I've got the following SIGSEGV when terminating sway:
```
Program terminated with signal SIGSEGV, Segmentation fault.
0x00005607dc603af5 in view_unmap (view=0x5607dcb3d350) at ../sway/tree/view.c:599
599 if (surviving_ancestor->type >= C_WORKSPACE) {
```
surviving_ancestor was NULL at that time
This commit is trying to fix this problem.
- Some platforms don't expose kill() unless _POSIX_C_SOURCE is defined.
- fork(), execl(), and setsid() need unistd.h on some platforms.
Basically, this fixes some platform-specific build errors.
This creates a root.c and moves bits and pieces from elsewhere into it.
* layout_init has been renamed to root_create and moved into root.c
* root_destroy has been created and is called on shutdown
* scratchpad code has been moved into root.c, because hidden scratchpad
containers are stored in the root struct
Calling container_at_view fails an assertion if the container isn't a
view. Calling tiling_container_at works correctly, as that function
checks if the container is a view and calls container_at_view if so.
When a view unmaps, normally the surviving ancestor (ie. after reaping)
needs to be arranged. When a fullscreen view unmaps, it arranges the
workspace rather than the surviving ancestor, but didn't handle cases
where the workspace itself was reaped. This happens if the workspace is
not currently shown and the fullscreen view was the last container on
that workspace.
This commit rewrites this part of view_unmap so it's more readable, and
fixes the crash by not arranging the workspace if it's been reaped. Note
that it no longer arranges the output under any circumstance - this
wasn't required anyway.
* seat_set_focus_warp lacked a container NULL check
* view mapping code needs to use seat_get_focus_inactive
Also, seat_set_focus_warp triggered the wrong IPC event if focus was a
workspace, which resulted in swaybar not showing the workspace as
active.
wlroots uses wl_event_loop_add_signal to handle SIGUSR1 from Xwayland.
wl_event_loop_add_signal works by masking the signal and receiving it from a
signalfd. The signal mask is preserved across fork and exec, so subprocesses
spawned by Sway start with SIGUSR1 masked. Most subprocesses do not expect this
and never unmask the signal, resulting in missing functionality or unexpected
behavior for processes that use SIGUSR1 (such as i3status).
Fix this by unmasking all signals between fork and exec.
