Source code for PIL.ContainerIO

#
# 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.
#

##
# A file object that provides read access to a part of an existing
# file (for example a TAR file).


[docs]class ContainerIO(object): 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.
[docs] def isatty(self): return 0
[docs] def seek(self, offset, mode=0): """ 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)
[docs] def tell(self): """ Get current file pointer. :returns: Offset from start of region, in bytes. """ return self.pos
[docs] 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 "" self.pos = self.pos + n return self.fh.read(n)
[docs] def readline(self): """ Read a line of text. :returns: An 8-bit string. """ s = "" while True: c = self.read(1) if not c: break s = s + c if c == "\n": break return s
[docs] 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