7034532: (fs) AssertionError when working directory is UNC

[Alan Bateman]

Someone testing jdk7 in NetBeans reported the following stack trace when 
attempting to run their JUnit tests:

Exception in thread "main" java.lang.AssertionError: Default directory 
must be absolute/non-UNC
        at sun.nio.fs.WindowsFileSystem.<init>(WindowsFileSystem.java:60)
        at 
sun.nio.fs.WindowsFileSystemProvider.<init>(WindowsFileSystemProvider.java:52)
        at 
sun.nio.fs.DefaultFileSystemProvider.create(DefaultFileSystemProvider.java:36)
        :
        at 
org.apache.tools.ant.taskdefs.optional.junit.JUnitTestRunner.main(JUnitTestRunner.java:906)

The bug is that the code assumes that the process working directory 
cannot be an UNC. You can't "cd" to a UNC but you can launch a process 
with a UNC path as the working directory and that seems to be the case here.

The fix is trivial and just allows the default directory to be a UNC:

diff --git a/src/windows/classes/sun/nio/fs/WindowsFileSystem.java 
b/src/windows/classes/sun/nio/fs/WindowsFileSystem.java
--- a/src/windows/classes/sun/nio/fs/WindowsFileSystem.java
+++ b/src/windows/classes/sun/nio/fs/WindowsFileSystem.java
@@ -56,8 +56,9 @@ class WindowsFileSystem
         // parse default directory and check it is absolute
         WindowsPathParser.Result result = WindowsPathParser.parse(dir);
 
-        if (result.type() != WindowsPathType.ABSOLUTE)
-            throw new AssertionError("Default directory must be 
absolute/non-UNC");
+        if ((result.type() != WindowsPathType.ABSOLUTE) &&
+            (result.type() != WindowsPathType.UNC))
+            throw new AssertionError("Default directory is not an 
absolute path");
         this.defaultDirectory = result.path();
         this.defaultRoot = result.root();

I don't propose to include a regression test for this.

Thanks,

-Alan.