| # 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) |
