Request for review: 7190897 (fs) Files.isWritable method returns false when the path is writable (win). (original) (raw)

Alexey Utkin alexey.utkin at oracle.com
Mon Mar 4 12:23:04 UTC 2013

On 04.03.2013 15:51, Alan Bateman wrote:

On 04/03/2013 09:31, Alexey Utkin wrote:

Alan, Do you agree with

/** * Check the access right against the securityInfo in the current thread. */ static boolean checkAccessMask(long securityInfo, int accessMask, int genericRead, int genericWrite, int genericExecute, int genericAll) throws WindowsException { int privilegies = TOKENQUERY; long hToken = OpenThreadToken(GetCurrentThread(), privilegies, false); if (hToken == 0L && processTokenWithDuplicateAccess != 0L) hToken = DuplicateTokenEx(processTokenWithDuplicateAccess, privilegies); We can have the situation with:

  1. OpenThreadToken return 0 without exception - that is ok for thread without impersonation.
  2. processTokenWithDuplicateAccess is 0 for some reason (weak precess privileges) For that case we have no access to process token without exception (hToken :=: 0).

    boolean hasRight = false; if (hToken != 0L) { So, in upper line we need to check token for non-empty value. ! Do you concern about the [false] return value for that case? try { hasRight = AccessCheck(hToken, securityInfo, accessMask, genericRead, genericWrite, genericExecute, genericAll); Here is the actual work, that can make an exception (for example it happens for invalid SID) } finally { CloseHandle(hToken); If token was open it have to be closed without excuses. } } return hasRight; } implementation approach? Can the handle to the token (hToken) be 0? In my comment I was suggesting: long hToken = OpenThreadToken(...); try { ... } finally { CloseHandle(hToken); }

but that doesn't work if OpenThreadToken succeeds with a handle of 0. If 0 is not possible then there are a few other clean-ups that we could do at a later time.

Ah, I remember now, we handle ERRORNOTOKEN so this means that hToken can be 0. So this means that the CloseHandle does need to check for 0 in the finally block.

-Alan. -Alan

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