/*
 * Alexandre Chartre - Sun Microsystems, Inc.
 * http://blogs.sun.com/achartre
 */

#pragma ident	"@(#)vdlinux.c	1.1	07/08/20 SMI"

#include <fcntl.h>
#include <stdio.h>
#include <unistd.h>
#include <sys/dklabel.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <sys/vtoc.h>

static ushort_t
lbl2cksum(struct dk_label *label)
{
	int	count;
	ushort_t sum, *sp;

	count =	(sizeof (struct dk_label)) / (sizeof (short)) - 1;
	sp = (ushort_t *)label;
	sum = 0;
	while (count--) {
		sum ^= *sp++;
	}

	return (sum);
}

void
usage()
{
	fprintf(stderr, "Usage: vdlinux file\n");
	fprintf(stderr, "Version: 1.1\n");
	fprintf(stderr, "\n");
}

int
main(int argc, char *argv[])
{
	int fd, change = 0, rc = 0;
	char *filename;
	struct dk_label label;

	if (argc != 2) {
		usage();
		return (1);
	}

	filename = argv[1];

	fd = open64(filename, O_RDWR | O_LARGEFILE);

	if (fd == -1) {
		perror("open");
		return (1);
	}

	/* read existing label */
	if (pread64(fd, &label, sizeof (struct dk_label), 0) == -1) {
		perror("error reading label");
		rc = 1;
		goto done;
	}

	/* check if label is correct */
	if (label.dkl_vtoc.v_nparts != V_NUMPAR) {
		printf("Incorrect number of partition (%d).\n",
		    label.dkl_vtoc.v_nparts);
		printf("Updating number of partition to %d.\n",
		    V_NUMPAR);
		/* update number of partitions */
		label.dkl_vtoc.v_nparts = V_NUMPAR;
		change++;
	}

	if (label.dkl_vtoc.v_sanity != VTOC_SANE) {
		printf("Incorrect vtoc sanity (%x).\n",
		    label.dkl_vtoc.v_sanity);
		printf("Correcting vtoc sanity (%x).\n",
		    VTOC_SANE);
		/* update vtoc sane */
		label.dkl_vtoc.v_sanity = VTOC_SANE;
		change++;
	}

	if (change) {
		/* update checksum */
		label.dkl_cksum = lbl2cksum(&label);
	} else {
		printf("Label looks correct.\n");
	}

	/* check bug 6544963 */
	if (label.dkl_cksum & 0x8000) {
		printf("Applying workaround for bug 6544963.\n");
		label.dkl_cksum &= 0x7fff;
		label.dkl_obs3 ^= 0x8000;
		change++;
	}

	if (change) {
		/* write new label */
		printf("Updating label and checksum.\n");
		if (pwrite64(fd, &label, sizeof (struct dk_label), 0) == -1) {
			perror("error writing label");
			rc = 1;
		}
	}

done:
	(void) close(fd);

	return (rc);
}