These are formatters that can only be used with debug print
functions, such as dbgln(). Currently this is limited to
Formatter<ErrorOr<T>>. With this you can still debug log ErrorOr
values (good for debugging), but trying to use them in any
String::formatted() call will fail (which prevents .to_string()
errors with the new failable strings being ignored).
You make a formatter debug only by adding a constexpr method like:
static constexpr bool is_debug_only() { return true; }
In the continuous effort of better handling OOM in the kernel,
we want to move away from all AK::String usage. One of the final
pieces left to accomplish this goal is replacing all of the usages
of `String::formatted` with something that can actually propagate
failure.
The StringBuilder API was enhanced in the recent past to propagate
failure and thus a slightly modified version of what exists in
`AK::format` will work well for implementing failable format with
`KString`.
This isn't a complete conversion to ErrorOr<void>, but a good chunk.
The end goal here is to propagate buffer allocation failures to the
caller, and allow the use of TRY() with formatting functions.
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 adds a formatter function for OwnPtr<KString>. This is added mainly
because lots of dbgln() statements generate Strings (such as absolute
paths) which are only used for debugging. Instead of catching possible
OOM situations at all the dbgln() callsites, this makes it possible to
let the formatter code handle those situations by outputting "[out of
memory]" if the OwnPtr is null.
This doesn't change anything because our global operator delete also
calls kfree() - however instead of relying on this implementation
detail this makes this dependency more explicit.
The user is supposed to hold these in an OwnPtr but bad things would
happen if the user takes these out of the OwnPtr so let's make the
class non-copyable and non-movable.
There are a bunch of places like drivers which for all intense and
purposes can't really fail allocation during boot, and if they do
fail we should crash immediately.
This change adds `KString::must_create_uninitialized(..)` as well as
`KString::must_create(..)` for use during early boot initialization of
the Kernel. They enforce that they are only used during early boot.
This is a simple string class for use in the kernel. It encapsulates
a length + character array in a single-allocation object.
Main differences from AK::String:
- Single-owner (no reference counting.)
- Allocation failures are exposed, not hidden.
The basic idea is to allow better and more precise string management
in the kernel.
