| /* |
| * e2label.c - Print or change the volume label on an ext2 fs |
| * |
| * aeb, 970714 |
| * |
| */ |
| |
| #include <stdio.h> |
| #include <string.h> |
| #include <fcntl.h> |
| #include <ctype.h> |
| #include <termios.h> |
| #include <time.h> |
| #ifdef HAVE_GETOPT_H |
| #include <getopt.h> |
| #endif |
| #ifdef HAVE_UNISTD_H |
| #include <unistd.h> |
| #endif |
| #ifdef HAVE_STDLIB_H |
| #include <stdlib.h> |
| #endif |
| #ifdef HAVE_ERRNO_H |
| #include <errno.h> |
| #endif |
| |
| #define EXT2_SUPER_MAGIC 0xEF53 |
| |
| #define VOLNAMSZ 16 |
| |
| struct ext2_super_block { |
| char s_dummy0[56]; |
| unsigned char s_magic[2]; |
| char s_dummy1[62]; |
| char s_volume_name[VOLNAMSZ]; |
| char s_last_mounted[64]; |
| char s_dummy2[824]; |
| } sb; |
| |
| int |
| open_e2fs (char *dev, int mode) { |
| int fd; |
| |
| fd = open(dev, mode); |
| if (fd < 0) { |
| perror(dev); |
| fprintf (stderr, "e2label: cannot open %s\n", dev); |
| exit(1); |
| } |
| if (lseek(fd, 1024, SEEK_SET) != 1024) { |
| perror(dev); |
| fprintf (stderr, "e2label: cannot seek to superblock\n"); |
| exit(1); |
| } |
| if (read(fd, (char *) &sb, sizeof(sb)) != sizeof(sb)) { |
| perror(dev); |
| fprintf (stderr, "e2label: error reading superblock\n"); |
| exit(1); |
| } |
| if (sb.s_magic[0] + 256*sb.s_magic[1] != EXT2_SUPER_MAGIC) { |
| fprintf (stderr, "e2label: not an ext2 filesystem\n"); |
| exit(1); |
| } |
| |
| return fd; |
| } |
| |
| void |
| print_label (char *dev) { |
| char label[VOLNAMSZ+1]; |
| |
| open_e2fs (dev, O_RDONLY); |
| label[VOLNAMSZ] = 0; |
| strncpy(label, sb.s_volume_name, VOLNAMSZ); |
| printf("%s\n", label); |
| } |
| |
| void |
| change_label (char *dev, char *label) { |
| int fd; |
| |
| fd = open_e2fs(dev, O_RDWR); |
| memset(sb.s_volume_name, 0, VOLNAMSZ); |
| strncpy(sb.s_volume_name, label, VOLNAMSZ); |
| if (lseek(fd, 1024, SEEK_SET) != 1024) { |
| perror(dev); |
| fprintf (stderr, "e2label: cannot seek to superblock again\n"); |
| exit(1); |
| } |
| if (write(fd, (char *) &sb, sizeof(sb)) != sizeof(sb)) { |
| perror(dev); |
| fprintf (stderr, "e2label: error writing superblock\n"); |
| exit(1); |
| } |
| } |
| |
| int |
| main (int argc, char ** argv) { |
| if (argc == 2) |
| print_label(argv[1]); |
| else if (argc == 3) |
| change_label(argv[1], argv[2]); |
| else { |
| fprintf(stderr, "Usage: e2label device [newlabel]\n"); |
| exit(1); |
| } |
| return 0; |
| } |