rmdir(2) behavior to prevent pax(1) from working

[Hiroki Sato]

Hi,

 I notice that the current rmdir(2) implementation allows
 rmdir(2) to remove a directory path whose final component is
 either "." or ".." (such as /tmp/foo/bar/.).
 This sounds no problem, but the pax(1) utility depends on this
 behavior at least.  Try the following commands:

  % cd /tmp
  % mkdir a b
  % touch a/foo
  % cd a
  % pax -r -w . ../b

 In this case pax(1) should go into a infinite loop.
 The SUSv3 also says "If the path argument refers to a path
 whose final component is either dot or dot-dot, rmdir() shall fail."
 so I think it is better to be fixed.

 Probably kern_rmdir() @ sys/kern/vfs_syscalls.c needs
 some sort of sanity check for the trailing "." and "..",
 but unfortunately I have no idea about a concrete solution because
 I am not familiar with the new VFS/namecache API...

 Could anyone investigate this problem?

-- 
| Hiroki SATO
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