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# Copyright 2015 The Bazel Authors. All rights reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
"""Archive manipulation library for the Docker rules."""
# pylint: disable=g-import-not-at-top
import gzip
import io
import os
import subprocess
import tarfile
class SimpleArFile(object):
"""A simple AR file reader.
This enable to read AR file (System V variant) as described
in https://en.wikipedia.org/wiki/Ar_(Unix).
The standard usage of this class is:
with SimpleArFile(filename) as ar:
nextFile = ar.next()
while nextFile:
print(nextFile.filename)
nextFile = ar.next()
Upon error, this class will raise a ArError exception.
"""
# TODO(dmarting): We should use a standard library instead but python 2.7
# does not have AR reading library.
class ArError(Exception):
pass
class SimpleArFileEntry(object):
"""Represent one entry in a AR archive.
Attributes:
filename: the filename of the entry, as described in the archive.
timestamp: the timestamp of the file entry.
owner_id, group_id: numeric id of the user and group owning the file.
mode: unix permission mode of the file
size: size of the file
data: the content of the file.
"""
def __init__(self, f):
self.filename = f.read(16).decode('utf-8').strip()
if self.filename.endswith('/'): # SysV variant
self.filename = self.filename[:-1]
self.timestamp = int(f.read(12).strip())
self.owner_id = int(f.read(6).strip())
self.group_id = int(f.read(6).strip())
self.mode = int(f.read(8).strip(), 8)
self.size = int(f.read(10).strip())
pad = f.read(2)
if pad != b'\x60\x0a':
raise SimpleArFile.ArError('Invalid AR file header')
self.data = f.read(self.size)
MAGIC_STRING = b'!<arch>\n'
def __init__(self, filename):
self.filename = filename
def __enter__(self):
self.f = open(self.filename, 'rb')
if self.f.read(len(self.MAGIC_STRING)) != self.MAGIC_STRING:
raise self.ArError('Not a ar file: ' + self.filename)
return self
def __exit__(self, t, v, traceback):
self.f.close()
def next(self):
"""Read the next file. Returns None when reaching the end of file."""
# AR sections are two bit aligned using new lines.
if self.f.tell() % 2 != 0:
self.f.read(1)
# An AR sections is at least 60 bytes. Some file might contains garbage
# bytes at the end of the archive, ignore them.
if self.f.tell() > os.fstat(self.f.fileno()).st_size - 60:
return None
return self.SimpleArFileEntry(self.f)
class TarFileWriter(object):
"""A wrapper to write tar files."""
class Error(Exception):
pass
def __init__(self, name, compression='', root_directory='./'):
if compression in ['bzip2', 'bz2']:
mode = 'w:bz2'
else:
mode = 'w:'
self.gz = compression in ['tgz', 'gz']
# Support xz compression through xz... until we can use Py3
self.xz = compression in ['xz', 'lzma']
self.name = name
self.root_directory = root_directory.rstrip('/')
self.fileobj = None
if self.gz:
# The Tarfile class doesn't allow us to specify gzip's mtime attribute.
# Instead, we manually re-implement gzopen from tarfile.py and set mtime.
self.fileobj = gzip.GzipFile(
filename=name, mode='w', compresslevel=9, mtime=0)
self.tar = tarfile.open(name=name, mode=mode, fileobj=self.fileobj)
self.members = set([])
self.directories = set([])
def __enter__(self):
return self
def __exit__(self, t, v, traceback):
self.close()
def add_dir(self,
name,
path,
uid=0,
gid=0,
uname='',
gname='',
mtime=0,
mode=None,
depth=100):
"""Recursively add a directory.
Args:
name: the destination path of the directory to add.
path: the path of the directory to add.
uid: owner user identifier.
gid: owner group identifier.
uname: owner user names.
gname: owner group names.
mtime: modification time to put in the archive.
mode: unix permission mode of the file, default 0644 (0755).
depth: maximum depth to recurse in to avoid infinite loops
with cyclic mounts.
Raises:
TarFileWriter.Error: when the recursion depth has exceeded the
`depth` argument.
"""
if not (name == self.root_directory or name.startswith('/') or
name.startswith(self.root_directory + '/')):
name = os.path.join(self.root_directory, name)
if os.path.isdir(path):
# Remove trailing '/' (index -1 => last character)
if name[-1] == '/':
name = name[:-1]
# Add the x bit to directories to prevent non-traversable directories.
# The x bit is set only to if the read bit is set.
dirmode = (mode | ((0o444 & mode) >> 2)) if mode else mode
self.add_file(name + '/',
tarfile.DIRTYPE,
uid=uid,
gid=gid,
uname=uname,
gname=gname,
mtime=mtime,
mode=dirmode)
if depth <= 0:
raise self.Error('Recursion depth exceeded, probably in '
'an infinite directory loop.')
# Iterate over the sorted list of file so we get a deterministic result.
filelist = os.listdir(path)
filelist.sort()
for f in filelist:
new_name = os.path.join(name, f)
new_path = os.path.join(path, f)
self.add_dir(new_name, new_path, uid, gid, uname, gname, mtime, mode,
depth - 1)
else:
self.add_file(name,
tarfile.REGTYPE,
file_content=path,
uid=uid,
gid=gid,
uname=uname,
gname=gname,
mtime=mtime,
mode=mode)
def _addfile(self, info, fileobj=None):
"""Add a file in the tar file if there is no conflict."""
if not info.name.endswith('/') and info.type == tarfile.DIRTYPE:
# Enforce the ending / for directories so we correctly deduplicate.
info.name += '/'
if info.name not in self.members:
self.tar.addfile(info, fileobj)
self.members.add(info.name)
elif info.type != tarfile.DIRTYPE:
print('Duplicate file in archive: %s, '
'picking first occurrence' % info.name)
def add_file(self,
name,
kind=tarfile.REGTYPE,
content=None,
link=None,
file_content=None,
uid=0,
gid=0,
uname='',
gname='',
mtime=0,
mode=None):
"""Add a file to the current tar.
Args:
name: the name of the file to add.
kind: the type of the file to add, see tarfile.*TYPE.
content: a textual content to put in the file.
link: if the file is a link, the destination of the link.
file_content: file to read the content from. Provide either this
one or `content` to specifies a content for the file.
uid: owner user identifier.
gid: owner group identifier.
uname: owner user names.
gname: owner group names.
mtime: modification time to put in the archive.
mode: unix permission mode of the file, default 0644 (0755).
"""
if file_content and os.path.isdir(file_content):
# Recurse into directory
self.add_dir(name, file_content, uid, gid, uname, gname, mtime, mode)
return
if not (name == self.root_directory or name.startswith('/') or
name.startswith(self.root_directory + '/')):
name = os.path.join(self.root_directory, name)
if kind == tarfile.DIRTYPE:
name = name.rstrip('/')
if name in self.directories:
return
components = name.rsplit('/', 1)
if len(components) > 1:
d = components[0]
self.add_file(d,
tarfile.DIRTYPE,
uid=uid,
gid=gid,
uname=uname,
gname=gname,
mtime=mtime,
mode=0o755)
tarinfo = tarfile.TarInfo(name)
tarinfo.mtime = mtime
tarinfo.uid = uid
tarinfo.gid = gid
tarinfo.uname = uname
tarinfo.gname = gname
tarinfo.type = kind
if mode is None:
tarinfo.mode = 0o644 if kind == tarfile.REGTYPE else 0o755
else:
tarinfo.mode = mode
if link:
tarinfo.linkname = link
if content:
content_bytes = content.encode('utf-8')
tarinfo.size = len(content_bytes)
self._addfile(tarinfo, io.BytesIO(content_bytes))
elif file_content:
with open(file_content, 'rb') as f:
tarinfo.size = os.fstat(f.fileno()).st_size
self._addfile(tarinfo, f)
else:
if kind == tarfile.DIRTYPE:
self.directories.add(name)
self._addfile(tarinfo)
def add_tar(self,
tar,
rootuid=None,
rootgid=None,
numeric=False,
name_filter=None,
root=None):
"""Merge a tar content into the current tar, stripping timestamp.
Args:
tar: the name of tar to extract and put content into the current tar.
rootuid: user id that we will pretend is root (replaced by uid 0).
rootgid: group id that we will pretend is root (replaced by gid 0).
numeric: set to true to strip out name of owners (and just use the
numeric values).
name_filter: filter out file by names. If not none, this method will be
called for each file to add, given the name and should return true if
the file is to be added to the final tar and false otherwise.
root: place all non-absolute content under given root directory, if not
None.
Raises:
TarFileWriter.Error: if an error happens when uncompressing the tar file.
"""
if root and root[0] not in ['/', '.']:
# Root prefix should start with a '/', adds it if missing
root = '/' + root
compression = os.path.splitext(tar)[-1][1:]
if compression == 'tgz':
compression = 'gz'
elif compression == 'bzip2':
compression = 'bz2'
elif compression == 'lzma':
compression = 'xz'
elif compression not in ['gz', 'bz2', 'xz']:
compression = ''
if compression == 'xz':
# Python 2 does not support lzma, our py3 support is terrible so let's
# just hack around.
# Note that we buffer the file in memory and it can have an important
# memory footprint but it's probably fine as we don't use them for really
# large files.
# TODO(dmarting): once our py3 support gets better, compile this tools
# with py3 for proper lzma support.
if subprocess.call('which xzcat', shell=True, stdout=subprocess.PIPE):
raise self.Error('Cannot handle .xz and .lzma compression: '
'xzcat not found.')
p = subprocess.Popen('cat %s | xzcat' % tar,
shell=True,
stdout=subprocess.PIPE)
f = io.BytesIO(p.stdout.read())
p.wait()
intar = tarfile.open(fileobj=f, mode='r:')
else:
if compression in ['gz', 'bz2']:
# prevent performance issues due to accidentally-introduced seeks
# during intar traversal by opening in "streaming" mode. gz, bz2
# are supported natively by python 2.7 and 3.x
inmode = 'r|' + compression
else:
inmode = 'r:' + compression
intar = tarfile.open(name=tar, mode=inmode)
for tarinfo in intar:
if name_filter is None or name_filter(tarinfo.name):
tarinfo.mtime = 0
if rootuid is not None and tarinfo.uid == rootuid:
tarinfo.uid = 0
tarinfo.uname = 'root'
if rootgid is not None and tarinfo.gid == rootgid:
tarinfo.gid = 0
tarinfo.gname = 'root'
if numeric:
tarinfo.uname = ''
tarinfo.gname = ''
name = tarinfo.name
if (not name.startswith('/') and
not name.startswith(self.root_directory)):
name = os.path.join(self.root_directory, name)
if root is not None:
if name.startswith('.'):
name = '.' + root + name.lstrip('.')
# Add root dir with same permissions if missing. Note that
# add_file deduplicates directories and is safe to call here.
self.add_file('.' + root,
tarfile.DIRTYPE,
uid=tarinfo.uid,
gid=tarinfo.gid,
uname=tarinfo.uname,
gname=tarinfo.gname,
mtime=tarinfo.mtime,
mode=0o755)
# Relocate internal hardlinks as well to avoid breaking them.
link = tarinfo.linkname
if link.startswith('.') and tarinfo.type == tarfile.LNKTYPE:
tarinfo.linkname = '.' + root + link.lstrip('.')
tarinfo.name = name
if tarinfo.isfile():
# use extractfile(tarinfo) instead of tarinfo.name to preserve
# seek position in intar
self._addfile(tarinfo, intar.extractfile(tarinfo))
else:
self._addfile(tarinfo)
intar.close()
def close(self):
"""Close the output tar file.
This class should not be used anymore after calling that method.
Raises:
TarFileWriter.Error: if an error happens when compressing the output file.
"""
self.tar.close()
# Close the gzip file object if necessary.
if self.fileobj:
self.fileobj.close()
if self.xz:
# Support xz compression through xz... until we can use Py3
if subprocess.call('which xz', shell=True, stdout=subprocess.PIPE):
raise self.Error('Cannot handle .xz and .lzma compression: '
'xz not found.')
subprocess.call(
'mv {0} {0}.d && xz -z {0}.d && mv {0}.d.xz {0}'.format(self.name),
shell=True,
stdout=subprocess.PIPE)