/*
 * sgtblsz.c - Look up max number of scatter-gather table entries on
 * 	       an SG device
 *
 * Copyright (C) 2006 Oracle Corporation
 * Written by Martin K. Petersen <martin.petersen@oracle.com>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License version
 * 2 as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
#include <stdarg.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <sys/ioctl.h>
#include <errno.h>
#include <string.h>
#include <scsi/sg.h>

int die (const char *fmt, ...)
{
	va_list val;

	va_start(val, fmt);
	vfprintf(stderr, fmt, val);
	if (errno != 0)
		fprintf(stderr, ": %s", strerror(errno));
	fprintf(stderr, "\n");
	va_end(val);

	exit(EXIT_FAILURE);
}

int main (int argc, char *argv[])
{
	int fd;
	struct stat st;
	unsigned long num;

	if (argc < 2)
		die("Must specify sg device to query");

        if ((fd = open(argv[1], O_RDONLY)) < 0) 
                die("Can't open %s", argv[1]);

        if (stat(argv[1], &st) < 0)
                die("Can't stat device %s", argv[1]);

        if (!S_ISCHR(st.st_mode)) 
                die("Argument must be an sg device");
	
	if (ioctl(fd, SG_GET_VERSION_NUM, &num) < 0) 
                die("%s is not an sg device", argv[1]);
	
	if (ioctl(fd, SG_GET_SG_TABLESIZE, &num) < 0) 
                die("Can't get table size from sg device");
	
	printf("Max sgl entries for %s = %ld\n", argv[1], num);

	exit(EXIT_SUCCESS);
}