problem with readonly pinfo?

Christopher Faylor
Wed Sep 17 15:17:00 GMT 2003

On Wed, Sep 17, 2003 at 12:03:00AM -0400, Pierre A. Humblet wrote:
>At 11:32 PM 9/16/2003 -0400, Christopher Faylor wrote:
>>On Tue, Sep 16, 2003 at 10:48:33PM -0400, Pierre A. Humblet wrote:
>>>>Yes, I know about those problems.  That's why I haven't checked in the
>>>>pipe stuff yet.
>>>Is SIGCHLD the only case where that occurs (in addition to the process
>>>group leader who isn't an ancestor)? 
>>I believe so, yes.
>A solution for SIGCHLD could be to have an event just for that,
>settable by Everyone.

Yes, I know.  That would involve a new thread or removing one potential
process from the list of processes that are currently waited for in the
process thread.

>The parent has pinfo's for all its children and can scan them to see
>who did it.
>That doesn't solve the case of the group leader who isn't an ancestor.
>I am looking at your changes in fhandler_process::fill_filebuf.
>By insisting on PID_MAP_RW we will be depriving ourselves (in the future)
>of the possibility of getting information that doesn't require writing.

The command line passing mechanism involves sending pseudo signals.  You
can't send a signal unless you've opened the pinfo region with
read/write.  The winpids code first tries to open the shared region with
RW and then drops back to read-only if it fails.


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