1 /* 2 * e2label.c - Print or change the volume label on an ext2 fs 3 * 4 * Written by Andries Brouwer (aeb (at) 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 24 extern char *optarg; 25 extern 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 "support/nls-enable.h" 37 38 #define EXT2_SUPER_MAGIC 0xEF53 39 40 #define VOLNAMSZ 16 41 42 struct 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 51 static 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 79 static 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 89 static 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 } 109 110 int 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
