RFR 8164705: Remove pathname canonicalization from FilePermission

[Weijun Wang]

Hi All

Please take a look at

    http://cr.openjdk.java.net/~weijun/8164705/webrev.00

 From the beginning of JDK, FilePermission canonicalizes the input path 
and use the result in implies() and equals(). This has been a big 
performance hurt and leads to confusing results when symlinks are involved.

The code change above removes the canonicalization.

This means FilePermission on "/the/current/working/directory/x" no 
longer implies that on "x". Since this might bring quite some 
compatibility risk, the code change includes some tweaks in permission 
checking to make sure an app is still able to read "x" when the 
FilePermission granted is on "/the/current/working/directory/x". 
However, we still hope the policy to be updated to be consistent of how 
a file is actually accessed.

No tweak is devoted to make granting "/this/is/a/symlink" to imply 
reading of "/the/actual/target/file", because we think it should not.

This is quite a big behavior change. If it breaks your app/lib, or does 
not work with your customized security manager or policy implementation, 
please let us know.

Feel free to provide any feedback.

Finally, a new system property "jdk.filepermission.canonicalize" is 
introduced and it can be "true", "false", or "compat". The out-of-box 
default is "compat", which means no canonicalization with check tweaks.

Thanks
Max