Current File : //lib/python3/dist-packages/debian/arfile.py
""" Representation of ar archives for use with Debian binary packages
These classes are primarily intended to be used with the
:class:`debian.debfile.DebFile` class for working with Debian binary
packages.
"""
# Copyright (C) 2007 Stefano Zacchiroli <zack@debian.org>
# Copyright (C) 2007 Filippo Giunchedi <filippo@debian.org>
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program 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
# General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
from pathlib import Path
import sys
try:
# pylint: disable=unused-import
from typing import (
Any,
BinaryIO,
Dict,
Generator,
IO,
Iterator,
List,
NoReturn,
Optional,
Union,
)
except ImportError:
# Missing types aren't important at runtime
pass
GLOBAL_HEADER = b"!<arch>\n"
GLOBAL_HEADER_LENGTH = len(GLOBAL_HEADER)
FILE_HEADER_LENGTH = 60
FILE_MAGIC = b"`\n"
class ArError(Exception):
""" Common base for all exceptions raised within the arfile module """
class ArFile(object):
""" Representation of an ar archive, see man 1 ar.
The interface of this class tries to mimic that of the TarFile module in
the standard library.
ArFile objects have the following (read-only) properties:
- members same as getmembers()
"""
def __init__(self,
filename=None, # type: Optional[Union[str, Path]]
mode='r', # type: str
fileobj=None, # type: Optional[BinaryIO]
encoding=None, # type: Optional[str]
errors=None, # type: Optional[str]
):
# type: (...) -> None
""" Build an ar file representation starting from either a filename or
an existing file object. The only supported mode is 'r'.
The encoding and errors parameters control how member
names are decoded into Unicode strings. Like tarfile, the default
encoding is sys.getfilesystemencoding() and the default error handling
scheme is 'surrogateescape'.
"""
self.__members = [] # type: List[ArMember]
self.__members_dict = {} # type: Dict[str, ArMember]
self.__fname = filename # type: Optional[Union[str, Path]]
self.__fileobj = fileobj
self.__encoding = encoding or sys.getfilesystemencoding()
if errors is None:
errors = 'surrogateescape'
self.__errors = errors
if mode == "r":
self.__index_archive()
# TODO write support
def __index_archive(self):
# type: () -> None
if self.__fname:
with open(self.__fname, "rb") as fp:
self.__collect_members(fp)
elif self.__fileobj:
self.__collect_members(self.__fileobj)
else:
raise ArError("Unable to open valid file")
def __collect_members(self, fp):
# type: (BinaryIO) -> None
if fp.read(GLOBAL_HEADER_LENGTH) != GLOBAL_HEADER:
raise ArError("Unable to find global header")
while True:
newmember = ArMember.from_file(fp, self.__fname,
encoding=self.__encoding,
errors=self.__errors)
if not newmember:
break
self.__members.append(newmember)
self.__members_dict[newmember.name] = newmember
if newmember.size % 2 == 0: # even, no padding
fp.seek(newmember.size, 1) # skip to next header
else:
fp.seek(newmember.size + 1, 1) # skip to next header
def getmember(self, name):
# type: (str) -> ArMember
""" Return the (last occurrence of a) member in the archive whose name
is 'name'. Raise KeyError if no member matches the given name.
Note that in case of name collisions the only way to retrieve all
members matching a given name is to use getmembers. """
return self.__members_dict[name]
def getmembers(self):
# type: () -> List[ArMember]
""" Return a list of all members contained in the archive.
The list has the same order of members in the archive and can contain
duplicate members (i.e. members with the same name) if they are
duplicate in the archive itself. """
return self.__members
members = property(getmembers)
def getnames(self):
# type: () -> List[str]
""" Return a list of all member names in the archive. """
return [f.name for f in self.__members]
def extractall(self):
# type: () -> NoReturn
""" Not (yet) implemented. """
raise NotImplementedError # TODO
def extract(self, member, path):
# type: (str, str) -> NoReturn
""" Not (yet) implemented. """
raise NotImplementedError # TODO
def extractfile(self, member):
# type: (str) -> Optional[ArMember]
""" Return a file object corresponding to the requested member. A member
can be specified either as a string (its name) or as a ArMember
instance. """
# TODO(jsw): What is the point of this method? It differs from
# getmember in the following ways:
# - It returns the *first* member with the given name instead of the
# last.
# - If member is an ArMember, it uses that ArMember's name as the key.
# The former just seems confusing (and this implementation less
# efficient than getmember's - probably historical), and I'm having a
# hard time seeing the use-case for the latter.
for m in self.__members:
if isinstance(member, ArMember) and m.name == member.name:
return m
if member == m.name:
return m
return None
# container emulation
def __iter__(self):
# type: () -> Iterator[ArMember]
""" Iterate over the members of the present ar archive. """
return iter(self.__members)
def __getitem__(self, name):
# type: (str) -> ArMember
""" Same as .getmember(name). """
return self.getmember(name)
class ArMember(object):
""" Member of an ar archive.
Implements most of a file object interface: read, readline, next,
readlines, seek, tell, close.
ArMember objects have the following (read-only) properties:
- name member name in an ar archive
- mtime modification time
- owner owner user
- group owner group
- fmode file permissions
- size size in bytes
- fname file name"""
def __init__(self):
# type: () -> None
# member name (i.e. filename) in the archive
self.__name = None # type: Optional[str]
# last modification time
self.__mtime = None # type: Optional[int]
# owner user id
self.__owner = None # type: Optional[int]
# owner group id
self.__group = None # type: Optional[int]
# permissions as octal bytes
self.__fmode = None # type: Optional[bytes]
# member size in bytes
self.__size = None # type: Optional[int]
# file name associated with this member
self.__fname = "" # type: Optional[Union[str, Path]]
# file pointer
self.__fp = None # type: Optional[BinaryIO]
# start-of-data offset
self.__offset = 0 # type: int
# end-of-data offset
self.__end = 0 # type: int
# current position
self.__cur = 0 # type: int
@staticmethod
def from_file(fp, # type: BinaryIO
fname, # type: Optional[Union[str, Path]]
encoding=None, # type: Optional[str]
errors=None, # type: Optional[str]
):
# type: (...) -> Optional[ArMember]
"""fp is an open File object positioned on a valid file header inside
an ar archive. Return a new ArMember on success, None otherwise. """
buf = fp.read(FILE_HEADER_LENGTH)
if not buf:
return None
# sanity checks
if len(buf) < FILE_HEADER_LENGTH:
raise IOError("Incorrect header length")
if buf[58:60] != FILE_MAGIC:
raise IOError("Incorrect file magic")
if encoding is None:
encoding = sys.getfilesystemencoding()
if errors is None:
errors = 'surrogateescape'
# http://en.wikipedia.org/wiki/Ar_(Unix)
# from to Name Format
# 0 15 File name ASCII
# 16 27 File modification date Decimal
# 28 33 Owner ID Decimal
# 34 39 Group ID Decimal
# 40 47 File mode Octal
# 48 57 File size in bytes Decimal
# 58 59 File magic \140\012
# XXX struct.unpack can be used as well here
f = ArMember()
# pylint: disable=unused-private-member
# pylint 2.11 is very confused here.
name = buf[0:16].split(b"/")[0].strip()
f.__name = name.decode(encoding, errors)
f.__mtime = int(buf[16:28])
f.__owner = int(buf[28:34])
f.__group = int(buf[34:40])
f.__fmode = buf[40:48] # XXX octal value
f.__size = int(buf[48:58])
f.__fname = fname
if not fname:
f.__fp = fp
f.__offset = fp.tell() # start-of-data
f.__end = f.__offset + f.__size
f.__cur = f.__offset
return f
# file interface
# XXX this is not a sequence like file objects
def read(self, size=0):
# type: (int) -> bytes
if self.__fp is None:
if self.__fname is None:
raise ValueError("Cannot have both fp and fname undefined")
self.__fp = open(self.__fname, "rb") # pylint: disable = consider-using-with
self.__fp.seek(self.__cur)
if 0 < size <= self.__end - self.__cur: # there's room
buf = self.__fp.read(size)
self.__cur = self.__fp.tell()
return buf
if self.__cur >= self.__end or self.__cur < self.__offset:
return b''
buf = self.__fp.read(self.__end - self.__cur)
self.__cur = self.__fp.tell()
return buf
def readline(self, size=None):
# type: (Optional[int]) -> bytes
if self.__fp is None:
if self.__fname is None:
raise ValueError("Cannot have both fp and fname undefined")
self.__fp = open(self.__fname, "rb") # pylint: disable = consider-using-with
self.__fp.seek(self.__cur)
if size is not None:
buf = self.__fp.readline(size)
self.__cur = self.__fp.tell()
if self.__cur > self.__end:
return b''
return buf
buf = self.__fp.readline()
self.__cur = self.__fp.tell()
if self.__cur > self.__end:
return b''
return buf
def readlines(self, sizehint=0):
# type: (int) -> List[bytes]
# pylint: disable=unused-argument
buf = None
lines = []
while True:
buf = self.readline()
if not buf:
break
lines.append(buf)
return lines
def seek(self, offset, whence=0):
# type: (int, int) -> None
if self.__cur < self.__offset:
self.__cur = self.__offset
if whence < 2 and offset + self.__cur < self.__offset:
raise IOError("Can't seek at %d" % offset)
if whence == 1:
self.__cur = self.__cur + offset
elif whence == 0:
self.__cur = self.__offset + offset
elif whence == 2:
self.__cur = self.__end + offset
def tell(self):
# type: () -> int
if self.__cur < self.__offset:
return 0
return self.__cur - self.__offset
def seekable(self):
# type: () -> bool
return True
def close(self):
# type: () -> None
if self.__fp is not None and self.__fname is not None:
self.__fp.close()
self.__fp = None
def next(self):
# type: () -> bytes
return self.readline()
def __iter__(self):
# type: () -> Iterator[bytes]
def nextline():
# type: () -> Generator[bytes, None, None]
line = self.readline()
if line:
yield line
return iter(nextline())
name = property(lambda self: self.__name)
mtime = property(lambda self: self.__mtime)
owner = property(lambda self: self.__owner)
group = property(lambda self: self.__group)
fmode = property(lambda self: self.__fmode)
size = property(lambda self: self.__size)
fname = property(lambda self: self.__fname)
if __name__ == '__main__':
# test
# ar r test.ar <file1> <file2> .. <fileN>
a = ArFile("test.ar")
print("\n".join(a.getnames()))
Mini Shell