hyprland/src/config/ConfigWatcher.cpp

#include "ConfigWatcher.hpp"
#include <sys/inotify.h>
#include "../debug/Log.hpp"
#include <ranges>
#include <fcntl.h>
#include <unistd.h>

CConfigWatcher::CConfigWatcher() : m_inotifyFd(inotify_init()) {
    if (m_inotifyFd < 0) {
        Debug::log(ERR, "CConfigWatcher couldn't open an inotify node. Config will not be automatically reloaded");
        return;
    }

    const int FLAGS = fcntl(m_inotifyFd, F_GETFL, 0);
    if (fcntl(m_inotifyFd, F_SETFL, FLAGS | O_NONBLOCK) < 0) {
        Debug::log(ERR, "CConfigWatcher couldn't non-block inotify node. Config will not be automatically reloaded");
        close(m_inotifyFd);
        m_inotifyFd = -1;
        return;
    }
}

CConfigWatcher::~CConfigWatcher() {
    if (m_inotifyFd >= 0)
        close(m_inotifyFd);
}

int CConfigWatcher::getInotifyFD() {
    return m_inotifyFd;
}

void CConfigWatcher::setWatchList(const std::vector<std::string>& paths) {

    // we clear all watches first, because whichever fired is now invalid
    // or that is at least what it seems to be.
    // since we don't know which fired,
    // plus it doesn't matter that much, these ops are done rarely and fast anyways.

    // cleanup old paths
    for (auto& watch : m_watches) {
        inotify_rm_watch(m_inotifyFd, watch.wd);
    }

    m_watches.clear();

    // add new paths
    for (const auto& path : paths) {
        m_watches.emplace_back(SInotifyWatch{
            .wd   = inotify_add_watch(m_inotifyFd, path.c_str(), IN_MODIFY),
            .file = path,
        });
    }
}

void CConfigWatcher::setOnChange(const std::function<void(const SConfigWatchEvent&)>& fn) {
    m_watchCallback = fn;
}

void CConfigWatcher::onInotifyEvent() {
    inotify_event ev;
    while (read(m_inotifyFd, &ev, sizeof(ev)) > 0) {
        const auto WD = std::ranges::find_if(m_watches.begin(), m_watches.end(), [wd = ev.wd](const auto& e) { return e.wd == wd; });

        if (WD == m_watches.end()) {
            Debug::log(ERR, "CConfigWatcher: got an event for wd {} which we don't have?!", ev.wd);
            return;
        }

        m_watchCallback(SConfigWatchEvent{
            .file = WD->file,
        });
    }
}