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)
Package build machines may have module loading disabled, thus AF_ALG
sockets are not available. Skip the tests that cover those (khash and
id128) instead of failing them in this case.
Fixes#5524
Let's take inspiration from bluez's ELL library, and let's move our
cryptographic primitives away from libgcrypt and towards the kernel's AF_ALG
cryptographic userspace API.
In the long run we should try to remove the dependency on libgcrypt, in favour
of using only the kernel's own primitives, however this is unlikely to happen
anytime soon, as the kernel does not provide Elliptic Curve APIs to userspace
at this time, and we need them for the DNSSEC cryptographic.
This commit only covers hashing for now, symmetric encryption/decryption or
even asymetric encryption/decryption is not available for now.
"khash" is little more than a lightweight wrapper around the kernel's AF_ALG
socket API.
