This function is an extended version of `chmod(2)` that lets one control
whether to dereference symlinks, and specify a file descriptor to a
directory that will be used as the base for relative paths.
Previously we were uncaching inodes from TmpFSInode::one_ref_left().
This was not safe, since one_ref_left() was effectively being called
on a raw pointer after decrementing the local ref count and observing
it become 1. There was a race here where someone else could trigger
the destructor by unreffing to 0 before one_ref_left() got called,
causing us to call one_ref_left() on a deleted inode.
We fix this by using the new remove_from_secondary_lists() mechanism
in ListedRefCounted and synchronizing all access to the TmpFS inode
map with the main Inode::all_instances() lock.
There's probably a nicer way to solve this.
When writing into a block via an O_DIRECT open file description, we
would first flush every dirty block *except* the one we're about to
write into.
The purpose of flushing is to ensure coherency when mixing direct and
indirect accesses to the same file. This patch fixes the issue by only
flushing the affected block.
Our behavior was totally backwards and could end up doing a lot of
unnecessary work while avoiding the work that actually mattered.
Since this function always returns a CacheEntry& (after potentially
evicting someone else to make room), let's call it "ensure" instead of
"get" to match how we usually use these terms.
Previously we were using this vector to store the inodes as we iterated.
However, we don't need to store all of them, just the previous inode, as
we know it will be safe to remove it once we've iterated past that
element.
This modifies sys$chown to allow specifying whether or not to follow
symlinks and in which directory.
This was then used to implement lchown and fchownat in LibC and LibCore.
This is required for SlavePTY's custom unref handler to function
correctly, as otherwise a SlavePTY held in a File RefPtr would call
the base's (RefCounted<>) unref method instead of SlavePTY's version.
Since RefCounted automatically calls a method named `will_be_destoyed`
on classes that have one, so there's no need to have a custom
implementation of unref in File.
This will allow File and it's descendants to use RefCounted instead of
having a custom implementation of unref. (Since RefCounted calls
will_be_destroyed automatically)
This commit also removes an erroneous call to `before_removing` in
AHCIPort, this is a duplicate call, as the only reference to the device
is immediately dropped following the call, which in turns calls
`before_removing` via File::unref.
Custody's unref is one of many implementions of ListedRefCounted's
behaviour in the Kernel, which results in avoidable bugs caused by
the fragmentation of the implementations. This commit starts the work
of replacing all custom implementations with ListedRefCounted by
porting Custody to it.
This was a premature optimization from the early days of SerenityOS.
The eternal heap was a simple bump pointer allocator over a static
byte array. My original idea was to avoid heap fragmentation and improve
data locality, but both ideas were rooted in cargo culting, not data.
We would reserve 4 MiB at boot and only ended up using ~256 KiB, wasting
the rest.
This patch replaces all kmalloc_eternal() usage by regular kmalloc().
We were doing this dance in notify_watchers():
set_metadata_dirty(true);
set_metadata_dirty(false);
This was done in order to force out inode watcher events immediately.
Unfortunately, this was racy, as if SyncTask got scheduled at the wrong
moment, it would try to flush metadata for a clean inode. This then got
trapped by the VERIFY() statement in Inode::sync_all():
VERIFY(inode.is_metadata_dirty());
This patch fixes the issue by replacing notify_watchers() with lazy
metadata notifications like all other filesystems.
If the data passed to sys$write() is backed by a not-yet-paged-in inode
mapping, we could end up in a situation where we get a page fault when
trying to copy data from userspace.
If that page fault handler tried reading from an inode that someone else
had locked while waiting for the disk cache lock, we'd deadlock.
This patch fixes the issue by copying the userspace data into a local
buffer before acquiring the disk cache lock. This is not ideal since it
incurs an extra copy, and I'm sure we can think of a better solution
eventually.
This was a frequent cause of startup deadlocks on x86_64 for me. :^)
As pointed out by BertalanD on Discord, POSIX specifies that
_SC_SYMLOOP_MAX (implemented in the following commit) always needs to be
equal or more than _POSIX_SYMLOOP_MAX (8, defined in
LibC/bits/posix1_lim.h), hence I've increased it to that value to
comply with the standard.
The move to header is required for the following commit - to make this
constant accessible outside of the VFS class, namely in sysconf.
This fixes at least half of our LibC includes in the kernel. The source
of truth for errno codes and their description strings now lives in
Kernel/API/POSIX/errno.h as an enumeration, which LibC includes.
Instead, allocate before constructing the object and pass NonnullOwnPtr
of KString to the object if needed. Some classes can determine their
names as they have a known attribute to look for or have a static name.
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.
This option is already enabled when building Lagom, so let's enable it
for the main build too. We will no longer be surprised by Lagom Clang
CI builds failing while everything compiles locally.
Furthermore, the stronger `-Wsuggest-override` warning is enabled in
this commit, which enforces the use of the `override` keyword in all
classes, not just those which already have some methods marked as
`override`. This works with both GCC and Clang.
