SVr4/SVID/SUS IPC conformance

[Anton Arapov <aarapov@redhat.com>]

Hi!

* Please, gurus, who cares about standards conformance, do not ignore this message!

  SysV code returns EIDRM for collision of IDs. I sure it should return EINVAL.

  Steps to reproduce: (this for shared memory code, for msg/sem it is the same)
   1. Create then drop 2 shmem segments, then create a third.
   2. Try to shmctl(IPC_STAT) the two now-invalid shm IDs.
   3. Note error codes returned.

   One call gives EINVAL, one gives EIDRM due to collision with the third shmem \
segment.  Should both give EINVAL, this is what I've got on every other Unix I've \
tried it on. 

  IPC code is good, EIDRM is justification of EINVAL. But neither SVr4 nor SVID \
documents EIDRM.   Single Unix Specification mentions EINVAL but not EIDRM as a \
possible failure for shmctl(), so the current kernel behavior is not merely \
self-inconsistent but a flat violation of the spec. 

  Can somebody explain why do we have EIDRM?

Anton.
SUS: http://www.opengroup.org/onlinepubs/007908799/xsh/shmctl.html
-- 
Anton Arapov, <aarapov@redhat.com>