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InodeWatcher.cpp
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InodeWatcher.cpp
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/*
* Copyright (c) 2018-2020, Andreas Kling <[email protected]>
* Copyright (c) 2021, sin-ack <[email protected]>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <Kernel/FileSystem/Inode.h>
#include <Kernel/FileSystem/InodeWatcher.h>
#include <Kernel/Tasks/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(OpenFileDescription const&, u64) const
{
return m_queue.with([](auto& queue) { return !queue.is_empty(); });
}
ErrorOr<size_t> InodeWatcher::read(OpenFileDescription&, u64, UserOrKernelBuffer& buffer, size_t buffer_size)
{
auto event = TRY(m_queue.with([](auto& queue) -> ErrorOr<Event> {
if (queue.is_empty()) {
// can_read will catch the blocking case.
return EAGAIN;
}
return queue.dequeue();
}));
size_t bytes_to_write = sizeof(InodeWatcherEvent);
if (event.path)
bytes_to_write += event.path->length() + 1;
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) {
size_t name_length = event.path->length() + 1;
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()
{
m_watch_maps.with([this](auto& watch_maps) {
for (auto& entry : watch_maps.wd_to_watches) {
auto& inode = const_cast<Inode&>(entry.value->inode);
inode.unregister_watcher({}, *this);
}
watch_maps.inode_to_watches.clear();
watch_maps.wd_to_watches.clear();
});
return {};
}
ErrorOr<NonnullOwnPtr<KString>> InodeWatcher::pseudo_path(OpenFileDescription const&) const
{
return m_watch_maps.with([](auto& watch_maps) -> ErrorOr<NonnullOwnPtr<KString>> {
return KString::formatted("InodeWatcher:({})", watch_maps.wd_to_watches.size());
});
}
void InodeWatcher::notify_inode_event(Badge<Inode>, InodeIdentifier inode_id, InodeWatcherEvent::Type event_type, StringView name)
{
m_watch_maps.with([this, inode_id, event_type, name](auto& watch_maps) {
auto it = watch_maps.inode_to_watches.find(inode_id);
if (it == watch_maps.inode_to_watches.end())
return;
auto& watcher = *it->value;
if (!(watcher.event_mask & static_cast<unsigned>(event_type)))
return;
m_queue.with([watcher, event_type, name](auto& queue) {
OwnPtr<KString> path;
if (!name.is_null())
path = KString::try_create(name).release_value_but_fixme_should_propagate_errors();
queue.enqueue({ watcher.wd, event_type, move(path) });
});
});
evaluate_block_conditions();
}
ErrorOr<int> InodeWatcher::register_inode(Inode& inode, unsigned event_mask)
{
return m_watch_maps.with([this, &inode, event_mask](auto& watch_maps) -> ErrorOr<int> {
if (watch_maps.inode_to_watches.find(inode.identifier()) != watch_maps.inode_to_watches.end())
return EEXIST;
int wd = -1;
do {
wd = m_wd_counter.value();
m_wd_counter++;
if (m_wd_counter.has_overflow())
m_wd_counter = 1;
} while (watch_maps.wd_to_watches.find(wd) != watch_maps.wd_to_watches.end());
auto description = TRY(WatchDescription::create(wd, inode, event_mask));
TRY(watch_maps.inode_to_watches.try_set(inode.identifier(), description.ptr()));
auto set_result = watch_maps.wd_to_watches.try_set(wd, move(description));
if (set_result.is_error()) {
watch_maps.inode_to_watches.remove(inode.identifier());
return set_result.release_error();
}
auto register_result = inode.register_watcher({}, *this);
if (register_result.is_error()) {
watch_maps.inode_to_watches.remove(inode.identifier());
watch_maps.wd_to_watches.remove(wd);
return register_result.release_error();
}
return wd;
});
}
ErrorOr<void> InodeWatcher::unregister_by_wd(int wd)
{
TRY(m_watch_maps.with([this, wd](auto& watch_maps) -> ErrorOr<void> {
auto it = watch_maps.wd_to_watches.find(wd);
if (it == watch_maps.wd_to_watches.end())
return ENOENT;
auto& inode = it->value->inode;
inode.unregister_watcher({}, *this);
watch_maps.inode_to_watches.remove(inode.identifier());
watch_maps.wd_to_watches.remove(it);
return {};
}));
return {};
}
void InodeWatcher::unregister_by_inode(Badge<Inode>, InodeIdentifier identifier)
{
m_watch_maps.with([identifier](auto& watch_maps) {
auto it = watch_maps.inode_to_watches.find(identifier);
if (it == watch_maps.inode_to_watches.end())
return;
// NOTE: no need to call unregister_watcher here, the Inode calls us.
watch_maps.inode_to_watches.remove(identifier);
watch_maps.wd_to_watches.remove(it->value->wd);
});
}
}