This function simply does a handle table lookup for a writable event
instance identified by the given handle value. If a writable event
cannot be found for the given handle, then an invalid handle error is
returned. If a writable event is found, then it simply signals the
event, as one would expect.
svcCreateEvent operates by creating both a readable and writable event
and then attempts to add both to the current process' handle table.
If adding either of the events to the handle table fails, then the
relevant error from the handle table is returned.
If adding the readable event after the writable event to the table
fails, then the writable event is removed from the handle table and the
relevant error from the handle table is returned.
Note that since we do not currently test resource limits, we don't check
the resource limit table yet.
Two kernel object should absolutely never have the same handle ID type.
This can cause incorrect behavior when it comes to retrieving object
types from the handle table. In this case it allows converting a
WritableEvent into a ReadableEvent and vice-versa, which is undefined
behavior, since the object types are not the same.
This also corrects ClearEvent() to check both kernel types like the
kernel itself does.
Load() is already given the process instance as a parameter, so instead
of coupling the class to the System class, we can just forward that
parameter to LoadNro()
These slots are only ever attached to event handling mechanisms within
the class itself, they're never used externally. Because of this, we can
make the functions private.
This also removes redundant usages of the private access specifier.
The previous code could potentially be a compilation issue waiting to
occur, given we forward declare the type for a std::unique_ptr. If the
complete definition of the forward declared type isn't visible in a
translation unit that the class is used in, then it would fail to
compile.
Defaulting the destructor in a cpp file ensures the std::unique_ptr's
destructor is only invoked where its complete type is known.
The kernel uses the handle table of the current process to retrieve the
process that should be used to retrieve certain information. To someone
not familiar with the kernel, this might raise the question of "Ok,
sounds nice, but doesn't this make it impossible to retrieve information
about the current process?".
No, it doesn't, because HandleTable instances in the kernel have the
notion of a "pseudo-handle", where certain values allow the kernel to
lookup objects outside of a given handle table. Currently, there's only
a pseudo-handle for the current process (0xFFFF8001) and a pseudo-handle
for the current thread (0xFFFF8000), so to retrieve the current process,
one would just pass 0xFFFF8001 into svcGetInfo.
The lookup itself in the handle table would be something like:
template <typename T>
T* Lookup(Handle handle) {
if (handle == PSEUDO_HANDLE_CURRENT_PROCESS) {
return CurrentProcess();
}
if (handle == PSUEDO_HANDLE_CURRENT_THREAD) {
return CurrentThread();
}
return static_cast<T*>(&objects[handle]);
}
which, as is shown, allows accessing the current process or current
thread, even if those two objects aren't actually within the HandleTable
instance.
