When cleaning up after a caught signal, quark forwards the signal to all
processes in the process group with `kill(0, ...)`. If we do not open up a new
process group in the parent process, quarks parent will be sent a SIG... too,
resulting it to shut down (especially considering that the parent process might
run as root).
As a result, if we set up the service with djb's excellent daemontools,
`svc -d quark` will terminate the svscan-process and tear all other services
down with it.
See also <https://cr.yp.to/daemontools/faq/create.html#pgrphack>.
The previous parsing of the -v vhosts made sure there were 4 tokens.
If there was no prefix specified, usage() is called. Now, it only
checks for the firsts 3, with .prefix set to null if there are only
3 tokens.
Since now config.def.h has been reduced we don't have any more unused
variables and thus the manual fiddling with error-levels is no longer
necessary.
To get a completely clean result though we have to still cast some
variables here and there.
The config.h-interface has proven to be very effective for a lot of
suckless tools, but it just does not make too much sense for a web
server like quark.
$ quark
If you run multiple instances of it, you want to see in the command line
(or top) what it does, and given the amount of options it's logical to
just express them as options given in the command line.
It also is a problem if you can modify quark via the config.h,
contradicting the manual. Just saying "Well, then don't touch config.h"
is also not good, as the vhost and map options were only exposed via
this interface.
What is left in config.h are mime-types and two constants relating to
the incoming HTTP-header-limits.
In order to introduce these changes, some structs and safe utility
functions were added and imported from OpenBSD respectively.
To make the code a bit more flexible, let's get rid of the forking-code
in serve() and do it in main(). This way, we are more liberal in the
future to possibly handle it in a different way.
And many other things, too many to list here. For example, it now
properly logs uds instead of erroring out.
Separating concerns in many places definitely improves the readability.
