1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
|
#
# Copyright (C) 2017 Codethink Limited
#
# This program is free software; you can redistribute it and/or
# modify it under the terms of the GNU Lesser General Public
# License as published by the Free Software Foundation; either
# version 2 of the License, or (at your option) any later version.
#
# This library is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
# Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public
# License along with this library. If not, see <http://www.gnu.org/licenses/>.
#
# Authors:
# Jonathan Maw <jonathan.maw@codethink.co.uk>
"""
tar - stage files from tar archives
===================================
**Host dependencies:**
* lzip (for .tar.lz files)
**Usage:**
.. code:: yaml
# Specify the tar source kind
kind: tar
# Specify the tar url. Using an alias defined in your project
# configuration is encouraged. 'bst source track' will update the
# sha256sum in 'ref' to the downloaded file's sha256sum.
url: upstream:foo.tar
# Specify the ref. It's a sha256sum of the file you download.
ref: 6c9f6f68a131ec6381da82f2bff978083ed7f4f7991d931bfa767b7965ebc94b
# Specify a glob pattern to indicate the base directory to extract
# from the tarball. The first matching directory will be used.
#
# Note that this is '*' by default since most standard release
# tarballs contain a self named subdirectory at the root which
# contains the files one normally wants to extract to build.
#
# To extract the root of the tarball directly, this can be set
# to an empty string.
base-dir: '*'
See :ref:`built-in functionality doumentation <core_source_builtins>` for
details on common configuration options for sources.
"""
import os
import tarfile
from contextlib import contextmanager
from tempfile import TemporaryFile
from buildstream import SourceError
from buildstream import utils
from ._downloadablefilesource import DownloadableFileSource
class ReadableTarInfo(tarfile.TarInfo):
"""
The goal is to override `TarFile`'s `extractall` semantics by ensuring that on extraction, the
files are readable by the owner of the file. This is done by overriding the accessor for the
`mode` attribute in `TarInfo`, the class that encapsulates the internal meta-data of the tarball,
so that the owner-read bit is always set.
"""
@property
def mode(self):
# ensure file is readable by owner
return self.__permission | 0o400
@mode.setter
def mode(self, permission):
self.__permission = permission
class TarSource(DownloadableFileSource):
# pylint: disable=attribute-defined-outside-init
def configure(self, node):
super().configure(node)
self.base_dir = node.get_str("base-dir", "*")
node.validate_keys(DownloadableFileSource.COMMON_CONFIG_KEYS + ["base-dir"])
def preflight(self):
self.host_lzip = None
if self.url.endswith(".lz"):
self.host_lzip = utils.get_host_tool("lzip")
def get_unique_key(self):
return super().get_unique_key() + [self.base_dir]
@contextmanager
def _run_lzip(self):
assert self.host_lzip
with TemporaryFile() as lzip_stdout:
with open(self._get_mirror_file(), "r") as lzip_file:
self.call([self.host_lzip, "-d"], stdin=lzip_file, stdout=lzip_stdout)
lzip_stdout.seek(0, 0)
yield lzip_stdout
@contextmanager
def _get_tar(self):
if self.url.endswith(".lz"):
with self._run_lzip() as lzip_dec:
with tarfile.open(
fileobj=lzip_dec, mode="r:", tarinfo=ReadableTarInfo
) as tar:
yield tar
else:
with tarfile.open(self._get_mirror_file(), tarinfo=ReadableTarInfo) as tar:
yield tar
def stage(self, directory):
try:
with self._get_tar() as tar:
base_dir = None
if self.base_dir:
base_dir = self._find_base_dir(tar, self.base_dir)
if base_dir:
tar.extractall(
path=directory,
members=self._extract_members(tar, base_dir, directory),
)
else:
tar.extractall(path=directory)
except (tarfile.TarError, OSError) as e:
raise SourceError("{}: Error staging source: {}".format(self, e)) from e
# Override and translate which filenames to extract
def _extract_members(self, tar, base_dir, target_dir):
# Assert that a tarfile is safe to extract; specifically, make
# sure that we don't do anything outside of the target
# directory (this is possible, if, say, someone engineered a
# tarfile to contain paths that start with ..).
def assert_safe(member):
final_path = os.path.abspath(os.path.join(target_dir, member.path))
if not final_path.startswith(target_dir):
raise SourceError(
"{}: Tarfile attempts to extract outside the staging area: "
"{} -> {}".format(self, member.path, final_path)
)
if member.islnk():
linked_path = os.path.abspath(os.path.join(target_dir, member.linkname))
if not linked_path.startswith(target_dir):
raise SourceError(
"{}: Tarfile attempts to hardlink outside the staging area: "
"{} -> {}".format(self, member.path, final_path)
)
# Don't need to worry about symlinks because they're just
# files here and won't be able to do much harm once we are
# in a sandbox.
if not base_dir.endswith(os.sep):
base_dir = base_dir + os.sep
L = len(base_dir)
for member in tar.getmembers():
# First, ensure that a member never starts with `./`
if member.path.startswith("./"):
member.path = member.path[2:]
if member.islnk() and member.linkname.startswith("./"):
member.linkname = member.linkname[2:]
# Now extract only the paths which match the normalized path
if member.path.startswith(base_dir):
# Hardlinks are smart and collapse into the "original"
# when their counterpart doesn't exist. This means we
# only need to modify links to files whose location we
# change.
#
# Since we assert that we're not linking to anything
# outside the target directory, this should only ever
# be able to link to things inside the target
# directory, so we should cover all bases doing this.
#
if member.islnk() and member.linkname.startswith(base_dir):
member.linkname = member.linkname[L:]
member.path = member.path[L:]
assert_safe(member)
yield member
# We want to iterate over all paths of a tarball, but getmembers()
# is not enough because some tarballs simply do not contain the leading
# directory paths for the archived files.
def _list_tar_paths(self, tar):
visited = set()
for member in tar.getmembers():
# Remove any possible leading './', offer more consistent behavior
# across tarballs encoded with or without a leading '.'
member_name = member.name.lstrip("./")
if not member.isdir():
# Loop over the components of a path, for a path of a/b/c/d
# we will first visit 'a', then 'a/b' and then 'a/b/c', excluding
# the final component
components = member_name.split("/")
for i in range(len(components) - 1):
dir_component = "/".join([components[j] for j in range(i + 1)])
if dir_component not in visited:
visited.add(dir_component)
try:
# Dont yield directory members which actually do
# exist in the archive
_ = tar.getmember(dir_component)
except KeyError:
if dir_component != ".":
yield dir_component
continue
# Avoid considering the '.' directory, if any is included in the archive
# this is to avoid the default 'base-dir: *' value behaving differently
# depending on whether the tarball was encoded with a leading '.' or not
elif member_name == ".":
continue
yield member_name
def _find_base_dir(self, tar, pattern):
paths = self._list_tar_paths(tar)
matches = sorted(list(utils.glob(paths, pattern)))
if not matches:
raise SourceError(
"{}: Could not find base directory matching pattern: {}".format(
self, pattern
)
)
return matches[0]
def setup():
return TarSource
|
