Aluode/PerceptionLabPortable

1#
2# The Python Imaging Library.
3# $Id$
4#
5# read files from within a tar file
6#
7# History:
8# 95-06-18 fl   Created
9# 96-05-28 fl   Open files in binary mode
10#
11# Copyright (c) Secret Labs AB 1997.
12# Copyright (c) Fredrik Lundh 1995-96.
13#
14# See the README file for information on usage and redistribution.
15#
16from __future__ import annotations
17
18import io
19
20from . import ContainerIO
21
22
23class TarIO(ContainerIO.ContainerIO[bytes]):
24    """A file object that provides read access to a given member of a TAR file."""
25
26    def __init__(self, tarfile: str, file: str) -> None:
27        """
28        Create file object.
29
30        :param tarfile: Name of TAR file.
31        :param file: Name of member file.
32        """
33        self.fh = open(tarfile, "rb")
34
35        while True:
36            s = self.fh.read(512)
37            if len(s) != 512:
38                self.fh.close()
39
40                msg = "unexpected end of tar file"
41                raise OSError(msg)
42
43            name = s[:100].decode("utf-8")
44            i = name.find("\0")
45            if i == 0:
46                self.fh.close()
47
48                msg = "cannot find subfile"
49                raise OSError(msg)
50            if i > 0:
51                name = name[:i]
52
53            size = int(s[124:135], 8)
54
55            if file == name:
56                break
57
58            self.fh.seek((size + 511) & (~511), io.SEEK_CUR)
59
60        # Open region
61        super().__init__(self.fh, self.fh.tell(), size)
62