transmission/libtransmission/watchdir-kqueue.cc

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/*
* This file Copyright (C) 2015-2016 Mnemosyne LLC
*
* It may be used under the GNU GPL versions 2 or 3
* or any future license endorsed by Mnemosyne LLC.
*
*/
#include <errno.h>
#include <string.h> /* strcmp() */
#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>
#define LIBTRANSMISSION_WATCHDIR_MODULE
#include "transmission.h"
#include "log.h"
#include "ptrarray.h"
#include "tr-assert.h"
#include "utils.h"
#include "watchdir.h"
#include "watchdir-common.h"
/***
****
***/
#define log_error(...) \
(!tr_logLevelIsActive(TR_LOG_ERROR) ? (void)0 : \
tr_logAddMessage(__FILE__, __LINE__, TR_LOG_ERROR, "watchdir:kqueue", __VA_ARGS__))
/***
****
***/
typedef struct tr_watchdir_kqueue
{
tr_watchdir_backend base;
int kq;
int dirfd;
struct event* event;
tr_ptrArray dir_entries;
} tr_watchdir_kqueue;
#define BACKEND_UPCAST(b) ((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)
{
TR_UNUSED(fd);
TR_UNUSED(type);
auto const handle = static_cast<tr_watchdir_t>(context);
tr_watchdir_kqueue* const backend = BACKEND_UPCAST(tr_watchdir_get_backend(handle));
struct kevent ke;
auto ts = timespec{};
if (kevent(backend->kq, NULL, 0, &ke, 1, &ts) == -1)
{
log_error("Failed to fetch kevent: %s", tr_strerror(errno));
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 == NULL)
{
return;
}
TR_ASSERT(backend->base.free_func == &tr_watchdir_kqueue_free);
if (backend->event != NULL)
{
event_del(backend->event);
event_free(backend->event);
}
if (backend->kq != -1)
{
close(backend->kq);
}
if (backend->dirfd != -1)
{
close(backend->dirfd);
}
tr_ptrArrayDestruct(&backend->dir_entries, &tr_free);
tr_free(backend);
}
tr_watchdir_backend* tr_watchdir_kqueue_new(tr_watchdir_t handle)
{
char const* const path = tr_watchdir_get_path(handle);
struct kevent ke;
tr_watchdir_kqueue* backend;
backend = tr_new0(tr_watchdir_kqueue, 1);
backend->base.free_func = &tr_watchdir_kqueue_free;
backend->kq = -1;
backend->dirfd = -1;
if ((backend->kq = kqueue()) == -1)
{
log_error("Failed to start kqueue");
goto fail;
}
/* Open fd for watching */
if ((backend->dirfd = open(path, O_RDONLY | O_EVTONLY)) == -1)
{
log_error("Failed to passively watch directory \"%s\": %s", path, tr_strerror(errno));
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, NULL, 0, NULL) == -1)
{
log_error("Failed to set directory event filter with fd %d: %s", backend->kq, tr_strerror(errno));
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)) == NULL)
{
log_error("Failed to create event: %s", tr_strerror(errno));
goto fail;
}
if (event_add(backend->event, NULL) == -1)
{
log_error("Failed to add event: %s", tr_strerror(errno));
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 NULL;
}