A simple program to print whether a CD tray is ejectable, on FreeBSD.

get_ejectability_freebsd.c

/*
Copyright electrolysis 2015.
Distributed under the Boost Software License, Version 1.0.
(See copy at http://www.boost.org/LICENSE_1_0.txt)
*/

// A simple program to print whether a CD tray is ejectable, on FreeBSD.

#include <stdio.h>
#include <string.h>
#include <fcntl.h>

#include <camlib.h> // requires -lcam

#include <cam/scsi/scsi_message.h> // MSG_SIMPLE_Q_TAG

#define GET_CONFIGURETION_CMD_LEN 12
#define GET_CONFIGURATION_RESPONSE_BUF_LEN 16

int main(){
	const char* path = "/dev/cd0";
	char dev_name[DEV_IDLEN + 1];
	int unit;

 	int cgd = cam_get_device(path, dev_name, DEV_IDLEN, &unit);
	if(cgd == -1){
		puts("cam_get_device: failed");
		puts(cam_errbuf);
		return -1;
	}

	struct cam_device* cam_dev = cam_open_spec_device(dev_name, unit, O_RDWR, NULL);
	if(!cam_dev){
		puts("cam_open_spec_device: failed");
		puts(cam_errbuf);
		return -2;
	}

	union ccb ccb;
	unsigned char get_configuration_response_buf[GET_CONFIGURATION_RESPONSE_BUF_LEN];
	unsigned char get_configuration_cmd [GET_CONFIGURETION_CMD_LEN] =
    	{0x46, 0, 0, 0x03, 0, 0, 0, 0, GET_CONFIGURATION_RESPONSE_BUF_LEN, 0, 0, 0};

	cam_fill_csio(&ccb.csio, 1, NULL, CAM_DIR_IN, MSG_SIMPLE_Q_TAG, get_configuration_response_buf,
		GET_CONFIGURATION_RESPONSE_BUF_LEN, 0, GET_CONFIGURETION_CMD_LEN, 5000);
    memcpy(ccb.csio.cdb_io.cdb_bytes, get_configuration_cmd, GET_CONFIGURETION_CMD_LEN);

	int csc = cam_send_ccb(cam_dev, &ccb);
	if(csc == -1){
		cam_close_device(cam_dev);

		puts("cam_send_ccb: failed");
		puts(cam_errbuf);
		return -3;
	}
	printf("Tray is %sejectable!\n",get_configuration_response_buf[12] & 0b00001000 ? "" : "not ");

	cam_close_device(cam_dev);

	return 0;
}