/*
 * DF-4911 probe — checks whether the raw DP AUX character device exists,
 * which would give an unprivileged user a direct handle on dm_dp_aux_transfer.
 * On DragonFly CONFIG_DRM_DP_AUX_CHARDEV is unset (sys/dev/drm/kconfig.h),
 * so /dev/drm_dp_auxN is never created and the buggy write paths are only
 * reachable through kernel-initiated DPCD traffic on real AMD DP hardware.
 */
#include <stdio.h>
#include <fcntl.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>

int main(void)
{
	int i, found = 0;
	char path[64];

	for (i = 0; i < 16; i++) {
		snprintf(path, sizeof(path), "/dev/drm_dp_aux%d", i);
		int fd = open(path, O_RDWR);
		if (fd >= 0) {
			printf("FOUND %s — direct AUX access possible\n", path);
			close(fd);
			found++;
		}
	}
	if (!found)
		printf("no /dev/drm_dp_aux* devices — AUX chardev disabled; "
		       "dm_dp_aux_transfer reachable only via kernel DPCD "
		       "traffic on AMD hardware\n");
	return found ? 0 : 1;
}