util-linux/disk-utils/swaplabel.c

/*
 * swaplabel.c - Print or change the label / UUID of a swap partition
 *
 * Copyright (C) 2010 Jason Borden <jborden@bluehost.com>
 * Copyright (C) 2010 Karel Zak <kzak@redhat.com>
 *
 * Usage: swaplabel [-L label] [-U UUID] device
 *
 * This file may be redistributed under the terms of the GNU Public License
 * version 2 or later.
 *
 */
#include <stdio.h>
#include <stddef.h>
#include <string.h>
#include <fcntl.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include <stdlib.h>
#include <getopt.h>

#ifdef HAVE_LIBUUID
# include <uuid.h>
#endif

#include "c.h"
#include "nls.h"
#include "all-io.h"
#include "strutils.h"
#include "closestream.h"

#include "swapheader.h"
#include "swapprober.h"

#define SWAP_UUID_OFFSET	(offsetof(struct swap_header_v1_2, uuid))
#define SWAP_LABEL_OFFSET	(offsetof(struct swap_header_v1_2, volume_name))

/* Print the swap partition information */
static int print_info(blkid_probe pr)
{
	const char *data;

	if (!blkid_probe_lookup_value(pr, "LABEL", &data, NULL))
		printf("LABEL: %s\n", data);

	if (!blkid_probe_lookup_value(pr, "UUID", &data, NULL))
		printf("UUID:  %s\n", data);

	return 0;
}

/* Change the swap partition info */
#ifdef HAVE_LIBUUID
static int change_info(const char *devname, const char *label, const char *uuid)
#else
static int change_info(const char *devname, const char *label,
		       const char *uuid __attribute__((__unused__)))
#endif
{
	int fd;

	fd = open(devname, O_RDWR);
	if (fd < 0) {
		warn(_("cannot open %s"), devname);
		goto err;
	}
#ifdef HAVE_LIBUUID
	/* Write the uuid if it was provided */
	if (uuid) {
		uuid_t newuuid;

		if (uuid_parse(uuid, newuuid) == -1)
			warnx(_("failed to parse UUID: %s"), uuid);
		else {
			if (lseek(fd, SWAP_UUID_OFFSET, SEEK_SET) !=
							SWAP_UUID_OFFSET) {
				warn(_("%s: failed to seek to swap UUID"), devname);
				goto err;

			} else if (write_all(fd, newuuid, sizeof(newuuid))) {
				warn(_("%s: failed to write UUID"), devname);
				goto err;
			}
		}
	}
#endif
	/* Write the label if it was provided */
	if (label) {
		char newlabel[SWAP_LABEL_LENGTH];

		if (lseek(fd, SWAP_LABEL_OFFSET, SEEK_SET) != SWAP_LABEL_OFFSET) {
			warn(_("%s: failed to seek to swap label "), devname);
			goto err;
		}
		memset(newlabel, 0, sizeof(newlabel));
		xstrncpy(newlabel, label, sizeof(newlabel));

		if (strlen(label) > strlen(newlabel))
			warnx(_("label is too long. Truncating it to '%s'"),
					newlabel);
		if (write_all(fd, newlabel, sizeof(newlabel))) {
			warn(_("%s: failed to write label"), devname);
			goto err;
		}
	}

	if (close_fd(fd) != 0) {
		warn(_("write failed: %s"), devname);
		return -1;
	}
	return 0;
err:
	if (fd >= 0)
		close(fd);
	return -1;
}

static void __attribute__((__noreturn__)) usage(void)
{
	FILE *out = stdout;
	fputs(USAGE_HEADER, out);
	fprintf(out, _(" %s [options] <device>\n"),
		program_invocation_short_name);

	fputs(USAGE_SEPARATOR, out);
	fputs(_("Display or change the label or UUID of a swap area.\n"), out);

	fputs(USAGE_OPTIONS, out);
	fputs(_(" -L, --label <label> specify a new label\n"
		" -U, --uuid <uuid>   specify a new uuid\n"), out);
	fputs(USAGE_SEPARATOR, out);
	printf(USAGE_HELP_OPTIONS(21));
	printf(USAGE_MAN_TAIL("swaplabel(8)"));
	exit(EXIT_SUCCESS);
}

int main(int argc, char *argv[])
{
	blkid_probe pr = NULL;
	char *uuid = NULL, *label = NULL, *devname;
	int c, rc = -1;

	static const struct option longopts[] = {
	    { "help",      no_argument,       NULL, 'h' },
	    { "version",   no_argument,       NULL, 'V' },
	    { "label",     required_argument, NULL, 'L' },
	    { "uuid",      required_argument, NULL, 'U' },
	    { NULL,        0, NULL, 0 }
	};

	setlocale(LC_ALL, "");
	bindtextdomain(PACKAGE, LOCALEDIR);
	textdomain(PACKAGE);
	close_stdout_atexit();

	while ((c = getopt_long(argc, argv, "hVL:U:", longopts, NULL)) != -1) {
		switch (c) {
		case 'h':
			usage();
			break;
		case 'V':
			print_version(EXIT_SUCCESS);
		case 'L':
			label = optarg;
			break;
		case 'U':
#ifdef HAVE_LIBUUID
			uuid = optarg;
#else
			warnx(_("ignore -U (UUIDs are unsupported)"));
#endif
			break;
		default:
			errtryhelp(EXIT_FAILURE);
		}
	}

	if (optind == argc) {
		warnx(_("no device specified"));
		errtryhelp(EXIT_FAILURE);
	}
	devname = argv[optind];
	pr = get_swap_prober(devname);
	if (pr) {
		if (uuid || label)
			rc = change_info(devname, label, uuid);
		else
			rc  = print_info(pr);
		blkid_free_probe(pr);
	}
	return rc ? EXIT_FAILURE : EXIT_SUCCESS;
}