SF #651082, tarfile module implementation from Lars Gustäbel

1 files changed, 1927 insertions, 0 deletions

diff --git a/Lib/tarfile.py b/Lib/tarfile.py
new file mode 100644
index 0000000..3e334be
--- /dev/null
+++ b/Lib/tarfile.py
@@ -0,0 +1,1927 @@
+#!/usr/bin/env python
+# -*- coding: iso-8859-1 -*-
+#-------------------------------------------------------------------
+# tarfile.py
+#-------------------------------------------------------------------
+# Copyright (C) 2002 Lars Gustäbel <lars@gustaebel.de>
+# All rights reserved.
+#
+# Permission  is  hereby granted,  free  of charge,  to  any person
+# obtaining a  copy of  this software  and associated documentation
+# files  (the  "Software"),  to   deal  in  the  Software   without
+# restriction,  including  without limitation  the  rights to  use,
+# copy, modify, merge, publish, distribute, sublicense, and/or sell
+# copies  of  the  Software,  and to  permit  persons  to  whom the
+# Software  is  furnished  to  do  so,  subject  to  the  following
+# conditions:
+#
+# The above copyright  notice and this  permission notice shall  be
+# included in all copies or substantial portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS  IS", WITHOUT WARRANTY OF ANY  KIND,
+# EXPRESS OR IMPLIED, INCLUDING  BUT NOT LIMITED TO  THE WARRANTIES
+# OF  MERCHANTABILITY,  FITNESS   FOR  A  PARTICULAR   PURPOSE  AND
+# NONINFRINGEMENT.  IN  NO  EVENT SHALL  THE  AUTHORS  OR COPYRIGHT
+# HOLDERS  BE LIABLE  FOR ANY  CLAIM, DAMAGES  OR OTHER  LIABILITY,
+# WHETHER  IN AN  ACTION OF  CONTRACT, TORT  OR OTHERWISE,  ARISING
+# FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+# OTHER DEALINGS IN THE SOFTWARE.
+#
+"""Read from and write to tar format archives.
+"""
+
+__version__ = "$Revision$"
+# $Source$
+
+version     = "0.6.4"
+__author__  = "Lars Gustäbel (lars@gustaebel.de)"
+__date__    = "$Date$"
+__cvsid__   = "$Id$"
+__credits__ = "Gustavo Niemeyer, Niels Gustäbel, Richard Townsend."
+
+#---------
+# Imports
+#---------
+import sys
+import os
+import shutil
+import stat
+import errno
+import time
+import struct
+
+try:
+    import grp, pwd
+except ImportError:
+    grp = pwd = None
+
+# from tarfile import *
+__all__ = ["TarFile", "TarInfo", "is_tarfile", "TarError"]
+
+#---------------------------------------------------------
+# tar constants
+#---------------------------------------------------------
+NUL        = "\0"               # the null character
+BLOCKSIZE  = 512                # length of processing blocks
+RECORDSIZE = BLOCKSIZE * 20     # length of records
+MAGIC      = "ustar"            # magic tar string
+VERSION    = "00"               # version number
+
+LENGTH_NAME    = 100            # maximum length of a filename
+LENGTH_LINK    = 100            # maximum length of a linkname
+LENGTH_PREFIX  = 155            # maximum length of the prefix field
+MAXSIZE_MEMBER = 077777777777L  # maximum size of a file (11 octal digits)
+
+REGTYPE  = "0"                  # regular file
+AREGTYPE = "\0"                 # regular file
+LNKTYPE  = "1"                  # link (inside tarfile)
+SYMTYPE  = "2"                  # symbolic link
+CHRTYPE  = "3"                  # character special device
+BLKTYPE  = "4"                  # block special device
+DIRTYPE  = "5"                  # directory
+FIFOTYPE = "6"                  # fifo special device
+CONTTYPE = "7"                  # contiguous file
+
+GNUTYPE_LONGNAME = "L"          # GNU tar extension for longnames
+GNUTYPE_LONGLINK = "K"          # GNU tar extension for longlink
+GNUTYPE_SPARSE   = "S"          # GNU tar extension for sparse file
+
+#---------------------------------------------------------
+# tarfile constants
+#---------------------------------------------------------
+SUPPORTED_TYPES = (REGTYPE, AREGTYPE, LNKTYPE,  # file types that tarfile
+                   SYMTYPE, DIRTYPE, FIFOTYPE,  # can cope with.
+                   CONTTYPE, CHRTYPE, BLKTYPE,
+                   GNUTYPE_LONGNAME, GNUTYPE_LONGLINK,
+                   GNUTYPE_SPARSE)
+
+REGULAR_TYPES = (REGTYPE, AREGTYPE,             # file types that somehow
+                 CONTTYPE, GNUTYPE_SPARSE)      # represent regular files
+
+#---------------------------------------------------------
+# Bits used in the mode field, values in octal.
+#---------------------------------------------------------
+S_IFLNK = 0120000        # symbolic link
+S_IFREG = 0100000        # regular file
+S_IFBLK = 0060000        # block device
+S_IFDIR = 0040000        # directory
+S_IFCHR = 0020000        # character device
+S_IFIFO = 0010000        # fifo
+
+TSUID   = 04000          # set UID on execution
+TSGID   = 02000          # set GID on execution
+TSVTX   = 01000          # reserved
+
+TUREAD  = 0400           # read by owner
+TUWRITE = 0200           # write by owner
+TUEXEC  = 0100           # execute/search by owner
+TGREAD  = 0040           # read by group
+TGWRITE = 0020           # write by group
+TGEXEC  = 0010           # execute/search by group
+TOREAD  = 0004           # read by other
+TOWRITE = 0002           # write by other
+TOEXEC  = 0001           # execute/search by other
+
+#---------------------------------------------------------
+# Some useful functions
+#---------------------------------------------------------
+def nts(s):
+    """Convert a null-terminated string buffer to a python string.
+    """
+    return s.split(NUL, 1)[0]
+
+def calc_chksum(buf):
+    """Calculate the checksum for a member's header. It's a simple addition
+       of all bytes, treating the chksum field as if filled with spaces.
+       buf is a 512 byte long string buffer which holds the header.
+    """
+    chk = 256                           # chksum field is treated as blanks,
+                                        # so the initial value is 8 * ord(" ")
+    for c in buf[:148]: chk += ord(c)   # sum up all bytes before chksum
+    for c in buf[156:]: chk += ord(c)   # sum up all bytes after chksum
+    return chk
+
+def copyfileobj(src, dst, length=None):
+    """Copy length bytes from fileobj src to fileobj dst.
+       If length is None, copy the entire content.
+    """
+    if length == 0:
+        return
+    if length is None:
+        shutil.copyfileobj(src, dst)
+        return
+
+    BUFSIZE = 16 * 1024
+    blocks, remainder = divmod(length, BUFSIZE)
+    for b in xrange(blocks):
+        buf = src.read(BUFSIZE)
+        if len(buf) < BUFSIZE:
+            raise IOError, "end of file reached"
+        dst.write(buf)
+
+    if remainder != 0:
+        buf = src.read(remainder)
+        if len(buf) < remainder:
+            raise IOError, "end of file reached"
+        dst.write(buf)
+    return
+
+filemode_table = (
+    (S_IFLNK, "l",
+     S_IFREG, "-",
+     S_IFBLK, "b",
+     S_IFDIR, "d",
+     S_IFCHR, "c",
+     S_IFIFO, "p"),
+    (TUREAD,  "r"),
+    (TUWRITE, "w"),
+    (TUEXEC,  "x", TSUID, "S", TUEXEC|TSUID, "s"),
+    (TGREAD,  "r"),
+    (TGWRITE, "w"),
+    (TGEXEC,  "x", TSGID, "S", TGEXEC|TSGID, "s"),
+    (TOREAD,  "r"),
+    (TOWRITE, "w"),
+    (TOEXEC,  "x", TSVTX, "T", TOEXEC|TSVTX, "t"))
+
+def filemode(mode):
+    """Convert a file's mode to a string of the form
+       -rwxrwxrwx.
+       Used by TarFile.list()
+    """
+    s = ""
+    for t in filemode_table:
+        while True:
+            if mode & t[0] == t[0]:
+                s += t[1]
+            elif len(t) > 2:
+                t = t[2:]
+                continue
+            else:
+                s += "-"
+            break
+    return s
+
+if os.sep != "/":
+    normpath = lambda path: os.path.normpath(path).replace(os.sep, "/")
+else:
+    normpath = os.path.normpath
+
+class TarError(Exception):
+    """Base exception."""
+    pass
+class ExtractError(TarError):
+    """General exception for extract errors."""
+    pass
+class ReadError(TarError):
+    """Exception for unreadble tar archives."""
+    pass
+class CompressionError(TarError):
+    """Exception for unavailable compression methods."""
+    pass
+class StreamError(TarError):
+    """Exception for unsupported operations on stream-like TarFiles."""
+    pass
+
+#---------------------------
+# internal stream interface
+#---------------------------
+class _LowLevelFile:
+    """Low-level file object. Supports reading and writing.
+       It is used instead of a regular file object for streaming
+       access.
+    """
+
+    def __init__(self, name, mode):
+        mode = {
+            "r": os.O_RDONLY,
+            "w": os.O_WRONLY | os.O_CREAT | os.O_TRUNC,
+        }[mode]
+        if hasattr(os, "O_BINARY"):
+            mode |= os.O_BINARY
+        self.fd = os.open(name, mode)
+
+    def close(self):
+        os.close(self.fd)
+
+    def read(self, size):
+        return os.read(self.fd, size)
+
+    def write(self, s):
+        os.write(self.fd, s)
+
+class _Stream:
+    """Class that serves as an adapter between TarFile and
+       a stream-like object.  The stream-like object only
+       needs to have a read() or write() method and is accessed
+       blockwise.  Use of gzip or bzip2 compression is possible.
+       A stream-like object could be for example: sys.stdin,
+       sys.stdout, a socket, a tape device etc.
+
+       _Stream is intended to be used only internally.
+    """
+
+    def __init__(self, name, mode, type, fileobj, bufsize):
+        """Construct a _Stream object.
+        """
+        self._extfileobj = True
+        if fileobj is None:
+            fileobj = _LowLevelFile(name, mode)
+            self._extfileobj = False
+
+        self.name    = name or ""
+        self.mode    = mode
+        self.type    = type
+        self.fileobj = fileobj
+        self.bufsize = bufsize
+        self.buf     = ""
+        self.pos     = 0L
+        self.closed  = False
+
+        if type == "gz":
+            try:
+                import zlib
+            except ImportError:
+                raise CompressionError, "zlib module is not available"
+            self.zlib = zlib
+            self.crc = zlib.crc32("")
+            if mode == "r":
+                self._init_read_gz()
+            else:
+                self._init_write_gz()
+
+        if type == "bz2":
+            try:
+                import bz2
+            except ImportError:
+                raise CompressionError, "bz2 module is not available"
+            if mode == "r":
+                self.dbuf = ""
+                self.cmp = bz2.BZ2Decompressor()
+            else:
+                self.cmp = bz2.BZ2Compressor()
+
+    def __del__(self):
+        if not self.closed:
+            self.close()
+
+    def _init_write_gz(self):
+        """Initialize for writing with gzip compression.
+        """
+        self.cmp = self.zlib.compressobj(9, self.zlib.DEFLATED,
+                                            -self.zlib.MAX_WBITS,
+                                            self.zlib.DEF_MEM_LEVEL,
+                                            0)
+        timestamp = struct.pack("<L", long(time.time()))
+        self.__write("\037\213\010\010%s\002\377" % timestamp)
+        if self.name.endswith(".gz"):
+            self.name = self.name[:-3]
+        self.__write(self.name + NUL)
+
+    def write(self, s):
+        """Write string s to the stream.
+        """
+        if self.type == "gz":
+            self.crc = self.zlib.crc32(s, self.crc)
+        self.pos += len(s)
+        if self.type != "tar":
+            s = self.cmp.compress(s)
+        self.__write(s)
+
+    def __write(self, s):
+        """Write string s to the stream if a whole new block
+           is ready to be written.
+        """
+        self.buf += s
+        while len(self.buf) > self.bufsize:
+            self.fileobj.write(self.buf[:self.bufsize])
+            self.buf = self.buf[self.bufsize:]
+
+    def close(self):
+        """Close the _Stream object. No operation should be
+           done on it afterwards.
+        """
+        if self.closed:
+            return
+
+        if self.mode == "w" and self.buf:
+            if self.type != "tar":
+                self.buf += self.cmp.flush()
+            self.fileobj.write(self.buf)
+            self.buf = ""
+            if self.type == "gz":
+                self.fileobj.write(struct.pack("<l", self.crc))
+                self.fileobj.write(struct.pack("<L", self.pos))
+
+        if not self._extfileobj:
+            self.fileobj.close()
+
+        self.closed = True
+
+    def _init_read_gz(self):
+        """Initialize for reading a gzip compressed fileobj.
+        """
+        self.cmp = self.zlib.decompressobj(-self.zlib.MAX_WBITS)
+        self.dbuf = ""
+
+        # taken from gzip.GzipFile with some alterations
+        if self.__read(2) != "\037\213":
+            raise ReadError, "not a gzip file"
+        if self.__read(1) != "\010":
+            raise CompressionError, "unsupported compression method"
+
+        flag = ord(self.__read(1))
+        self.__read(6)
+
+        if flag & 4:
+            xlen = ord(self.__read(1)) + 256 * ord(self.__read(1))
+            self.read(xlen)
+        if flag & 8:
+            while True:
+                s = self.__read(1)
+                if not s or s == NUL:
+                    break
+        if flag & 16:
+            while True:
+                s = self.__read(1)
+                if not s or s == NUL:
+                    break
+        if flag & 2:
+            self.__read(2)
+
+    def tell(self):
+        """Return the stream's file pointer position.
+        """
+        return self.pos
+
+    def seek(self, pos=0):
+        """Set the stream's file pointer to pos. Negative seeking
+           is forbidden.
+        """
+        if pos - self.pos >= 0:
+            blocks, remainder = divmod(pos - self.pos, self.bufsize)
+            for i in xrange(blocks):
+                self.read(self.bufsize)
+            self.read(remainder)
+        else:
+            raise StreamError, "seeking backwards is not allowed"
+        return self.pos
+
+    def read(self, size=None):
+        """Return the next size number of bytes from the stream.
+           If size is not defined, return all bytes of the stream
+           up to EOF.
+        """
+        if size is None:
+            t = []
+            while True:
+                buf = self._read(self.bufsize)
+                if not buf:
+                    break
+                t.append(buf)
+            buf = "".join(t)
+        else:
+            buf = self._read(size)
+        self.pos += len(buf)
+        return buf
+
+    def _read(self, size):
+        """Return size bytes from the stream.
+        """
+        if self.type == "tar":
+            return self.__read(size)
+
+        c = len(self.dbuf)
+        t = [self.dbuf]
+        while c < size:
+            buf = self.__read(self.bufsize)
+            if not buf:
+                break
+            buf = self.cmp.decompress(buf)
+            t.append(buf)
+            c += len(buf)
+        t = "".join(t)
+        self.dbuf = t[size:]
+        return t[:size]
+
+    def __read(self, size):
+        """Return size bytes from stream. If internal buffer is empty,
+           read another block from the stream.
+        """
+        c = len(self.buf)
+        t = [self.buf]
+        while c < size:
+            buf = self.fileobj.read(self.bufsize)
+            if not buf:
+                break
+            t.append(buf)
+            c += len(buf)
+        t = "".join(t)
+        self.buf = t[size:]
+        return t[:size]
+# class _Stream
+
+#------------------------
+# Extraction file object
+#------------------------
+class ExFileObject(object):
+    """File-like object for reading an archive member.
+       Is returned by TarFile.extractfile(). Support for
+       sparse files included.
+    """
+
+    def __init__(self, tarfile, tarinfo):
+        self.fileobj = tarfile.fileobj
+        self.name    = tarinfo.name
+        self.mode    = "r"
+        self.closed  = False
+        self.offset  = tarinfo.offset_data
+        self.size    = tarinfo.size
+        self.pos     = 0L
+        self.linebuffer = ""
+        if tarinfo.issparse():
+            self.sparse = tarinfo.sparse
+            self.read = self._readsparse
+        else:
+            self.read = self._readnormal
+
+    def __read(self, size):
+        """Overloadable read method.
+        """
+        return self.fileobj.read(size)
+
+    def readline(self, size=-1):
+        """Read a line with approx. size. If size is negative,
+           read a whole line. readline() and read() must not
+           be mixed up (!).
+        """
+        if size < 0:
+            size = sys.maxint
+
+        nl = self.linebuffer.find("\n")
+        if nl >= 0:
+            nl = min(nl, size)
+        else:
+            size -= len(self.linebuffer)
+            while nl < 0:
+                buf = self.read(min(size, 100))
+                if not buf:
+                    break
+                self.linebuffer += buf
+                size -= len(buf)
+                if size <= 0:
+                    break
+                nl = self.linebuffer.find("\n")
+            if nl == -1:
+                s = self.linebuffer
+                self.linebuffer = ""
+                return s
+        buf = self.linebuffer[:nl]
+        self.linebuffer = self.linebuffer[nl + 1:]
+        while buf[-1:] == "\r":
+            buf = buf[:-1]
+        return buf + "\n"
+
+    def readlines(self):
+        """Return a list with all (following) lines.
+        """
+        result = []
+        while True:
+            line = self.readline()
+            if not line: break
+            result.append(line)
+        return result
+
+    def _readnormal(self, size=None):
+        """Read operation for regular files.
+        """
+        if self.closed:
+            raise ValueError, "file is closed"
+        self.fileobj.seek(self.offset + self.pos)
+        bytesleft = self.size - self.pos
+        if size is None:
+            bytestoread = bytesleft
+        else:
+            bytestoread = min(size, bytesleft)
+        self.pos += bytestoread
+        return self.__read(bytestoread)
+
+    def _readsparse(self, size=None):
+        """Read operation for sparse files.
+        """
+        if self.closed:
+            raise ValueError, "file is closed"
+
+        if size is None:
+            size = self.size - self.pos
+
+        data = []
+        while size > 0:
+            buf = self._readsparsesection(size)
+            if not buf:
+                break
+            size -= len(buf)
+            data.append(buf)
+        return "".join(data)
+
+    def _readsparsesection(self, size):
+        """Read a single section of a sparse file.
+        """
+        section = self.sparse.find(self.pos)
+
+        if section is None:
+            return ""
+
+        toread = min(size, section.offset + section.size - self.pos)
+        if isinstance(section, _data):
+            realpos = section.realpos + self.pos - section.offset
+            self.pos += toread
+            self.fileobj.seek(self.offset + realpos)
+            return self.__read(toread)
+        else:
+            self.pos += toread
+            return NUL * toread
+
+    def tell(self):
+        """Return the current file position.
+        """
+        return self.pos
+
+    def seek(self, pos, whence=0):
+        """Seek to a position in the file.
+        """
+        self.linebuffer = ""
+        if whence == 0:
+            self.pos = min(max(pos, 0), self.size)
+        if whence == 1:
+            if pos < 0:
+                self.pos = max(self.pos + pos, 0)
+            else:
+                self.pos = min(self.pos + pos, self.size)
+        if whence == 2:
+            self.pos = max(min(self.size + pos, self.size), 0)
+
+    def close(self):
+        """Close the file object.
+        """
+        self.closed = True
+#class ExFileObject
+
+#------------------
+# Exported Classes
+#------------------
+class TarInfo(object):
+    """Informational class which holds the details about an
+       archive member given by a tar header block.
+       TarInfo objects are returned by TarFile.getmember(),
+       TarFile.getmembers() and TarFile.gettarinfo() and are
+       usually created internally.
+    """
+
+    def __init__(self, name=""):
+        """Construct a TarInfo object. name is the optional name
+           of the member.
+        """
+
+        self.name     = name       # member name (dirnames must end with '/')
+        self.mode     = 0666       # file permissions
+        self.uid      = 0          # user id
+        self.gid      = 0          # group id
+        self.size     = 0          # file size
+        self.mtime    = 0          # modification time
+        self.chksum   = 0          # header checksum
+        self.type     = REGTYPE    # member type
+        self.linkname = ""         # link name
+        self.uname    = "user"     # user name
+        self.gname    = "group"    # group name
+        self.devmajor = 0          #-
+        self.devminor = 0          #-for use with CHRTYPE and BLKTYPE
+        self.prefix   = ""         # prefix to filename or holding information
+                                   # about sparse files
+
+        self.offset   = 0          # the tar header starts here
+        self.offset_data = 0       # the file's data starts here
+
+    def __repr__(self):
+        return "<%s %r at %#x>" % (self.__class__.__name__,self.name,id(self))
+
+    def frombuf(cls, buf):
+        """Construct a TarInfo object from a 512 byte string buffer.
+        """
+        tarinfo = cls()
+        tarinfo.name   =  nts(buf[0:100])
+        tarinfo.mode   = int(buf[100:108], 8)
+        tarinfo.uid    = int(buf[108:116],8)
+        tarinfo.gid    = int(buf[116:124],8)
+        tarinfo.size   = long(buf[124:136], 8)
+        tarinfo.mtime  = long(buf[136:148], 8)
+        tarinfo.chksum = int(buf[148:156], 8)
+        tarinfo.type   = buf[156:157]
+        tarinfo.linkname = nts(buf[157:257])
+        tarinfo.uname  = nts(buf[265:297])
+        tarinfo.gname  = nts(buf[297:329])
+        try:
+            tarinfo.devmajor = int(buf[329:337], 8)
+            tarinfo.devminor = int(buf[337:345], 8)
+        except ValueError:
+            tarinfo.devmajor = tarinfo.devmajor = 0
+
+        # The prefix field is used for filenames > 100 in
+        # the POSIX standard.
+        # name = prefix + "/" + name
+        prefix = buf[345:500]
+        while prefix and prefix[-1] == NUL:
+            prefix = prefix[:-1]
+        if len(prefix.split(NUL)) == 1:
+            tarinfo.prefix = prefix
+            tarinfo.name = normpath(os.path.join(tarinfo.prefix, tarinfo.name))
+        else:
+            tarinfo.prefix = buf[345:500]
+
+        # Directory names should have a '/' at the end.
+        if tarinfo.isdir() and tarinfo.name[-1:] != "/":
+            tarinfo.name += "/"
+        return tarinfo
+
+    frombuf = classmethod(frombuf)
+
+    def tobuf(self):
+        """Return a tar header block as a 512 byte string.
+        """
+        name = self.name
+
+        # The following code was contributed by Detlef Lannert.
+        parts = []
+        for value, fieldsize in (
+                (name, 100),
+                ("%07o" % (self.mode & 07777), 8),
+                ("%07o" % self.uid, 8),
+                ("%07o" % self.gid, 8),
+                ("%011o" % self.size, 12),
+                ("%011o" % self.mtime, 12),
+                ("        ", 8),
+                (self.type, 1),
+                (self.linkname, 100),
+                (MAGIC, 6),
+                (VERSION, 2),
+                (self.uname, 32),
+                (self.gname, 32),
+                ("%07o" % self.devmajor, 8),
+                ("%07o" % self.devminor, 8),
+                (self.prefix, 155)
+            ):
+            l = len(value)
+            parts.append(value + (fieldsize - l) * NUL)
+
+        buf = "".join(parts)
+        chksum = calc_chksum(buf)
+        buf = buf[:148] + "%06o\0" % chksum + buf[155:]
+        buf += (BLOCKSIZE - len(buf)) * NUL
+        self.buf = buf
+        return buf
+
+    def isreg(self):
+        return self.type in REGULAR_TYPES
+    def isfile(self):
+        return self.isreg()
+    def isdir(self):
+        return self.type == DIRTYPE
+    def issym(self):
+        return self.type == SYMTYPE
+    def islnk(self):
+        return self.type == LNKTYPE
+    def ischr(self):
+        return self.type == CHRTYPE
+    def isblk(self):
+        return self.type == BLKTYPE
+    def isfifo(self):
+        return self.type == FIFOTYPE
+    def issparse(self):
+        return self.type == GNUTYPE_SPARSE
+    def isdev(self):
+        return self.type in (CHRTYPE, BLKTYPE, FIFOTYPE)
+# class TarInfo
+
+class TarFile(object):
+    """The TarFile Class provides an interface to tar archives.
+    """
+
+    debug = 0                   # May be set from 0 (no msgs) to 3 (all msgs)
+
+    dereference = False         # If true, add content of linked file to the
+                                # tar file, else the link.
+
+    ignore_zeros = False        # If true, skips empty or invalid blocks and
+                                # continues processing.
+
+    errorlevel = 0              # If 0, fatal errors only appear in debug
+                                # messages (if debug >= 0). If > 0, errors
+                                # are passed to the caller as exceptions.
+
+    posix = True                # If True, generates POSIX.1-1990-compliant
+                                # archives (no GNU extensions!)
+
+    fileobject = ExFileObject
+
+    def __init__(self, name=None, mode="r", fileobj=None):
+        """Open an (uncompressed) tar archive `name'. `mode' is either 'r' to
+           read from an existing archive, 'a' to append data to an existing
+           file or 'w' to create a new file overwriting an existing one. `mode'
+           defaults to 'r'.
+           If `fileobj' is given, it is used for reading or writing data. If it
+           can be determined, `mode' is overridden by `fileobj's mode.
+           `fileobj' is not closed, when TarFile is closed.
+        """
+        self.name = name
+
+        if len(mode) > 1 or mode not in "raw":
+            raise ValueError, "mode must be 'r', 'a' or 'w'"
+        self._mode = mode
+        self.mode = {"r": "rb", "a": "r+b", "w": "wb"}[mode]
+
+        if not fileobj:
+            fileobj = file(self.name, self.mode)
+            self._extfileobj = False
+        else:
+            if self.name is None and hasattr(fileobj, "name"):
+                self.name = fileobj.name
+            if hasattr(fileobj, "mode"):
+                self.mode = fileobj.mode
+            self._extfileobj = True
+        self.fileobj = fileobj
+
+        # Init datastructures
+        self.closed      = False
+        self.members     = []       # list of members as TarInfo objects
+        self.membernames = []       # names of members
+        self.chunks      = [0]      # chunk cache
+        self._loaded     = False    # flag if all members have been read
+        self.offset      = 0L       # current position in the archive file
+        self.inodes      = {}       # dictionary caching the inodes of
+                                    # archive members already added
+
+        if self._mode == "r":
+            self.firstmember = None
+            self.firstmember = self.next()
+
+        if self._mode == "a":
+            # Move to the end of the archive,
+            # before the first empty block.
+            self.firstmember = None
+            while True:
+                try:
+                    tarinfo = self.next()
+                except ReadError:
+                    self.fileobj.seek(0)
+                    break
+                if tarinfo is None:
+                    self.fileobj.seek(- BLOCKSIZE, 1)
+                    break
+
+        if self._mode in "aw":
+            self._loaded = True
+
+    #--------------------------------------------------------------------------
+    # Below are the classmethods which act as alternate constructors to the
+    # TarFile class. The open() method is the only one that is needed for
+    # public use; it is the "super"-constructor and is able to select an
+    # adequate "sub"-constructor for a particular compression using the mapping
+    # from OPEN_METH.
+    #
+    # This concept allows one to subclass TarFile without losing the comfort of
+    # the super-constructor. A sub-constructor is registered and made available
+    # by adding it to the mapping in OPEN_METH.
+
+    def open(cls, name=None, mode="r", fileobj=None, bufsize=20*512):
+        """Open a tar archive for reading, writing or appending. Return
+           an appropriate TarFile class.
+
+           mode:
+           'r'          open for reading with transparent compression
+           'r:'         open for reading exclusively uncompressed
+           'r:gz'       open for reading with gzip compression
+           'r:bz2'      open for reading with bzip2 compression
+           'a' or 'a:'  open for appending
+           'w' or 'w:'  open for writing without compression
+           'w:gz'       open for writing with gzip compression
+           'w:bz2'      open for writing with bzip2 compression
+           'r|'         open an uncompressed stream of tar blocks for reading
+           'r|gz'       open a gzip compressed stream of tar blocks
+           'r|bz2'      open a bzip2 compressed stream of tar blocks
+           'w|'         open an uncompressed stream for writing
+           'w|gz'       open a gzip compressed stream for writing
+           'w|bz2'      open a bzip2 compressed stream for writing
+        """
+
+        if not name and not fileobj:
+            raise ValueError, "nothing to open"
+
+        if ":" in mode:
+            filemode, comptype = mode.split(":", 1)
+            filemode = filemode or "r"
+            comptype = comptype or "tar"
+
+            # Select the *open() function according to
+            # given compression.
+            if comptype in cls.OPEN_METH:
+                func = getattr(cls, cls.OPEN_METH[comptype])
+            else:
+                raise CompressionError, "unknown compression type %r" % comptype
+            return func(name, filemode, fileobj)
+
+        elif "|" in mode:
+            filemode, comptype = mode.split("|", 1)
+            filemode = filemode or "r"
+            comptype = comptype or "tar"
+
+            if filemode not in "rw":
+                raise ValueError, "mode must be 'r' or 'w'"
+
+            t = cls(name, filemode,
+                    _Stream(name, filemode, comptype, fileobj, bufsize))
+            t._extfileobj = False
+            return t
+
+        elif mode == "r":
+            # Find out which *open() is appropriate for opening the file.
+            for comptype in cls.OPEN_METH:
+                func = getattr(cls, cls.OPEN_METH[comptype])
+                try:
+                    return func(name, "r", fileobj)
+                except (ReadError, CompressionError):
+                    continue
+            raise ReadError, "file could not be opened successfully"
+
+        elif mode in "aw":
+            return cls.taropen(name, mode, fileobj)
+
+        raise ValueError, "undiscernible mode"
+
+    open = classmethod(open)
+
+    def taropen(cls, name, mode="r", fileobj=None):
+        """Open uncompressed tar archive name for reading or writing.
+        """
+        if len(mode) > 1 or mode not in "raw":
+            raise ValueError, "mode must be 'r', 'a' or 'w'"
+        return cls(name, mode, fileobj)
+
+    taropen = classmethod(taropen)
+
+    def gzopen(cls, name, mode="r", fileobj=None, compresslevel=9):
+        """Open gzip compressed tar archive name for reading or writing.
+           Appending is not allowed.
+        """
+        if len(mode) > 1 or mode not in "rw":
+            raise ValueError, "mode must be 'r' or 'w'"
+
+        try:
+            import gzip
+        except ImportError:
+            raise CompressionError, "gzip module is not available"
+
+        pre, ext = os.path.splitext(name)
+        pre = os.path.basename(pre)
+        if ext == ".tgz":
+            ext = ".tar"
+        if ext == ".gz":
+            ext = ""
+        tarname = pre + ext
+
+        if fileobj is None:
+            fileobj = file(name, mode + "b")
+
+        if mode != "r":
+            name = tarname
+
+        try:
+            t = cls.taropen(tarname, mode,
+                gzip.GzipFile(name, mode, compresslevel, fileobj)
+            )
+        except IOError:
+            raise ReadError, "not a gzip file"
+        t._extfileobj = False
+        return t
+
+    gzopen = classmethod(gzopen)
+
+    def bz2open(cls, name, mode="r", fileobj=None, compresslevel=9):
+        """Open bzip2 compressed tar archive name for reading or writing.
+           Appending is not allowed.
+        """
+        if len(mode) > 1 or mode not in "rw":
+            raise ValueError, "mode must be 'r' or 'w'."
+
+        try:
+            import bz2
+        except ImportError:
+            raise CompressionError, "bz2 module is not available"
+
+        pre, ext = os.path.splitext(name)
+        pre = os.path.basename(pre)
+        if ext == ".tbz2":
+            ext = ".tar"
+        if ext == ".bz2":
+            ext = ""
+        tarname = pre + ext
+
+        if fileobj is not None:
+            raise ValueError, "no support for external file objects"
+
+        try:
+            t = cls.taropen(tarname, mode, bz2.BZ2File(name, mode, compresslevel=compresslevel))
+        except IOError:
+            raise ReadError, "not a bzip2 file"
+        t._extfileobj = False
+        return t
+
+    bz2open = classmethod(bz2open)
+
+    # All *open() methods are registered here.
+    OPEN_METH = {
+        "tar": "taropen",   # uncompressed tar
+        "gz":  "gzopen",    # gzip compressed tar
+        "bz2": "bz2open"    # bzip2 compressed tar
+    }
+
+    #--------------------------------------------------------------------------
+    # The public methods which TarFile provides:
+
+    def close(self):
+        """Close the TarFile. In write-mode, two finishing zero blocks are
+           appended to the archive.
+        """
+        if self.closed:
+            return
+
+        if self._mode in "aw":
+            self.fileobj.write(NUL * (BLOCKSIZE * 2))
+            self.offset += (BLOCKSIZE * 2)
+            # fill up the end with zero-blocks
+            # (like option -b20 for tar does)
+            blocks, remainder = divmod(self.offset, RECORDSIZE)
+            if remainder > 0:
+                self.fileobj.write(NUL * (RECORDSIZE - remainder))
+
+        if not self._extfileobj:
+            self.fileobj.close()
+        self.closed = True
+
+    def getmember(self, name):
+        """Return a TarInfo object for member `name'. If `name' can not be
+           found in the archive, KeyError is raised. If a member occurs more
+           than once in the archive, its last occurence is assumed to be the
+           most up-to-date version.
+        """
+        self._check()
+        if name not in self.membernames and not self._loaded:
+            self._load()
+        if name not in self.membernames:
+            raise KeyError, "filename %r not found" % name
+        return self._getmember(name)
+
+    def getmembers(self):
+        """Return the members of the archive as a list of TarInfo objects. The
+           list has the same order as the members in the archive.
+        """
+        self._check()
+        if not self._loaded:    # if we want to obtain a list of
+            self._load()        # all members, we first have to
+                                # scan the whole archive.
+        return self.members
+
+    def getnames(self):
+        """Return the members of the archive as a list of their names. It has
+           the same order as the list returned by getmembers().
+        """
+        self._check()
+        if not self._loaded:
+            self._load()
+        return self.membernames
+
+    def gettarinfo(self, name=None, arcname=None, fileobj=None):
+        """Create a TarInfo object for either the file `name' or the file
+           object `fileobj' (using os.fstat on its file descriptor). You can
+           modify some of the TarInfo's attributes before you add it using
+           addfile(). If given, `arcname' specifies an alternative name for the
+           file in the archive.
+        """
+        self._check("aw")
+
+        # When fileobj is given, replace name by
+        # fileobj's real name.
+        if fileobj is not None:
+            name = fileobj.name
+
+        # Building the name of the member in the archive.
+        # Backward slashes are converted to forward slashes,
+        # Absolute paths are turned to relative paths.
+        if arcname is None:
+            arcname = name
+        arcname = normpath(arcname)
+        drv, arcname = os.path.splitdrive(arcname)
+        while arcname[0:1] == "/":
+            arcname = arcname[1:]
+
+        # Now, fill the TarInfo object with
+        # information specific for the file.
+        tarinfo = TarInfo()
+
+        # Use os.stat or os.lstat, depending on platform
+        # and if symlinks shall be resolved.
+        if fileobj is None:
+            if hasattr(os, "lstat") and not self.dereference:
+                statres = os.lstat(name)
+            else:
+                statres = os.stat(name)
+        else:
+            statres = os.fstat(fileobj.fileno())
+        linkname = ""
+
+        stmd = statres.st_mode
+        if stat.S_ISREG(stmd):
+            inode = (statres.st_ino, statres.st_dev)
+            if inode in self.inodes and not self.dereference:
+                # Is it a hardlink to an already
+                # archived file?
+                type = LNKTYPE
+                linkname = self.inodes[inode]
+            else:
+                # The inode is added only if its valid.
+                # For win32 it is always 0.
+                type = REGTYPE
+                if inode[0]:
+                    self.inodes[inode] = arcname
+        elif stat.S_ISDIR(stmd):
+            type = DIRTYPE
+            if arcname[-1:] != "/":
+                arcname += "/"
+        elif stat.S_ISFIFO(stmd):
+            type = FIFOTYPE
+        elif stat.S_ISLNK(stmd):
+            type = SYMTYPE
+            linkname = os.readlink(name)
+        elif stat.S_ISCHR(stmd):
+            type = CHRTYPE
+        elif stat.S_ISBLK(stmd):
+            type = BLKTYPE
+        else:
+            return None
+
+        # Fill the TarInfo object with all
+        # information we can get.
+        tarinfo.name  = arcname
+        tarinfo.mode  = stmd
+        tarinfo.uid   = statres.st_uid
+        tarinfo.gid   = statres.st_gid
+        tarinfo.size  = statres.st_size
+        tarinfo.mtime = statres.st_mtime
+        tarinfo.type  = type
+        tarinfo.linkname = linkname
+        if pwd:
+            try:
+                tarinfo.uname = pwd.getpwuid(tarinfo.uid)[0]
+            except KeyError:
+                pass
+        if grp:
+            try:
+                tarinfo.gname = grp.getgrgid(tarinfo.gid)[0]
+            except KeyError:
+                pass
+
+        if type in (CHRTYPE, BLKTYPE):
+            if hasattr(os, "major") and hasattr(os, "minor"):
+                tarinfo.devmajor = os.major(statres.st_rdev)
+                tarinfo.devminor = os.minor(statres.st_rdev)
+        return tarinfo
+
+    def list(self, verbose=True):
+        """Print a table of contents to sys.stdout. If `verbose' is False, only
+           the names of the members are printed. If it is True, an `ls -l'-like
+           output is produced.
+        """
+        self._check()
+
+        for tarinfo in self:
+            if verbose:
+                print filemode(tarinfo.mode),
+                print "%s/%s" % (tarinfo.uname or tarinfo.uid,
+                                 tarinfo.gname or tarinfo.gid),
+                if tarinfo.ischr() or tarinfo.isblk():
+                    print "%10s" % ("%d,%d" \
+                                    % (tarinfo.devmajor, tarinfo.devminor)),
+                else:
+                    print "%10d" % tarinfo.size,
+                print "%d-%02d-%02d %02d:%02d:%02d" \
+                      % time.localtime(tarinfo.mtime)[:6],
+
+            print tarinfo.name,
+
+            if verbose:
+                if tarinfo.issym():
+                    print "->", tarinfo.linkname,
+                if tarinfo.islnk():
+                    print "link to", tarinfo.linkname,
+            print
+
+    def add(self, name, arcname=None, recursive=True):
+        """Add the file `name' to the archive. `name' may be any type of file
+           (directory, fifo, symbolic link, etc.). If given, `arcname'
+           specifies an alternative name for the file in the archive.
+           Directories are added recursively by default. This can be avoided by
+           setting `recursive' to False.
+        """
+        self._check("aw")
+
+        if arcname is None:
+            arcname = name
+
+        # Skip if somebody tries to archive the archive...
+        if self.name is not None \
+            and os.path.abspath(name) == os.path.abspath(self.name):
+            self._dbg(2, "tarfile: Skipped %r" % name)
+            return
+
+        # Special case: The user wants to add the current
+        # working directory.
+        if name == ".":
+            if recursive:
+                if arcname == ".":
+                    arcname = ""
+                for f in os.listdir("."):
+                    self.add(f, os.path.join(arcname, f))
+            return
+
+        self._dbg(1, name)
+
+        # Create a TarInfo object from the file.
+        tarinfo = self.gettarinfo(name, arcname)
+
+        if tarinfo is None:
+            self._dbg(1, "tarfile: Unsupported type %r" % name)
+            return
+
+        # Append the tar header and data to the archive.
+        if tarinfo.isreg():
+            f = file(name, "rb")
+            self.addfile(tarinfo, f)
+            f.close()
+
+        if tarinfo.type in (LNKTYPE, SYMTYPE, FIFOTYPE, CHRTYPE, BLKTYPE):
+            tarinfo.size = 0L
+            self.addfile(tarinfo)
+
+        if tarinfo.isdir():
+            self.addfile(tarinfo)
+            if recursive:
+                for f in os.listdir(name):
+                    self.add(os.path.join(name, f), os.path.join(arcname, f))
+
+    def addfile(self, tarinfo, fileobj=None):
+        """Add the TarInfo object `tarinfo' to the archive. If `fileobj' is
+           given, tarinfo.size bytes are read from it and added to the archive.
+           You can create TarInfo objects using gettarinfo().
+           On Windows platforms, `fileobj' should always be opened with mode
+           'rb' to avoid irritation about the file size.
+        """
+        self._check("aw")
+
+        tarinfo.name = normpath(tarinfo.name)
+        if tarinfo.isdir():
+            # directories should end with '/'
+            tarinfo.name += "/"
+
+        if tarinfo.linkname:
+            tarinfo.linkname = normpath(tarinfo.linkname)
+
+        if tarinfo.size > MAXSIZE_MEMBER:
+            raise ValueError, "file is too large (>8GB)"
+
+        if len(tarinfo.linkname) > LENGTH_LINK:
+            if self.posix:
+                raise ValueError, "linkname is too long (>%d)" \
+                                  % (LENGTH_LINK)
+            else:
+                self._create_gnulong(tarinfo.linkname, GNUTYPE_LONGLINK)
+                tarinfo.linkname = tarinfo.linkname[:LENGTH_LINK -1]
+                self._dbg(2, "tarfile: Created GNU tar extension LONGLINK")
+
+        if len(tarinfo.name) > LENGTH_NAME:
+            if self.posix:
+                prefix = tarinfo.name[:LENGTH_PREFIX + 1]
+                while prefix and prefix[-1] != "/":
+                        prefix = prefix[:-1]
+
+                name = tarinfo.name[len(prefix):]
+                prefix = prefix[:-1]
+
+                if not prefix or len(name) > LENGTH_NAME:
+                    raise ValueError, "name is too long (>%d)" \
+                                      % (LENGTH_NAME)
+
+                tarinfo.name   = name
+                tarinfo.prefix = prefix
+            else:
+                self._create_gnulong(tarinfo.name, GNUTYPE_LONGNAME)
+                tarinfo.name = tarinfo.name[:LENGTH_NAME - 1]
+                self._dbg(2, "tarfile: Created GNU tar extension LONGNAME")
+
+        self.fileobj.write(tarinfo.tobuf())
+        self.offset += BLOCKSIZE
+
+        # If there's data to follow, append it.
+        if fileobj is not None:
+            copyfileobj(fileobj, self.fileobj, tarinfo.size)
+            blocks, remainder = divmod(tarinfo.size, BLOCKSIZE)
+            if remainder > 0:
+                self.fileobj.write(NUL * (BLOCKSIZE - remainder))
+                blocks += 1
+            self.offset += blocks * BLOCKSIZE
+
+        self.members.append(tarinfo)
+        self.membernames.append(tarinfo.name)
+        self.chunks.append(self.offset)
+
+    def extract(self, member, path=""):
+        """Extract a member from the archive to the current working directory,
+           using its full name. Its file information is extracted as accurately
+           as possible. `member' may be a filename or a TarInfo object. You can
+           specify a different directory using `path'.
+        """
+        self._check("r")
+
+        if isinstance(member, TarInfo):
+            tarinfo = member
+        else:
+            tarinfo = self.getmember(member)
+
+        try:
+            self._extract_member(tarinfo, os.path.join(path, tarinfo.name))
+        except EnvironmentError, e:
+            if self.errorlevel > 0:
+                raise
+            else:
+                if e.filename is None:
+                    self._dbg(1, "tarfile: %s" % e.strerror)
+                else:
+                    self._dbg(1, "tarfile: %s %r" % (e.strerror, e.filename))
+        except ExtractError, e:
+            if self.errorlevel > 1:
+                raise
+            else:
+                self._dbg(1, "tarfile: %s" % e)
+
+    def extractfile(self, member):
+        """Extract a member from the archive as a file object. `member' may be
+           a filename or a TarInfo object. If `member' is a regular file, a
+           file-like object is returned. If `member' is a link, a file-like
+           object is constructed from the link's target. If `member' is none of
+           the above, None is returned.
+           The file-like object is read-only and provides the following
+           methods: read(), readline(), readlines(), seek() and tell()
+        """
+        self._check("r")
+
+        if isinstance(member, TarInfo):
+            tarinfo = member
+        else:
+            tarinfo = self.getmember(member)
+
+        if tarinfo.isreg():
+            return self.fileobject(self, tarinfo)
+
+        elif tarinfo.type not in SUPPORTED_TYPES:
+            # If a member's type is unknown, it is treated as a
+            # regular file.
+            return self.fileobject(self, tarinfo)
+
+        elif tarinfo.islnk() or tarinfo.issym():
+            if isinstance(self.fileobj, _Stream):
+                # A small but ugly workaround for the case that someone tries
+                # to extract a (sym)link as a file-object from a non-seekable
+                # stream of tar blocks.
+                raise StreamError, "cannot extract (sym)link as file object"
+            else:
+                # A (sym)link's file object is it's target's file object.
+                return self.extractfile(self._getmember(tarinfo.linkname,
+                                                        tarinfo))
+        else:
+            # If there's no data associated with the member (directory, chrdev,
+            # blkdev, etc.), return None instead of a file object.
+            return None
+
+    def _extract_member(self, tarinfo, targetpath):
+        """Extract the TarInfo object tarinfo to a physical
+           file called targetpath.
+        """
+        # Fetch the TarInfo object for the given name
+        # and build the destination pathname, replacing
+        # forward slashes to platform specific separators.
+        if targetpath[-1:] == "/":
+            targetpath = targetpath[:-1]
+        targetpath = os.path.normpath(targetpath)
+
+        # Create all upper directories.
+        upperdirs = os.path.dirname(targetpath)
+        if upperdirs and not os.path.exists(upperdirs):
+            ti = TarInfo()
+            ti.name  = upperdirs
+            ti.type  = DIRTYPE
+            ti.mode  = 0777
+            ti.mtime = tarinfo.mtime
+            ti.uid   = tarinfo.uid
+            ti.gid   = tarinfo.gid
+            ti.uname = tarinfo.uname
+            ti.gname = tarinfo.gname
+            try:
+                self._extract_member(ti, ti.name)
+            except:
+                pass
+
+        if tarinfo.islnk() or tarinfo.issym():
+            self._dbg(1, "%s -> %s" % (tarinfo.name, tarinfo.linkname))
+        else:
+            self._dbg(1, tarinfo.name)
+
+        if tarinfo.isreg():
+            self.makefile(tarinfo, targetpath)
+        elif tarinfo.isdir():
+            self.makedir(tarinfo, targetpath)
+        elif tarinfo.isfifo():
+            self.makefifo(tarinfo, targetpath)
+        elif tarinfo.ischr() or tarinfo.isblk():
+            self.makedev(tarinfo, targetpath)
+        elif tarinfo.islnk() or tarinfo.issym():
+            self.makelink(tarinfo, targetpath)
+        elif tarinfo.type not in SUPPORTED_TYPES:
+            self.makeunknown(tarinfo, targetpath)
+        else:
+            self.makefile(tarinfo, targetpath)
+
+        self.chown(tarinfo, targetpath)
+        if not tarinfo.issym():
+            self.chmod(tarinfo, targetpath)
+            self.utime(tarinfo, targetpath)
+
+    #--------------------------------------------------------------------------
+    # Below are the different file methods. They are called via
+    # _extract_member() when extract() is called. They can be replaced in a
+    # subclass to implement other functionality.
+
+    def makedir(self, tarinfo, targetpath):
+        """Make a directory called targetpath.
+        """
+        try:
+            os.mkdir(targetpath)
+        except EnvironmentError, e:
+            if e.errno != errno.EEXIST:
+                raise
+
+    def makefile(self, tarinfo, targetpath):
+        """Make a file called targetpath.
+        """
+        source = self.extractfile(tarinfo)
+        target = file(targetpath, "wb")
+        copyfileobj(source, target)
+        source.close()
+        target.close()
+
+    def makeunknown(self, tarinfo, targetpath):
+        """Make a file from a TarInfo object with an unknown type
+           at targetpath.
+        """
+        self.makefile(tarinfo, targetpath)
+        self._dbg(1, "tarfile: Unknown file type %r, " \
+                     "extracted as regular file." % tarinfo.type)
+
+    def makefifo(self, tarinfo, targetpath):
+        """Make a fifo called targetpath.
+        """
+        if hasattr(os, "mkfifo"):
+            os.mkfifo(targetpath)
+        else:
+            raise ExtractError, "fifo not supported by system"
+
+    def makedev(self, tarinfo, targetpath):
+        """Make a character or block device called targetpath.
+        """
+        if not hasattr(os, "mknod") or not hasattr(os, "makedev"):
+            raise ExtractError, "special devices not supported by system"
+
+        mode = tarinfo.mode
+        if tarinfo.isblk():
+            mode |= stat.S_IFBLK
+        else:
+            mode |= stat.S_IFCHR
+
+        os.mknod(targetpath, mode,
+                 os.makedev(tarinfo.devmajor, tarinfo.devminor))
+
+    def makelink(self, tarinfo, targetpath):
+        """Make a (symbolic) link called targetpath. If it cannot be created
+          (platform limitation), we try to make a copy of the referenced file
+          instead of a link.
+        """
+        linkpath = tarinfo.linkname
+        try:
+            if tarinfo.issym():
+                os.symlink(linkpath, targetpath)
+            else:
+                os.link(linkpath, targetpath)
+        except AttributeError:
+            if tarinfo.issym():
+                linkpath = os.path.join(os.path.dirname(tarinfo.name),
+                                        linkpath)
+                linkpath = normpath(linkpath)
+
+            try:
+                self._extract_member(self.getmember(linkpath), targetpath)
+            except (EnvironmentError, KeyError), e:
+                linkpath = os.path.normpath(linkpath)
+                try:
+                    shutil.copy2(linkpath, targetpath)
+                except EnvironmentError, e:
+                    raise IOError, "link could not be created"
+
+    def chown(self, tarinfo, targetpath):
+        """Set owner of targetpath according to tarinfo.
+        """
+        if pwd and hasattr(os, "geteuid") and os.geteuid() == 0:
+            # We have to be root to do so.
+            try:
+                g = grp.getgrnam(tarinfo.gname)[2]
+            except KeyError:
+                try:
+                    g = grp.getgrgid(tarinfo.gid)[2]
+                except KeyError:
+                    g = os.getgid()
+            try:
+                u = pwd.getpwnam(tarinfo.uname)[2]
+            except KeyError:
+                try:
+                    u = pwd.getpwuid(tarinfo.uid)[2]
+                except KeyError:
+                    u = os.getuid()
+            try:
+                if tarinfo.issym() and hasattr(os, "lchown"):
+                    os.lchown(targetpath, u, g)
+                else:
+                    os.chown(targetpath, u, g)
+            except EnvironmentError, e:
+                raise ExtractError, "could not change owner"
+
+    def chmod(self, tarinfo, targetpath):
+        """Set file permissions of targetpath according to tarinfo.
+        """
+        try:
+            os.chmod(targetpath, tarinfo.mode)
+        except EnvironmentError, e:
+            raise ExtractError, "could not change mode"
+
+    def utime(self, tarinfo, targetpath):
+        """Set modification time of targetpath according to tarinfo.
+        """
+        if sys.platform == "win32" and tarinfo.isdir():
+            # According to msdn.microsoft.com, it is an error (EACCES)
+            # to use utime() on directories.
+            return
+        try:
+            os.utime(targetpath, (tarinfo.mtime, tarinfo.mtime))
+        except EnvironmentError, e:
+            raise ExtractError, "could not change modification time"
+
+    #--------------------------------------------------------------------------
+
+    def next(self):
+        """Return the next member of the archive as a TarInfo object, when
+           TarFile is opened for reading. Return None if there is no more
+           available.
+        """
+        self._check("ra")
+        if self.firstmember is not None:
+            m = self.firstmember
+            self.firstmember = None
+            return m
+
+        # Read the next block.
+        self.fileobj.seek(self.chunks[-1])
+        while True:
+            buf = self.fileobj.read(BLOCKSIZE)
+            if not buf:
+                return None
+            try:
+                tarinfo = TarInfo.frombuf(buf)
+            except ValueError:
+                if self.ignore_zeros:
+                    if buf.count(NUL) == BLOCKSIZE:
+                        adj = "empty"
+                    else:
+                        adj = "invalid"
+                    self._dbg(2, "0x%X: %s block" % (self.offset, adj))
+                    self.offset += BLOCKSIZE
+                    continue
+                else:
+                    # Block is empty or unreadable.
+                    if self.chunks[-1] == 0:
+                        # If the first block is invalid. That does not
+                        # look like a tar archive we can handle.
+                        raise ReadError,"empty, unreadable or compressed file"
+                    return None
+            break
+
+        # We shouldn't rely on this checksum, because some tar programs
+        # calculate it differently and it is merely validating the
+        # header block. We could just as well skip this part, which would
+        # have a slight effect on performance...
+        if tarinfo.chksum != calc_chksum(buf):
+            self._dbg(1, "tarfile: Bad Checksum %r" % tarinfo.name)
+
+        # Set the TarInfo object's offset to the current position of the
+        # TarFile and set self.offset to the position where the data blocks
+        # should begin.
+        tarinfo.offset = self.offset
+        self.offset += BLOCKSIZE
+
+        # Check if the TarInfo object has a typeflag for which a callback
+        # method is registered in the TYPE_METH. If so, then call it.
+        if tarinfo.type in self.TYPE_METH:
+            tarinfo = self.TYPE_METH[tarinfo.type](self, tarinfo)
+        else:
+            tarinfo.offset_data = self.offset
+            if tarinfo.isreg() or tarinfo.type not in SUPPORTED_TYPES:
+                # Skip the following data blocks.
+                self.offset += self._block(tarinfo.size)
+
+        if tarinfo.isreg() and tarinfo.name[:-1] == "/":
+            # some old tar programs don't know DIRTYPE
+            tarinfo.type = DIRTYPE
+
+        self.members.append(tarinfo)
+        self.membernames.append(tarinfo.name)
+        self.chunks.append(self.offset)
+        return tarinfo
+
+    #--------------------------------------------------------------------------
+    # Below are some methods which are called for special typeflags in the
+    # next() method, e.g. for unwrapping GNU longname/longlink blocks. They
+    # are registered in TYPE_METH below. You can register your own methods
+    # with this mapping.
+    # A registered method is called with a TarInfo object as only argument.
+    #
+    # During its execution the method MUST perform the following tasks:
+    # 1. set tarinfo.offset_data to the position where the data blocks begin,
+    #    if there is data to follow.
+    # 2. set self.offset to the position where the next member's header will
+    #    begin.
+    # 3. return a valid TarInfo object.
+
+    def proc_gnulong(self, tarinfo):
+        """Evaluate the blocks that hold a GNU longname
+           or longlink member.
+        """
+        buf = ""
+        name = None
+        linkname = None
+        count = tarinfo.size
+        while count > 0:
+            block = self.fileobj.read(BLOCKSIZE)
+            buf += block
+            self.offset += BLOCKSIZE
+            count -= BLOCKSIZE
+
+        if tarinfo.type == GNUTYPE_LONGNAME:
+            name = nts(buf)
+        if tarinfo.type == GNUTYPE_LONGLINK:
+            linkname = nts(buf)
+
+        buf = self.fileobj.read(BLOCKSIZE)
+
+        tarinfo = TarInfo.frombuf(buf)
+        tarinfo.offset = self.offset
+        self.offset += BLOCKSIZE
+        tarinfo.offset_data = self.offset
+        tarinfo.name = name or tarinfo.name
+        tarinfo.linkname = linkname or tarinfo.linkname
+
+        if tarinfo.isreg() or tarinfo.type not in SUPPORTED_TYPES:
+            # Skip the following data blocks.
+            self.offset += self._block(tarinfo.size)
+        return tarinfo
+
+    def proc_sparse(self, tarinfo):
+        """Analyze a GNU sparse header plus extra headers.
+        """
+        buf = tarinfo.tobuf()
+        sp = _ringbuffer()
+        pos = 386
+        lastpos = 0L
+        realpos = 0L
+        # There are 4 possible sparse structs in the
+        # first header.
+        for i in xrange(4):
+            try:
+                offset = int(buf[pos:pos + 12], 8)
+                numbytes = int(buf[pos + 12:pos + 24], 8)
+            except ValueError:
+                break
+            if offset > lastpos:
+                sp.append(_hole(lastpos, offset - lastpos))
+            sp.append(_data(offset, numbytes, realpos))
+            realpos += numbytes
+            lastpos = offset + numbytes
+            pos += 24
+
+        isextended = ord(buf[482])
+        origsize = int(buf[483:495], 8)
+
+        # If the isextended flag is given,
+        # there are extra headers to process.
+        while isextended == 1:
+            buf = self.fileobj.read(BLOCKSIZE)
+            self.offset += BLOCKSIZE
+            pos = 0
+            for i in xrange(21):
+                try:
+                    offset = int(buf[pos:pos + 12], 8)
+                    numbytes = int(buf[pos + 12:pos + 24], 8)
+                except ValueError:
+                    break
+                if offset > lastpos:
+                    sp.append(_hole(lastpos, offset - lastpos))
+                sp.append(_data(offset, numbytes, realpos))
+                realpos += numbytes
+                lastpos = offset + numbytes
+                pos += 24
+            isextended = ord(buf[504])
+
+        if lastpos < origsize:
+            sp.append(_hole(lastpos, origsize - lastpos))
+
+        tarinfo.sparse = sp
+
+        tarinfo.offset_data = self.offset
+        self.offset += self._block(tarinfo.size)
+        tarinfo.size = origsize
+        return tarinfo
+
+    # The type mapping for the next() method. The keys are single character
+    # strings, the typeflag. The values are methods which are called when
+    # next() encounters such a typeflag.
+    TYPE_METH = {
+        GNUTYPE_LONGNAME: proc_gnulong,
+        GNUTYPE_LONGLINK: proc_gnulong,
+        GNUTYPE_SPARSE:   proc_sparse
+    }
+
+    #--------------------------------------------------------------------------
+    # Little helper methods:
+
+    def _block(self, count):
+        """Round up a byte count by BLOCKSIZE and return it,
+           e.g. _block(834) => 1024.
+        """
+        blocks, remainder = divmod(count, BLOCKSIZE)
+        if remainder:
+            blocks += 1
+        return blocks * BLOCKSIZE
+
+    def _getmember(self, name, tarinfo=None):
+        """Find an archive member by name from bottom to top.
+           If tarinfo is given, it is used as the starting point.
+        """
+        if tarinfo is None:
+            end = len(self.members)
+        else:
+            end = self.members.index(tarinfo)
+
+        for i in xrange(end - 1, -1, -1):
+            if name == self.membernames[i]:
+                return self.members[i]
+
+    def _load(self):
+        """Read through the entire archive file and look for readable
+           members.
+        """
+        while True:
+            tarinfo = self.next()
+            if tarinfo is None:
+                break
+        self._loaded = True
+
+    def _check(self, mode=None):
+        """Check if TarFile is still open, and if the operation's mode
+           corresponds to TarFile's mode.
+        """
+        if self.closed:
+            raise IOError, "%s is closed" % self.__class__.__name__
+        if mode is not None and self._mode not in mode:
+            raise IOError, "bad operation for mode %r" % self._mode
+
+    def __iter__(self):
+        """Provide an iterator object.
+        """
+        if self._loaded:
+            return iter(self.members)
+        else:
+            return TarIter(self)
+
+    def _create_gnulong(self, name, type):
+        """Write a GNU longname/longlink member to the TarFile.
+           It consists of an extended tar header, with the length
+           of the longname as size, followed by data blocks,
+           which contain the longname as a null terminated string.
+        """
+        tarinfo = TarInfo()
+        tarinfo.name = "././@LongLink"
+        tarinfo.type = type
+        tarinfo.mode = 0
+        tarinfo.size = len(name)
+
+        # write extended header
+        self.fileobj.write(tarinfo.tobuf())
+        # write name blocks
+        self.fileobj.write(name)
+        blocks, remainder = divmod(tarinfo.size, BLOCKSIZE)
+        if remainder > 0:
+            self.fileobj.write(NUL * (BLOCKSIZE - remainder))
+            blocks += 1
+        self.offset += blocks * BLOCKSIZE
+
+    def _dbg(self, level, msg):
+        """Write debugging output to sys.stderr.
+        """
+        if level <= self.debug:
+            print >> sys.stderr, msg
+# class TarFile
+
+class TarIter:
+    """Iterator Class.
+
+       for tarinfo in TarFile(...):
+           suite...
+    """
+
+    def __init__(self, tarfile):
+        """Construct a TarIter object.
+        """
+        self.tarfile = tarfile
+    def __iter__(self):
+        """Return iterator object.
+        """
+        return self
+    def next(self):
+        """Return the next item using TarFile's next() method.
+           When all members have been read, set TarFile as _loaded.
+        """
+        tarinfo = self.tarfile.next()
+        if not tarinfo:
+            self.tarfile._loaded = True
+            raise StopIteration
+        return tarinfo
+
+# Helper classes for sparse file support
+class _section:
+    """Base class for _data and _hole.
+    """
+    def __init__(self, offset, size):
+        self.offset = offset
+        self.size = size
+    def __contains__(self, offset):
+        return self.offset <= offset < self.offset + self.size
+
+class _data(_section):
+    """Represent a data section in a sparse file.
+    """
+    def __init__(self, offset, size, realpos):
+        _section.__init__(self, offset, size)
+        self.realpos = realpos
+
+class _hole(_section):
+    """Represent a hole section in a sparse file.
+    """
+    pass
+
+class _ringbuffer(list):
+    """Ringbuffer class which increases performance
+       over a regular list.
+    """
+    def __init__(self):
+        self.idx = 0
+    def find(self, offset):
+        idx = self.idx
+        while True:
+            item = self[idx]
+            if offset in item:
+                break
+            idx += 1
+            if idx == len(self):
+                idx = 0
+            if idx == self.idx:
+                # End of File
+                return None
+        self.idx = idx
+        return item
+
+#---------------------------------------------
+# zipfile compatible TarFile class
+#---------------------------------------------
+TAR_PLAIN = 0           # zipfile.ZIP_STORED
+TAR_GZIPPED = 8         # zipfile.ZIP_DEFLATED
+class TarFileCompat:
+    """TarFile class compatible with standard module zipfile's
+       ZipFile class.
+    """
+    def __init__(self, file, mode="r", compression=TAR_PLAIN):
+        if compression == TAR_PLAIN:
+            self.tarfile = TarFile.taropen(file, mode)
+        elif compression == TAR_GZIPPED:
+            self.tarfile = TarFile.gzopen(file, mode)
+        else:
+            raise ValueError, "unknown compression constant"
+        if mode[0:1] == "r":
+            members = self.tarfile.getmembers()
+            for i in xrange(len(members)):
+                m = members[i]
+                m.filename = m.name
+                m.file_size = m.size
+                m.date_time = time.gmtime(m.mtime)[:6]
+    def namelist(self):
+        return map(lambda m: m.name, self.infolist())
+    def infolist(self):
+        return filter(lambda m: m.type in REGULAR_TYPES,
+                      self.tarfile.getmembers())
+    def printdir(self):
+        self.tarfile.list()
+    def testzip(self):
+        return
+    def getinfo(self, name):
+        return self.tarfile.getmember(name)
+    def read(self, name):
+        return self.tarfile.extractfile(self.tarfile.getmember(name)).read()
+    def write(self, filename, arcname=None, compress_type=None):
+        self.tarfile.add(filename, arcname)
+    def writestr(self, zinfo, bytes):
+        import StringIO
+        import calendar
+        zinfo.name = zinfo.filename
+        zinfo.size = zinfo.file_size
+        zinfo.mtime = calendar.timegm(zinfo.date_time)
+        self.tarfile.addfile(zinfo, StringIO.StringIO(bytes))
+    def close(self):
+        self.tarfile.close()
+#class TarFileCompat
+
+#--------------------
+# exported functions
+#--------------------
+def is_tarfile(name):
+    """Return True if name points to a tar archive that we
+       are able to handle, else return False.
+    """
+    try:
+        t = open(name)
+        t.close()
+        return True
+    except TarError:
+        return False
+
+open = TarFile.open