have_sys_socket.c: MacOS support for sys_socket_sendto_udp_target() a…

[vasiliyk]

Updated src/config/have_sys_socket.c to support MacOS.

MacOS does not support the flag MSG_NOSIGNAL used in:

• sys_socket_sendto_tcp_target()
• sys_socket_sendto_udp_target()

but it has an equivalent SO_NOSIGPIPE that prevents SIGPIPE from being raised when a write fails on a socket.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 90.59%. Comparing base (1d2df58) to head (106eec9).

Additional details and impacted files

@@           Coverage Diff           @@
##           latest     #469   +/-   ##
=======================================
  Coverage   90.59%   90.59%           
=======================================
  Files          47       47           
  Lines        4379     4381    +2     
  Branches      587      587           
=======================================
+ Hits         3967     3969    +2     
  Misses        279      279           
  Partials      133      133           

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[goatshriek]

Thanks very much for submitting this, it isn't something I was aware of.

From what I can see there are other BSD systems (FreeBSD, for example) that also have this difference. I'd most prefer to add this as a configure check in the CMakeLists.txt to define a configuration #define for the socket option in either case. The process for this is described here. This is a bit more work than what this pull request includes, so I understand if you'd rather not go through this. Let me know if you'd prefer not to go through that, and if so I'll put together a patch myself.

[vasiliyk]

Joel, I will do it and open another PR.