clients/simple-dmabuf-v4l.c

/*
 * Copyright © 2015 Collabora Ltd.
 *
 * Permission is hereby granted, free of charge, to any person obtaining
 * a copy of this software and associated documentation files (the
 * "Software"), to deal in the Software without restriction, including
 * without limitation the rights to use, copy, modify, merge, publish,
 * distribute, sublicense, and/or sell copies of the Software, and to
 * permit persons to whom the Software is furnished to do so, subject to
 * the following conditions:
 *
 * The above copyright notice and this permission notice (including the
 * next paragraph) shall be included in all copies or substantial
 * portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT.  IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

#include "config.h"

#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdbool.h>
#include <assert.h>
#include <unistd.h>
#include <sys/mman.h>
#include <signal.h>
#include <fcntl.h>

#include <drm_fourcc.h>

#include <sys/mman.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <errno.h>
#include <linux/videodev2.h>
#include <linux/input.h>

#include <wayland-client.h>
#include "shared/zalloc.h"
#include "xdg-shell-unstable-v6-client-protocol.h"
#include "fullscreen-shell-unstable-v1-client-protocol.h"
#include "linux-dmabuf-unstable-v1-client-protocol.h"

#define CLEAR(x) memset(&(x), 0, sizeof(x))

static void
redraw(void *data, struct wl_callback *callback, uint32_t time);

static int
xioctl(int fh, int request, void *arg)
{
	int r;

	do {
		r = ioctl(fh, request, arg);
	} while (r == -1 && errno == EINTR);

	return r;
}

static uint32_t
parse_format(const char fmt[4])
{
	return fourcc_code(fmt[0], fmt[1], fmt[2], fmt[3]);
}

static inline const char *
dump_format(uint32_t format, char out[4])
{
#if BYTE_ORDER == BIG_ENDIAN
	format = __builtin_bswap32(format);
#endif
	memcpy(out, &format, 4);
	return out;
}

struct buffer_format {
	int width;
	int height;
	enum v4l2_buf_type type;
	uint32_t format;

	unsigned num_planes;
	unsigned strides[VIDEO_MAX_PLANES];
};

struct display {
	struct wl_display *display;
	struct wl_registry *registry;
	struct wl_compositor *compositor;
	struct wl_seat *seat;
	struct wl_keyboard *keyboard;
	struct zxdg_shell_v6 *shell;
	struct zwp_fullscreen_shell_v1 *fshell;
	struct zwp_linux_dmabuf_v1 *dmabuf;
	bool requested_format_found;

	int v4l_fd;
	struct buffer_format format;
	uint32_t drm_format;
};

struct buffer {
	struct wl_buffer *buffer;
	struct display *display;
	int busy;
	int index;

	int dmabuf_fds[VIDEO_MAX_PLANES];
	int data_offsets[VIDEO_MAX_PLANES];
};

#define NUM_BUFFERS 3

struct window {
	struct display *display;
	struct wl_surface *surface;
	struct zxdg_surface_v6 *xdg_surface;
	struct zxdg_toplevel_v6 *xdg_toplevel;
	struct buffer buffers[NUM_BUFFERS];
	struct wl_callback *callback;
	bool wait_for_configure;
	bool initialized;
};

static bool running = true;

static int
queue(struct display *display, struct buffer *buffer)
{
	struct v4l2_buffer buf;
	struct v4l2_plane planes[VIDEO_MAX_PLANES];
	unsigned i;

	CLEAR(buf);
	buf.type = display->format.type;
	buf.memory = V4L2_MEMORY_MMAP;
	buf.index = buffer->index;

	if (display->format.type == V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE) {
		CLEAR(planes);
		buf.length = VIDEO_MAX_PLANES;
		buf.m.planes = planes;
	}

	if (xioctl(display->v4l_fd, VIDIOC_QUERYBUF, &buf) == -1) {
		perror("VIDIOC_QUERYBUF");
		return 0;
	}

	if (xioctl(display->v4l_fd, VIDIOC_QBUF, &buf) == -1) {
		perror("VIDIOC_QBUF");
		return 0;
	}

	if (display->format.type == V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE) {
		if (display->format.num_planes != buf.length) {
			fprintf(stderr, "Wrong number of planes returned by "
			                "QUERYBUF\n");
			return 0;
		}

		for (i = 0; i < buf.length; ++i)
			buffer->data_offsets[i] = buf.m.planes[i].data_offset;
	}

	return 1;
}

static void
buffer_release(void *data, struct wl_buffer *buffer)
{
	struct buffer *mybuf = data;

	mybuf->busy = 0;

	if (!queue(mybuf->display, mybuf))
		running = false;
}

static const struct wl_buffer_listener buffer_listener = {
	buffer_release
};

static unsigned int
set_format(struct display *display, uint32_t format)
{
	struct v4l2_format fmt;
	char buf[4];

	CLEAR(fmt);

	fmt.type = display->format.type;

	if (xioctl(display->v4l_fd, VIDIOC_G_FMT, &fmt) == -1) {
		perror("VIDIOC_G_FMT");
		return 0;
	}

	/* No need to set the format if it already is the one we want */
	if (display->format.type == V4L2_BUF_TYPE_VIDEO_CAPTURE &&
	    fmt.fmt.pix.pixelformat == format)
		return 1;
	if (display->format.type == V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE &&
	    fmt.fmt.pix_mp.pixelformat == format)
		return fmt.fmt.pix_mp.num_planes;

	if (display->format.type == V4L2_BUF_TYPE_VIDEO_CAPTURE)
		fmt.fmt.pix.pixelformat = format;
	else
		fmt.fmt.pix_mp.pixelformat = format;

	if (xioctl(display->v4l_fd, VIDIOC_S_FMT, &fmt) == -1) {
		perror("VIDIOC_S_FMT");
		return 0;
	}

	if ((display->format.type == V4L2_BUF_TYPE_VIDEO_CAPTURE &&
	     fmt.fmt.pix.pixelformat != format) ||
	    (display->format.type == V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE &&
	     fmt.fmt.pix_mp.pixelformat != format)) {
		fprintf(stderr, "Failed to set format to %.4s\n",
		        dump_format(format, buf));
		return 0;
	}

	if (display->format.type == V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE)
		return fmt.fmt.pix_mp.num_planes;

	return 1;
}

static int
v4l_connect(struct display *display, const char *dev_name)
{
	struct v4l2_capability cap;
	struct v4l2_requestbuffers req;
	unsigned int num_planes;

	display->v4l_fd = open(dev_name, O_RDWR);
	if (display->v4l_fd < 0) {
		perror(dev_name);
		return 0;
	}

	if (xioctl(display->v4l_fd, VIDIOC_QUERYCAP, &cap) == -1) {
		if (errno == EINVAL) {
			fprintf(stderr, "%s is no V4L2 device\n", dev_name);
		} else {
			perror("VIDIOC_QUERYCAP");
		}
		return 0;
	}

	if (cap.capabilities & V4L2_CAP_VIDEO_CAPTURE)
		display->format.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
	else if (cap.capabilities & V4L2_CAP_VIDEO_CAPTURE_MPLANE)
		display->format.type = V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE;
	else {
		fprintf(stderr, "%s is no video capture device\n", dev_name);
		return 0;
	}

	if (!(cap.capabilities & V4L2_CAP_STREAMING)) {
		fprintf(stderr, "%s does not support dmabuf i/o\n", dev_name);
		return 0;
	}

	/* Select video input, video standard and tune here */

	num_planes = set_format(display, display->format.format);
	if (num_planes < 1)
		return 0;

	CLEAR(req);

	req.type = display->format.type;
	req.memory = V4L2_MEMORY_MMAP;
	req.count = NUM_BUFFERS * num_planes;

	if (xioctl(display->v4l_fd, VIDIOC_REQBUFS, &req) == -1) {
		if (errno == EINVAL) {
			fprintf(stderr, "%s does not support dmabuf\n",
			        dev_name);
		} else {
			perror("VIDIOC_REQBUFS");
		}
		return 0;
	}

	if (req.count < NUM_BUFFERS * num_planes) {
		fprintf(stderr, "Insufficient buffer memory on %s\n", dev_name);
		return 0;
	}

	printf("Created %d buffers\n", req.count);

	return 1;
}

static void
v4l_shutdown(struct display *display)
{
	close(display->v4l_fd);
}

static void
create_succeeded(void *data,
		 struct zwp_linux_buffer_params_v1 *params,
		 struct wl_buffer *new_buffer)
{
	struct buffer *buffer = data;
	unsigned i;

	buffer->buffer = new_buffer;
	wl_buffer_add_listener(buffer->buffer, &buffer_listener, buffer);

	zwp_linux_buffer_params_v1_destroy(params);

	for (i = 0; i < buffer->display->format.num_planes; ++i)
		close(buffer->dmabuf_fds[i]);
}

static void
create_failed(void *data, struct zwp_linux_buffer_params_v1 *params)
{
	struct buffer *buffer = data;
	unsigned i;

	buffer->buffer = NULL;

	zwp_linux_buffer_params_v1_destroy(params);

	for (i = 0; i < buffer->display->format.num_planes; ++i)
		close(buffer->dmabuf_fds[i]);

	running = false;

	fprintf(stderr, "Error: zwp_linux_buffer_params.create failed.\n");
}

static const struct zwp_linux_buffer_params_v1_listener params_listener = {
	create_succeeded,
	create_failed
};

static void
create_dmabuf_buffer(struct display *display, struct buffer *buffer)
{
	struct zwp_linux_buffer_params_v1 *params;
	uint64_t modifier;
	uint32_t flags;
	unsigned i;

	modifier = 0;
	flags = 0;

	/* XXX: apparently some webcams may actually provide y-inverted images,
	 * in which case we should set
	 * flags = ZWP_LINUX_BUFFER_PARAMS_V1_FLAGS_Y_INVERT
	 */

	params = zwp_linux_dmabuf_v1_create_params(display->dmabuf);
	for (i = 0; i < display->format.num_planes; ++i)
		zwp_linux_buffer_params_v1_add(params,
		                               buffer->dmabuf_fds[i],
		                               i, /* plane_idx */
		                               buffer->data_offsets[i], /* offset */
		                               display->format.strides[i],
		                               modifier >> 32,
		                               modifier & 0xffffffff);
	zwp_linux_buffer_params_v1_add_listener(params, &params_listener,
	                                        buffer);
	zwp_linux_buffer_params_v1_create(params,
	                                  display->format.width,
	                                  display->format.height,
	                                  display->drm_format,
	                                  flags);
}

static int
buffer_export(struct display *display, int index, int dmafd[])
{
	struct v4l2_exportbuffer expbuf;
	unsigned i;

	CLEAR(expbuf);

	for (i = 0; i < display->format.num_planes; ++i) {
		expbuf.type = display->format.type;
		expbuf.index = index;
		expbuf.plane = i;
		if (xioctl(display->v4l_fd, VIDIOC_EXPBUF, &expbuf) == -1) {
			perror("VIDIOC_EXPBUF");
			while (i)
				close(dmafd[--i]);
			return 0;
		}
		dmafd[i] = expbuf.fd;
	}

	return 1;
}

static int
queue_initial_buffers(struct display *display,
                      struct buffer buffers[NUM_BUFFERS])
{
	struct buffer *buffer;
	int index;

	for (index = 0; index < NUM_BUFFERS; ++index) {
		buffer = &buffers[index];
		buffer->display = display;
		buffer->index = index;

		if (!queue(display, buffer)) {
			fprintf(stderr, "Failed to queue buffer\n");
			return 0;
		}

		assert(!buffer->buffer);
		if (!buffer_export(display, index, buffer->dmabuf_fds))
			return 0;

		create_dmabuf_buffer(display, buffer);
	}

	return 1;
}

static int
dequeue(struct display *display)
{
	struct v4l2_buffer buf;
	struct v4l2_plane planes[VIDEO_MAX_PLANES];

	CLEAR(buf);
	buf.type = display->format.type;
	buf.memory = V4L2_MEMORY_MMAP;
	buf.length = VIDEO_MAX_PLANES;
	buf.m.planes = planes;

	/* This ioctl is blocking until a buffer is ready to be displayed */
	if (xioctl(display->v4l_fd, VIDIOC_DQBUF, &buf) == -1) {
		perror("VIDIOC_DQBUF");
		return -1;
	}

	assert(buf.flags & V4L2_BUF_FLAG_DONE);

	return buf.index;
}

static int
fill_buffer_format(struct display *display)
{
	struct v4l2_format fmt;
	struct v4l2_pix_format *pix;
	struct v4l2_pix_format_mplane *pix_mp;
	int i;
	char buf[4];

	CLEAR(fmt);
	fmt.type = display->format.type;

	/* Preserve original settings as set by v4l2-ctl for example */
	if (xioctl(display->v4l_fd, VIDIOC_G_FMT, &fmt) == -1) {
		perror("VIDIOC_G_FMT");
		return 0;
	}

	if (display->format.type == V4L2_BUF_TYPE_VIDEO_CAPTURE) {
		pix = &fmt.fmt.pix;

		printf("%d×%d, %.4s\n", pix->width, pix->height,
		       dump_format(pix->pixelformat, buf));

		display->format.num_planes = 1;
		display->format.width = pix->width;
		display->format.height = pix->height;
		display->format.strides[0] = pix->bytesperline;
	} else {
		pix_mp = &fmt.fmt.pix_mp;

		display->format.num_planes = pix_mp->num_planes;
		display->format.width = pix_mp->width;
		display->format.height = pix_mp->height;

		for (i = 0; i < pix_mp->num_planes; ++i)
			display->format.strides[i] = pix_mp->plane_fmt[i].bytesperline;

		printf("%d×%d, %.4s, %d planes\n",
		       pix_mp->width, pix_mp->height,
		       dump_format(pix_mp->pixelformat, buf),
		       pix_mp->num_planes);
	}

	return 1;
}

static int
v4l_init(struct display *display, struct buffer buffers[NUM_BUFFERS]) {
	if (!fill_buffer_format(display)) {
		fprintf(stderr, "Failed to fill buffer format\n");
		return 0;
	}

	if (!queue_initial_buffers(display, buffers)) {
		fprintf(stderr, "Failed to queue initial buffers\n");
		return 0;
	}

	return 1;
}

static int
start_capture(struct display *display)
{
	int type = display->format.type;

	if (xioctl(display->v4l_fd, VIDIOC_STREAMON, &type) == -1) {
		perror("VIDIOC_STREAMON");
		return 0;
	}

	return 1;
}

static void
xdg_surface_handle_configure(void *data, struct zxdg_surface_v6 *surface,
			     uint32_t serial)
{
	struct window *window = data;

	zxdg_surface_v6_ack_configure(surface, serial);

	if (window->initialized && window->wait_for_configure)
		redraw(window, NULL, 0);
	window->wait_for_configure = false;
}

static const struct zxdg_surface_v6_listener xdg_surface_listener = {
	xdg_surface_handle_configure,
};

static void
xdg_toplevel_handle_configure(void *data, struct zxdg_toplevel_v6 *toplevel,
			      int32_t width, int32_t height,
			      struct wl_array *states)
{
}

static void
xdg_toplevel_handle_close(void *data, struct zxdg_toplevel_v6 *xdg_toplevel)
{
	running = 0;
}

static const struct zxdg_toplevel_v6_listener xdg_toplevel_listener = {
	xdg_toplevel_handle_configure,
	xdg_toplevel_handle_close,
};

static struct window *
create_window(struct display *display)
{
	struct window *window;

	window = zalloc(sizeof *window);
	if (!window)
		return NULL;

	window->callback = NULL;
	window->display = display;
	window->surface = wl_compositor_create_surface(display->compositor);

	if (display->shell) {
		window->xdg_surface =
			zxdg_shell_v6_get_xdg_surface(display->shell,
						      window->surface);

		assert(window->xdg_surface);

		zxdg_surface_v6_add_listener(window->xdg_surface,
					     &xdg_surface_listener, window);

		window->xdg_toplevel =
			zxdg_surface_v6_get_toplevel(window->xdg_surface);

		assert(window->xdg_toplevel);

		zxdg_toplevel_v6_add_listener(window->xdg_toplevel,
					      &xdg_toplevel_listener, window);

		zxdg_toplevel_v6_set_title(window->xdg_toplevel, "simple-dmabuf-v4l");

		window->wait_for_configure = true;
		wl_surface_commit(window->surface);
	} else if (display->fshell) {
		zwp_fullscreen_shell_v1_present_surface(display->fshell,
		                                        window->surface,
		                                        ZWP_FULLSCREEN_SHELL_V1_PRESENT_METHOD_DEFAULT,
		                                        NULL);
	} else {
		assert(0);
	}

	return window;
}

static void
destroy_window(struct window *window)
{
	int i;
	unsigned j;

	if (window->callback)
		wl_callback_destroy(window->callback);

	if (window->xdg_toplevel)
		zxdg_toplevel_v6_destroy(window->xdg_toplevel);
	if (window->xdg_surface)
		zxdg_surface_v6_destroy(window->xdg_surface);
	wl_surface_destroy(window->surface);

	for (i = 0; i < NUM_BUFFERS; i++) {
		if (!window->buffers[i].buffer)
			continue;

		wl_buffer_destroy(window->buffers[i].buffer);
		for (j = 0; j < window->display->format.num_planes; ++j)
			close(window->buffers[i].dmabuf_fds[j]);
	}

	v4l_shutdown(window->display);

	free(window);
}

static const struct wl_callback_listener frame_listener;

static void
redraw(void *data, struct wl_callback *callback, uint32_t time)
{
	struct window *window = data;
	struct buffer *buffer;
	int index, num_busy = 0;

	/* Check for a deadlock situation where we would block forever trying
	 * to dequeue a buffer while all of them are locked by the compositor.
	 */
	for (index = 0; index < NUM_BUFFERS; ++index)
		if (window->buffers[index].busy)
			++num_busy;

	/* A robust application would just postpone redraw until it has queued
	 * a buffer.
	 */
	assert(num_busy < NUM_BUFFERS);

	index = dequeue(window->display);
	if (index < 0) {
		/* We couldn’t get any buffer out of the camera, exiting. */
		running = false;
		return;
	}

	buffer = &window->buffers[index];
	assert(!buffer->busy);

	wl_surface_attach(window->surface, buffer->buffer, 0, 0);
	wl_surface_damage(window->surface, 0, 0,
	                  window->display->format.width,
	                  window->display->format.height);

	if (callback)
		wl_callback_destroy(callback);

	window->callback = wl_surface_frame(window->surface);
	wl_callback_add_listener(window->callback, &frame_listener, window);
	wl_surface_commit(window->surface);
	buffer->busy = 1;
}

static const struct wl_callback_listener frame_listener = {
	redraw
};

static void
dmabuf_format(void *data, struct zwp_linux_dmabuf_v1 *zwp_linux_dmabuf,
              uint32_t format)
{
	struct display *d = data;

	if (format == d->drm_format)
		d->requested_format_found = true;
}

static const struct zwp_linux_dmabuf_v1_listener dmabuf_listener = {
	dmabuf_format
};

static void
keyboard_handle_keymap(void *data, struct wl_keyboard *keyboard,
                       uint32_t format, int fd, uint32_t size)
{
	/* Just so we don’t leak the keymap fd */
	close(fd);
}

static void
keyboard_handle_enter(void *data, struct wl_keyboard *keyboard,
                      uint32_t serial, struct wl_surface *surface,
                      struct wl_array *keys)
{
}

static void
keyboard_handle_leave(void *data, struct wl_keyboard *keyboard,
                      uint32_t serial, struct wl_surface *surface)
{
}

static void
keyboard_handle_key(void *data, struct wl_keyboard *keyboard,
                    uint32_t serial, uint32_t time, uint32_t key,
                    uint32_t state)
{
	struct display *d = data;

	if (!d->shell)
		return;

	if (key == KEY_ESC && state)
		running = false;
}

static void
keyboard_handle_modifiers(void *data, struct wl_keyboard *keyboard,
                          uint32_t serial, uint32_t mods_depressed,
                          uint32_t mods_latched, uint32_t mods_locked,
                          uint32_t group)
{
}

static const struct wl_keyboard_listener keyboard_listener = {
	keyboard_handle_keymap,
	keyboard_handle_enter,
	keyboard_handle_leave,
	keyboard_handle_key,
	keyboard_handle_modifiers,
};

static void
seat_handle_capabilities(void *data, struct wl_seat *seat,
                         enum wl_seat_capability caps)
{
	struct display *d = data;

	if ((caps & WL_SEAT_CAPABILITY_KEYBOARD) && !d->keyboard) {
		d->keyboard = wl_seat_get_keyboard(seat);
		wl_keyboard_add_listener(d->keyboard, &keyboard_listener, d);
	} else if (!(caps & WL_SEAT_CAPABILITY_KEYBOARD) && d->keyboard) {
		wl_keyboard_destroy(d->keyboard);
		d->keyboard = NULL;
	}
}

static const struct wl_seat_listener seat_listener = {
	seat_handle_capabilities,
};

static void
xdg_shell_ping(void *data, struct zxdg_shell_v6 *shell, uint32_t serial)
{
	zxdg_shell_v6_pong(shell, serial);
}

static const struct zxdg_shell_v6_listener xdg_shell_listener = {
	xdg_shell_ping,
};

static void
registry_handle_global(void *data, struct wl_registry *registry,
                       uint32_t id, const char *interface, uint32_t version)
{
	struct display *d = data;

	if (strcmp(interface, "wl_compositor") == 0) {
		d->compositor =
			wl_registry_bind(registry,
			                 id, &wl_compositor_interface, 1);
	} else if (strcmp(interface, "wl_seat") == 0) {
		d->seat = wl_registry_bind(registry,
		                           id, &wl_seat_interface, 1);
		wl_seat_add_listener(d->seat, &seat_listener, d);
	} else if (strcmp(interface, "zxdg_shell_v6") == 0) {
		d->shell = wl_registry_bind(registry,
		                            id, &zxdg_shell_v6_interface, 1);
		zxdg_shell_v6_add_listener(d->shell, &xdg_shell_listener, d);
	} else if (strcmp(interface, "zwp_fullscreen_shell_v1") == 0) {
		d->fshell = wl_registry_bind(registry,
		                             id, &zwp_fullscreen_shell_v1_interface,
		                             1);
	} else if (strcmp(interface, "zwp_linux_dmabuf_v1") == 0) {
		d->dmabuf = wl_registry_bind(registry,
		                             id, &zwp_linux_dmabuf_v1_interface,
		                             1);
		zwp_linux_dmabuf_v1_add_listener(d->dmabuf, &dmabuf_listener,
		                                 d);
	}
}

static void
registry_handle_global_remove(void *data, struct wl_registry *registry,
                              uint32_t name)
{
}

static const struct wl_registry_listener registry_listener = {
	registry_handle_global,
	registry_handle_global_remove
};

static struct display *
create_display(uint32_t requested_format)
{
	struct display *display;

	display = malloc(sizeof *display);
	if (display == NULL) {
		fprintf(stderr, "out of memory\n");
		exit(1);
	}
	display->display = wl_display_connect(NULL);
	assert(display->display);

	display->drm_format = requested_format;

	display->registry = wl_display_get_registry(display->display);
	wl_registry_add_listener(display->registry,
	                         &registry_listener, display);
	wl_display_roundtrip(display->display);
	if (display->dmabuf == NULL) {
		fprintf(stderr, "No zwp_linux_dmabuf global\n");
		exit(1);
	}

	wl_display_roundtrip(display->display);

	/* XXX: fake, because the compositor does not yet advertise anything */
	display->requested_format_found = true;

	if (!display->requested_format_found) {
		fprintf(stderr, "DRM_FORMAT_YUYV not available\n");
		exit(1);
	}

	return display;
}

static void
destroy_display(struct display *display)
{
	if (display->dmabuf)
		zwp_linux_dmabuf_v1_destroy(display->dmabuf);

	if (display->shell)
		zxdg_shell_v6_destroy(display->shell);

	if (display->fshell)
		zwp_fullscreen_shell_v1_release(display->fshell);

	if (display->compositor)
		wl_compositor_destroy(display->compositor);

	wl_registry_destroy(display->registry);
	wl_display_flush(display->display);
	wl_display_disconnect(display->display);
	free(display);
}

static void
usage(const char *argv0)
{
	printf("Usage: %s [V4L2 device] [V4L2 format] [DRM format]\n"
	       "\n"
	       "The default V4L2 device is /dev/video0\n"
	       "\n"
	       "Both formats are FOURCC values (see http://fourcc.org/)\n"
	       "V4L2 formats are defined in <linux/videodev2.h>\n"
	       "DRM formats are defined in <libdrm/drm_fourcc.h>\n"
	       "The default for both formats is YUYV.\n"
	       "If the V4L2 and DRM formats differ, the data is simply "
	       "reinterpreted rather than converted.\n", argv0);

	printf("\n"
	       "How to set up Vivid the virtual video driver for testing:\n"
	       "- build your kernel with CONFIG_VIDEO_VIVID=m\n"
	       "- add this to a /etc/modprobe.d/ file:\n"
	       "    options vivid node_types=0x1 num_inputs=1 input_types=0x00\n"
	       "- modprobe vivid and check which device was created,\n"
	       "  here we assume /dev/video0\n"
	       "- set the pixel format:\n"
	       "    $ v4l2-ctl -d /dev/video0 --set-fmt-video=width=640,pixelformat=XR24\n"
	       "- launch the demo:\n"
	       "    $ %s /dev/video0 XR24 XR24\n"
	       "You should see a test pattern with color bars, and some text.\n"
	       "\n"
	       "More about vivid: https://www.kernel.org/doc/Documentation/video4linux/vivid.txt\n"
	       "\n", argv0);

	exit(0);
}

static void
signal_int(int signum)
{
	running = false;
}

int
main(int argc, char **argv)
{
	struct sigaction sigint;
	struct display *display;
	struct window *window;
	const char *v4l_device;
	uint32_t v4l_format, drm_format;
	int ret = 0;

	if (argc < 2) {
		v4l_device = "/dev/video0";
	} else if (!strcmp(argv[1], "--help")) {
		usage(argv[0]);
	} else {
		v4l_device = argv[1];
	}

	if (argc < 3)
		v4l_format = parse_format("YUYV");
	else
		v4l_format = parse_format(argv[2]);

	if (argc < 4)
		drm_format = v4l_format;
	else
		drm_format = parse_format(argv[3]);

	display = create_display(drm_format);
	display->format.format = v4l_format;

	window = create_window(display);
	if (!window)
		return 1;

	if (!v4l_connect(display, v4l_device))
		return 1;

	if (!v4l_init(display, window->buffers))
		return 1;

	sigint.sa_handler = signal_int;
	sigemptyset(&sigint.sa_mask);
	sigint.sa_flags = SA_RESETHAND;
	sigaction(SIGINT, &sigint, NULL);

	/* Here we retrieve the linux-dmabuf objects, or error */
	wl_display_roundtrip(display->display);

	/* In case of error, running will be 0 */
	if (!running)
		return 1;

	/* We got all of our buffers, we can start the capture! */
	if (!start_capture(display))
		return 1;

	window->initialized = true;

	if (!window->wait_for_configure)
		redraw(window, NULL, 0);

	while (running && ret != -1)
		ret = wl_display_dispatch(display->display);

	fprintf(stderr, "simple-dmabuf-v4l exiting\n");
	destroy_window(window);
	destroy_display(display);

	return 0;
}