ladybird/Kernel/FileSystem/Inode.cpp
2021-08-08 00:03:45 +02:00

403 lines
11 KiB
C++

/*
* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
* Copyright (c) 2021, sin-ack <sin-ack@protonmail.com>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <AK/NonnullRefPtrVector.h>
#include <AK/Singleton.h>
#include <AK/StringBuilder.h>
#include <AK/StringView.h>
#include <Kernel/API/InodeWatcherEvent.h>
#include <Kernel/FileSystem/Custody.h>
#include <Kernel/FileSystem/FileDescription.h>
#include <Kernel/FileSystem/Inode.h>
#include <Kernel/FileSystem/InodeWatcher.h>
#include <Kernel/FileSystem/VirtualFileSystem.h>
#include <Kernel/KBufferBuilder.h>
#include <Kernel/Memory/SharedInodeVMObject.h>
#include <Kernel/Net/LocalSocket.h>
#include <Kernel/Process.h>
namespace Kernel {
static SpinLock s_all_inodes_lock;
static Singleton<Inode::List> s_list;
static Inode::List& all_with_lock()
{
VERIFY(s_all_inodes_lock.is_locked());
return *s_list;
}
void Inode::sync()
{
NonnullRefPtrVector<Inode, 32> inodes;
{
ScopedSpinLock all_inodes_lock(s_all_inodes_lock);
for (auto& inode : all_with_lock()) {
if (inode.is_metadata_dirty())
inodes.append(inode);
}
}
for (auto& inode : inodes) {
VERIFY(inode.is_metadata_dirty());
inode.flush_metadata();
}
}
KResultOr<NonnullOwnPtr<KBuffer>> Inode::read_entire(FileDescription* description) const
{
KBufferBuilder builder;
size_t nread;
u8 buffer[4096];
off_t offset = 0;
for (;;) {
auto buf = UserOrKernelBuffer::for_kernel_buffer(buffer);
auto result = read_bytes(offset, sizeof(buffer), buf, description);
if (result.is_error())
return result.error();
nread = result.value();
VERIFY(nread <= sizeof(buffer));
if (nread == 0)
break;
builder.append((const char*)buffer, nread);
offset += nread;
if (nread < sizeof(buffer))
break;
}
auto entire_file = builder.build();
if (!entire_file)
return ENOMEM;
return entire_file.release_nonnull();
}
KResultOr<NonnullRefPtr<Custody>> Inode::resolve_as_link(Custody& base, RefPtr<Custody>* out_parent, int options, int symlink_recursion_level) const
{
// The default implementation simply treats the stored
// contents as a path and resolves that. That is, it
// behaves exactly how you would expect a symlink to work.
auto contents_or = read_entire();
if (contents_or.is_error())
return contents_or.error();
auto& contents = contents_or.value();
auto path = StringView(contents->data(), contents->size());
return VirtualFileSystem::the().resolve_path(path, base, out_parent, options, symlink_recursion_level);
}
Inode::Inode(FileSystem& fs, InodeIndex index)
: m_file_system(fs)
, m_index(index)
{
ScopedSpinLock all_inodes_lock(s_all_inodes_lock);
all_with_lock().append(*this);
}
Inode::~Inode()
{
ScopedSpinLock all_inodes_lock(s_all_inodes_lock);
all_with_lock().remove(*this);
for (auto& watcher : m_watchers) {
watcher->unregister_by_inode({}, identifier());
}
}
void Inode::will_be_destroyed()
{
MutexLocker locker(m_inode_lock);
if (m_metadata_dirty)
flush_metadata();
}
KResult Inode::set_atime(time_t)
{
return ENOTIMPL;
}
KResult Inode::set_ctime(time_t)
{
return ENOTIMPL;
}
KResult Inode::set_mtime(time_t)
{
return ENOTIMPL;
}
KResult Inode::increment_link_count()
{
return ENOTIMPL;
}
KResult Inode::decrement_link_count()
{
return ENOTIMPL;
}
void Inode::set_shared_vmobject(Memory::SharedInodeVMObject& vmobject)
{
MutexLocker locker(m_inode_lock);
m_shared_vmobject = vmobject;
}
bool Inode::bind_socket(LocalSocket& socket)
{
MutexLocker locker(m_inode_lock);
if (m_socket)
return false;
m_socket = socket;
return true;
}
bool Inode::unbind_socket()
{
MutexLocker locker(m_inode_lock);
if (!m_socket)
return false;
m_socket = nullptr;
return true;
}
void Inode::register_watcher(Badge<InodeWatcher>, InodeWatcher& watcher)
{
MutexLocker locker(m_inode_lock);
VERIFY(!m_watchers.contains(&watcher));
m_watchers.set(&watcher);
}
void Inode::unregister_watcher(Badge<InodeWatcher>, InodeWatcher& watcher)
{
MutexLocker locker(m_inode_lock);
VERIFY(m_watchers.contains(&watcher));
m_watchers.remove(&watcher);
}
NonnullRefPtr<FIFO> Inode::fifo()
{
MutexLocker locker(m_inode_lock);
VERIFY(metadata().is_fifo());
// FIXME: Release m_fifo when it is closed by all readers and writers
if (!m_fifo) {
m_fifo = FIFO::try_create(metadata().uid);
// FIXME: We need to be able to observe OOM here.
VERIFY(!m_fifo.is_null());
}
VERIFY(m_fifo);
return *m_fifo;
}
void Inode::set_metadata_dirty(bool metadata_dirty)
{
MutexLocker locker(m_inode_lock);
if (metadata_dirty) {
// Sanity check.
VERIFY(!fs().is_readonly());
}
if (m_metadata_dirty == metadata_dirty)
return;
m_metadata_dirty = metadata_dirty;
if (m_metadata_dirty) {
// FIXME: Maybe we should hook into modification events somewhere else, I'm not sure where.
// We don't always end up on this particular code path, for instance when writing to an ext2fs file.
for (auto& watcher : m_watchers) {
watcher->notify_inode_event({}, identifier(), InodeWatcherEvent::Type::MetadataModified);
}
}
}
void Inode::did_add_child(InodeIdentifier const&, String const& name)
{
MutexLocker locker(m_inode_lock);
for (auto& watcher : m_watchers) {
watcher->notify_inode_event({}, identifier(), InodeWatcherEvent::Type::ChildCreated, name);
}
}
void Inode::did_remove_child(InodeIdentifier const&, String const& name)
{
MutexLocker locker(m_inode_lock);
if (name == "." || name == "..") {
// These are just aliases and are not interesting to userspace.
return;
}
for (auto& watcher : m_watchers) {
watcher->notify_inode_event({}, identifier(), InodeWatcherEvent::Type::ChildDeleted, name);
}
}
void Inode::did_modify_contents()
{
MutexLocker locker(m_inode_lock);
for (auto& watcher : m_watchers) {
watcher->notify_inode_event({}, identifier(), InodeWatcherEvent::Type::ContentModified);
}
}
void Inode::did_delete_self()
{
MutexLocker locker(m_inode_lock);
for (auto& watcher : m_watchers) {
watcher->notify_inode_event({}, identifier(), InodeWatcherEvent::Type::Deleted);
}
}
KResult Inode::prepare_to_write_data()
{
// FIXME: It's a poor design that filesystems are expected to call this before writing out data.
// We should funnel everything through an interface at the VirtualFileSystem layer so this can happen from a single place.
MutexLocker locker(m_inode_lock);
if (fs().is_readonly())
return EROFS;
auto metadata = this->metadata();
if (metadata.is_setuid() || metadata.is_setgid()) {
dbgln("Inode::prepare_to_write_data(): Stripping SUID/SGID bits from {}", identifier());
return chmod(metadata.mode & ~(04000 | 02000));
}
return KSuccess;
}
RefPtr<Memory::SharedInodeVMObject> Inode::shared_vmobject() const
{
MutexLocker locker(m_inode_lock);
return m_shared_vmobject.strong_ref();
}
template<typename T>
static inline bool range_overlap(T start1, T len1, T start2, T len2)
{
return ((start1 < start2 + len2) || len2 == 0) && ((start2 < start1 + len1) || len1 == 0);
}
static inline KResult normalize_flock(FileDescription const& description, flock& lock)
{
off_t start;
switch (lock.l_whence) {
case SEEK_SET:
start = lock.l_start;
break;
case SEEK_CUR:
start = description.offset() + lock.l_start;
break;
case SEEK_END:
// FIXME: Implement SEEK_END and negative lengths.
return ENOTSUP;
default:
return EINVAL;
}
lock = { lock.l_type, SEEK_SET, start, lock.l_len, 0 };
return KSuccess;
}
KResult Inode::can_apply_flock(FileDescription const& description, flock const& new_lock) const
{
VERIFY(new_lock.l_whence == SEEK_SET);
MutexLocker locker(m_inode_lock, Mutex::Mode::Shared);
if (new_lock.l_type == F_UNLCK) {
for (auto& lock : m_flocks) {
if (&description == lock.owner && lock.start == new_lock.l_start && lock.len == new_lock.l_len)
return KSuccess;
}
return EINVAL;
}
for (auto& lock : m_flocks) {
if (!range_overlap(lock.start, lock.len, new_lock.l_start, new_lock.l_len))
continue;
if (new_lock.l_type == F_RDLCK && lock.type == F_WRLCK)
return EAGAIN;
if (new_lock.l_type == F_WRLCK)
return EAGAIN;
}
return KSuccess;
}
KResult Inode::apply_flock(Process const& process, FileDescription const& description, Userspace<flock const*> input_lock)
{
flock new_lock;
if (!copy_from_user(&new_lock, input_lock))
return EFAULT;
auto rc = normalize_flock(description, new_lock);
if (rc.is_error())
return rc;
MutexLocker locker(m_inode_lock);
rc = can_apply_flock(description, new_lock);
if (rc.is_error())
return rc;
if (new_lock.l_type == F_UNLCK) {
for (size_t i = 0; i < m_flocks.size(); ++i) {
if (&description == m_flocks[i].owner && m_flocks[i].start == new_lock.l_start && m_flocks[i].len == new_lock.l_len) {
m_flocks.remove(i);
return KSuccess;
}
}
return EINVAL;
}
m_flocks.append(Flock { new_lock.l_type, new_lock.l_start, new_lock.l_len, &description, process.pid().value() });
return KSuccess;
}
KResult Inode::get_flock(FileDescription const& description, Userspace<flock*> reference_lock) const
{
flock lookup;
if (!copy_from_user(&lookup, reference_lock))
return EFAULT;
auto rc = normalize_flock(description, lookup);
if (rc.is_error())
return rc;
MutexLocker locker(m_inode_lock, Mutex::Mode::Shared);
for (auto& lock : m_flocks) {
if (!range_overlap(lock.start, lock.len, lookup.l_start, lookup.l_len))
continue;
if ((lookup.l_type == F_RDLCK && lock.type == F_WRLCK) || lookup.l_type == F_WRLCK) {
lookup = { lock.type, SEEK_SET, lock.start, lock.len, lock.pid };
if (!copy_to_user(reference_lock, &lookup))
return EFAULT;
return KSuccess;
}
}
lookup.l_type = F_UNLCK;
if (!copy_to_user(reference_lock, &lookup))
return EFAULT;
return KSuccess;
}
void Inode::remove_flocks_for_description(FileDescription const& description)
{
MutexLocker locker(m_inode_lock);
for (size_t i = 0; i < m_flocks.size(); ++i) {
if (&description == m_flocks[i].owner)
m_flocks.remove(i--);
}
}
}