e2label.c revision d1154eb460efe588eaed3d439c1caaca149fa362 
1/*
2 * e2label.c		- Print or change the volume label on an ext2 fs
3 *
4 * Written by Andries Brouwer (aeb@cwi.nl), 970714
5 *
6 * Copyright 1997, 1998 by Theodore Ts'o.
7 *
8 * %Begin-Header%
9 * This file may be redistributed under the terms of the GNU Public
10 * License.
11 * %End-Header%
12 */
13
14#include "config.h"
15#include <stdio.h>
16#include <string.h>
17#include <fcntl.h>
18#include <ctype.h>
19#include <termios.h>
20#include <time.h>
21#ifdef HAVE_GETOPT_H
22#include <getopt.h>
23#else
24extern char *optarg;
25extern int optind;
26#endif
27#ifdef HAVE_UNISTD_H
28#include <unistd.h>
29#endif
30#ifdef HAVE_STDLIB_H
31#include <stdlib.h>
32#endif
33#ifdef HAVE_ERRNO_H
34#include <errno.h>
35#endif
36#include "nls-enable.h"
37
38#define EXT2_SUPER_MAGIC 0xEF53
39
40#define VOLNAMSZ 16
41
42struct ext2_super_block {
43	char  s_dummy0[56];
44	unsigned char  s_magic[2];
45	char  s_dummy1[62];
46	char  s_volume_name[VOLNAMSZ];
47	char  s_last_mounted[64];
48	char  s_dummy2[824];
49} sb;
50
51static int open_e2fs (char *dev, int mode)
52{
53	int fd;
54
55	fd = open(dev, mode);
56	if (fd < 0) {
57	     perror(dev);
58	     fprintf (stderr, _("e2label: cannot open %s\n"), dev);
59	     exit(1);
60	}
61	if (lseek(fd, 1024, SEEK_SET) != 1024) {
62	     perror(dev);
63	     fprintf (stderr, _("e2label: cannot seek to superblock\n"));
64	     exit(1);
65	}
66	if (read(fd, (char *) &sb, sizeof(sb)) != sizeof(sb)) {
67	     perror(dev);
68	     fprintf (stderr, _("e2label: error reading superblock\n"));
69	     exit(1);
70	}
71	if (sb.s_magic[0] + 256*sb.s_magic[1] != EXT2_SUPER_MAGIC) {
72	     fprintf (stderr, _("e2label: not an ext2 filesystem\n"));
73	     exit(1);
74	}
75
76	return fd;
77}
78
79static void print_label (char *dev)
80{
81	char label[VOLNAMSZ+1];
82
83	open_e2fs (dev, O_RDONLY);
84	strncpy(label, sb.s_volume_name, VOLNAMSZ);
85	label[VOLNAMSZ] = 0;
86	printf("%s\n", label);
87}
88
89static void change_label (char *dev, char *label)
90{
91	int fd;
92
93	fd = open_e2fs(dev, O_RDWR);
94	memset(sb.s_volume_name, 0, VOLNAMSZ);
95	strncpy(sb.s_volume_name, label, VOLNAMSZ);
96	if (strlen(label) > VOLNAMSZ)
97		fprintf(stderr, _("Warning: label too long, truncating.\n"));
98	if (lseek(fd, 1024, SEEK_SET) != 1024) {
99	     perror(dev);
100	     fprintf (stderr, _("e2label: cannot seek to superblock again\n"));
101	     exit(1);
102	}
103	if (write(fd, (char *) &sb, sizeof(sb)) != sizeof(sb)) {
104	     perror(dev);
105	     fprintf (stderr, _("e2label: error writing superblock\n"));
106	     exit(1);
107	}
108}
109
110int main (int argc, char ** argv)
111{
112	if (argc == 2)
113	     print_label(argv[1]);
114	else if (argc == 3)
115	     change_label(argv[1], argv[2]);
116	else {
117	     fprintf(stderr, _("Usage: e2label device [newlabel]\n"));
118	     exit(1);
119	}
120	return 0;
121}
122