It appears that Hubbe tested socketpair() and found it to return EAGAIN and EADDRINUSE on occasion on AmigaOS? Even though all the UNIX manpages list it as incapable of returning either EAGAIN or EADDRINUSE? Anyone here who can still recall the circumstances?
AmigaOS (at the time, not sure about now) probably doesn't have true AF_UNIX sockets, and simulates them with AF_INET sockets (just like socketpair_ultra), which can run out of ports on the loopback-interface, which will fail with EADDRINUSE. Note the following comment in src/modules/files/file.c:
/* Don't try to use socketpair() on AmigaOS, socketpair_ultra works better */
I can't even begin to imagine why the socketpair() call would fail with an EADDRINUSE. Any clues? -- Sincerely, Stephen R. van den Berg.