Don't Merge - LTP: Fixed rename09 testcase

[vamsikrishna935]

• Patch Description:
  Test was failing due to lackof fork support to create child processes.
  So modified the tests using threads instead of fork.
  Please refer test description above

[davidchisnall]

I don't understand this change. The original version was creating a child process so that we could do things as nobody and then as root. The modified version appears to be doing setreuid in two different threads, yet the second one should fail once the current real UID is no longer 0, so I don't see how this can possibly pass (the saved UID feature should allow setting UID back to 0, but you should need to do that explicitly).

The threads are not needed at all and complicate this test unnecessarily. Only one is running at any given time.

[hukoyu]

@vamsikrishna935 can you address David's feedback please.

[vamsikrishna935]

I don't understand this change. The original version was creating a child process so that we could do things as nobody and then as root. The modified version appears to be doing setreuid in two different threads, yet the second one should fail once the current real UID is no longer 0, so I don't see how this can possibly pass (the saved UID feature should allow setting UID back to 0, but you should need to do that explicitly).

The threads are not needed at all and complicate this test unnecessarily. Only one is running at any given time.

@davidchisnall In the original test, it is creating a child process so that we could do things as nobody and then as bin not as root at end it is setting back to root. I tried implementing this without threads but after setting it nobody i am not able set back the UID. With this threads approach i could able to perform.

[hukoyu]

@davidchisnall can we proceed with this multithread approach or close this PR and keep test disabled as non-supported?

[davidchisnall]

The fact that the modified version is passing appears to indicate a bug to me. I hope @vtikoo's patch will make it fail, so please don't merge it. Does the modified version pass on normal Linux? I don't believe you should be able to change uid on threads independently.