device_select_x11.c

/*
 * Copyright © 2019 Red Hat
 *
 * 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.
 */

/* connect to an X server and work out the default device. */

#include <xcb/xcb.h>
#include <xcb/dri3.h>
#include <unistd.h>
#include <stdlib.h>
#include <fcntl.h>
#include <xf86drm.h>

#include "device_select.h"
static int
ds_dri3_open(xcb_connection_t *conn,
	     xcb_window_t root,
	     uint32_t provider)
{
   xcb_dri3_open_cookie_t       cookie;
   xcb_dri3_open_reply_t        *reply;
   int                          fd;

   cookie = xcb_dri3_open(conn,
                          root,
                          provider);

   reply = xcb_dri3_open_reply(conn, cookie, NULL);
   if (!reply)
      return -1;

   if (reply->nfd != 1) {
      free(reply);
      return -1;
   }

   fd = xcb_dri3_open_reply_fds(conn, reply)[0];
   free(reply);
   fcntl(fd, F_SETFD, fcntl(fd, F_GETFD) | FD_CLOEXEC);

   return fd;
}

int device_select_find_xcb_pci_default(struct device_pci_info *devices, uint32_t device_count)
{
  const xcb_setup_t *setup;
  xcb_screen_iterator_t iter;
  int scrn;
  xcb_connection_t *conn;
  int default_idx = -1;
  conn = xcb_connect(NULL, &scrn);
  if (!conn)
    return -1;

  xcb_query_extension_cookie_t dri3_cookie;
  xcb_query_extension_reply_t *dri3_reply;

  dri3_cookie = xcb_query_extension(conn, 4, "DRI3");
  dri3_reply = xcb_query_extension_reply(conn, dri3_cookie, NULL);

  if (!dri3_reply)
    goto out;

  if (dri3_reply->present == 0)
    goto out;
  setup = xcb_get_setup(conn);
  iter = xcb_setup_roots_iterator(setup);

  xcb_screen_t *screen = iter.data;

  int dri3_fd = ds_dri3_open(conn, screen->root, 0);
  if (dri3_fd == -1)
    goto out;

  drmDevicePtr xdev;
  int ret = drmGetDevice2(dri3_fd, 0, &xdev);
  if (ret < 0)
    goto out;

  for (unsigned i = 0; i < device_count; i++) {
    if (devices[i].has_bus_info) {
      if (xdev->businfo.pci->domain == devices[i].bus_info.domain &&
	  xdev->businfo.pci->bus == devices[i].bus_info.bus &&
	  xdev->businfo.pci->dev == devices[i].bus_info.dev &&
	  xdev->businfo.pci->func == devices[i].bus_info.func) {
	default_idx = i;
      }
    } else {
      if (xdev->deviceinfo.pci->vendor_id == devices[i].dev_info.vendor_id &&
	  xdev->deviceinfo.pci->device_id == devices[i].dev_info.device_id)
	default_idx = i;
    }
    if (default_idx != -1)
      break;
  }
out:
  xcb_disconnect(conn);
  return default_idx;
}