As with the previous commit, we put a distinction between filesystems
that require a file description and those which don't, but now in a much
more readable mechanism - all initialization properties as well as the
create static method are grouped to create the FileSystemInitializer
structure. Then when we need to initialize an instance, we iterate over
a table of these structures, checking for matching structure and then
validating the given arguments from userspace against the requirements
to ensure we can create a valid instance of the requested filesystem.
We now use AK::Error and AK::ErrorOr<T> in both kernel and userspace!
This was a slightly tedious refactoring that took a long time, so it's
not unlikely that some bugs crept in.
Nevertheless, it does pass basic functionality testing, and it's just
real nice to finally see the same pattern in all contexts. :^)
This FIXME does not seem to apply anymore. Yes, symbolic links in all
filesystems appear to be slightly broken, but that has nothing to do
with File::absolute_path. Let's remove the wrong FIXME instead of adding
to the confusion.
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.
We are no longer have a separate Inode object class for the pts
directory. With a small exception to this, all chmod and chown code
is now at one place.
It's now possible to create any name of a sub-directory in the
filesystem.
The current implementation of DevFS resembles the linux devtmpfs, and
not the traditional DevFS, so let's rename it to better represent the
direction of the development in regard to this filesystem.
The abbreviation for DevTmpFS is still "dev", because it doesn't add
value as a commandline option to make it longer.
In quick summary - DevFS in unix OSes is simply a static filesystem, so
device nodes are generated and removed by the kernel code. DevTmpFS
is a "modern reinvention" of the DevFS, so it is much more like a TmpFS
in the sense that not only it's stored entirely in RAM, but the userland
is responsible to add and remove devices nodes as it sees fit, and no
kernel code is directly being involved to keep the filesystem in sync.
2021-09-08 00:42:20 +02:00
Renamed from Kernel/FileSystem/DevFS.cpp (Browse further)
