Signal Handling Woes

[Volker Stolz]

In local.cvs-ghc, you wrote:
> I'm really not sure what happens when two signal handlers try to write 
> to the same pipe at the same time. Are multi-byte writes from separate 
> threads atomic with respect to each other? They seem to be on Mac OS, 
> but I'd prefer a written guarantee... But see 6) below.

SUSv3 says:
"Write requests to a pipe or FIFO shall be handled in the same way as a
 regular file with the following exceptions:

There is no file offset associated with a pipe, hence each write request
 shall append to the end of the pipe.

Write requests of {PIPE_BUF} bytes or less shall not be interleaved with
 data from other processes doing writes on the same pipe. Writes of greater
 than {PIPE_BUF} bytes may have data interleaved, on arbitrary boundaries,
 with writes by other processes, whether or not the O_NONBLOCK flag of the
 file status flags is set."
-- 
http://www-i2.informatik.rwth-aachen.de/stolz/ *** PGP *** S/MIME
rage against the finite state machine