.lang.reflect.InvocationTargetException
        at java.desktop/sun.font.FontManagerFactory$1.run(FontManagerFactory.java:87)
        ...
Caused by: java.lang.reflect.InvocationTargetException
        ...
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:1262)
        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)
        ... 13 more

$ ./jdk-21/bin/java ListFonts
Exception in thread "main" java.lang.NullPointerException: Cannot load from short array because "sun.awt.FontConfiguration.head" is null
        at java.desktop/sun.awt.FontConfiguration.getVersion(FontConfiguration.java:1256)
        at java.desktop/sun.awt.FontConfiguration.readFontConfigFile(FontConfiguration.java:221)
        at java.desktop/sun.awt.FontConfiguration.init(FontConfiguration.java:105)
        at java.desktop/sun.awt.X11FontManager.createFontConfiguration(X11FontManager.java:696)
        at java.desktop/sun.font.SunFontManager$2.run(SunFontManager.java:352)
        at java.desktop/sun.font.SunFontManager$2.run(SunFontManager.java:309)
        at java.base/java.security.AccessController.doPrivileged(AccessController.java:319)
        at java.desktop/sun.font.SunFontManager.<init>(SunFontManager.java:309)
        at java.desktop/sun.awt.FcFontManager.<init>(FcFontManager.java:35)
        at java.desktop/sun.awt.X11FontManager.<init>(X11FontManager.java:55)
        at java.desktop/sun.font.PlatformFontInfo.createFontManager(PlatformFontInfo.java:37)
        at java.desktop/sun.font.FontManagerFactory.getInstance(FontManagerFactory.java:51)
        at java.desktop/sun.java2d.SunGraphicsEnvironment.getFontManagerForSGE(SunGraphicsEnvironment.java:137)
        at java.desktop/sun.java2d.SunGraphicsEnvironment.getAvailableFontFamilyNames(SunGraphicsEnvironment.java:171)
        at java.desktop/sun.java2d.SunGraphicsEnvironment.getAvailableFontFamilyNames(SunGraphicsEnvironment.java:195)
        at java.desktop/sun.java2d.HeadlessGraphicsEnvironment.getAvailableFontFamilyNames(HeadlessGraphicsEnvironment.java:80)
        at ListFonts.main(ListFonts.java:8)



With explicit `fontconfig.properties`:


$ ./jdk-17.0.6/bin/java -Dsun.awt.fontconfig=~/fontconfig.properties ListFonts
Dialog
DialogInput
Monospaced
SansSerif
Serif

$ ./jdk-21/bin/java -Dsun.awt.fontconfig=~/fontconfig.properties ListFonts
Dialog
DialogInput
Monospaced
SansSerif
Serif


The sample app `ListFonts.java`:

import java.awt.GraphicsEnvironment;
import java.util.Arrays;

public class ListFonts {
    public static void main(String[] args) {
        Arrays.stream(GraphicsEnvironment
                      .getLocalGraphicsEnvironment()
                      .getAvailableFontFamilyNames())
              .forEach(System.out::println);
    }
}


The dummy `fontconfig.properties`:

version=1
sequence.allfonts=default


With Matthias's fix, the message in the exception is clearer:

$ ./jdk-21-fix/jdk-21/bin/java ListFonts
Exception in thread "main" java.lang.RuntimeException: Fontconfig head is null, check your fonts or fonts configuration
        at java.desktop/sun.awt.FontConfiguration.getVersion(FontConfiguration.java:1262)
        at java.desktop/sun.awt.FontConfiguration.readFontConfigFile(FontConfiguration.java:223)
        ...


As with the cases above, passing `fontconfig.properties` explicitly, resolves the problem, and the logical fonts get listed.

Obviously, I get another error if I try rendering the text:

Exception in thread "main" java.lang.Error: Probable fatal error: No physical fonts found.
        at java.desktop/sun.font.SunFontManager.lambda$getDefaultPhysicalFont$0(SunFontManager.java:1034)
        at java.base/java.util.Optional.orElseThrow(Optional.java:403)
        ...


A clearer error message was added by [JDK-8221741](https://bugs.openjdk.org/browse/JDK-8221741).

-------------

PR Comment: https://git.openjdk.org/jdk/pull/13045#issuecomment-1507552539

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