swaplabel: new command
Print or change the label / UUID of a swap area.
[kzak@redhat.com: - code refactoring
- add long options
- clean up Makefile.am]
Signed-off-by: Jason Borden <jborden@bluehost.com>
Signed-off-by: Karel Zak <kzak@redhat.com>
This commit is contained in:
Jason Borden
Karel Zak
parent
1f7a33f135
commit
4dddc2d4aa
2
AUTHORS
2
AUTHORS
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@ -35,6 +35,8 @@ AUTHORS (merged projects & commands):
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Jeremy Katz <katzj@redhat.com>
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unshare: Mikhail Gusarov <dottedmag@dottedmag.net>
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wipefs: Karel Zak <kzak@redhat.com>
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swaplabel: Jason Borden <jborden@bluehost.com>
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Karel Zak <kzak@redhat.com>
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CONTRIBUTORS:
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@ -10,3 +10,4 @@ mkswap
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mkfs.cramfs
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elvtune
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raw
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swaplabel
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@ -5,17 +5,32 @@ if LINUX
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utils_common += ../lib/linux_version.c
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endif
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if HAVE_UUID
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if BUILD_LIBUUID
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uuid_cflags = -I$(ul_libuuid_srcdir)
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uuid_ldadd = $(ul_libuuid_la)
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else
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uuid_cflags = $(UUID_CFLAGS)
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uuid_ldadd = $(UUID_LIBS)
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endif
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endif
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dist_man_MANS = isosize.8 mkfs.8 mkswap.8 \
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fsck.minix.8 mkfs.minix.8 mkfs.bfs.8
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sbin_PROGRAMS = mkfs mkswap fsck.minix mkfs.minix mkfs.bfs
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fsck_minix_SOURCES = fsck.minix.c minix.h
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mkfs_minix_SOURCES = mkfs.minix.c minix.h $(utils_common)
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mkfs_bfs_SOURCES = mkfs.bfs.c $(utils_common)
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swaplabel_SOURCES = swaplabel.c $(utils_common)
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swaplabel_LDADD = $(uuid_ldadd)
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swaplabel_CFLAGS = $(AM_CFLAGS) $(uuid_cflags)
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mkswap_SOURCES = mkswap.c $(utils_common) ../lib/wholedisk.c
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mkswap_LDADD =
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mkswap_CFLAGS = $(AM_CFLAGS)
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mkswap_LDADD = $(uuid_ldadd)
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mkswap_CFLAGS = $(AM_CFLAGS) $(uuid_cflags)
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usrbin_exec_PROGRAMS = isosize
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usrsbin_exec_PROGRAMS =
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@ -27,6 +42,13 @@ usrsbin_exec_PROGRAMS += fdformat
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blockdev_SOURCES = blockdev.c $(utils_common)
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endif
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if BUILD_LIBBLKID
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sbin_PROGRAMS += swaplabel
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dist_man_MANS += swaplabel.8
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swaplabel_LDADD += $(ul_libblkid_la)
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swaplabel_CFLAGS += -I$(ul_libblkid_incdir)
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endif
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if BUILD_ELVTUNE
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sbin_PROGRAMS += elvtune
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dist_man_MANS += elvtune.8
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@ -49,16 +71,6 @@ fsck_cramfs_LDADD = -lz
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mkfs_cramfs_LDADD = -lz
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endif
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if HAVE_UUID
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if BUILD_LIBUUID
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mkswap_LDADD += $(ul_libuuid_la)
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mkswap_CFLAGS += -I$(ul_libuuid_srcdir)
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else
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mkswap_LDADD += $(UUID_LIBS)
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mkswap_CFLAGS += $(UUID_CFLAGS)
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endif
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endif
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if BUILD_LIBBLKID
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# only in-tree libblkid has partitions parsing support
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mkswap_LDADD += $(ul_libblkid_la)
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@ -0,0 +1,66 @@
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.\" Copyright 2010 Jason Borden <jborden@bluehost.com>
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.\"
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.\" This file may be copied under the terms of the GNU Public License.
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.\"
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.TH SWAPLABEL 8 "2 April 2010" "Linux" "Linux Programmer's Manual"
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.SH NAME
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swaplabel \- Print or change the label / UUID of a swap area
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.SH SYNOPSIS
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.B swaplabel
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.RB [ \-L
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.IR label ]
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.RB [ \-U
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.IR UUID ]
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.I device
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.SH DESCRIPTION
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.B swaplabel
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will display or change the label / UUID of a swap partition located on
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.IR device
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(or regular file).
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.PP
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If the optional arguments
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.B \-L
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and
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.B \-U
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are not present,
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.B swaplabel
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will simply display the awap area label and UUID of
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.IR device .
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.PP
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If an optional argument is present, then
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.B swaplabel
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will change the appropriate value of
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.IR device .
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These values can also be set during swap creation using
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.BR mkswap (8).
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The
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.B swaplabel
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utility allows to change the label or UUID on actively used swap device.
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.SH OPTIONS
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.IP "\fB\-h, \-\-help\fP"
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Print help and exit.
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.IP "\fB\-L, \-\-label\fP \fIlabel\fP"
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Specify a new label for
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.IR device .
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Swap partition labels can be at most 16 characters long. If
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.IR label
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is longer than 16 characters,
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.B swapinfo
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will truncate it and print a warning message.
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.IP "\fB\-U, \-\-uuid\fP \fIuuid\fP"
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Specify a new UUID for
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.IR device .
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.IR UUID
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must be in the standard 8-4-4-4-12 character format, such as is ouput by
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.BR uuidgen (1) .
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.PP
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.SH AUTHOR
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.B swaplabel
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was written by Jason Borden <jborden@bluehost.com> and Karel Zak <kzak@redhat.com>.
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.SH AVAILABILITY
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.B swaplabel
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is part of the util-linux-ng package and is available from ftp://ftp.kernel.org/pub/linux/utils/util-linux-ng/.
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.SH SEE ALSO
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.BR mkswap (8),
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.BR swapon (8),
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.BR uuidgen (1)
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@ -0,0 +1,226 @@
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/*
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* swaplabel.c - Print or change the label / UUID of a swap partition
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*
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* Copyright (C) 2010 Jason Borden <jborden@bluehost.com>
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* Copyright (C) 2010 Karel Zak <kzak@redhat.com>
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*
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* Usage: swaplabel [-L label] [-U UUID] device
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*
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* This file may be redistributed under the terms of the GNU Public License
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* version 2 or later.
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*
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*/
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#include <stdio.h>
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#include <stddef.h>
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#include <string.h>
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#include <fcntl.h>
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <unistd.h>
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#include <stdlib.h>
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#include <err.h>
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#include <blkid.h>
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#include <getopt.h>
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#ifdef HAVE_LIBUUID
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# ifdef HAVE_UUID_UUID_H
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# include <uuid/uuid.h>
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# else
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# include <uuid.h>
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# endif
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#endif
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#include "c.h"
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#include "writeall.h"
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#include "swapheader.h"
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#include "xstrncpy.h"
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#include "nls.h"
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#define SWAP_UUID_OFFSET (offsetof(struct swap_header_v1_2, uuid))
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#define SWAP_LABEL_OFFSET (offsetof(struct swap_header_v1_2, volume_name))
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/*
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* Returns new libblkid prober. This function call exit() on error.
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*/
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static blkid_probe get_swap_prober(const char *devname)
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{
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blkid_probe pr;
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int rc;
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const char *version = NULL;
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char *swap_filter[] = { "swap", NULL };
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pr = blkid_new_probe_from_filename(devname);
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if (!pr) {
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warn(_("%s: unable to probe device"), devname);
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return NULL;
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}
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blkid_probe_enable_superblocks(pr, TRUE);
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blkid_probe_set_superblocks_flags(pr,
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BLKID_SUBLKS_LABEL | BLKID_SUBLKS_UUID |
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BLKID_SUBLKS_VERSION);
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blkid_probe_filter_superblocks_type(pr, BLKID_FLTR_ONLYIN, swap_filter);
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rc = blkid_do_safeprobe(pr);
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if (rc == -1)
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warn(_("%s: unable to probe device"), devname);
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else if (rc == -2)
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warnx(_("%s: ambivalent probing result, use wipefs(8)"), devname);
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else if (rc == 1)
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warnx(_("%s: not a valid swap partition"), devname);
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if (rc == 0) {
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/* supported is SWAPSPACE2 only */
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blkid_probe_lookup_value(pr, "VERSION", &version, NULL);
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if (strcmp(version, "2"))
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warnx(_("%s: unsupported swap version '%s'"),
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devname, version);
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else
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return pr;
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}
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blkid_free_probe(pr);
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return NULL;
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}
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/* Print the swap partition information */
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static int print_info(blkid_probe pr, const char *devname)
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{
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const char *data;
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if (!blkid_probe_lookup_value(pr, "LABEL", &data, NULL))
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printf("LABEL: %s\n", data);
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if (!blkid_probe_lookup_value(pr, "UUID", &data, NULL))
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printf("UUID: %s\n", data);
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return 0;
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}
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/* Change the swap partition info */
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static int change_info(const char *devname, const char *label, const char *uuid)
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{
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int fd;
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fd = open(devname, O_RDWR);
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if (fd < 0) {
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warn(_("%s: failed to open"), devname);
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goto err;
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}
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#ifdef HAVE_LIBUUID
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/* Write the uuid if it was provided */
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if (uuid) {
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uuid_t newuuid;
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if (uuid_parse(uuid, newuuid) == -1)
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warnx(_("failed to parse UUID: %s"), uuid);
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else {
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if (lseek(fd, SWAP_UUID_OFFSET, SEEK_SET) !=
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SWAP_UUID_OFFSET) {
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warn(_("%s: failed to seek to swap UUID"), devname);
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goto err;
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} else if (write_all(fd, newuuid, sizeof(newuuid))) {
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warn(_("%s: failed to write UUID"), devname);
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goto err;
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}
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}
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}
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#endif
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/* Write the label if it was provided */
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if (label) {
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char newlabel[SWAP_LABEL_LENGTH];
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if (lseek(fd, SWAP_LABEL_OFFSET, SEEK_SET) != SWAP_LABEL_OFFSET) {
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warn(_("%s: failed to seek to swap label "), devname);
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goto err;
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}
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memset(newlabel, 0, sizeof(newlabel));
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xstrncpy(newlabel, label, sizeof(newlabel));
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if (strlen(label) > strlen(newlabel))
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warnx(_("label is too long. Truncating it to '%s'"),
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newlabel);
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if (write_all(fd, newlabel, sizeof(newlabel))) {
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warn(_("%s: failed to write label"), devname);
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goto err;
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}
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}
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close(fd);
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return 0;
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err:
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if (fd >= 0)
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close(fd);
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return -1;
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}
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static void __attribute__((__noreturn__)) usage(FILE *out)
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{
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fprintf(out, _("Usage: %s [options] <device>\n\nOptions:\n"),
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program_invocation_short_name);
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fprintf(out, _(
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" -h, --help this help\n"
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" -L, --label <label> specify a new label\n"
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" -U, --uuid <uuid> specify a new uuid\n"));
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fprintf(out, _("\nFor more information see swaplabel(8).\n"));
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exit(out == stderr ? EXIT_FAILURE : EXIT_SUCCESS);
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}
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int main(int argc, char *argv[])
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{
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blkid_probe pr = NULL;
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char *uuid = NULL, *label = NULL, *devname;
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int c, rc = -1;
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struct option longopts[] = {
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{ "help", 0, 0, 'h' },
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{ "label", 1, 0, 'L' },
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{ "uuid", 1, 0, 'U' },
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{ NULL, 0, 0, 0 }
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};
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setlocale(LC_ALL, "");
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bindtextdomain(PACKAGE, LOCALEDIR);
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textdomain(PACKAGE);
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while ((c = getopt_long(argc, argv, "hL:U:", longopts, NULL)) != -1) {
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switch (c) {
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case 'h':
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usage(stdout);
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break;
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case 'L':
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label = optarg;
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break;
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case 'U':
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#ifdef HAVE_LIBUUID
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uuid = optarg;
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#else
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warnx(_("ignore -U (UUIDs are unsupported)"));
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#endif
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break;
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default:
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usage(stderr);
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break;
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}
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}
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if (optind == argc)
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usage(stderr);
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devname = argv[optind];
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pr = get_swap_prober(devname);
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if (pr) {
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if (uuid || label)
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rc = change_info(devname, label, uuid);
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else
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rc = print_info(pr, devname);
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blkid_free_probe(pr);
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}
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return rc ? EXIT_FAILURE : EXIT_SUCCESS;
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}
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@ -10,13 +10,17 @@ struct swap_header_v1 {
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unsigned int badpages[1];
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};
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#define SWAP_UUID_LENGTH 16
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#define SWAP_LABEL_LENGTH 16
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struct swap_header_v1_2 {
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char bootbits[1024]; /* Space for disklabel etc. */
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unsigned int version;
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unsigned int last_page;
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unsigned int nr_badpages;
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unsigned char uuid[16];
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char volume_name[16];
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unsigned char uuid[SWAP_UUID_LENGTH];
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char volume_name[SWAP_LABEL_LENGTH];
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unsigned int padding[117];
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unsigned int badpages[1];
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};
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