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# -*- coding: utf-8 -*-
"""
Common verification infrastructure for v2 streams
"""
from struct import calcsize, unpack
class StreamError(Exception):
"""Error with the stream"""
pass
class RecordError(Exception):
"""Error with a record in the stream"""
pass
class VerifyBase(object):
def __init__(self, info, read):
self.info = info
self.read = read
def rdexact(self, nr_bytes):
"""Read exactly nr_bytes from the stream"""
_ = self.read(nr_bytes)
if len(_) != nr_bytes:
raise IOError("Stream truncated")
return _
def unpack_exact(self, fmt):
"""Unpack a struct format string from the stream"""
sz = calcsize(fmt)
return unpack(fmt, self.rdexact(sz))
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