This singleton simplifies many aspects that we struggled with before:
1. There's no need to make derived classes of Device expose the
constructor as public anymore. The singleton is a friend of them, so he
can call the constructor. This solves the issue with try_create_device
helper neatly, hopefully for good.
2. Getting a reference of the NullDevice is now being done from this
singleton, which means that NullDevice no longer needs to use its own
singleton, and we can apply the try_create_device helper on it too :)
3. We can now defer registration completely after the Device constructor
which means the Device constructor is merely assigning the major and
minor numbers of the Device, and the try_create_device helper ensures it
calls the after_inserting method immediately after construction. This
creates a great opportunity to make registration more OOM-safe.
These interfaces are broken for about 9 months, maybe longer than that.
At this point, this is just a dead code nobody tests or tries to use, so
let's remove it instead of keeping a stale code just for the sake of
keeping it and hoping someone will fix it.
To better justify this, I read that OpenBSD removed loadable kernel
modules in 5.7 release (2014), mainly for the same reason we do -
nobody used it so they had no good reason to maintain it.
Still, OpenBSD had LKMs being effectively working, which is not the
current state in our project for a long time.
An arguably better approach to minimize the Kernel image size is to
allow dropping drivers and features while compiling a new image.
This patch converts all the usage of AK::String around sys$execve() to
using KString instead, allowing us to catch and propagate OOM errors.
It also required changing the kernel CommandLine helper class to return
a vector of KString for the userspace init program arguments.
This patch adds KBufferBuilder::try_create() and treats it like anything
else that can fail. And so, failure to allocate the initial internal
buffer of the builder will now propagate an ENOMEM to the caller. :^)
Make use of the new FileDescription::try_serialize_absolute_path() to
avoid String in favor of KString throughout much of sys$execve() and
its helpers.
We previously allowed Thread to exist in a state where its m_name was
null, and had to work around that in various places.
This patch removes that possibility and forces those who would create a
thread (or change the name of one) to provide a NonnullOwnPtr<KString>
with the name.
This expands the reach of error propagation greatly throughout the
kernel. Sadly, it also exposes the fact that we're allocating (and
doing other fallible things) in constructors all over the place.
This patch doesn't attempt to address that of course. That's work for
our future selves.
Instead of checking it at every call site (to generate EBADF), we make
file_description(fd) return a KResultOr<NonnullRefPtr<FileDescription>>.
This allows us to wrap all the calls in TRY(). :^)
The only place that got a little bit messier from this is sys$mount(),
and there's a whole bunch of things there in need of cleanup.
This function is currently only ever used to create the init process
(SystemServer). It had a few idiosyncratic things about it that this
patch cleans up:
- Errors were returned in an int& out-param.
- It had a path for non-0 process PIDs which was never taken.
REQUIRE_PROMISE and REQUIRE_NO_PROMISES were macros for some reason,
and used all over the place.
This patch adds require_promise(Pledge) and require_no_promises()
to Process and makes the macros call these on the current process
instead of inlining code everywhere.
Prior to this change, both uid_t and gid_t were typedef'ed to `u32`.
This made it easy to use them interchangeably. Let's not allow that.
This patch adds UserID and GroupID using the AK::DistinctNumeric
mechanism we've already been employing for pid_t/ProcessID.
There are callers of processes().with or processes().for_each that
require interrupts to be disabled. Taking a Mutexe with interrupts
disabled is a recipe for deadlock, so convert this to a Spinlock.
This has several benefits:
1) We no longer just blindly derefence a null pointer in various places
2) We will get nicer runtime error messages if the current process does
turn out to be null in the call location
3) GCC no longer complains about possible nullptr dereferences when
compiling without KUBSAN
We are not using this for anything and it's just been sitting there
gathering dust for well over a year, so let's stop carrying all this
complexity around for no good reason.
This makes the following scenario impossible with an SMP setup:
1) CPU A enters unref() and decrements the link count to 0.
2) CPU B sees the process in the process list and ref()s it.
3) CPU A removes the process from the list and continues destructing.
4) CPU B is now holding a destructed Process object.
By holding the process list lock before doing anything with it, we
ensure that other CPUs can't find this process in the middle of it being
destructed.
This allows us to 1) let go of the Process when an inode is ref'ing for
ProcFSExposedComponent related reasons, and 2) change our ref/unref
implementation.
This patch removes KResult::operator int() and deals with the fallout.
This forces a lot of code to be more explicit in its handling of errors,
greatly improving readability.
The only two paths for copying strings in the kernel should be going
through the existing Userspace<char const*>, or StringArgument methods.
Lets enforce this by removing the option for using the raw cstring APIs
that were previously available.
