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#include "file_watcher.hpp"
// inotify is libc (NOT wlroots), so it does not go through wlr.hpp. Integrated
// into the kernel's wl_event_loop via wl_event_loop_add_fd — never blocks.
#include <sys/inotify.h>
#include <unistd.h>
#include <algorithm>
#include <filesystem>
namespace unbox::kernel {
FileWatcher::FileWatcher(wl_event_loop* loop, std::function<void(ExtensionId)> disable)
: loop_(loop), disable_(std::move(disable)) {}
FileWatcher::~FileWatcher() {
// Tear down before the loop/display dies: remove the event source, then
// close the fd (closing drops every inotify watch).
if (source_ != nullptr) {
wl_event_source_remove(source_);
source_ = nullptr;
}
if (fd_ >= 0) {
close(fd_);
fd_ = -1;
}
}
auto FileWatcher::dispatch(int /*fd*/, std::uint32_t /*mask*/, void* data) -> int {
static_cast<FileWatcher*>(data)->on_readable();
return 0;
}
bool FileWatcher::ensure_started() {
if (fd_ >= 0) {
return true;
}
if (loop_ == nullptr) {
return false;
}
fd_ = inotify_init1(IN_NONBLOCK | IN_CLOEXEC);
if (fd_ < 0) {
wlr_log(WLR_ERROR, "file-watcher: inotify_init1 failed; watching disabled");
return false;
}
source_ = wl_event_loop_add_fd(loop_, fd_, WL_EVENT_READABLE, dispatch, this);
if (source_ == nullptr) {
close(fd_);
fd_ = -1;
wlr_log(WLR_ERROR, "file-watcher: wl_event_loop_add_fd failed; watching disabled");
return false;
}
return true;
}
void FileWatcher::stop_if_idle() noexcept {
if (!entries_.empty()) {
return;
}
if (source_ != nullptr) {
wl_event_source_remove(source_);
source_ = nullptr;
}
if (fd_ >= 0) {
close(fd_); // drops all inotify watches
fd_ = -1;
}
wd_dirs_.clear();
}
void FileWatcher::arm_dir(const std::string& dir) {
if (fd_ < 0) {
return;
}
// inotify_add_watch on an already-watched path returns the SAME wd, so this
// is idempotent and auto re-arms after a watched file is replaced (we watch
// the directory, not the inode).
const int wd = inotify_add_watch(fd_, dir.c_str(),
IN_CLOSE_WRITE | IN_MOVED_TO | IN_CREATE);
if (wd >= 0) {
wd_dirs_[wd] = dir;
}
}
void FileWatcher::rearm_all_dirs() {
for (const auto& [token, e] : entries_) {
arm_dir(e.dir);
}
}
auto FileWatcher::add(const std::string& path, std::function<void()> on_change, ExtensionId who)
-> FileWatch {
if (!ensure_started()) {
return FileWatch{}; // no loop / inotify unavailable: inert handle
}
std::filesystem::path p(path);
std::string dir = p.parent_path().string();
if (dir.empty()) {
dir = "."; // a bare filename watches the cwd
}
std::string base = p.filename().string();
if (base.empty()) {
return FileWatch{};
}
const Token token = ++next_token_;
entries_.emplace(token, Entry{std::move(dir), std::move(base), std::move(on_change), who});
arm_dir(entries_.at(token).dir);
return FileWatch(this, token);
}
auto FileWatcher::add_dir(const std::string& dir, std::function<void()> on_change, ExtensionId who)
-> FileWatch {
if (!ensure_started()) {
return FileWatch{};
}
std::string d = dir.empty() ? std::string(".") : dir;
const Token token = ++next_token_;
// Empty basename => match ANY file change in `d`.
entries_.emplace(token, Entry{std::move(d), std::string{}, std::move(on_change), who});
arm_dir(entries_.at(token).dir);
return FileWatch(this, token);
}
void FileWatcher::remove_watch(Token token) noexcept {
auto it = entries_.find(token);
if (it == entries_.end()) {
return;
}
entries_.erase(it);
// Re-derive the inotify dir watches from the surviving entries: drop watches
// for directories no longer referenced. Cheapest correct approach — clear
// all wd watches and re-arm the dirs still in use. (Watch counts are tiny:
// unbox.toml + a handful of asset dirs.)
if (fd_ >= 0) {
for (const auto& [wd, dir] : wd_dirs_) {
inotify_rm_watch(fd_, wd);
}
wd_dirs_.clear();
rearm_all_dirs();
}
stop_if_idle();
}
void FileWatcher::on_readable() {
if (fd_ < 0) {
return;
}
// Drain ALL queued events (one readable notification may carry many; the fd
// is non-blocking). Collect the set of (dir, basename) pairs that changed,
// then fire each matching watch's callback AT MOST ONCE this drain
// (coalesced: one save = one callback even though it emits several events).
alignas(struct inotify_event) char buf[4096];
std::vector<std::pair<std::string, std::string>> changed; // (dir, name)
for (;;) {
const ssize_t n = read(fd_, buf, sizeof(buf));
if (n <= 0) {
break; // EAGAIN (drained) or closed
}
std::size_t off = 0;
while (off + sizeof(struct inotify_event) <= static_cast<std::size_t>(n)) {
auto* ev = reinterpret_cast<struct inotify_event*>(buf + off);
auto wd_it = wd_dirs_.find(ev->wd);
if (wd_it != wd_dirs_.end() && ev->len > 0) {
changed.emplace_back(wd_it->second, std::string(ev->name));
}
off += sizeof(struct inotify_event) + ev->len;
}
}
if (changed.empty()) {
return;
}
// Find the tokens whose (dir, basename) matched at least one event. Snapshot
// them so a callback that destroys its own (or another) watch mid-fire can't
// invalidate the iteration.
std::vector<Token> to_fire;
for (const auto& [token, e] : entries_) {
for (const auto& [dir, name] : changed) {
// A file-specific entry matches its basename; a directory entry
// (empty basename) matches ANY file change in its dir.
if (e.dir == dir && (e.basename.empty() || e.basename == name)) {
to_fire.push_back(token);
break;
}
}
}
for (const Token token : to_fire) {
auto it = entries_.find(token);
if (it == entries_.end()) {
continue; // removed by an earlier callback this drain
}
// Copy what we need before invoking: the callback may remove this watch.
std::function<void()> cb = it->second.on_change;
const ExtensionId who = it->second.who;
if (!cb) {
continue;
}
try {
cb();
} catch (...) {
// Same isolation boundary as a throwing hook/getter: disable the
// owning extension, never take down the loop/session.
if (disable_) {
disable_(who);
}
}
}
}
} // namespace unbox::kernel
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