In most typical Linux X servers (like Xvfb, Xephyr, or Xwayland),
no child process outlives the server, so this issue rarely arises.
However, in embedded X servers (based on Xvfb or Kdrive) or in
custom Xorg modules, the server might launch a long-running command
with regular fork+exec calls. If the X server crashes or exits while
that command is still running (for example, it spawns a tombstone
generator or any process that hangs or turns to zombie), the file
descriptor associated with the abstract socket can remain open in the
child process. This leads to the kernel refusing to allow another X
server to bind the same socket until the child process terminates
(because there is no explicit way to unlink abstract socket, unlike
Unix socket). By marking the file descriptor as close-on-exec, we
ensure it is automatically closed in child processes, preserving the
ability of a new X server process to bind the socket immediately.
Signed-off-by: Twaik Yont <9674930+twaik@users.noreply.github.com>
Part-of: <https://gitlab.freedesktop.org/xorg/xserver/-/merge_requests/1906>
(cherry picked from commit 5568b0f83f)
(cherry picked from commit 59673c0503)
986202ce4d