21.4 hangs in the absence of a net connection

Karl> If my dialup network connection drops, but the nameserver is Karl> still running, XEmacs hangs evidently forever, trying to Karl> learn something about its network environment. "strace Karl> xemacs -q" shows that it gets stuck in poll(2), looking for Karl> data from the nameserver. Probably IPv6. From PROBLEMS: **** New problem: IPv6 CNAME lookup A newer problem is due to XEmacs changing to use the modern getaddrinfo() interface from the older gethostbyname() interface. The solution above is insufficient, because getaddrinfo() by default tries to get IPv6 information for localhost. This always involves a dns lookup to get the CNAME, and the strategies above don't work. It then falls back to IPv4 behavior. This is good[tm]; trust us. ***** Robust network case Configure your network so that there are no nameservers configured until the network is actually running. getaddrinfo() will not try to access a nameserver that isn't configured. ***** Flaky network case If you have a flaky modem or DSL connection that can be relied on only to go down whenever you want to bring XEmacs up, you need to force IPv4 behavior. Explicitly setting DISPLAY=127.0.0.1:0.0 (or whatever is appropriate) works in most cases. If you cannot or do not want to do that, you can hard code IPv4 behavior in src/process-unix.c. This is bad[tm], on your own head be it. In the function unix_canonicalize_host_name() about ten lines down, change the statement hints.ai_family = AF_UNSPEC; to hints.ai_family = PF_INET; and rebuild XEmacs. getaddrinfo() is also called in src/sysdep.c:init_system_name() and in src/process-unix.c:unix_open_network_stream(). It should not be useful to make this change in either of those places. Karl> Why should XEmacs care at all about network matters during Karl> startup? Those Who Know insist that this is a feature, and that you should fix your network configuration. -- University of Tsukuba Tennodai 1-1-1 Tsukuba 305-8573 JAPAN Institute of Policy and Planning Sciences Tel/fax: +81 (298) 53-5091 _________________ _________________ _________________ _________________ What are those straight lines for? "XEmacs rules."