IPv6 is broken in OpenJDK 21

[omolenkamp]

IPv6 is unavailable in the OpenJDK 21 builds:

jshell> new Socket("::1", 80).getOutputStream()
|  Exception java.net.SocketException: Protocol family unavailable
|        at Net.connect0 (Native Method)
|        at Net.connect (Net.java:589)
|        at Net.connect (Net.java:578)
|        at NioSocketImpl.connect (NioSocketImpl.java:583)
|        at SocksSocketImpl.connect (SocksSocketImpl.java:327)
|        at Socket.connect (Socket.java:751)
|        at Socket.connect (Socket.java:686)
|        at Socket.<init> (Socket.java:555)
|        at Socket.<init> (Socket.java:324)
|        at (#2:1)

In OpenJDK 17, IPv6 works as expected.

This bug is caused by the IPv6_supported function no longer working correctly as it tries to used a closed file descriptor, and is easy to fix:

--- jdk21u-jdk-21.0.6-7/src/java.base/unix/native/libnet/net_util_md.c.orig     2025-03-09 12:46:00.190813687 +0100
+++ jdk21u-jdk-21.0.6-7/src/java.base/unix/native/libnet/net_util_md.c  2025-03-09 13:04:33.720866346 +0100
@@ -233,7 +233,9 @@
          */
         return JNI_FALSE;
     }
+#ifndef __solaris__
     close(fd);
+#endif
 
     /**
      * Linux - check if any interface has an IPv6 address.

I'm not sure what the preferred way of fixing a bug in OpenJDK is: should java-solaris-sparc.patch be updated to correctly patch the IPv6_supported function, or should a separate patch file be added for this?