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273c3903 MM |
1 | #!/usr/bin/perl |
2 | # ntfsresizecopy: Copy an NTFS filesystem from one block device to another, | |
3 | # resizing it to the size of the destination device in the process. (Uses | |
4 | # ntfsprogs from http://linux-ntfs.org/doku.php?id=ntfsprogs .) This is | |
5 | # EXPERIMENTAL; after using this script, you should mount the destination | |
6 | # read-only and check that everything looks intact. | |
7 | # | |
8 | # usage: ntfsresizecopy SRC DEST | |
9 | # | |
10 | # An expanding copy is just done with ntfsclone followed by ntfsresize. | |
11 | # A shrinking copy is done by running ntfsclone and ntfsresize on devices | |
12 | # specially crafted with the Linux device-mapper (requires dmsetup and losetup); | |
13 | # you may save time by checking first that the shrinkage is possible with | |
14 | # `ntfsresize -n -s SIZE SRC'. | |
15 | # | |
16 | # The special shrinking technique should be applicable to any filesystem type | |
17 | # that has an in-place shrinking command that doesn't write outside the new | |
18 | # size. Just change the calls to ntfsclone and ntfsresize; ntfsclone can be | |
19 | # replaced by a dd of the beginning of the source for filesystems that don't | |
20 | # have a sparse clone command. | |
21 | # | |
22 | # Version 2008.06.01 | |
23 | # Maintained at http://mattmccutchen.net/utils/#ntfsresizecopy . | |
24 | # -- Matt McCutchen <matt@mattmccutchen.net> | |
25 | ||
26 | use strict; | |
27 | use warnings; | |
28 | use Fcntl qw(SEEK_SET SEEK_CUR SEEK_END); | |
29 | use List::Util qw(min); | |
30 | use filetest 'access'; | |
31 | $| = 1; | |
32 | ||
33 | # These are not currently used but might be useful when modifying this script | |
34 | # for a filesystem that doesn't have an ntfsclone analogue. | |
35 | #my $shownProgress = ''; # cursor at its end | |
36 | #sub showProgress($) { | |
37 | # my ($newProgress) = @_; | |
38 | # my $shrink = length($shownProgress) - length($newProgress); | |
39 | # print("\b" x length($shownProgress), $newProgress, | |
40 | # $shrink > 0 ? (" " x $shrink, "\b" x $shrink) : ()); | |
41 | # $shownProgress = $newProgress; | |
42 | #} | |
43 | #sub dd(**$) { | |
44 | # my ($srcfh, $destfh, $len) = @_; | |
45 | # while ($len > 0) { | |
46 | # showProgress("$len bytes left"); | |
47 | # my $chunkLen = min(1048576, $len); | |
48 | # sysread($srcfh, my $data, $chunkLen) == $chunkLen or die 'read error'; | |
49 | # syswrite($destfh, $data, $chunkLen) == $chunkLen or die 'write error'; | |
50 | # $len -= $chunkLen; | |
51 | # } | |
52 | # showProgress(''); | |
53 | #} | |
54 | ||
55 | sub deviceSize(*) { | |
56 | # Determine the size of a device by seeking to its end. The ioctl used | |
57 | # by `blockdev --getsize64' might be more official, but this one is | |
58 | # easy and perhaps more portable. | |
59 | my ($fh) = @_; | |
60 | my $origPos = sysseek($fh, 0, SEEK_CUR) or die; | |
61 | my $size = sysseek($fh, 0, SEEK_END) or die; | |
62 | sysseek($fh, $origPos, SEEK_SET) or die; | |
63 | return 0 + $size; | |
64 | } | |
65 | # Wrappers for dmsetup and losetup | |
66 | sub dm_create($@) { | |
67 | my ($name, @table) = @_; | |
68 | open(my $toDms, '|-', 'dmsetup', 'create', $name) or die; | |
69 | print $toDms map(join(' ', @{$_}) . "\n", @table); | |
70 | close($toDms) or die "dmsetup create $name failed"; | |
71 | } | |
72 | sub dm_remove($) { | |
73 | my ($name) = @_; | |
74 | system('dmsetup', 'remove', $name) and warn "dmsetup remove $name failed"; | |
75 | } | |
76 | sub losetup($) { | |
77 | my ($file) = @_; | |
78 | open(my $fromLs, '-|', 'losetup', '-fs', $file); | |
79 | my $dev = <$fromLs>; | |
80 | close($fromLs) and defined($dev) or die "losetup -fs $file failed"; | |
81 | chomp($dev); | |
82 | return $dev; | |
83 | } | |
84 | sub losetup_d($) { | |
85 | my ($dev) = @_; | |
86 | system('losetup', '-d', $dev) and warn "losetup -d $dev failed"; | |
87 | } | |
88 | ||
89 | scalar(@ARGV) == 2 or die <<EOU; | |
90 | usage: ntfsresizecopy SRC DEST | |
91 | See the comment at the top of the script for more information. | |
92 | EOU | |
93 | my ($src, $dest) = @ARGV[0..1]; | |
94 | ||
95 | open(my $srcfh, '<', $src) or die "open($src) for reading failed: $!"; | |
96 | -b $srcfh or die "Source $src must be a block device.\n"; | |
97 | my $srcRdev = (stat(_))[6]; | |
98 | open(my $destfh, '+<', $dest) or die "open($dest) for reading/writing failed: $!"; | |
99 | -b $destfh or die "Destination $dest must be a block device.\n"; | |
100 | my $destRdev = (stat(_))[6]; | |
101 | $srcRdev == $destRdev and die "Source $src and destination $dest must not be " | |
102 | . "the same block device.\nUse ntfsresize for in-place resizing.\n"; | |
103 | ||
104 | my ($srcSize, $destSize) = (deviceSize($srcfh), deviceSize($destfh)); | |
105 | # Assume that, since src and dest are block devices, sizes are divisible by 512. | |
106 | my ($srcBlocks, $destBlocks) = map($_ / 512, $srcSize, $destSize); | |
107 | my $shrinkBlocks = $srcBlocks - $destBlocks; | |
108 | ||
109 | print "Going to copy $src ($srcSize bytes) => $dest ($destSize bytes).\n"; | |
110 | ||
111 | if ($shrinkBlocks > 0) { | |
112 | ||
113 | print "\nSTEP 1: ntfsclone the beginning of the src to the dest.\n"; | |
114 | # Really, clone the whole src to a magical dest consisting of the real dest | |
115 | # followed by a zero target to make up the size difference. | |
116 | # Writes outside the dest's size will be lost to the zero target, but that | |
117 | # doesn't hurt anything. And under the assumption that the shrinkage is | |
118 | # possible, ntfsclone copies at most as much data as a simple dd of the | |
119 | # beginning of the src to the dest would. | |
120 | my $mdn = "ntfsresizecopy.$$.magicdest"; | |
121 | my $magicDest = "/dev/mapper/$mdn"; | |
122 | # If something in the "eval" fails, still clean up as much as possible. | |
123 | eval { | |
124 | dm_create($mdn, | |
125 | [0, $destBlocks, 'linear', $dest, 0], | |
126 | [$destBlocks, $shrinkBlocks, 'zero']); | |
127 | system('ntfsclone', '--overwrite', $magicDest, $src) and die 'ntfsclone failed.'; | |
128 | }; | |
129 | dm_remove($mdn); | |
130 | die $@ if $@; | |
131 | ||
132 | print "\n", <<EOM; | |
133 | STEP 2: ntfsresize the dest, bringing in the end of the src. | |
134 | NOTE: Please ignore ntfsresize's remarks about data loss (the src isn't being | |
135 | written so you haven't lost anything if this fails) and about shrinking the | |
136 | device (the device is already smaller). | |
137 | EOM | |
138 | # Really, resize a magical dest consisting of the real one plus the end of the | |
139 | # src. This leaves a shrunken filesystem on the beginning of the magical dest, | |
140 | # i.e., on the real dest. | |
141 | # ntfsresize doesn't seem to write outside the new size, but we use a snapshot | |
142 | # layer to be extra sure we don't mess up the src. The snapshot layer needs a | |
143 | # COW file that is at least one page in size, even though we expect no data to | |
144 | # be written to it. | |
145 | my $cowdev; | |
146 | eval { | |
147 | open(my $cowfh, "+>", undef) or die 'failed to create temporary COW file'; | |
148 | truncate($cowfh, 4096) or die 'failed to expand temporary COW file'; | |
149 | $cowdev = losetup("/proc/$$/fd/" . fileno($cowfh)); | |
150 | dm_create($mdn, | |
151 | [0, $destBlocks, 'linear', $dest, 0], | |
152 | [$destBlocks, $shrinkBlocks, 'snapshot', $src, $cowdev, 'N', 1]); | |
153 | open(my $toNr, '|-', 'ntfsresize', '-s', $destSize, $magicDest) or die 'ntfsresize failed.'; | |
154 | print $toNr "y\n"; # Confirm automatically because we aren't endangering the src. | |
155 | close($toNr) or die 'ntfsresize failed.'; | |
156 | }; | |
157 | dm_remove($mdn); | |
158 | losetup_d($cowdev) if defined($cowdev); | |
159 | die $@ if $@; | |
160 | ||
161 | } else { | |
162 | ||
163 | print "\nSTEP 1: ntfsclone the src to the dest.\n"; | |
164 | system('ntfsclone', '--overwrite', $dest, $src) and die 'ntfsclone failed.'; | |
165 | ||
166 | print "\n", <<EOM; | |
167 | STEP 2: ntfsresize the dest. | |
168 | NOTE: Please ignore ntfsresize's remarks about data loss (the src isn't being | |
169 | written so you haven't lost anything if this fails). | |
170 | EOM | |
171 | open(my $toNr, '|-', 'ntfsresize', '-s', $destSize, $dest) or die 'ntfsresize failed.'; | |
172 | print $toNr "y\n"; # Confirm automatically because we aren't endangering the src. | |
173 | close($toNr) or die 'ntfsresize failed.'; | |
174 | ||
175 | } | |
176 | ||
177 | print "\nFinished!\n"; | |
178 |