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Joel Sherrill
b4e3b2bd68
I just happened across the sync_io support in
c/src/exec/score/cpu/unix/cpu.c
(is this documented anywhere?). That looked more useful than the
signal driven I/O I was using before, so I tried it. I ran across a
few bugs in the way it uses select.
Select changes its fd_set arguments, so you can't use global variables
for them. You have to copy them into local variables first.
If select returns -1 with errno set to EINTR, then it has not changed
any of the fd_sets. You can't start looking at them.
When clearing a descriptor, the code has the usual select off by one
error when setting sync_io_nfds.
I don't see how this code could ever have worked correctly.
I have appended a patch for the problems I found.