Why does Path check for the Default FileSystem?

[Alan Bateman]

On 23/03/2021 18:57, Michael Hall wrote:
> :
>
> No, that doesn’t do it either. It seems to get back to the 
> ClassNotFoundException without the jar after getting into the Path code?
>
> at 
> java.base/java.nio.file.FileSystems$DefaultFileSystemHolder.getDefaultProvider(FileSystems.java:133)
> at 
> java.base/java.nio.file.FileSystems$DefaultFileSystemHolder$1.run(FileSystems.java:102)
> at 
> java.base/java.nio.file.FileSystems$DefaultFileSystemHolder$1.run(FileSystems.java:100)
> at 
> java.base/java.security.AccessController.doPrivileged(AccessController.java:312)
> at 
> java.base/java.nio.file.FileSystems$DefaultFileSystemHolder.defaultFileSystem(FileSystems.java:100)
> at 
> java.base/java.nio.file.FileSystems$DefaultFileSystemHolder.<clinit>(FileSystems.java:94)
> at java.base/java.nio.file.FileSystems.getDefault(FileSystems.java:182)
> at java.base/java.nio.file.Path.of(Path.java:147)
> at java.base/java.nio.file.Paths.get(Paths.java:69)
>
> Verbose class loading similar to before…
>
> [0.035s][info][class,load] java.lang.SecurityException source: 
> jrt:/java.base
> Error: A JNI error has occurred, please check your installation and 
> try again
> Exception in thread "main" [0.035s][info][class,load] 
> java.lang.Throwable$PrintStreamOrWriter source: jrt:/java.base
> [0.035s][info][class,load] java.lang.Throwable$WrappedPrintStream 
> source: jrt:/java.base
> [0.035s][info][class,load] java.util.IdentityHashMap source: shared 
> objects file
> [0.035s][info][class,load] java.util.IdentityHashMap$KeySet source: 
> shared objects file
> java.lang.Error: java.lang.ClassNotFoundException: 
> us.hall.trz.osx.MacFileSystemProvider
>
> It would be nice if I knew the source of the SecurityException before 
> it percolates out to the strange ClassNotFoundException’s
>
> My question as to why does it need to be only the DefaultProvider 
> still remains? That still seems to totally defeat passthrough.
>
> https://docs.oracle.com/javase/8/docs/technotes/guides/io/fsp/filesystemprovider.html 
> <https://docs.oracle.com/javase/8/docs/technotes/guides/io/fsp/filesystemprovider.html>
> • Replacing or supplementing the default file system provider. The 
> custom provider can augment the default provider by performing 
> specific operations, such as logging all system operations, and 
> delegate to the default provider for other routine operations.
>
> This is what I am trying to do but the code doesn’t seem to allow 
> delegating?
>
I just tried the TestProvider that we have in the test tree and it works 
as the default file system provider when exploded on the file system 
(not packaged as a JAR file on the class path as thee is an issue 
there). I commented out the override of toFile() and it does the right 
thing. So I'm not 100% sure how you are running into an issue, I think 
we need something that reproduces it.

-Alan



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