Re: [PATCH 3/4] scoped_ignore_signal: Use sigprocmask+sigtimedwait instead of signal

[Simon Marchi via Gdb-patches <gdb-patches@sourceware.org>]

> Thanks, that looks right to me.  We're using sigtimewait with zero timeout to consume
> a pending signal.  sigpending + sigwait effectively does the same thing.
> 
> According to gnulib, sigpending exists everywhere but mingw:
> 
>  https://www.gnu.org/software/gnulib/manual/html_node/sigpending.html
> 
> and sigtimedwait is missing on "Mac OS X 10.13, OpenBSD 6.7, Minix 3.1.8, Cygwin 2.9, mingw, MSVC 14, Android 5.1.":
> 
>   https://www.gnu.org/software/gnulib/manual/html_node/sigtimedwait.html
> 
> So the approach you propose should work well.
> 
> Given sigpending is everywhere Unix-like, if we'd like, we could instead use the sigpending + sigwait path
> unconditionally everywhere, but that's two syscalls instead of one, and the configure check is
> trivial (just add sigtimedwait to AC_CHECK_FUNCS in gdbsupport/common.m4), so why not indeed save one
> syscall, seems easy enough.
> 
> Let me know if you'd rather me do the leg work of writing the actual patch.

Thanks, I'll do it since I have access to a macOS system, and therefore
I can at least compile-test it.

Simon