:A first cut of the libc-based implementation, using a (new) syscall to
:get/set the signal its is available, and can be found here:
:http://www.gsicomp.on.ca/~matt/dfly/ (rev3, bottom of page)
:
:Note that this implementation is not complete, as it is missing the userland
:get/set_mcontext code. I'm sure I've also missed some nuance wrt signal
:handling (locking, ordering, etc) in the design and use of the new sigmask
:syscall.
:
:--
:Matt Emmerton
Ok, I see a few things, all easy to fix:
* sigpend is not swapped in and out. This is the bitmask of pending
signals. It stays as it is.
* sigmask must be adjusted by the kernel to remove unmaskable signals
using SIG_CANTMASK(sigmask);
* There is a naming conflict between the sigmask() system call and
thethe 'sigmask' identifier, but (see next item)...
* You shouldn't need a new system call anyway, the sigprocmask() system
call can be used to retrieve and set the signal mask. I recommend
using that.
There is one more issue, and that is an atomicy issue. We want the
new signal mask to be set simultaniously with the restoration of the
context (or most of it). This means that all signals must be masked
temporarily while restoring the context. But don't worry about it,
I can handle that part as well. It does mean an extra system call
but that isn't our concern at the moment.
I can fill in the missing code assembly, no problem. If you do one
more rev using sigprocmask() instead of creating a new system call
I can then take it from there.
-Matt
Matthew Dillon
<[EMAIL PROTECTED]>
