[jdk8u-dev] RFR: 8301246: NPE in FcFontManager.getDefaultPlatformFont() on Linux without installed fontconfig

[Alexander Scherbatiy]

The issues is reproduced only with OpenJDK. Oracle 1.8.0_351 does not throw the NPE.

OpenJDK 8u built from sources with custom fontconfig.properties file throws NPE  
`at sun.awt.FcFontManager.getDefaultPlatformFont(FcFontManager.java:76)` 
on Linux where fontconfig is not installed.

The fix allows to return a default font info from  FcFontManager.getDefaultPlatformFont() method even FontConfigManager.getFontConfigFonts() returns null.

The issue has been already fixed in JDK 11 as part of the fix `8191522: Remove Bigelow&Holmes Lucida fonts from JDK sources` https://github.com/openjdk/jdk/commit/9a9dad8b63e6234829132d5557fbd412d295bb26

This is a backport of only small part of the fix `8191522` related to NPE in FcFontManager.getDefaultPlatformFont() method.

Steps to reproduce:
- Build jdk8u from sources: https://github.com/openjdk/jdk8u-dev/
- Copy custom [fontconfig.properties](https://bugs.openjdk.org/secure/attachment/102432/fontconfig.properties) file to build/linux-x86_64-normal-server-release/images/j2sdk-image/jre/lib
- Run docker with ubuntu 20.04, install dejavu fonts, and freetype (do not install fontconfig)

docker run -it ubuntu:20.04 bash
apt update
apt install -y fonts-dejavu
apt install -y libfreetype6

- Run HelloImage java sample in the docker with the build jdk

import javax.imageio.ImageIO;
import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.File;

public class HelloImage {

    public static void main(String[] args) throws Exception {

        BufferedImage buff = new BufferedImage(300, 200, BufferedImage.TYPE_INT_RGB);
        Graphics2D g = buff.createGraphics();
        g.setColor(Color.WHITE);
        g.fillRect(0, 0, buff.getWidth(), buff.getHeight());

        g.setColor(Color.BLUE);
        g.setFont(g.getFont().deriveFont(32f));
        g.drawString("Hello, Image!", 50, 50);
        g.dispose();

        File file = new File("hello-image.png");
        ImageIO.write(buff, "png", file);
    }
}



build/linux-x86_64-normal-server-release/images/j2sdk-image/bin/javac HelloImage.java
build/linux-x86_64-normal-server-release/images/j2sdk-image/bin/java HelloImage      
Exception in thread "main" java.lang.NullPointerException
	at sun.awt.FcFontManager.getDefaultPlatformFont(FcFontManager.java:76)
	at sun.font.SunFontManager$2.run(SunFontManager.java:443)
	at java.security.AccessController.doPrivileged(Native Method)
	at sun.font.SunFontManager.<init>(SunFontManager.java:386)
	at sun.awt.FcFontManager.<init>(FcFontManager.java:35)
	at sun.awt.X11FontManager.<init>(X11FontManager.java:57)
	at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
	at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
	at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
	at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
	at java.lang.Class.newInstance(Class.java:442)
	at sun.font.FontManagerFactory$1.run(FontManagerFactory.java:83)
	at java.security.AccessController.doPrivileged(Native Method)
	at sun.font.FontManagerFactory.getInstance(FontManagerFactory.java:74)
	at java.awt.Font.getFont2D(Font.java:491)
	at java.awt.Font.access$000(Font.java:224)
	at java.awt.Font$FontAccessImpl.getFont2D(Font.java:228)
	at sun.font.FontUtilities.getFont2D(FontUtilities.java:200)
	at sun.java2d.SunGraphics2D.checkFontInfo(SunGraphics2D.java:669)
	at sun.java2d.SunGraphics2D.getFontInfo(SunGraphics2D.java:835)
	at sun.java2d.pipe.GlyphListPipe.drawString(GlyphListPipe.java:50)
	at sun.java2d.SunGraphics2D.drawString(SunGraphics2D.java:2933)
	at HelloImage.main(HelloImage.java:17)

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

Commit messages:
 - 8301246: NPE in FcFontManager.getDefaultPlatformFont() on Linux without installed fontconfig

Changes: https://git.openjdk.org/jdk8u-dev/pull/246/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk8u-dev&pr=246&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8301246
  Stats: 9 lines in 1 file changed: 2 ins; 0 del; 7 mod
  Patch: https://git.openjdk.org/jdk8u-dev/pull/246.diff
  Fetch: git fetch https://git.openjdk.org/jdk8u-dev pull/246/head:pull/246

PR: https://git.openjdk.org/jdk8u-dev/pull/246