Changing the default file system provider is broken :(
Peter Levart
peter.levart at gmail.com
Sat Apr 22 15:14:32 UTC 2017
Hi Remi,
On 04/22/2017 01:20 PM, 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.
>
> With exploded modules, when trying to initialize the default file system, the part of jigsaw that reads exploded modules uses path.toFile() that fails it checks that the path belongs to the default file system which is not already initialized
> (see below for the whole stacktrace)
>
> With modular jars, when trying to initialize the default file system, the JarModuleReader also uses path.toFile(), leading to the same error
>
> One way to solve that is to change the code in FileSystems.getDefault() to add a nullcheck,
> FileSystem defaultFileSystem = DefaultFileSystemHolder.defaultFileSystem;
> if (jdk.internal.misc.VM.isBooted() && defaultFileSystem != null) {
> return defaultFileSystem;
> } else {
> return BuiltinFileSystemHolder.builtinFileSystem;
> }
> Another solution is to change the code of jigsaw to only use the builtinFileSystem, delaying the initialization of the default system which will also solve the case where an application uses System.setProperty.
I think the problem is that what FileSystems.getDefault() returns,
changes over time. So you have Path instances associated with "builtin"
filesystem, constructed before VM.isBooted() and after it is booted,
Path instances are associated with what is configured to be the
"default" filesystem. If those two differ and an instance, constructed
before VM.isBooted() lives past the boot time and then .toFile() is
called on such instance, we get "UnsupportedOperationException: Path not
associated with default file system"...
Maybe Alan could shed some light into this. As part of jigsaw
implementation, the FileSystems.getDefault() was changed from:
public static FileSystem getDefault() {
return DefaultFileSystemHolder.defaultFileSystem;
}
to:
public static FileSystem getDefault() {
if (jdk.internal.misc.VM.isBooted()) {
return DefaultFileSystemHolder.defaultFileSystem;
} else {
return BuiltinFileSystemHolder.builtinFileSystem;
}
}
Probably because of early bootstrap issues. Module system needs
FileSystem and custom FileSystem classes can not be loaded at that time yet.
So I think that your second solution would be the right one. Jigsaw
should only use the builtin filesystem explicitly, refraining from
initializing the default filesystem. And Path.toFile() should allow
creating a File from a Path in either case: whether Path is associated
with builtin or default filesystem.
Regards, Peter
> cheers,
> Rémi
>
>
> Stacktrace with exploded modules:
> Error: A JNI error has occurred, please check your installation and try again
> Exception in thread "main" java.lang.Error: java.lang.UnsupportedOperationException: Path not associated with default file system.
> at java.base/java.nio.file.FileSystems$DefaultFileSystemHolder.getDefaultProvider(FileSystems.java:139)
> at java.base/java.nio.file.FileSystems$DefaultFileSystemHolder.access$100(FileSystems.java:100)
> at java.base/java.nio.file.FileSystems$DefaultFileSystemHolder$1.run(FileSystems.java:109)
> at java.base/java.nio.file.FileSystems$DefaultFileSystemHolder$1.run(FileSystems.java:107)
> at java.base/java.security.AccessController.doPrivileged(Native Method)
> at java.base/java.nio.file.FileSystems$DefaultFileSystemHolder.defaultFileSystem(FileSystems.java:107)
> at java.base/java.nio.file.FileSystems$DefaultFileSystemHolder.<clinit>(FileSystems.java:101)
> at java.base/java.nio.file.FileSystems.getDefault(FileSystems.java:188)
> at java.base/java.nio.file.Path.toFile(Path.java:655)
> at java.base/jdk.internal.module.ModuleReferences$JarModuleReader.newJarFile(ModuleReferences.java:229)
> at java.base/jdk.internal.module.ModuleReferences$JarModuleReader.<init>(ModuleReferences.java:239)
> at java.base/jdk.internal.module.ModuleReferences.lambda$newJarModule$0(ModuleReferences.java:96)
> at java.base/jdk.internal.module.ModuleReferenceImpl.open(ModuleReferenceImpl.java:88)
> at java.base/jdk.internal.loader.BuiltinClassLoader.createModuleReader(BuiltinClassLoader.java:953)
> at java.base/java.util.concurrent.ConcurrentHashMap.computeIfAbsent(ConcurrentHashMap.java:1719)
> at java.base/jdk.internal.loader.BuiltinClassLoader.moduleReaderFor(BuiltinClassLoader.java:945)
> at java.base/jdk.internal.loader.BuiltinClassLoader.defineClass(BuiltinClassLoader.java:702)
> at java.base/jdk.internal.loader.BuiltinClassLoader.findClassInModuleOrNull(BuiltinClassLoader.java:651)
> at java.base/jdk.internal.loader.BuiltinClassLoader.findClass(BuiltinClassLoader.java:532)
> at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:585)
> at java.base/java.lang.Class.forName(Class.java:447)
> at java.base/sun.launcher.LauncherHelper.loadModuleMainClass(LauncherHelper.java:585)
> at java.base/sun.launcher.LauncherHelper.checkAndLoadMain(LauncherHelper.java:523)
> Caused by: java.lang.UnsupportedOperationException: Path not associated with default file system.
> at java.base/java.nio.file.Path.toFile(Path.java:658)
> at java.base/jdk.internal.module.ModuleReferences$JarModuleReader.newJarFile(ModuleReferences.java:229)
> at java.base/jdk.internal.module.ModuleReferences$JarModuleReader.<init>(ModuleReferences.java:239)
> at java.base/jdk.internal.module.ModuleReferences.lambda$newJarModule$0(ModuleReferences.java:96)
> at java.base/jdk.internal.module.ModuleReferenceImpl.open(ModuleReferenceImpl.java:88)
> at java.base/jdk.internal.loader.BuiltinClassLoader.createModuleReader(BuiltinClassLoader.java:953)
> at java.base/java.util.concurrent.ConcurrentHashMap.computeIfAbsent(ConcurrentHashMap.java:1719)
> at java.base/jdk.internal.loader.BuiltinClassLoader.moduleReaderFor(BuiltinClassLoader.java:945)
> at java.base/jdk.internal.loader.BuiltinClassLoader.defineClass(BuiltinClassLoader.java:702)
> at java.base/jdk.internal.loader.BuiltinClassLoader.findClassInModuleOrNull(BuiltinClassLoader.java:651)
> at java.base/jdk.internal.loader.BuiltinClassLoader.loadClassOrNull(BuiltinClassLoader.java:576)
> at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:550)
> at java.base/jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(ClassLoaders.java:185)
> at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:473)
> at java.base/java.lang.Class.forName0(Native Method)
> at java.base/java.lang.Class.forName(Class.java:374)
> at java.base/java.nio.file.FileSystems$DefaultFileSystemHolder.getDefaultProvider(FileSystems.java:129)
> ... 22 more
>
>
> StackTrace with modular jars:
> Error: A JNI error has occurred, please check your installation and try again
> Exception in thread "main" java.lang.Error: java.lang.UnsupportedOperationException: Path not associated with default file system.
> at java.base/java.nio.file.FileSystems$DefaultFileSystemHolder.getDefaultProvider(FileSystems.java:139)
> at java.base/java.nio.file.FileSystems$DefaultFileSystemHolder.access$100(FileSystems.java:100)
> at java.base/java.nio.file.FileSystems$DefaultFileSystemHolder$1.run(FileSystems.java:109)
> at java.base/java.nio.file.FileSystems$DefaultFileSystemHolder$1.run(FileSystems.java:107)
> at java.base/java.security.AccessController.doPrivileged(Native Method)
> at java.base/java.nio.file.FileSystems$DefaultFileSystemHolder.defaultFileSystem(FileSystems.java:107)
> at java.base/java.nio.file.FileSystems$DefaultFileSystemHolder.<clinit>(FileSystems.java:101)
> at java.base/java.nio.file.FileSystems.getDefault(FileSystems.java:188)
> at java.base/java.nio.file.Path.toFile(Path.java:655)
> at java.base/jdk.internal.module.ModuleReferences$JarModuleReader.newJarFile(ModuleReferences.java:229)
> at java.base/jdk.internal.module.ModuleReferences$JarModuleReader.<init>(ModuleReferences.java:239)
> at java.base/jdk.internal.module.ModuleReferences.lambda$newJarModule$0(ModuleReferences.java:96)
> at java.base/jdk.internal.module.ModuleReferenceImpl.open(ModuleReferenceImpl.java:88)
> at java.base/jdk.internal.loader.BuiltinClassLoader.createModuleReader(BuiltinClassLoader.java:953)
> at java.base/java.util.concurrent.ConcurrentHashMap.computeIfAbsent(ConcurrentHashMap.java:1719)
> at java.base/jdk.internal.loader.BuiltinClassLoader.moduleReaderFor(BuiltinClassLoader.java:945)
> at java.base/jdk.internal.loader.BuiltinClassLoader.defineClass(BuiltinClassLoader.java:702)
> at java.base/jdk.internal.loader.BuiltinClassLoader.findClassInModuleOrNull(BuiltinClassLoader.java:651)
> at java.base/jdk.internal.loader.BuiltinClassLoader.findClass(BuiltinClassLoader.java:532)
> at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:585)
> at java.base/java.lang.Class.forName(Class.java:447)
> at java.base/sun.launcher.LauncherHelper.loadModuleMainClass(LauncherHelper.java:585)
> at java.base/sun.launcher.LauncherHelper.checkAndLoadMain(LauncherHelper.java:523)
> Caused by: java.lang.UnsupportedOperationException: Path not associated with default file system.
> at java.base/java.nio.file.Path.toFile(Path.java:658)
> at java.base/jdk.internal.module.ModuleReferences$JarModuleReader.newJarFile(ModuleReferences.java:229)
> at java.base/jdk.internal.module.ModuleReferences$JarModuleReader.<init>(ModuleReferences.java:239)
> at java.base/jdk.internal.module.ModuleReferences.lambda$newJarModule$0(ModuleReferences.java:96)
> at java.base/jdk.internal.module.ModuleReferenceImpl.open(ModuleReferenceImpl.java:88)
> at java.base/jdk.internal.loader.BuiltinClassLoader.createModuleReader(BuiltinClassLoader.java:953)
> at java.base/java.util.concurrent.ConcurrentHashMap.computeIfAbsent(ConcurrentHashMap.java:1719)
> at java.base/jdk.internal.loader.BuiltinClassLoader.moduleReaderFor(BuiltinClassLoader.java:945)
> at java.base/jdk.internal.loader.BuiltinClassLoader.defineClass(BuiltinClassLoader.java:702)
> at java.base/jdk.internal.loader.BuiltinClassLoader.findClassInModuleOrNull(BuiltinClassLoader.java:651)
> at java.base/jdk.internal.loader.BuiltinClassLoader.loadClassOrNull(BuiltinClassLoader.java:576)
> at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:550)
> at java.base/jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(ClassLoaders.java:185)
> at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:473)
> at java.base/java.lang.Class.forName0(Native Method)
> at java.base/java.lang.Class.forName(Class.java:374)
> at java.base/java.nio.file.FileSystems$DefaultFileSystemHolder.getDefaultProvider(FileSystems.java:129)
> ... 22 more
>
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