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Re: signal semaphores inheritance

On Wed, Feb 21, 2001 at 02:40:30PM +0300, Egor Duda wrote:
>Wednesday, 21 February, 2001 Corinna Vinschen wrote:
>>> >>   if  ntsec is on and cygwin app a.exe  (with pid x) starts non-cygwin
>>> >> app  b.exe,  b.exe  inherits  cygwin1S3.sigcatch.x semaphore. if a.exe
>>> >> dies  and  b.exe continue  execution,  and  if  new  cygwin  app c.exe
>>> >> got  pid  x it, fails to create sigcatch semaphore. looks like typo in
>>> >> getsem() to me. is this patch ok?
>>> CV> Did you check it with apps chenging the user context? AFAIR I had
>>> CV> a reason using an inheritable SD...
>>> hmm.  i  haven't noticed any differences. i may have missed something,
>>> though.  but,  if this handle is supposed to be inheritable, shouldn't
>>> it  be  DuplicateHandle()'d  in  child  process?  I've grepped through
>>> sources  and haven't find any DuplicateHandle() used on semaphores. so
>>> even   if   this   handle  is  made inheritable, i don't see the place
>>> where child is using it.
>CV> Please don't misunderstand me. I'm asking that question because I'm
>CV> really unsure why this is an inheritable SD and I only remember (in
>CV> the deepest corner of my brain) that there might have been _some_ issue
>CV> to do it that way but my alzheimer disease is getting worse...
>CV> If you have tested the patch with using telnet or ssh to actually
>CV> change the user context and an `id' results in the correct identity
>CV> and the permissions seem to be ok then I have no problem with your patch.
>i've    tested   it in several simple scenarios, and it seems to work.
>user  context is changed, id shows correct info, and i can send SIGINT
>to process run under sshd via pressing Ctrl-C.

Knowing how signals work, I can't imagine a scenario where inheriting the
semaphore would be useful.  I think that Egor's patch is correct.


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