372 lines
14 KiB
Python
372 lines
14 KiB
Python
import time
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from .exceptions import EOF, TIMEOUT
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class Expecter(object):
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def __init__(self, spawn, searcher, searchwindowsize=-1):
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self.spawn = spawn
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self.searcher = searcher
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# A value of -1 means to use the figure from spawn, which should
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# be None or a positive number.
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if searchwindowsize == -1:
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searchwindowsize = spawn.searchwindowsize
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self.searchwindowsize = searchwindowsize
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self.lookback = None
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if hasattr(searcher, 'longest_string'):
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self.lookback = searcher.longest_string
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def do_search(self, window, freshlen):
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spawn = self.spawn
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searcher = self.searcher
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if freshlen > len(window):
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freshlen = len(window)
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index = searcher.search(window, freshlen, self.searchwindowsize)
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if index >= 0:
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spawn._buffer = spawn.buffer_type()
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spawn._buffer.write(window[searcher.end:])
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spawn.before = spawn._before.getvalue()[
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0:-(len(window) - searcher.start)]
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spawn._before = spawn.buffer_type()
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spawn._before.write(window[searcher.end:])
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spawn.after = window[searcher.start:searcher.end]
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spawn.match = searcher.match
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spawn.match_index = index
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# Found a match
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return index
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elif self.searchwindowsize or self.lookback:
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maintain = self.searchwindowsize or self.lookback
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if spawn._buffer.tell() > maintain:
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spawn._buffer = spawn.buffer_type()
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spawn._buffer.write(window[-maintain:])
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def existing_data(self):
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# First call from a new call to expect_loop or expect_async.
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# self.searchwindowsize may have changed.
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# Treat all data as fresh.
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spawn = self.spawn
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before_len = spawn._before.tell()
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buf_len = spawn._buffer.tell()
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freshlen = before_len
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if before_len > buf_len:
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if not self.searchwindowsize:
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spawn._buffer = spawn.buffer_type()
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window = spawn._before.getvalue()
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spawn._buffer.write(window)
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elif buf_len < self.searchwindowsize:
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spawn._buffer = spawn.buffer_type()
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spawn._before.seek(
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max(0, before_len - self.searchwindowsize))
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window = spawn._before.read()
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spawn._buffer.write(window)
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else:
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spawn._buffer.seek(max(0, buf_len - self.searchwindowsize))
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window = spawn._buffer.read()
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else:
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if self.searchwindowsize:
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spawn._buffer.seek(max(0, buf_len - self.searchwindowsize))
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window = spawn._buffer.read()
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else:
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window = spawn._buffer.getvalue()
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return self.do_search(window, freshlen)
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def new_data(self, data):
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# A subsequent call, after a call to existing_data.
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spawn = self.spawn
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freshlen = len(data)
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spawn._before.write(data)
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if not self.searchwindowsize:
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if self.lookback:
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# search lookback + new data.
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old_len = spawn._buffer.tell()
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spawn._buffer.write(data)
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spawn._buffer.seek(max(0, old_len - self.lookback))
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window = spawn._buffer.read()
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else:
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# copy the whole buffer (really slow for large datasets).
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spawn._buffer.write(data)
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window = spawn.buffer
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else:
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if len(data) >= self.searchwindowsize or not spawn._buffer.tell():
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window = data[-self.searchwindowsize:]
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spawn._buffer = spawn.buffer_type()
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spawn._buffer.write(window[-self.searchwindowsize:])
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else:
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spawn._buffer.write(data)
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new_len = spawn._buffer.tell()
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spawn._buffer.seek(max(0, new_len - self.searchwindowsize))
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window = spawn._buffer.read()
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return self.do_search(window, freshlen)
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def eof(self, err=None):
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spawn = self.spawn
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spawn.before = spawn._before.getvalue()
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spawn._buffer = spawn.buffer_type()
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spawn._before = spawn.buffer_type()
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spawn.after = EOF
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index = self.searcher.eof_index
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if index >= 0:
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spawn.match = EOF
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spawn.match_index = index
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return index
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else:
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spawn.match = None
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spawn.match_index = None
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msg = str(spawn)
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msg += '\nsearcher: %s' % self.searcher
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if err is not None:
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msg = str(err) + '\n' + msg
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exc = EOF(msg)
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exc.__cause__ = None # in Python 3.x we can use "raise exc from None"
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raise exc
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def timeout(self, err=None):
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spawn = self.spawn
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spawn.before = spawn._before.getvalue()
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spawn.after = TIMEOUT
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index = self.searcher.timeout_index
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if index >= 0:
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spawn.match = TIMEOUT
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spawn.match_index = index
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return index
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else:
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spawn.match = None
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spawn.match_index = None
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msg = str(spawn)
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msg += '\nsearcher: %s' % self.searcher
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if err is not None:
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msg = str(err) + '\n' + msg
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exc = TIMEOUT(msg)
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exc.__cause__ = None # in Python 3.x we can use "raise exc from None"
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raise exc
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def errored(self):
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spawn = self.spawn
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spawn.before = spawn._before.getvalue()
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spawn.after = None
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spawn.match = None
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spawn.match_index = None
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def expect_loop(self, timeout=-1):
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"""Blocking expect"""
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spawn = self.spawn
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if timeout is not None:
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end_time = time.time() + timeout
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try:
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idx = self.existing_data()
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if idx is not None:
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return idx
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while True:
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# No match at this point
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if (timeout is not None) and (timeout < 0):
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return self.timeout()
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# Still have time left, so read more data
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incoming = spawn.read_nonblocking(spawn.maxread, timeout)
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if self.spawn.delayafterread is not None:
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time.sleep(self.spawn.delayafterread)
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idx = self.new_data(incoming)
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# Keep reading until exception or return.
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if idx is not None:
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return idx
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if timeout is not None:
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timeout = end_time - time.time()
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except EOF as e:
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return self.eof(e)
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except TIMEOUT as e:
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return self.timeout(e)
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except:
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self.errored()
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raise
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class searcher_string(object):
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'''This is a plain string search helper for the spawn.expect_any() method.
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This helper class is for speed. For more powerful regex patterns
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see the helper class, searcher_re.
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Attributes:
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eof_index - index of EOF, or -1
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timeout_index - index of TIMEOUT, or -1
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After a successful match by the search() method the following attributes
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are available:
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start - index into the buffer, first byte of match
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end - index into the buffer, first byte after match
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match - the matching string itself
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'''
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def __init__(self, strings):
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'''This creates an instance of searcher_string. This argument 'strings'
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may be a list; a sequence of strings; or the EOF or TIMEOUT types. '''
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self.eof_index = -1
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self.timeout_index = -1
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self._strings = []
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self.longest_string = 0
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for n, s in enumerate(strings):
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if s is EOF:
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self.eof_index = n
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continue
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if s is TIMEOUT:
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self.timeout_index = n
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continue
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self._strings.append((n, s))
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if len(s) > self.longest_string:
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self.longest_string = len(s)
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def __str__(self):
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'''This returns a human-readable string that represents the state of
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the object.'''
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ss = [(ns[0], ' %d: %r' % ns) for ns in self._strings]
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ss.append((-1, 'searcher_string:'))
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if self.eof_index >= 0:
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ss.append((self.eof_index, ' %d: EOF' % self.eof_index))
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if self.timeout_index >= 0:
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ss.append((self.timeout_index,
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' %d: TIMEOUT' % self.timeout_index))
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ss.sort()
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ss = list(zip(*ss))[1]
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return '\n'.join(ss)
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def search(self, buffer, freshlen, searchwindowsize=None):
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'''This searches 'buffer' for the first occurrence of one of the search
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strings. 'freshlen' must indicate the number of bytes at the end of
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'buffer' which have not been searched before. It helps to avoid
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searching the same, possibly big, buffer over and over again.
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See class spawn for the 'searchwindowsize' argument.
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If there is a match this returns the index of that string, and sets
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'start', 'end' and 'match'. Otherwise, this returns -1. '''
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first_match = None
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# 'freshlen' helps a lot here. Further optimizations could
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# possibly include:
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#
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# using something like the Boyer-Moore Fast String Searching
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# Algorithm; pre-compiling the search through a list of
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# strings into something that can scan the input once to
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# search for all N strings; realize that if we search for
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# ['bar', 'baz'] and the input is '...foo' we need not bother
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# rescanning until we've read three more bytes.
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#
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# Sadly, I don't know enough about this interesting topic. /grahn
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for index, s in self._strings:
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if searchwindowsize is None:
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# the match, if any, can only be in the fresh data,
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# or at the very end of the old data
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offset = -(freshlen + len(s))
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else:
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# better obey searchwindowsize
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offset = -searchwindowsize
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n = buffer.find(s, offset)
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if n >= 0 and (first_match is None or n < first_match):
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first_match = n
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best_index, best_match = index, s
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if first_match is None:
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return -1
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self.match = best_match
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self.start = first_match
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self.end = self.start + len(self.match)
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return best_index
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class searcher_re(object):
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'''This is regular expression string search helper for the
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spawn.expect_any() method. This helper class is for powerful
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pattern matching. For speed, see the helper class, searcher_string.
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Attributes:
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eof_index - index of EOF, or -1
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timeout_index - index of TIMEOUT, or -1
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After a successful match by the search() method the following attributes
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are available:
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start - index into the buffer, first byte of match
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end - index into the buffer, first byte after match
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match - the re.match object returned by a successful re.search
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'''
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def __init__(self, patterns):
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'''This creates an instance that searches for 'patterns' Where
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'patterns' may be a list or other sequence of compiled regular
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expressions, or the EOF or TIMEOUT types.'''
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self.eof_index = -1
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self.timeout_index = -1
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self._searches = []
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for n, s in enumerate(patterns):
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if s is EOF:
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self.eof_index = n
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continue
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if s is TIMEOUT:
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self.timeout_index = n
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continue
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self._searches.append((n, s))
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def __str__(self):
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'''This returns a human-readable string that represents the state of
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the object.'''
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#ss = [(n, ' %d: re.compile("%s")' %
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# (n, repr(s.pattern))) for n, s in self._searches]
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ss = list()
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for n, s in self._searches:
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ss.append((n, ' %d: re.compile(%r)' % (n, s.pattern)))
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ss.append((-1, 'searcher_re:'))
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if self.eof_index >= 0:
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ss.append((self.eof_index, ' %d: EOF' % self.eof_index))
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if self.timeout_index >= 0:
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ss.append((self.timeout_index, ' %d: TIMEOUT' %
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self.timeout_index))
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ss.sort()
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ss = list(zip(*ss))[1]
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return '\n'.join(ss)
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def search(self, buffer, freshlen, searchwindowsize=None):
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'''This searches 'buffer' for the first occurrence of one of the regular
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expressions. 'freshlen' must indicate the number of bytes at the end of
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'buffer' which have not been searched before.
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See class spawn for the 'searchwindowsize' argument.
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If there is a match this returns the index of that string, and sets
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'start', 'end' and 'match'. Otherwise, returns -1.'''
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first_match = None
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# 'freshlen' doesn't help here -- we cannot predict the
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# length of a match, and the re module provides no help.
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if searchwindowsize is None:
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searchstart = 0
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else:
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searchstart = max(0, len(buffer) - searchwindowsize)
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for index, s in self._searches:
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match = s.search(buffer, searchstart)
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if match is None:
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continue
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n = match.start()
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if first_match is None or n < first_match:
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first_match = n
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the_match = match
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best_index = index
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if first_match is None:
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return -1
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self.start = first_match
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self.match = the_match
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self.end = self.match.end()
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return best_index
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