mirror of
https://github.com/obsproject/obs-studio.git
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8b370c4218
Parentheses are needed due to operator precedence (although the previous
code happened to work because POLLIN has the value 1).
Fixes: 91f986ec99
("linux-v4l2: Check udev fd events")
214 lines
4.6 KiB
C
214 lines
4.6 KiB
C
/*
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Copyright (C) 2014 by Leonhard Oelke <leonhard@in-verted.de>
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This program is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 2 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include <sys/eventfd.h>
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#include <poll.h>
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#include <unistd.h>
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#include <libudev.h>
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#include <util/threading.h>
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#include <util/darray.h>
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#include <obs.h>
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#include "v4l2-udev.h"
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/** udev action enum */
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enum udev_action {
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UDEV_ACTION_ADDED,
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UDEV_ACTION_REMOVED,
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UDEV_ACTION_UNKNOWN
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};
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static const char *udev_signals[] = {"void device_added(string device)",
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"void device_removed(string device)",
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NULL};
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/* global data */
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static uint_fast32_t udev_refs = 0;
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static pthread_mutex_t udev_mutex = PTHREAD_MUTEX_INITIALIZER;
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static pthread_t udev_thread;
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static os_event_t *udev_event;
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static int udev_event_fd;
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static signal_handler_t *udev_signalhandler = NULL;
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/**
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* udev gives us the device action as string, so we convert it here ...
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*
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* @param action the udev action as string
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* @return the udev action as enum value
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*/
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static enum udev_action udev_action_to_enum(const char *action)
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{
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if (!action)
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return UDEV_ACTION_UNKNOWN;
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if (!strncmp("add", action, 3))
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return UDEV_ACTION_ADDED;
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if (!strncmp("remove", action, 6))
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return UDEV_ACTION_REMOVED;
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return UDEV_ACTION_UNKNOWN;
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}
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/**
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* Call all registered callbacks with the event
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*
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* @param dev udev device that had an event occuring
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*/
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static inline void udev_signal_event(struct udev_device *dev)
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{
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const char *node;
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enum udev_action action;
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struct calldata data;
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pthread_mutex_lock(&udev_mutex);
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node = udev_device_get_devnode(dev);
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action = udev_action_to_enum(udev_device_get_action(dev));
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calldata_init(&data);
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calldata_set_string(&data, "device", node);
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switch (action) {
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case UDEV_ACTION_ADDED:
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signal_handler_signal(udev_signalhandler, "device_added",
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&data);
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break;
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case UDEV_ACTION_REMOVED:
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signal_handler_signal(udev_signalhandler, "device_removed",
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&data);
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break;
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default:
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break;
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}
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calldata_free(&data);
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pthread_mutex_unlock(&udev_mutex);
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}
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/**
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* Event listener thread
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*/
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static void *udev_event_thread(void *vptr)
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{
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UNUSED_PARAMETER(vptr);
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int fd;
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struct udev *udev;
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struct udev_monitor *mon;
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struct udev_device *dev;
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/* set up udev monitoring */
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os_set_thread_name("v4l2: udev");
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udev = udev_new();
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mon = udev_monitor_new_from_netlink(udev, "udev");
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udev_monitor_filter_add_match_subsystem_devtype(mon, "video4linux",
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NULL);
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if (udev_monitor_enable_receiving(mon) < 0)
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return NULL;
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/* set up fds */
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fd = udev_monitor_get_fd(mon);
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while (os_event_try(udev_event) == EAGAIN) {
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struct pollfd fds[2];
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fds[0].fd = fd;
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fds[0].events = POLLIN;
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fds[0].revents = 0;
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fds[1].fd = udev_event_fd;
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fds[1].events = POLLIN;
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if (poll(fds, 2, 1000) <= 0)
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continue;
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if (!(fds[0].revents & POLLIN))
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continue;
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dev = udev_monitor_receive_device(mon);
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if (!dev)
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continue;
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udev_signal_event(dev);
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udev_device_unref(dev);
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}
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udev_monitor_unref(mon);
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udev_unref(udev);
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return NULL;
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}
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void v4l2_init_udev(void)
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{
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pthread_mutex_lock(&udev_mutex);
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/* set up udev */
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if (udev_refs == 0) {
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if (os_event_init(&udev_event, OS_EVENT_TYPE_MANUAL) != 0)
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goto fail;
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if ((udev_event_fd = eventfd(0, EFD_CLOEXEC)) < 0)
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goto fail;
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if (pthread_create(&udev_thread, NULL, udev_event_thread,
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NULL) != 0) {
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close(udev_event_fd);
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goto fail;
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}
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udev_signalhandler = signal_handler_create();
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if (!udev_signalhandler) {
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close(udev_event_fd);
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goto fail;
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}
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signal_handler_add_array(udev_signalhandler, udev_signals);
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}
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udev_refs++;
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fail:
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pthread_mutex_unlock(&udev_mutex);
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}
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void v4l2_unref_udev(void)
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{
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pthread_mutex_lock(&udev_mutex);
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/* unref udev monitor */
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if (udev_refs && --udev_refs == 0) {
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os_event_signal(udev_event);
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eventfd_write(udev_event_fd, 1);
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pthread_join(udev_thread, NULL);
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os_event_destroy(udev_event);
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close(udev_event_fd);
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if (udev_signalhandler)
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signal_handler_destroy(udev_signalhandler);
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udev_signalhandler = NULL;
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}
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pthread_mutex_unlock(&udev_mutex);
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}
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signal_handler_t *v4l2_get_udev_signalhandler(void)
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{
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return udev_signalhandler;
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}
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