Spaces:
Sleeping
Sleeping
File size: 4,604 Bytes
d015b2a |
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 |
#
# 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.
#
from __future__ import annotations
import io
from collections.abc import Iterable
from typing import IO, AnyStr, NoReturn
class ContainerIO(IO[AnyStr]):
"""
A file object that provides read access to a part of an existing
file (for example a TAR file).
"""
def __init__(self, file: IO[AnyStr], offset: int, length: int) -> None:
"""
Create file object.
:param file: Existing file.
:param offset: Start of region, in bytes.
:param length: Size of region, in bytes.
"""
self.fh: IO[AnyStr] = file
self.pos = 0
self.offset = offset
self.length = length
self.fh.seek(offset)
##
# Always false.
def isatty(self) -> bool:
return False
def seekable(self) -> bool:
return True
def seek(self, offset: int, mode: int = io.SEEK_SET) -> int:
"""
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.
:returns: Offset from start of region, in bytes.
"""
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)
return self.pos
def tell(self) -> int:
"""
Get current file pointer.
:returns: Offset from start of region, in bytes.
"""
return self.pos
def readable(self) -> bool:
return True
def read(self, n: int = -1) -> AnyStr:
"""
Read data.
:param n: Number of bytes to read. If omitted, zero or negative,
read until end of region.
:returns: An 8-bit string.
"""
if n > 0:
n = min(n, self.length - self.pos)
else:
n = self.length - self.pos
if n <= 0: # EOF
return b"" if "b" in self.fh.mode else "" # type: ignore[return-value]
self.pos = self.pos + n
return self.fh.read(n)
def readline(self, n: int = -1) -> AnyStr:
"""
Read a line of text.
:param n: Number of bytes to read. If omitted, zero or negative,
read until end of line.
:returns: An 8-bit string.
"""
s: AnyStr = b"" if "b" in self.fh.mode else "" # type: ignore[assignment]
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 or len(s) == n:
break
return s
def readlines(self, n: int | None = -1) -> list[AnyStr]:
"""
Read multiple lines of text.
:param n: Number of lines to read. If omitted, zero, negative or None,
read until end of region.
:returns: A list of 8-bit strings.
"""
lines = []
while True:
s = self.readline()
if not s:
break
lines.append(s)
if len(lines) == n:
break
return lines
def writable(self) -> bool:
return False
def write(self, b: AnyStr) -> NoReturn:
raise NotImplementedError()
def writelines(self, lines: Iterable[AnyStr]) -> NoReturn:
raise NotImplementedError()
def truncate(self, size: int | None = None) -> int:
raise NotImplementedError()
def __enter__(self) -> ContainerIO[AnyStr]:
return self
def __exit__(self, *args: object) -> None:
self.close()
def __iter__(self) -> ContainerIO[AnyStr]:
return self
def __next__(self) -> AnyStr:
line = self.readline()
if not line:
msg = "end of region"
raise StopIteration(msg)
return line
def fileno(self) -> int:
return self.fh.fileno()
def flush(self) -> None:
self.fh.flush()
def close(self) -> None:
self.fh.close()
|