Problem:
- `(void)` simply casts the expression to void. This is understood to
indicate that it is ignored, but this is really a compiler trick to
get the compiler to not generate a warning.
Solution:
- Use the `[[maybe_unused]]` attribute to indicate the value is unused.
Note:
- Functions taking a `(void)` argument list have also been changed to
`()` because this is not needed and shows up in the same grep
command.
This makes the Scheduler a lot leaner by not having to evaluate
block conditions every time it is invoked. Instead evaluate them as
the states change, and unblock threads at that point.
This also implements some more waitid/waitpid/wait features and
behavior. For example, WUNTRACED and WNOWAIT are now supported. And
wait will now not return EINTR when SIGCHLD is delivered at the
same time.
This makes most operations thread safe, especially so that they
can safely be used in the Kernel. This includes obtaining a strong
reference from a weak reference, which now requires an explicit
call to WeakPtr::strong_ref(). Another major change is that
Weakable::make_weak_ref() may require the explicit target type.
Previously we used reinterpret_cast in WeakPtr, assuming that it
can be properly converted. But WeakPtr does not necessarily have
the knowledge to be able to do this. Instead, we now ask the class
itself to deliver a WeakPtr to the type that we want.
Also, WeakLink is no longer specific to a target type. The reason
for this is that we want to be able to safely convert e.g. WeakPtr<T>
to WeakPtr<U>, and before this we just reinterpret_cast the internal
WeakLink<T> to WeakLink<U>, which is a bold assumption that it would
actually produce the correct code. Instead, WeakLink now operates
on just a raw pointer and we only make those constructors/operators
available if we can verify that it can be safely cast.
In order to guarantee thread safety, we now use the least significant
bit in the pointer for locking purposes. This also means that only
properly aligned pointers can be used.
Since the CPU already does almost all necessary validation steps
for us, we don't really need to attempt to do this. Doing it
ourselves doesn't really work very reliably, because we'd have to
account for other processors modifying virtual memory, and we'd
have to account for e.g. pages not being able to be allocated
due to insufficient resources.
So change the copy_to/from_user (and associated helper functions)
to use the new safe_memcpy, which will return whether it succeeded
or not. The only manual validation step needed (which the CPU
can't perform for us) is making sure the pointers provided by user
mode aren't pointing to kernel mappings.
To make it easier to read/write from/to either kernel or user mode
data add the UserOrKernelBuffer helper class, which will internally
either use copy_from/to_user or directly memcpy, or pass the data
through directly using a temporary buffer on the stack.
Last but not least we need to keep syscall params trivial as we
need to copy them from/to user mode using copy_from/to_user.
MemoryManager cannot use the Singleton class because
MemoryManager::initialize is called before the global constructors
are run. That caused the Singleton to be re-initialized, causing
it to create another MemoryManager instance.
Fixes#3226
This does not add any behaviour change to the processes, but it ties a
TTY to an active process group via TIOCSPGRP, and returns the TTY to the
kernel when all processes in the process group die.
Also makes the TTY keep a link to the original controlling process' parent (for
SIGCHLD) instead of the process itself.
This compiles, and fixes two bugs:
- setpgid() confusion (see previous commit)
- tcsetpgrp() now allows to set a non-empty process group even if
the group leader has already died. This makes Serenity slightly
more POSIX-compatible.
A process that is not in the foreground process group of a TTY should
not be allowed to read/write that TTY. Instead, we now send either a
SIGTTIN (on read) or SIGTTOU (on write) signal to the process, and fail
the I/O syscall with EINTR.
Fixes#205.
- Remove goofy _r suffix from syscall names.
- Don't take a signed buffer size.
- Use Userspace<T>.
- Make TTY::tty_name() return a String instead of a StringView.
By making the Process class RefCounted we don't really need
ProcessInspectionHandle anymore. This also fixes some race
conditions where a Process may be deleted while still being
used by ProcFS.
Also make sure to acquire the Process' lock when accessing
regions.
Last but not least, there's no reason why a thread can't be
scheduled while being inspected, though in practice it won't
happen anyway because the scheduler lock is held at the same
time.
Use copy_{to,from}_user() in the various File::ioctl() implementations
instead of disabling SMAP wholesale in sys$ioctl().
This patch does not port IPv4Socket::ioctl() to those API's since that
will be more involved. That function now creates a local SmapDisabler.
It is possible to switch to VirtualConsoles 1 to 4 via the shortcut
ALT + [1-4]. Therefor the array of VirtualConsoles should be guaranteed
to be initialized.
Also add an constant for the maximum number of VirtualConsoles to
guarantee consistency.
We can now properly initialize all processors without
crashing by sending SMP IPI messages to synchronize memory
between processors.
We now initialize the APs once we have the scheduler running.
This is so that we can process IPI messages from the other
cores.
Also rework interrupt handling a bit so that it's more of a
1:1 mapping. We need to allocate non-sharable interrupts for
IPIs.
This also fixes the occasional hang/crash because all
CPUs now synchronize memory with each other.
You can now request an update of the terminal's window progress by
sending this escape sequence:
<esc>]9;<value>;<max_value>;<escape><backslash>
I'm sure we can find many interesting uses for this! :^)
This was supposed to be the foundation for some kind of pre-kernel
environment, but nobody is working on it right now, so let's move
everything back into the kernel and remove all the confusion.
