This exposes the child processes for a process as a directory
of symlinks to the respective /proc entries for each child.
This makes for an easier and possibly more efficient way
to find and count a process's children. Previously the only
method was to parse the entire /proc/all JSON file.
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.
This file refers to the controlling terminal associated with the current
process. It's specified by POSIX, and is used by ports like openssh to
interface with the terminal even if the standard input/output is
redirected to somewhere else.
Our implementation leverages ProcFS's existing facilities to create
process-specific symbolic links. In our setup, `/dev/tty` is a symbolic
link to `/proc/self/tty`, which itself is a symlink to the appropriate
`/dev/pts` entry. If no TTY is attached, `/dev/tty` is left dangling.
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.
Instead of checking it at every call site (to generate EBADF), we make
file_description(fd) return a KResultOr<NonnullRefPtr<FileDescription>>.
This allows us to wrap all the calls in TRY(). :^)
The only place that got a little bit messier from this is sys$mount(),
and there's a whole bunch of things there in need of cleanup.
This has several benefits:
1) We no longer just blindly derefence a null pointer in various places
2) We will get nicer runtime error messages if the current process does
turn out to be null in the call location
3) GCC no longer complains about possible nullptr dereferences when
compiling without KUBSAN
...in a few more places, at least.
find(1) is about to start relying on the reported types more or less
reflecting reality. This is especially relevant for magic symlinks
in ProcFS.
We don't need to create a new string from a number in order to compare
an existing string to that number. Converting the existing string to a
number is much cheaper, since it does not require any heap allocations.
Ran into this while profiling "find /" :^)
We are not using this for anything and it's just been sitting there
gathering dust for well over a year, so let's stop carrying all this
complexity around for no good reason.
This allows us to 1) let go of the Process when an inode is ref'ing for
ProcFSExposedComponent related reasons, and 2) change our ref/unref
implementation.
This patch changes the semantics of purgeable memory.
- AnonymousVMObject now has a "purgeable" flag. It can only be set when
constructing the object. (Previously, all anonymous memory was
effectively purgeable.)
- AnonymousVMObject now has a "volatile" flag. It covers the entire
range of physical pages. (Previously, we tracked ranges of volatile
pages, effectively making it a page-level concept.)
- Non-volatile objects maintain a physical page reservation via the
committed pages mechanism, to ensure full coverage for page faults.
- When an object is made volatile, it relinquishes any unused committed
pages immediately. If later made non-volatile again, we then attempt
to make a new committed pages reservation. If this fails, we return
ENOMEM to userspace.
mmap() now creates purgeable objects if passed the MAP_PURGEABLE option
together with MAP_ANONYMOUS. anon_create() memory is always purgeable.
