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#
# The Python Imaging Library.
# $Id: ContainerIO.py 2134 2004-10-06 08:55:20Z fredrik $
#
# 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).
class ContainerIO:
##
# Create file object.
#
# @param file Existing file.
# @param offset Start of region, in bytes.
# @param length Size of region, in bytes.
def __init__(self, file, offset, length):
self.fh = file
self.pos = 0
self.offset = offset
self.length = length
self.fh.seek(offset)
##
# Always false.
def isatty(self):
return 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.
def seek(self, offset, mode = 0):
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)
##
# Get current file pointer.
#
# @return Offset from start of region, in bytes.
def tell(self):
return self.pos
##
# Read data.
#
# @def read(bytes=0)
# @param bytes Number of bytes to read. If omitted or zero,
# read until end of region.
# @return An 8-bit string.
def read(self, n = 0):
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)
##
# Read a line of text.
#
# @return An 8-bit string.
def readline(self):
s = ""
while 1:
c = self.read(1)
if not c:
break
s = s + c
if c == "\n":
break
return s
##
# Read multiple lines of text.
#
# @return A list of 8-bit strings.
def readlines(self):
l = []
while 1:
s = self.readline()
if not s:
break
l.append(s)
return l
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