Because meson does not provide a simple way to get the relative build
path, it is computed with a pair of foreach loops. As meson does not
have a simple way to compute string length (except via underscorify
and 63 split operations), the build script uses a shell command
instead.
If the compiler does not suppot -fmacro-prefix-map, then fall back
to passing in the relative path prefix, and use its length to offset
the uses of __FILE__ in log messages so that the build path is at
least still not included in the logs. This is significantly more
efficient than calling _sway_strip_path.
This commit mostly duplicates the wlr_log functions, although
with a sway_* prefix. (This is very similar to PR #2009.)
However, the logging function no longer needs to be replaceable,
so sway_log_init's second argument is used to set the exit
callback for sway_abort.
wlr_log_init is still invoked in sway/main.c
This commit makes it easier to remove the wlroots dependency for
the helper programs swaymsg, swaybg, swaybar, and swaynag.
Increase _POSIX_SOURCE value where needed.
Increase _XOPEN_SOURCE value where needed.
Conditionally link to libcap (only on Linux).
Possibly some trailing whitespace fixes (automatic).
_sway_assert is a variadic function which tries
to delegate to another variadic function. This
requires a vprintf-style variant of the delegate.
https://stackoverflow.com/a/150616
Calling `exit` in sway_terminate prevents sway from correctly shutting
down (freeing data, cleanly terminating the ipc server, etc.).
A better way is to exit straight away if the failure occurs before
`wlc_run` and use sway_abort as usual if it occur when wlc is running.
