Fixes error reporting in loading AWT and fonts
If there is problem with finding and calling e.g. java/awt/GraphicsEnvironment
in AWTIsHeadless, the env' Exception remains set and it not cleared.
Later, that manifests as:
Fatal error reported via JNI: Could not allocate library name
Which is misleading. The code path is perhaps rare in normal JDK usage,
but it has been complicating our users' bug reports in the GraalVM/native-image
ecosystem for quite some time.
Instead of failing later with some clear message that indicates that the
user has incorrectly configured JNI, it bails out very soon with a message
that seems as if a jstring could not have been allocated. It sends users
on wild goose chases, e.g.
https://github.com/oracle/graal/issues/9138
https://github.com/oracle/graal/issues/8475
https://github.com/oracle/graal/issues/9300
https://github.com/quarkusio/quarkus/issues/31596
https://github.com/graalvm/mandrel/issues/292
https://github.com/Karm/mandrel-integration-tests/issues/262
This commit fixes the error reporting in the AWTIsHeadless.
Furthermore, when AOT compiled, there is little sense for having a JAVA_HOME,
yet some parts of AWT code look for it to search fonts. In such case, an
empty directory structure is enough to accommodate it, e.g.
/tmp/JAVA_HOME/
/tmp/JAVA_HOME/conf
/tmp/JAVA_HOME/conf/fonts
/tmp/JAVA_HOME/lib
The exception is somewhat cryptic for users again, merely stating:
Exception in thread "main" java.io.IOException: Problem reading font data.
at java.desktop@22.0.1/java.awt.Font.createFont0(Font.java:1205)
at java.desktop@22.0.1/java.awt.Font.createFont(Font.java:1076)
at imageio.Main.loadFonts(Main.java:139
Adding the cause there makes it clearer, i.e. that JAVA_HOME might be missing:
Exception in thread "main" java.io.IOException: Problem reading font data.
at java.desktop@23-internal/java.awt.Font.createFont0(Font.java:1206)
at java.desktop@23-internal/java.awt.Font.createFont(Font.java:1076)
at imageio.Main.loadFonts(Main.java:139)
at imageio.Main.paintRectangles(Main.java:97)
at imageio.Main.main(Main.java:195)
at java.base@23-internal/java.lang.invoke.LambdaForm$DMH/sa346b79c.invokeStaticInit(LambdaForm$DMH)
Caused by: java.lang.Error: java.home property not set
at java.desktop@23-internal/sun.awt.FontConfiguration.findFontConfigFile(FontConfiguration.java:180)
at java.desktop@23-internal/sun.awt.FontConfiguration.<init>(FontConfiguration.java:97)
