Until now, our kernel has reimplemented a number of AK classes to
provide automatic internal locking:
- RefPtr
- NonnullRefPtr
- WeakPtr
- Weakable
This patch renames the Kernel classes so that they can coexist with
the original AK classes:
- RefPtr => LockRefPtr
- NonnullRefPtr => NonnullLockRefPtr
- WeakPtr => LockWeakPtr
- Weakable => LockWeakable
The goal here is to eventually get rid of the Lock* classes in favor of
using external locking.
Contrary to the past, we don't attempt to assume the real name of a TTY
device, but instead, we generate a pseudo name only when needed to do so
which is still OK because we don't break abstraction layer rules and we
still can provide userspace with the required information.
The obsolete ttyname and ptsname syscalls are removed.
LibC doesn't rely on these anymore, and it helps simplifying the Kernel
in many places, so it's an overall an improvement.
In addition to that, /proc/PID/tty node is removed too as it is not
needed anymore by userspace to get the attached TTY of a process, as
/dev/tty (which is already a character device) represents that as well.
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. :^)
Found due to smelly code in InodeFile::absolute_path.
In particular, this replaces the following misleading methods:
File::absolute_path
This method *never* returns an actual path, and if called on an
InodeFile (which is impossible), it would VERIFY_NOT_REACHED().
OpenFileDescription::try_serialize_absolute_path
OpenFileDescription::absolute_path
These methods do not guarantee to return an actual path (just like the
other method), and just like Custody::absolute_path they do not
guarantee accuracy. In particular, just renaming the method made a
TOCTOU bug obvious.
The new method signatures use KResultOr, just like
try_serialize_absolute_path() already did.
These methods are no longer needed because SystemServer is able to
populate the DevFS on its own.
Device absolute_path no longer assume a path to the /dev location,
because it really should not assume any path to a Device node.
Because StorageManagement still needs to know the storage name, we
declare a virtual method only for StorageDevices to override, but this
technique should really be removed later on.
It's easy to forget the responsibility of validating and safely copying
kernel parameters in code that is far away from syscalls. ioctl's are
one such example, and bugs there are just as dangerous as at the root
syscall level.
To avoid this case, utilize the AK::Userspace<T> template in the ioctl
kernel interface so that implementors have no choice but to properly
validate and copy ioctl pointer arguments.
Previously the VirtualConsole::on_tty_write() method would return an
incorrect value when an error had occurred. This prompted me to
update the TTY subsystem to use KResultOr<size_t> everywhere.
This commit cleans up some of the `#ifdef`-ed code smell in
`Terminal`, by extending the scroll APIs to take a range of lines as a
parameter. This makes it possible to use the same code for `IL`/`DL` as
for scrolling.
Note that the current scrolling implementation is very naive, and does
many insertions/deletions in the middle of arrays, whereas swaps should
be enough. This optimization will come in a later commit.
The `linefeed` override was removed from `VirtualConsole`. Previously,
it exhibited incorrect behavior by moving to column 0. Now that we use
the method defined in `Terminal`, code which relied on this behavior
stopped working. We go instead go through the TTY layer which handles
the various output flags. Passing the input character-by-character
seems a bit excessive, so a fix for it will come in another PR.
Previously, we would echo characters back just as they were passed to
us, even in canonical mode. This caused newlines to not work correctly
in some programs.
Fixes#7802
I introduced a regression in #7184 where `TTY` would report 1 byte read
in canonical mode even if we had no more characters left. This was
caused by counting the '\0' that denotes EOF into the number of
characters that were read.
The fix was simple: exclude the EOF character from the number of bytes.
This still wouldn't be correct by itself, as the EOF and EOL control
characters could change between when the data was written to the TTY and
when it is read. We fix this by signaling out-of-band whether something
is a special character. End-of-file markers have a value of zero and
have their special bits set. Any other bytes with a special flag are
treated as line endings. This is possible, as POSIX doesn't allow
special characters to be 0.
Fixes#7419
This commit adds support for the various ECHO* lflags and fixes some
POSIX conformance issues around newline handling. Also included are
error messages when setting not implemented settings.
SPDX License Identifiers are a more compact / standardized
way of representing file license information.
See: https://spdx.dev/resources/use/#identifiers
This was done with the `ambr` search and replace tool.
ambr --no-parent-ignore --key-from-file --rep-from-file key.txt rep.txt *
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.
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.
- 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.
As suggested by Joshua, this commit adds the 2-clause BSD license as a
comment block to the top of every source file.
For the first pass, I've just added myself for simplicity. I encourage
everyone to add themselves as copyright holders of any file they've
added or modified in some significant way. If I've added myself in
error somewhere, feel free to replace it with the appropriate copyright
holder instead.
Going forward, all new source files should include a license header.
The TTY driver now respects the ICANON flag, enabling basic line
editing like VKILL, VERASE, VEOF and VWERASE. Additionally,
ICANON is now set by default.
Basic echoing has can now be enabled via the ECHO flag, though
more complicated echoing like ECHOCTL or ECHONL has not been
implemented.
This papers over an immediate issue where pseudoterminals would choke
on more than 16 characters of pasted input in the GUI terminal.
Longer-term we should find a more elegant solution than using a static
size CircularQueue for this.
TTY::emit is called from an IRQ handler, and is used to push input data
into a buffer for later retrieval. Previously this was using DoubleBuffer,
but that class wants to take a lock. Our lock code wants to make sure
interrupts are enabled, but they're disabled while an IRQ handler is
running. This made the kernel sad, but this CircularQueue cheers it up by
avoiding the lock requirement completely.
After reading a bunch of POSIX specs, I've learned that a file descriptor
is the number that refers to a file description, not the description itself.
So this patch renames FileDescriptor to FileDescription, and Process now has
FileDescription* file_description(int fd).
Also run it across the whole tree to get everything using the One True Style.
We don't yet run this in an automated fashion as it's a little slow, but
there is a snippet to do so in makeall.sh.
