transmission/libtransmission/watchdir-kqueue.cc

189 lines
4.9 KiB
C++
Raw Normal View History

// This file Copyright © 2015-2022 Mnemosyne LLC.
// It may be used under GPLv2 (SPDX: GPL-2.0-only), GPLv3 (SPDX: GPL-3.0-only),
// or any future license endorsed by Mnemosyne LLC.
// License text can be found in the licenses/ folder.
#include <cerrno> /* errno */
#include <string>
#include <string_view>
#include <unordered_set>
#include <fcntl.h> /* open() */
#include <unistd.h> /* close() */
#include <sys/types.h>
#include <sys/event.h>
#ifndef O_EVTONLY
#define O_EVTONLY O_RDONLY
#endif
#include <event2/event.h>
#include <fmt/core.h>
#define LIBTRANSMISSION_WATCHDIR_MODULE
#include "transmission.h"
#include "log.h"
#include "tr-assert.h"
#include "utils.h"
#include "watchdir.h"
#include "watchdir-common.h"
/***
****
***/
struct tr_watchdir_kqueue
{
tr_watchdir_backend base;
int kq;
int dirfd;
struct event* event;
std::unordered_set<std::string> dir_entries;
};
#define BACKEND_UPCAST(b) (reinterpret_cast<tr_watchdir_kqueue*>(b))
#define KQUEUE_WATCH_MASK (NOTE_WRITE | NOTE_EXTEND)
/***
****
***/
static void tr_watchdir_kqueue_on_event(evutil_socket_t /*fd*/, short /*type*/, void* context)
{
auto const handle = static_cast<tr_watchdir_t>(context);
auto* const backend = BACKEND_UPCAST(tr_watchdir_get_backend(handle));
struct kevent ke;
auto ts = timespec{};
if (kevent(backend->kq, nullptr, 0, &ke, 1, &ts) == -1)
{
auto const error_code = errno;
tr_logAddError(fmt::format(
_("Couldn't read event: {error} ({error_code})"),
fmt::arg("error", tr_strerror(error_code)),
fmt::arg("error_code", error_code)));
return;
}
/* Read directory with generic scan */
tr_watchdir_scan(handle, &backend->dir_entries);
}
static void tr_watchdir_kqueue_free(tr_watchdir_backend* backend_base)
{
tr_watchdir_kqueue* const backend = BACKEND_UPCAST(backend_base);
if (backend == nullptr)
{
return;
}
TR_ASSERT(backend->base.free_func == &tr_watchdir_kqueue_free);
if (backend->event != nullptr)
{
event_del(backend->event);
event_free(backend->event);
}
if (backend->kq != -1)
{
close(backend->kq);
}
if (backend->dirfd != -1)
{
close(backend->dirfd);
}
delete backend;
}
tr_watchdir_backend* tr_watchdir_kqueue_new(tr_watchdir_t handle)
{
char const* const path = tr_watchdir_get_path(handle);
struct kevent ke;
auto* backend = new tr_watchdir_kqueue{};
backend->base.free_func = &tr_watchdir_kqueue_free;
backend->dirfd = -1;
backend->kq = kqueue();
if (backend->kq == -1)
{
auto const error_code = errno;
tr_logAddError(fmt::format(
_("Couldn't watch '{path}': {error} ({error_code})"),
fmt::arg("error", tr_strerror(error_code)),
fmt::arg("error_code", error_code)));
goto fail;
}
/* Open fd for watching */
backend->dirfd = open(path, O_RDONLY | O_EVTONLY);
if (backend->dirfd == -1)
{
auto const error_code = errno;
tr_logAddError(fmt::format(
_("Couldn't watch '{path}': {error} ({error_code})"),
fmt::arg("path", path),
fmt::arg("error", tr_strerror(error_code)),
fmt::arg("error_code", error_code)));
goto fail;
}
/* Register kevent filter with kqueue descriptor */
EV_SET(&ke, backend->dirfd, EVFILT_VNODE, EV_ADD | EV_ENABLE | EV_CLEAR, KQUEUE_WATCH_MASK, 0, NULL);
if (kevent(backend->kq, &ke, 1, nullptr, 0, nullptr) == -1)
{
auto const error_code = errno;
tr_logAddError(fmt::format(
_("Couldn't watch '{path}': {error} ({error_code})"),
fmt::arg("path", path),
fmt::arg("error", tr_strerror(error_code)),
fmt::arg("error_code", error_code)));
goto fail;
}
/* Create libevent task for event descriptor */
if ((backend->event = event_new(
tr_watchdir_get_event_base(handle),
backend->kq,
EV_READ | EV_ET | EV_PERSIST,
&tr_watchdir_kqueue_on_event,
handle)) == nullptr)
{
auto const error_code = errno;
tr_logAddError(fmt::format(
_("Couldn't create event: {error} ({error_code})"),
fmt::arg("error", tr_strerror(error_code)),
fmt::arg("error_code", error_code)));
goto fail;
}
if (event_add(backend->event, nullptr) == -1)
{
auto const error_code = errno;
tr_logAddError(fmt::format(
_("Couldn't add event: {error} ({error_code})"),
fmt::arg("error", tr_strerror(error_code)),
fmt::arg("error_code", error_code)));
goto fail;
}
/* Trigger one event for the initial scan */
event_active(backend->event, EV_READ, 0);
return BACKEND_DOWNCAST(backend);
fail:
tr_watchdir_kqueue_free(BACKEND_DOWNCAST(backend));
return nullptr;
}