Changing the default file system provider is broken :(

Alan Bateman Alan.Bateman at
Sat Apr 22 20:26:59 UTC 2017

On 22/04/2017 12:20, Remi Forax wrote:

> Ooops !
> if you use the module path, you can not change the default system provider mechanism anymore,
> mostly because the module implementation internally uses java.nio.file.Path at different places.
> First, trying to initialize the default system provider in Java code do not work at all,
> calling
>    System.setProperty("java.nio.file.spi.DefaultFileSystemProvider", "...");
> in a main does nothing because the jigsaw implementation has already loaded the default implementation to be able to inspect the modules.
> Then, if you try to use the command line
>   -Djava.nio.file.spi.DefaultFileSystemProvider=...
> you have various bootstrapping issues.
Sigh, this is a bug here. A custom default file system can't be used 
during early startup so this is why the module system uses the built-in 
implementation. The bug is that is should always derive paths and never 
use Paths.get or toFile as that risks mixing paths from the built-in 
file system provider with the custom provider. The patch to fix is 
straight-forward and I'll get that in jake soon. The only change needed 
in the file system code is that FileSystems.getDefault should use 
VM.isModuleSystemInited() rather than is VM.booted() to allow for the 
corner case that is a custom system class loader or custom security 
manager using the file system API.


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