Problems with getifaddrs

Ken Brown
Mon Jul 26 15:15:00 GMT 2021

While investigating emacs test failures, I found two problems with the 
interfaces returned by getifaddrs(3):

1. For an IPv6 interface, the netmask address family is always 0 instead of 

2. For a disconnected interface, the IPv4 address and netmask are sometimes 0.

I will be sending patches to fix these problems later today, but I wanted to 
report them here for reference.

I don't know enough about this to be sure that problem 2 is really a Cygwin bug. 
  Are there cases where a 0 IP address is appropriate?  Or should it be up to 
the caller of getifaddrs to handle that case?


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