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/*
* 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/Memory.h>
#include <Kernel/FileSystem/Inode.h>
#include <Kernel/FileSystem/InodeWatcher.h>
#include <Kernel/Process.h>
namespace Kernel {
ErrorOr<NonnullRefPtr<InodeWatcher>> InodeWatcher::try_create()
{
return adopt_nonnull_ref_or_enomem(new (nothrow) InodeWatcher);
}
InodeWatcher::~InodeWatcher()
{
(void)close();
}
bool InodeWatcher::can_read(const OpenFileDescription&, size_t) const
{
MutexLocker locker(m_lock);
return !m_queue.is_empty();
}
ErrorOr<size_t> InodeWatcher::read(OpenFileDescription&, u64, UserOrKernelBuffer& buffer, size_t buffer_size)
{
MutexLocker locker(m_lock);
if (m_queue.is_empty())
// can_read will catch the blocking case.
return EAGAIN;
auto event = m_queue.dequeue();
size_t name_length = event.path.length() + 1;
size_t bytes_to_write = sizeof(InodeWatcherEvent);
if (!event.path.is_null())
bytes_to_write += name_length;
if (buffer_size < bytes_to_write)
return EINVAL;
auto result = buffer.write_buffered<MAXIMUM_EVENT_SIZE>(bytes_to_write, [&](Bytes bytes) {
size_t offset = 0;
memcpy(bytes.offset(offset), &event.wd, sizeof(InodeWatcherEvent::watch_descriptor));
offset += sizeof(InodeWatcherEvent::watch_descriptor);
memcpy(bytes.offset(offset), &event.type, sizeof(InodeWatcherEvent::type));
offset += sizeof(InodeWatcherEvent::type);
if (!event.path.is_null()) {
memcpy(bytes.offset(offset), &name_length, sizeof(InodeWatcherEvent::name_length));
offset += sizeof(InodeWatcherEvent::name_length);
memcpy(bytes.offset(offset), event.path.characters(), name_length);
} else {
memset(bytes.offset(offset), 0, sizeof(InodeWatcherEvent::name_length));
}
return bytes.size();
});
evaluate_block_conditions();
return result;
}
ErrorOr<void> InodeWatcher::close()
{
MutexLocker locker(m_lock);
for (auto& entry : m_wd_to_watches) {
auto& inode = const_cast<Inode&>(entry.value->inode);
inode.unregister_watcher({}, *this);
}
m_wd_to_watches.clear();
m_inode_to_watches.clear();
return {};
}
ErrorOr<NonnullOwnPtr<KString>> InodeWatcher::pseudo_path(const OpenFileDescription&) const
{
return KString::formatted("InodeWatcher:({})", m_wd_to_watches.size());
}
void InodeWatcher::notify_inode_event(Badge<Inode>, InodeIdentifier inode_id, InodeWatcherEvent::Type event_type, StringView name)
{
MutexLocker locker(m_lock);
auto it = m_inode_to_watches.find(inode_id);
if (it == m_inode_to_watches.end())
return;
auto& watcher = *it->value;
if (!(watcher.event_mask & static_cast<unsigned>(event_type)))
return;
m_queue.enqueue({ watcher.wd, event_type, name });
evaluate_block_conditions();
}
ErrorOr<int> InodeWatcher::register_inode(Inode& inode, unsigned event_mask)
{
MutexLocker locker(m_lock);
if (m_inode_to_watches.find(inode.identifier()) != m_inode_to_watches.end())
return EEXIST;
int wd;
do {
wd = m_wd_counter.value();
m_wd_counter++;
if (m_wd_counter.has_overflow())
m_wd_counter = 1;
} while (m_wd_to_watches.find(wd) != m_wd_to_watches.end());
auto description = TRY(WatchDescription::create(wd, inode, event_mask));
m_inode_to_watches.set(inode.identifier(), description.ptr());
m_wd_to_watches.set(wd, move(description));
inode.register_watcher({}, *this);
return wd;
}
ErrorOr<void> InodeWatcher::unregister_by_wd(int wd)
{
MutexLocker locker(m_lock);
auto it = m_wd_to_watches.find(wd);
if (it == m_wd_to_watches.end())
return ENOENT;
auto& inode = it->value->inode;
inode.unregister_watcher({}, *this);
m_inode_to_watches.remove(inode.identifier());
m_wd_to_watches.remove(it);
return {};
}
void InodeWatcher::unregister_by_inode(Badge<Inode>, InodeIdentifier identifier)
{
MutexLocker locker(m_lock);
auto it = m_inode_to_watches.find(identifier);
if (it == m_inode_to_watches.end())
return;
// NOTE: no need to call unregister_watcher here, the Inode calls us.
m_inode_to_watches.remove(identifier);
m_wd_to_watches.remove(it->value->wd);
}
}
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