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https://git.kernel.org/pub/scm/fs/ext2/e2fsprogs.git
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bc56227376
The printf("%.*s") format requires both the buffer size and buffer
pointer to be specified for each use. Since this is repeatedly given
as "(int)sizeof(buf), (char *)buf" for mmp_nodename and mmp_bdevname
fields, with typecasts to avoid compiler warnings.
Add a helper macro EXT2_LEN_STR() to avoid repeated boilerplate code.
This can also be used for other superblock buffer fields that may not
have NUL-terminated strings (e.g. s_volume_name, s_last_mounted,
s_{first,last}_error_func, s_mount_opts) to simplify code and avoid
the need for temporary buffers for NUL-termination.
Annotate the superblock string fields that may not be NUL-terminated.
Signed-off-by: Andreas Dilger <adilger@dilger.ca>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
122 lines
2.6 KiB
C
122 lines
2.6 KiB
C
/*
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* e2label.c - Print or change the volume label on an ext2 fs
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*
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* Written by Andries Brouwer (aeb@cwi.nl), 970714
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*
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* Copyright 1997, 1998 by Theodore Ts'o.
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*
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* %Begin-Header%
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* This file may be redistributed under the terms of the GNU Public
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* License.
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* %End-Header%
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*/
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#include "config.h"
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#include <stdio.h>
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#include <string.h>
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#include <fcntl.h>
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#include <ctype.h>
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#include <termios.h>
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#include <time.h>
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#ifdef HAVE_GETOPT_H
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#include <getopt.h>
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#else
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extern char *optarg;
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extern int optind;
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#endif
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#ifdef HAVE_UNISTD_H
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#include <unistd.h>
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#endif
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#ifdef HAVE_STDLIB_H
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#include <stdlib.h>
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#endif
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#ifdef HAVE_ERRNO_H
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#include <errno.h>
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#endif
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#include "support/nls-enable.h"
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#define EXT2_SUPER_MAGIC 0xEF53
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#define VOLNAMSZ 16
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struct ext2_super_block {
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char s_dummy0[56];
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unsigned char s_magic[2];
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char s_dummy1[62];
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char s_volume_name[VOLNAMSZ];
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char s_last_mounted[64];
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char s_dummy2[824];
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} sb;
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static int open_e2fs (char *dev, int mode)
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{
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int fd;
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fd = open(dev, mode);
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if (fd < 0) {
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perror(dev);
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fprintf (stderr, _("e2label: cannot open %s\n"), dev);
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exit(1);
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}
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if (lseek(fd, 1024, SEEK_SET) != 1024) {
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perror(dev);
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fprintf (stderr, _("e2label: cannot seek to superblock\n"));
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exit(1);
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}
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if (read(fd, (char *) &sb, sizeof(sb)) != sizeof(sb)) {
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perror(dev);
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fprintf (stderr, _("e2label: error reading superblock\n"));
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exit(1);
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}
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if (sb.s_magic[0] + 256*sb.s_magic[1] != EXT2_SUPER_MAGIC) {
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fprintf (stderr, _("e2label: not an ext2 filesystem\n"));
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exit(1);
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}
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return fd;
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}
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static void print_label (char *dev)
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{
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char label[VOLNAMSZ+1];
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open_e2fs (dev, O_RDONLY);
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snprintf(label, sizeof(label), "%.*s", EXT2_LEN_STR(sb.s_volume_name));
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label[VOLNAMSZ] = 0;
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printf("%s\n", label);
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}
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static void change_label (char *dev, char *label)
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{
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int fd;
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fd = open_e2fs(dev, O_RDWR);
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memset(sb.s_volume_name, 0, VOLNAMSZ);
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strncpy(sb.s_volume_name, label, VOLNAMSZ);
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if (strlen(label) > VOLNAMSZ)
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fprintf(stderr, _("Warning: label too long, truncating.\n"));
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if (lseek(fd, 1024, SEEK_SET) != 1024) {
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perror(dev);
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fprintf (stderr, _("e2label: cannot seek to superblock again\n"));
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exit(1);
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}
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if (write(fd, (char *) &sb, sizeof(sb)) != sizeof(sb)) {
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perror(dev);
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fprintf (stderr, _("e2label: error writing superblock\n"));
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exit(1);
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}
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}
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int main (int argc, char ** argv)
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{
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if (argc == 2)
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print_label(argv[1]);
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else if (argc == 3)
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change_label(argv[1], argv[2]);
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else {
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fprintf(stderr, _("Usage: e2label device [newlabel]\n"));
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exit(1);
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}
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return 0;
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}
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