Arch Linux

Description:

ddd hangs because it cannot connect to X Window. Here is the output of strace:

connect(4, {sa_family=AF_LOCAL, sun_path=@"/tmp/.X11-unix/X0"}, 20) = 0
getpeername(4, {sa_family=AF_LOCAL, sun_path=@"/tmp/.X11-unix/X0"}, [20]) = 0
uname({sysname="Linux", nodename="terra-arch", ...}) = 0
access("/home/phil/.Xauthority", R_OK) = 0
open("/home/phil/.Xauthority", O_RDONLY) = 5
fstat(5, {st_mode=S_IFREG|0600, st_size=55, ...}) = 0
read(5, "\1\0\0\nterra-arch\0\0010\0\22MIT-MAGIC-COO"..., 4096) = 55
read(5, "", 4096) = 0
close(5) = 0
getsockname(4, {sa_family=AF_LOCAL, NULL}, [2]) = 0
fcntl(4, F_GETFL) = 0x2 (flags O_RDWR)
fcntl(4, F_SETFL, O_RDWR|O_NONBLOCK) = 0
fcntl(4, F_SETFD, FD_CLOEXEC) = 0
poll([{fd=4, events=POLLIN|POLLOUT}], 1, -1) = 1 ([{fd=4, revents=POLLOUT}])
writev(4, [{"...", 12}, {"", 0}, {"MIT-MAGIC-COOKIE-1", 18}, {"...", 2}, {"...", 16}, {"...", 0}], 6) = 48
recvmsg(4, 0x7ffc641c6e80, 0) = -1 EAGAIN (Resource temporarily unavailable)

Before the recvmsg call, it communicates with the "/tmp/.X11-unix/X0" socket and sends a MIT-MAGIC-COOKIE-1 with a writev call. Then it loops forever (the recvmsg call keeps failing).

It worked a short while ago, ddd is the only application that seems to be affected. Unfortunately, I am not familiar with the XWindow authorization protocol.

/tmp/.X11-unix/X0 exists and it owned by root:

$ ls -l /tmp/.X11-unix
total 0
srwxrwxrwx 1 root root 0 Apr 5 21:22 X0

If I run sudo ddd, it works.

I cannot rule out that the problem is caused by a misconfiguration on my system. Please let me know if additional config files or log outputs what you useful.

Additional info:
* ddd 3.3.12-7

Steps to reproduce:

Just start "ddd". The GUI opens, but hangs when you try interact with it.

It is more visible if you run "strace ddd". You should immediately see infinite loops like this:

poll([{fd=4, events=POLLIN}, {fd=6, events=POLLIN|POLLPRI|POLLRDNORM|POLLRDBAND}], 2, 0) = 0 (Timeout)
poll([{fd=6, events=POLLIN|POLLPRI|POLLRDNORM|POLLRDBAND}], 1, 0) = 0 (Timeout)
recvmsg(4, 0x7ffeeb2a2180, 0) = -1 EAGAIN (Resource temporarily unavailable)
recvmsg(4, 0x7ffeeb2a2180, 0) = -1 EAGAIN (Resource temporarily unavailable)