root / image_creator / disk.py @ bf3a282c
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1 | ae48a082 | Nikos Skalkotos | # Copyright 2012 GRNET S.A. All rights reserved.
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2 | ae48a082 | Nikos Skalkotos | #
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3 | ae48a082 | Nikos Skalkotos | # Redistribution and use in source and binary forms, with or
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4 | ae48a082 | Nikos Skalkotos | # without modification, are permitted provided that the following
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5 | ae48a082 | Nikos Skalkotos | # conditions are met:
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6 | ae48a082 | Nikos Skalkotos | #
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7 | ae48a082 | Nikos Skalkotos | # 1. Redistributions of source code must retain the above
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8 | ae48a082 | Nikos Skalkotos | # copyright notice, this list of conditions and the following
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9 | ae48a082 | Nikos Skalkotos | # disclaimer.
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10 | ae48a082 | Nikos Skalkotos | #
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11 | ae48a082 | Nikos Skalkotos | # 2. Redistributions in binary form must reproduce the above
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12 | ae48a082 | Nikos Skalkotos | # copyright notice, this list of conditions and the following
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13 | ae48a082 | Nikos Skalkotos | # disclaimer in the documentation and/or other materials
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14 | ae48a082 | Nikos Skalkotos | # provided with the distribution.
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15 | ae48a082 | Nikos Skalkotos | #
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16 | ae48a082 | Nikos Skalkotos | # THIS SOFTWARE IS PROVIDED BY GRNET S.A. ``AS IS'' AND ANY EXPRESS
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17 | ae48a082 | Nikos Skalkotos | # OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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18 | ae48a082 | Nikos Skalkotos | # WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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19 | ae48a082 | Nikos Skalkotos | # PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL GRNET S.A OR
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20 | ae48a082 | Nikos Skalkotos | # CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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21 | ae48a082 | Nikos Skalkotos | # SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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22 | ae48a082 | Nikos Skalkotos | # LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
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23 | ae48a082 | Nikos Skalkotos | # USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
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24 | ae48a082 | Nikos Skalkotos | # AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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25 | ae48a082 | Nikos Skalkotos | # LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
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26 | ae48a082 | Nikos Skalkotos | # ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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27 | ae48a082 | Nikos Skalkotos | # POSSIBILITY OF SUCH DAMAGE.
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28 | ae48a082 | Nikos Skalkotos | #
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29 | ae48a082 | Nikos Skalkotos | # The views and conclusions contained in the software and
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30 | ae48a082 | Nikos Skalkotos | # documentation are those of the authors and should not be
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31 | ae48a082 | Nikos Skalkotos | # interpreted as representing official policies, either expressed
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32 | ae48a082 | Nikos Skalkotos | # or implied, of GRNET S.A.
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33 | d57775d4 | Nikos Skalkotos | |
34 | 979096dd | Nikos Skalkotos | from image_creator.util import get_command |
35 | f3845095 | Nikos Skalkotos | from image_creator.util import try_fail_repeat |
36 | c16850ae | Nikos Skalkotos | from image_creator.util import free_space |
37 | f5174d2c | Nikos Skalkotos | from image_creator.util import FatalError |
38 | a939e3b8 | Nikos Skalkotos | from image_creator.bundle_volume import BundleVolume |
39 | f5174d2c | Nikos Skalkotos | from image_creator.image import Image |
40 | 8eea5572 | Nikos Skalkotos | |
41 | d57775d4 | Nikos Skalkotos | import stat |
42 | d57775d4 | Nikos Skalkotos | import os |
43 | d57775d4 | Nikos Skalkotos | import tempfile |
44 | d57775d4 | Nikos Skalkotos | import uuid |
45 | f6ea8d02 | Nikos Skalkotos | import shutil |
46 | 8c574358 | Nikos Skalkotos | |
47 | 3ccb2618 | Nikos Skalkotos | dd = get_command('dd')
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48 | 3ccb2618 | Nikos Skalkotos | dmsetup = get_command('dmsetup')
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49 | 3ccb2618 | Nikos Skalkotos | losetup = get_command('losetup')
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50 | 3ccb2618 | Nikos Skalkotos | blockdev = get_command('blockdev')
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51 | 01a7cff3 | Nikos Skalkotos | |
52 | 01a7cff3 | Nikos Skalkotos | |
53 | c16850ae | Nikos Skalkotos | TMP_CANDIDATES = ['/var/tmp', os.path.expanduser('~'), '/mnt'] |
54 | c16850ae | Nikos Skalkotos | |
55 | c16850ae | Nikos Skalkotos | |
56 | d57775d4 | Nikos Skalkotos | class Disk(object): |
57 | 3b2f6619 | Nikos Skalkotos | """This class represents a hard disk hosting an Operating System
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58 | 3b2f6619 | Nikos Skalkotos |
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59 | 3b2f6619 | Nikos Skalkotos | A Disk instance never alters the source media it is created from.
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60 | 3b2f6619 | Nikos Skalkotos | Any change is done on a snapshot created by the device-mapper of
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61 | 3b2f6619 | Nikos Skalkotos | the Linux kernel.
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62 | 3b2f6619 | Nikos Skalkotos | """
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63 | d57775d4 | Nikos Skalkotos | |
64 | c16850ae | Nikos Skalkotos | def __init__(self, source, output, tmp=None): |
65 | 3b2f6619 | Nikos Skalkotos | """Create a new Disk instance out of a source media. The source
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66 | f3845095 | Nikos Skalkotos | media can be an image file, a block device or a directory.
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67 | f3845095 | Nikos Skalkotos | """
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68 | d57775d4 | Nikos Skalkotos | self._cleanup_jobs = []
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69 | f5174d2c | Nikos Skalkotos | self._images = []
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70 | d57775d4 | Nikos Skalkotos | self.source = source
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71 | e77e66a9 | Nikos Skalkotos | self.out = output
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72 | 9517bf29 | Nikos Skalkotos | self.meta = {}
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73 | c16850ae | Nikos Skalkotos | self.tmp = tempfile.mkdtemp(prefix='.snf_image_creator.', |
74 | c16850ae | Nikos Skalkotos | dir=self._get_tmp_dir(tmp))
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75 | c16850ae | Nikos Skalkotos | |
76 | f6ea8d02 | Nikos Skalkotos | self._add_cleanup(shutil.rmtree, self.tmp) |
77 | c16850ae | Nikos Skalkotos | |
78 | c16850ae | Nikos Skalkotos | def _get_tmp_dir(self, default=None): |
79 | 88f83027 | Nikos Skalkotos | """Check tmp directory candidates and return the one with the most
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80 | 88f83027 | Nikos Skalkotos | available space.
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81 | 88f83027 | Nikos Skalkotos | """
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82 | c16850ae | Nikos Skalkotos | if default is not None: |
83 | c16850ae | Nikos Skalkotos | return default
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84 | c16850ae | Nikos Skalkotos | |
85 | c16850ae | Nikos Skalkotos | space = map(free_space, TMP_CANDIDATES)
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86 | c16850ae | Nikos Skalkotos | |
87 | c16850ae | Nikos Skalkotos | max_idx = 0
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88 | c16850ae | Nikos Skalkotos | max_val = space[0]
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89 | c16850ae | Nikos Skalkotos | for i, val in zip(range(len(space)), space): |
90 | c16850ae | Nikos Skalkotos | if val > max_val:
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91 | c16850ae | Nikos Skalkotos | max_val = val |
92 | c16850ae | Nikos Skalkotos | max_idx = i |
93 | c16850ae | Nikos Skalkotos | |
94 | c16850ae | Nikos Skalkotos | # Return the candidate path with more available space
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95 | c16850ae | Nikos Skalkotos | return TMP_CANDIDATES[max_idx]
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96 | d57775d4 | Nikos Skalkotos | |
97 | d57775d4 | Nikos Skalkotos | def _add_cleanup(self, job, *args): |
98 | 88f83027 | Nikos Skalkotos | """Add a new job in the cleanup list"""
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99 | d57775d4 | Nikos Skalkotos | self._cleanup_jobs.append((job, args))
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100 | d57775d4 | Nikos Skalkotos | |
101 | d57775d4 | Nikos Skalkotos | def _losetup(self, fname): |
102 | 88f83027 | Nikos Skalkotos | """Setup a loop device and add it to the cleanup list. The loop device
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103 | 88f83027 | Nikos Skalkotos | will be detached when cleanup is called.
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104 | 88f83027 | Nikos Skalkotos | """
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105 | 3ccb2618 | Nikos Skalkotos | loop = losetup('-f', '--show', fname) |
106 | ae48a082 | Nikos Skalkotos | loop = loop.strip() # remove the new-line char
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107 | f3845095 | Nikos Skalkotos | self._add_cleanup(try_fail_repeat, losetup, '-d', loop) |
108 | 3ccb2618 | Nikos Skalkotos | return loop
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109 | d57775d4 | Nikos Skalkotos | |
110 | d57775d4 | Nikos Skalkotos | def _dir_to_disk(self): |
111 | 88f83027 | Nikos Skalkotos | """Create a disk out of a directory"""
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112 | 9e4b4de2 | Nikos Skalkotos | if self.source == '/': |
113 | 8eea5572 | Nikos Skalkotos | bundle = BundleVolume(self.out, self.meta) |
114 | c16850ae | Nikos Skalkotos | image = '%s/%s.diskdump' % (self.tmp, uuid.uuid4().hex) |
115 | 567891a6 | Nikos Skalkotos | |
116 | 567891a6 | Nikos Skalkotos | def check_unlink(path): |
117 | 567891a6 | Nikos Skalkotos | if os.path.exists(path):
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118 | 567891a6 | Nikos Skalkotos | os.unlink(path) |
119 | 567891a6 | Nikos Skalkotos | |
120 | 567891a6 | Nikos Skalkotos | self._add_cleanup(check_unlink, image)
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121 | 567891a6 | Nikos Skalkotos | bundle.create_image(image) |
122 | 69a4f894 | Nikos Skalkotos | return self._losetup(image) |
123 | 9e4b4de2 | Nikos Skalkotos | raise FatalError("Using a directory as media source is supported") |
124 | d57775d4 | Nikos Skalkotos | |
125 | d57775d4 | Nikos Skalkotos | def cleanup(self): |
126 | 3b2f6619 | Nikos Skalkotos | """Cleanup internal data. This needs to be called before the
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127 | 3b2f6619 | Nikos Skalkotos | program ends.
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128 | 3b2f6619 | Nikos Skalkotos | """
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129 | 9c354f13 | Nikos Skalkotos | try:
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130 | f5174d2c | Nikos Skalkotos | while len(self._images): |
131 | f5174d2c | Nikos Skalkotos | image = self._images.pop()
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132 | f5174d2c | Nikos Skalkotos | image.destroy() |
133 | 9c354f13 | Nikos Skalkotos | finally:
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134 | 9c354f13 | Nikos Skalkotos | # Make sure those are executed even if one of the device.destroy
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135 | 9c354f13 | Nikos Skalkotos | # methods throws exeptions.
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136 | 9c354f13 | Nikos Skalkotos | while len(self._cleanup_jobs): |
137 | 9c354f13 | Nikos Skalkotos | job, args = self._cleanup_jobs.pop()
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138 | 9c354f13 | Nikos Skalkotos | job(*args) |
139 | d57775d4 | Nikos Skalkotos | |
140 | e22aa3a9 | Nikos Skalkotos | def snapshot(self): |
141 | e22aa3a9 | Nikos Skalkotos | """Creates a snapshot of the original source media of the Disk
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142 | e22aa3a9 | Nikos Skalkotos | instance.
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143 | 3b2f6619 | Nikos Skalkotos | """
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144 | 22a6d232 | Nikos Skalkotos | |
145 | 663f5f80 | Nikos Skalkotos | self.out.output("Examining source media `%s' ..." % self.source, False) |
146 | 3f70f242 | Nikos Skalkotos | sourcedev = self.source
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147 | 3f70f242 | Nikos Skalkotos | mode = os.stat(self.source).st_mode
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148 | 3f70f242 | Nikos Skalkotos | if stat.S_ISDIR(mode):
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149 | 279f2c7d | Nikos Skalkotos | self.out.success('looks like a directory') |
150 | 8eea5572 | Nikos Skalkotos | return self._dir_to_disk() |
151 | 3f70f242 | Nikos Skalkotos | elif stat.S_ISREG(mode):
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152 | 279f2c7d | Nikos Skalkotos | self.out.success('looks like an image file') |
153 | 3f70f242 | Nikos Skalkotos | sourcedev = self._losetup(self.source) |
154 | 3f70f242 | Nikos Skalkotos | elif not stat.S_ISBLK(mode): |
155 | e9a2d318 | Nikos Skalkotos | raise FatalError("Invalid media source. Only block devices, " |
156 | f99fe99d | Nikos Skalkotos | "regular files and directories are supported.")
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157 | 3f70f242 | Nikos Skalkotos | else:
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158 | e77e66a9 | Nikos Skalkotos | self.out.success('looks like a block device') |
159 | d57775d4 | Nikos Skalkotos | |
160 | d57775d4 | Nikos Skalkotos | # Take a snapshot and return it to the user
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161 | 3afe6b44 | Nikos Skalkotos | self.out.output("Snapshotting media source ...", False) |
162 | 8fed77f7 | Nikos Skalkotos | size = blockdev('--getsz', sourcedev)
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163 | c16850ae | Nikos Skalkotos | cowfd, cow = tempfile.mkstemp(dir=self.tmp)
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164 | 3f70f242 | Nikos Skalkotos | os.close(cowfd) |
165 | 3f70f242 | Nikos Skalkotos | self._add_cleanup(os.unlink, cow)
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166 | 8fed77f7 | Nikos Skalkotos | # Create cow sparse file
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167 | 8fed77f7 | Nikos Skalkotos | dd('if=/dev/null', 'of=%s' % cow, 'bs=512', 'seek=%d' % int(size)) |
168 | 3f70f242 | Nikos Skalkotos | cowdev = self._losetup(cow)
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169 | 3f70f242 | Nikos Skalkotos | |
170 | 3f70f242 | Nikos Skalkotos | snapshot = uuid.uuid4().hex |
171 | 3f70f242 | Nikos Skalkotos | tablefd, table = tempfile.mkstemp() |
172 | 3f70f242 | Nikos Skalkotos | try:
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173 | f99fe99d | Nikos Skalkotos | os.write(tablefd, "0 %d snapshot %s %s n 8" %
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174 | f99fe99d | Nikos Skalkotos | (int(size), sourcedev, cowdev))
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175 | 3f70f242 | Nikos Skalkotos | dmsetup('create', snapshot, table)
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176 | f3845095 | Nikos Skalkotos | self._add_cleanup(try_fail_repeat, dmsetup, 'remove', snapshot) |
177 | 3f70f242 | Nikos Skalkotos | |
178 | 3f70f242 | Nikos Skalkotos | finally:
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179 | 3f70f242 | Nikos Skalkotos | os.unlink(table) |
180 | e77e66a9 | Nikos Skalkotos | self.out.success('done') |
181 | e22aa3a9 | Nikos Skalkotos | return "/dev/mapper/%s" % snapshot |
182 | e22aa3a9 | Nikos Skalkotos | |
183 | f5174d2c | Nikos Skalkotos | def get_image(self, media): |
184 | c78ac789 | Nikos Skalkotos | """Returns a newly created Image instance."""
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185 | e22aa3a9 | Nikos Skalkotos | |
186 | f5174d2c | Nikos Skalkotos | image = Image(media, self.out)
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187 | f5174d2c | Nikos Skalkotos | self._images.append(image)
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188 | f5174d2c | Nikos Skalkotos | image.enable() |
189 | f5174d2c | Nikos Skalkotos | return image
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190 | d57775d4 | Nikos Skalkotos | |
191 | f5174d2c | Nikos Skalkotos | def destroy_image(self, image): |
192 | c78ac789 | Nikos Skalkotos | """Destroys an Image instance previously created by get_image method.
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193 | 3b2f6619 | Nikos Skalkotos | """
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194 | f5174d2c | Nikos Skalkotos | self._images.remove(image)
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195 | f5174d2c | Nikos Skalkotos | image.destroy() |
196 | d603d80d | Nikos Skalkotos | |
197 | d57775d4 | Nikos Skalkotos | # vim: set sta sts=4 shiftwidth=4 sw=4 et ai : |