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