TarIO.py 1.3 KB

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  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. #
  16. from __future__ import annotations
  17. import io
  18. from . import ContainerIO
  19. class TarIO(ContainerIO.ContainerIO[bytes]):
  20. """A file object that provides read access to a given member of a TAR file."""
  21. def __init__(self, tarfile: str, file: str) -> None:
  22. """
  23. Create file object.
  24. :param tarfile: Name of TAR file.
  25. :param file: Name of member file.
  26. """
  27. self.fh = open(tarfile, "rb")
  28. while True:
  29. s = self.fh.read(512)
  30. if len(s) != 512:
  31. msg = "unexpected end of tar file"
  32. raise OSError(msg)
  33. name = s[:100].decode("utf-8")
  34. i = name.find("\0")
  35. if i == 0:
  36. msg = "cannot find subfile"
  37. raise OSError(msg)
  38. if i > 0:
  39. name = name[:i]
  40. size = int(s[124:135], 8)
  41. if file == name:
  42. break
  43. self.fh.seek((size + 511) & (~511), io.SEEK_CUR)
  44. # Open region
  45. super().__init__(self.fh, self.fh.tell(), size)