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Copy pathlimited_reader.py
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70 lines (57 loc) · 2.2 KB
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# -*- coding: utf-8 -*-
# Minio Python Library for Amazon S3 Compatible Cloud Storage, (C) 2015 Minio, Inc.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
"""
minio.part
This module implements a Limited Reader.
A LimitedReader reads from *reader* but limits the amount
of data returned to just *limit* bytes. Each call to Read
updates *limit* to reflect the new amount remaining.
:copyright: (c) 2015 by Minio, Inc.
:license: Apache 2.0, see LICENSE for more details.
"""
from __future__ import absolute_import
import io
class LimitedReader(io.BufferedIOBase):
"""
LimitedReader returns a Reader that reads from *reader*
but stops with EOF after *limit* bytes.
LimitedReader is a wrapper over BufferedIOBase.
returns a class:`LimitedReader` that reads from
*reader* and stops with EOF after *limit* bytes.
:param reader: Input class:`io.BufferedIOBase`
:param limit: Trigger EOF after limit bytes.
"""
def __init__(self, reader, limit):
self.reader = reader
self._limit = limit
self._offset_location = 0
def read(self, amt=64*1024):
"""
Similar to :meth:`io.read`, with amt option.
:param amt:
How much of the content to read.
"""
data = self.reader.read(amt)
# If we really reach EOF return here.
if not data and len(data) == 0:
return b''
self._offset_location += len(data)
# If offset is bigger than size. Treat it as EOF return here.
if self._offset_location > self._limit:
# seek back frivolous read if any.
self.reader.seek(-len(data), 1)
# return empty bytes to indicate EOF.
return b''
return data