123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120 |
- #
- # The Python Imaging Library.
- # $Id$
- #
- # a class to read from a container file
- #
- # History:
- # 1995-06-18 fl Created
- # 1995-09-07 fl Added readline(), readlines()
- #
- # Copyright (c) 1997-2001 by Secret Labs AB
- # Copyright (c) 1995 by Fredrik Lundh
- #
- # See the README file for information on usage and redistribution.
- #
-
-
- import io
-
-
- class ContainerIO:
- """
- A file object that provides read access to a part of an existing
- file (for example a TAR file).
- """
-
- def __init__(self, file, offset, length):
- """
- Create file object.
-
- :param file: Existing file.
- :param offset: Start of region, in bytes.
- :param length: Size of region, in bytes.
- """
- self.fh = file
- self.pos = 0
- self.offset = offset
- self.length = length
- self.fh.seek(offset)
-
- ##
- # Always false.
-
- def isatty(self):
- return False
-
- def seek(self, offset, mode=io.SEEK_SET):
- """
- Move file pointer.
-
- :param offset: Offset in bytes.
- :param mode: Starting position. Use 0 for beginning of region, 1
- for current offset, and 2 for end of region. You cannot move
- the pointer outside the defined region.
- """
- if mode == 1:
- self.pos = self.pos + offset
- elif mode == 2:
- self.pos = self.length + offset
- else:
- self.pos = offset
- # clamp
- self.pos = max(0, min(self.pos, self.length))
- self.fh.seek(self.offset + self.pos)
-
- def tell(self):
- """
- Get current file pointer.
-
- :returns: Offset from start of region, in bytes.
- """
- return self.pos
-
- def read(self, n=0):
- """
- Read data.
-
- :param n: Number of bytes to read. If omitted or zero,
- read until end of region.
- :returns: An 8-bit string.
- """
- if n:
- n = min(n, self.length - self.pos)
- else:
- n = self.length - self.pos
- if not n: # EOF
- return b"" if "b" in self.fh.mode else ""
- self.pos = self.pos + n
- return self.fh.read(n)
-
- def readline(self):
- """
- Read a line of text.
-
- :returns: An 8-bit string.
- """
- s = b"" if "b" in self.fh.mode else ""
- newline_character = b"\n" if "b" in self.fh.mode else "\n"
- while True:
- c = self.read(1)
- if not c:
- break
- s = s + c
- if c == newline_character:
- break
- return s
-
- def readlines(self):
- """
- Read multiple lines of text.
-
- :returns: A list of 8-bit strings.
- """
- lines = []
- while True:
- s = self.readline()
- if not s:
- break
- lines.append(s)
- return lines
|