log.h really should only include the bare minimum of other headers, as
it is really pulled into pretty much everything else and already in
itself one of the most basic pieces of code we have.
Let's hence drop inclusion of:
1. sd-id128.h because it's entirely unneeded in current log.h
2. errno.h, dito.
3. sys/signalfd.h which we can replace by a simple struct forward
declaration
4. process-util.h which was needed for getpid_cached() which we now hide
in a funciton log_emergency_level() instead, which nicely abstracts
the details away.
5. sys/socket.h which was needed for struct iovec, but a simple struct
forward declaration suffices for that too.
Ultimately this actually makes our source tree larger (since users of
the functionality above must now include it themselves, log.h won't do
that for them), but I think it helps to untangle our web of includes a
tiny bit.
(Background: I'd like to isolate the generic bits of src/basic/ enough
so that we can do a git submodule import into casync for it)
There are more than enough calls doing string manipulations to deserve
its own files, hence do something about it.
This patch also sorts the #include blocks of all files that needed to be
updated, according to the sorting suggestions from CODING_STYLE. Since
pretty much every file needs our string manipulation functions this
effectively means that most files have sorted #include blocks now.
Also touches a few unrelated include files.
This patch removes includes that are not used. The removals were found with
include-what-you-use which checks if any of the symbols from a header is
in use.
D-Bus' type hierarchy as described in the spec is:
\- basic
\- fixed type (u, i, etc.)
\- string-like type (s, o, g)
\- container
Someone seems to have referred to basic types as "simple types" at
some point, but that term isn't defined in the D-Bus Specification,
and seems redundant.
So far I haven't renamed functions that use "trivial" in their names
to mean "fixed type", to avoid confusion about whether a struct of
constant length, like (iu), is a fixed type. The answer is that it is
fixed-length, but is not a "fixed type", so I can see that something
like bus_type_is_fixed() might be ambiguous.
