[OpenJDK 2D-Dev] NPE in X11FontManager.getDefaultPlatformFont

Wed Jun 5 08:56:47 UTC 2013

Hi!

This is known issue - Openjdk fails when no fonts are installed.

You can fix this by your own fontmanager (feel free to inspire at 
https://bugzilla.redhat.com/show_bug.cgi?id=862355#c5 where I'm creating an custom dummy fontmanager 
in case of failure)
You can set up similar manager class by -Dsun.font.fontmanager property.

Or you can support me and "force somebody" to review my patch where I have tried to smuggle inside 
Openjdk default fallback font[1]

On the contrary, if [1] will go in, then it can mask deeper problems (as can be eg yours).

[1]http://mail.openjdk.java.net/pipermail/2d-dev/2013-January/002999.html

Best regards
  J.

On 06/05/2013 01:32 AM, Jeremy Manson wrote:
> Hi Phil,
>
> Thanks for the response.  You've actually caught me out: this was a bug I found a while ago, and am
> only now just getting around to reporting.  I made this change locally (inside Google), and lost my
> repro instructions.  It was probably for a user issue, which means that I'm too chicken to back it
> out and see what happens.  This fix looked obvious enough that I thought I could get away with it,
> since it is clearly the case that X11FontManager expects a non-null fontConfigFonts regardless of
> the value of fontConfigFailed.
>
> IIRC, the cause was either that the fontconfig library wasn't installed or that the fontconfig file
> was obsolete / incorrect for the given system.  I almost certainly did not fix any ULEs (I would
> have a record of that).  We have some stripped down systems, and this may have been one of them.  It
> was a headless configuration.  I did preserve my stack trace:
>
> Exception in thread "main" java.lang.NullPointerException at
> sun.awt.X11FontManager.getDefaultPlatformFont(X11FontManager.java:779) at
> sun.font.SunFontManager$2.run(SunFontManager.java:428) at
> java.security.AccessController.doPrivileged(Native Method) at
> sun.font.SunFontManager.<init>(SunFontManager.java:371) at
> sun.awt.X11FontManager.<init>(X11FontManager.java:32) at
> sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) at
> sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:57) at
> sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
> at java.lang.reflect.Constructor.newInstance(Constructor.java:530) at
> java.lang.Class.newInstance0(Class.java:372) at java.lang.Class.newInstance(Class.java:325) at
> sun.font.FontManagerFactory$1.run(FontManagerFactory.java:80) at
> java.security.AccessController.doPrivileged(Native Method) at
> sun.font.FontManagerFactory.getInstance(FontManagerFactory.java:71) at
> sun.java2d.SunGraphicsEnvironment.getFontManagerForSGE(SunGraphicsEnvironment.java:185) at
> sun.java2d.SunGraphicsEnvironment.getAllFonts(SunGraphicsEnvironment.java:192) at
> sun.java2d.HeadlessGraphicsEnvironment.getAllFonts(HeadlessGraphicsEnvironment.java:91)
>
> I'm sure that the line numbers are obsolete, but you get the general idea. I don't seem to have what
> was beneath that in the stack, but I imagine it was something that was relatively comfortable with
> getAllFonts returning nothing (as appropriate).
>
> Having said all that, it seems to me that if fontConfigFailed is not allowed to be true unless you
> have a system configuration problem, then that should be made clear at runtime, and that you should
> not get rather mysterious NPEs at later points in the code.  You do have a fallback in
> getDefaultPlatformFont that says "make something up so that we don't get NPE", which made me think
> that the original author intended to prefer avoiding NPEs.
>
> Jeremy
>
>
> On Tue, Jun 4, 2013 at 3:29 PM, Phil Race <philip.race at oracle.com <mailto:philip.race at oracle.com>>
> wrote:
>
>     Jeremy,
>
>     Why didn't it return any fonts ? Is this because the libfontconfig library isn't installed ?
>
>     We've been runtime loading that lib but these days could potentially
>     switch to linking against it at compile time, in which case you won't
>     even get this far. So in other words this could be a system config issue.
>     The most common thing I've seen is that 64 bit Linux doesn't have
>     all the libs to run a 32 bit JRE. You probably found and fixed all of those
>     because it was Unsatisfiedlinkerror or similar but the runtime linking
>     is disguising that its really the same problem.
>
>     If you really don't have any fonts installed, then that's also
>     a missing package and we perhaps should have a better diagnostic,
>     but there isn't really any point in continuing anyway without any fonts.
>     Even headless applications may require fonts.
>
>     -phil.
>
>
>     On 6/4/2013 2:50 PM, Jeremy Manson wrote:
>
>         Hi folks,
>
>         I encountered a NullPointerException in the above method, when fontconfig doesn't return any
>         fonts:
>
>         http://hg.openjdk.java.net/__jdk8/jdk8/jdk/file/__7eae7c89dab4/src/solaris/__classes/sun/awt/__X11FontManager.java
>         <http://hg.openjdk.java.net/jdk8/jdk8/jdk/file/7eae7c89dab4/src/solaris/classes/sun/awt/X11FontManager.java>
>
>         Line 779.  The issue is that FontConfigManager sets fontConfigFonts to null when Fontconfig
>         doesn't return any fonts:
>
>         http://hg.openjdk.java.net/__jdk8/jdk8/jdk/file/__7eae7c89dab4/src/solaris/__classes/sun/font/__FontConfigManager.java
>         <http://hg.openjdk.java.net/jdk8/jdk8/jdk/file/7eae7c89dab4/src/solaris/classes/sun/font/FontConfigManager.java>
>
>         Line 218.
>
>         The solution I came up with is to initialize fontConfigFonts with a zero-element array in
>         this case:
>
>         diff --git a/src/solaris/classes/sun/__font/FontConfigManager.java
>         b/src/solaris/classes/sun/__font/FontConfigManager.java
>         --- a/src/solaris/classes/sun/__font/FontConfigManager.java
>         +++ b/src/solaris/classes/sun/__font/FontConfigManager.java
>         @@ -216,6 +216,7 @@
>         logger.info <http://logger.info> <http://logger.info>("__Fontconfig returned no fonts at all.");
>
>                       }
>                       fontConfigFailed = true;
>         +            fontConfigFonts = new FcCompFont[0];
>                       return;
>                   } else if (fontConfigFailed) {
>                       for (int i = 0; i< fontArr.length; i++) {
>
>         Thanks for your attention!
>
>         Jeremy
>
>
>