RFR: 8194154 patch for crash at File.getCanonicalPath()

[Alan Bateman]

On 08/02/2018 17:35, yumin qi wrote:
> HI, Alan
>
>   As in your email to RFR of 8194154 which now has a new fix in 
> canonicalize_md.c, switch back to discuss solution here again.
>   The current fix is not in java, instead, I put it in C function. In 
> the function before the fix, it assumes no more "//" pattern in the 
> string so failed to get correct substrings with the case as the test case.
>   The fix should not cause other problem since it does double check if 
> double or more slashes in sequential.
>   The APIs indicates 'user.dir' etc system property should not be 
> rewritten, but did not prevent modifying them in practise.
>
Sure, but it's really hairy for anything to be depend on that.  We can 
improve the reliability by changing java.io.UnixFileSystem to read the 
system property at most once. Second/subsequent usages should only need 
to do a permission check (for the security manager case). Going further 
then we need to get to the point where the APIs never read a modified 
property, this goes for java.home and several others too.

I'll study the patch you have but I think we also need to create issues 
to get us to the point where changing this system property in a running 
VM doesn't impact running code.

-Alan