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Re: problem with readonly pinfo?


On Tue, Sep 16, 2003 at 09:59:17PM -0400, Pierre A. Humblet wrote:
>At 09:46 PM 9/16/2003 -0400, Christopher Faylor wrote:
>>The problem is that UNIX sends signals (like CTRL-C) to processes in a
>>process group, regardless of process ownership.  In cygwin, it's up to
>>the parent process to do this.
>
>I am not sure I understand 100% what "up to the parent process" means.
>Do you mean the signals are propagated through generations (grandfather
>to father to child) and not directly from grandfather to grandchild as
>in UNIX?

Wow.  This is hard.

If you type CTRL-C on windows, any process in the tty process group
gets sent a CTRL-C.

How do you think this is handled in cygwin?  There is no help from the
operating system since the operating system doesn't know what a unix
process group is.

So, some process in cygwin has to send CTRL-Cs to everything in the
process group.  This is left to the process group leader.

In practice, the process gruop leader is usually the top level process
of a process tree although it could theoretically be a descendant
process.  Hmm.  This just occurred to me.

When the process group leader has not created all of the processes
in its group, I don't think the new scheme will work right, will it?
It's a similar problem to:

>>I think you're saying that this will work ok, right?  And we should be
>>able to use the same security for the pipe as well, I assume?
>
>Yes.  But I see a problem going in the other direction, from a child
>who has setuid'ed and exec'ed, to parent.  At least with the current
>code, hopefully not with your pipes.

Yes, I know about those problems.  That's why I haven't checked in the
pipe stuff yet.

cgf


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