v4l: camera capability and control query

gistfile1.c

#include <stdio.h>
#include <string.h>
#include <fcntl.h>
#include <errno.h>
#include <linux/videodev2.h>

int main() {
	int N = 100;
	char* deviceName = "/dev/video0";
	int fd = open(deviceName, O_RDWR);
	if (fd == -1) {
		printf("Couldn't open video device!\n");
		return -1;
	}

	printf("Quering camera capabilities...\n");
	struct v4l2_capability vid_cap;
	if(ioctl(fd, VIDIOC_QUERYCAP, &vid_cap) >= 0) {
		printf("  Driver: %s\n", vid_cap.driver);
		printf("  Card: %s\n", vid_cap.card);
		printf("  Bus Info: %s\n", vid_cap.bus_info);
		printf("  Version: %2d\n", vid_cap.version);
		printf("  Capabilities: \n");

		if (vid_cap.capabilities & V4L2_CAP_VIDEO_CAPTURE) {
			printf("    Video capture support: Yes\n");
		} else {
			printf("    Video capture support: No\n");
		}
		if (vid_cap.capabilities & V4L2_CAP_VIDEO_OUTPUT) {
			printf("    Video output support: Yes\n");
		} else {
			printf("    Video output support: No\n");
		}
		if (vid_cap.capabilities & V4L2_CAP_VIDEO_OVERLAY) {
			printf("    Video overlay support: Yes\n");
		} else {
			printf("    Video overlay support: No\n");
		}
		if (vid_cap.capabilities & V4L2_CAP_VBI_CAPTURE) {
			printf("    Raw VBI capture support: Yes\n");
		} else {
			printf("    Raw VBI capture support: No\n");
		}
		if (vid_cap.capabilities & V4L2_CAP_VBI_OUTPUT) {
			printf("    RAW VBI output support: Yes\n");
		} else {
			printf("    RAW VBI output support: No\n");
		}
		if (vid_cap.capabilities & V4L2_CAP_SLICED_VBI_CAPTURE){
			printf("    Sliced VBI capture support: Yes\n");
		} else {
			printf("    Sliced VBI capture support: No\n");
		}
		if (vid_cap.capabilities & V4L2_CAP_SLICED_VBI_OUTPUT){
			printf("    Sliced VBI capture support: Yes\n");
		} else {
			printf("    Sliced VBI capture support: No\n");
		}
		if (vid_cap.capabilities & V4L2_CAP_RDS_CAPTURE){
			printf("    RDS capture support: Yes\n");
		} else {
			printf("    RDS capture support: No\n");
		}
		if (vid_cap.capabilities & V4L2_CAP_TUNER){
			printf("    Device has a tuner: Yes\n");
		} else {
			printf("    Device has a tuner: No\n");
		}
		if (vid_cap.capabilities & V4L2_CAP_AUDIO){
			printf("    Audio support: Yes\n");
		} else {
			printf("    Audio support: No\n");
		}
		if (vid_cap.capabilities & V4L2_CAP_RADIO){
			printf("    Device has radio support: Yes\n");
		} else {
			printf("    Device has radio support: No\n");
		}
		if (vid_cap.capabilities & V4L2_CAP_READWRITE){
			printf("    Supports read/write system calls: Yes\n");
		} else {
			printf("    Supports read/write system calls: No\n");
		}
		if (vid_cap.capabilities & V4L2_CAP_ASYNCIO){
			printf("    Supports async i/o: Yes\n");
		} else {
			printf("    Supports async i/o: No\n");
		}
		if (vid_cap.capabilities & V4L2_CAP_STREAMING){
			printf("    Supports streaming: Yes\n");
		} else {
			printf("    Supports streaming: No\n");
		}
	} else {
		printf("Couldn't connect to the video device!\n");
		return -1;
	}

	printf("\n\n\n");

	printf("Discovering camera controls...\n");
	struct v4l2_queryctrl queryctrl;
	struct v4l2_querymenu querymenu;
	memset (&queryctrl, 0, sizeof (queryctrl));
	for (queryctrl.id = V4L2_CID_BASE; queryctrl.id < V4L2_CID_BASE+N; queryctrl.id++) {
		if (ioctl (fd, VIDIOC_QUERYCTRL, &queryctrl) >= 0) {
			if (queryctrl.flags & V4L2_CTRL_FLAG_DISABLED)
				continue;
			printf("VIDIOC_QUERYCTRL(V4L2_CID_BASE+%d)\n", queryctrl.id-V4L2_CID_BASE);
			printf("   id: %d\n", queryctrl.id);

			switch (queryctrl.type){
				case V4L2_CTRL_TYPE_INTEGER:
					printf("   type: INTEGER\n");
					break;
				case V4L2_CTRL_TYPE_BOOLEAN:
					printf("   type: BOOLEAN\n");
					break;
				case V4L2_CTRL_TYPE_MENU:
					printf("   type: MENU\n");
					querymenu.id = queryctrl.id;
					for (querymenu.index = queryctrl.minimum; querymenu.index < queryctrl.maximum; querymenu.index++){
						printf("      menu id: %d\n", querymenu.index);
						printf("      menu name: %s\n", querymenu.name);
					}
					break;
				case V4L2_CTRL_TYPE_BUTTON:
					printf("   type: BUTTON\n");
					break;
			} /* end switch */
			printf("   name: %s\n", queryctrl.name);
			printf("   minimum: %d\n", queryctrl.minimum);
			printf("   maximum: %d\n", queryctrl.maximum);
			printf("   step: %d\n", queryctrl.step);
			printf("   default_value: %d\n", queryctrl.default_value);
			printf("   flags: %d\n", queryctrl.flags);
		} else {
			if (errno == EINVAL)
				continue;
			perror("VIDIOC_QUERYCTRL");
			break;
		} /* end if*/
	} /* end for */
	
	return 0;
}

It's missing #include <sys/ioctl.h>