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legacy_wexpect.py
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"""Wexpect is a Windows variant of pexpect https://pexpect.readthedocs.io.
Wexpect is a Python module for spawning child applications and controlling
them automatically. Wexpect can be used for automating interactive applications
such as ssh, ftp, passwd, telnet, etc. It can be used to a automate setup
scripts for duplicating software package installations on different servers. It
can be used for automated software testing. Wexpect is in the spirit of Don
Libes' Expect, but Wexpect is pure Python. Other Expect-like modules for Python
require TCL and Expect or require C extensions to be compiled. Wexpect does not
use C, Expect, or TCL extensions.
There are two main interfaces to Wexpect -- the function, run() and the class,
spawn. You can call the run() function to execute a command and return the
output. This is a handy replacement for os.system().
For example::
wexpect.run('ls -la')
The more powerful interface is the spawn class. You can use this to spawn an
external child command and then interact with the child by sending lines and
expecting responses.
For example::
child = wexpect.spawn('scp foo [email protected]:.')
child.expect('Password:')
child.sendline(mypassword)
This works even for commands that ask for passwords or other input outside of
the normal stdio streams.
"""
#
# wexpect is windows only. Use pexpect on linux like systems.
#
import sys
if sys.platform != 'win32': # pragma: no cover
raise ImportError ("""sys.platform != 'win32': Wexpect supports only Windows.
Pexpect is intended for UNIX-like operating systems.""")
#
# Import built in modules
#
import logging
import os
import time
import re
import shutil
import types
import traceback
import signal
import pkg_resources
from io import StringIO
try:
from ctypes import windll
import pywintypes
import win32console
import win32process
import win32con
import win32gui
import win32api
import win32file
import winerror
except ImportError as e: # pragma: no cover
raise ImportError(str(e) + "\nThis package requires the win32 python packages.\r\nInstall with pip install pywin32")
#
# System-wide constants
#
screenbufferfillchar = '\4'
maxconsoleY = 8000
# The version is handled by the package: pbr, which derives the version from the git tags.
try:
__version__ = pkg_resources.require("wexpect")[0].version
except: # pragma: no cover
__version__ = '0.0.1.unkowndev0'
__all__ = ['ExceptionPexpect', 'EOF', 'TIMEOUT', 'spawn', 'run', 'which',
'split_command_line', '__version__']
#
# Create logger: We write logs only to file. Printing out logs are dangerous, because of the deep
# console manipulation.
#
pid=os.getpid()
logger = logging.getLogger('wexpect')
try:
logger_level = os.environ['WEXPECT_LOGGER_LEVEL']
logger.setLevel(logger_level)
fh = logging.FileHandler(f'wexpect_{pid}.log', 'w', 'utf-8')
formatter = logging.Formatter('%(asctime)s - %(filename)s::%(funcName)s - %(levelname)s - %(message)s')
fh.setFormatter(formatter)
logger.addHandler(fh)
except KeyError:
logger.setLevel(logging.ERROR)
# Test the logger
logger.info('wexpect imported; logger working')
####################################################################################################
#
# Exceptions
#
####################################################################################################
class ExceptionPexpect(Exception):
"""Base class for all exceptions raised by this module.
"""
def __init__(self, value):
self.value = value
def __str__(self):
return str(self.value)
def get_trace(self):
"""This returns an abbreviated stack trace with lines that only concern
the caller. In other words, the stack trace inside the Wexpect module
is not included. """
tblist = traceback.extract_tb(sys.exc_info()[2])
tblist = [item for item in tblist if self.__filter_not_wexpect(item)]
tblist = traceback.format_list(tblist)
return ''.join(tblist)
def __filter_not_wexpect(self, trace_list_item):
"""This returns True if list item 0 the string 'wexpect.py' in it. """
if trace_list_item[0].find('wexpect.py') == -1:
return True
else:
return False
class EOF(ExceptionPexpect):
"""Raised when EOF is read from a child. This usually means the child has exited.
The user can wait to EOF, which means he waits the end of the execution of the child process."""
class TIMEOUT(ExceptionPexpect):
"""Raised when a read time exceeds the timeout. """
def run (command, timeout=-1, withexitstatus=False, events=None, extra_args=None, logfile=None,
cwd=None, env=None, echo=True):
"""
This function runs the given command; waits for it to finish; then
returns all output as a string. STDERR is included in output. If the full
path to the command is not given then the path is searched.
Note that lines are terminated by CR/LF (\\r\\n) combination even on
UNIX-like systems because this is the standard for pseudo ttys. If you set
'withexitstatus' to true, then run will return a tuple of (command_output,
exitstatus). If 'withexitstatus' is false then this returns just
command_output.
The run() function can often be used instead of creating a spawn instance.
For example, the following code uses spawn::
child = spawn('scp foo [email protected]:.')
child.expect ('(?i)password')
child.sendline (mypassword)
The previous code can be replace with the following::
Examples
========
Start the apache daemon on the local machine::
run ("/usr/local/apache/bin/apachectl start")
Check in a file using SVN::
run ("svn ci -m 'automatic commit' my_file.py")
Run a command and capture exit status::
(command_output, exitstatus) = run ('ls -l /bin', withexitstatus=1)
Tricky Examples
===============
The following will run SSH and execute 'ls -l' on the remote machine. The
password 'secret' will be sent if the '(?i)password' pattern is ever seen::
run ("ssh [email protected] 'ls -l'", events={'(?i)password':'secret\\n'})
The 'events' argument should be a dictionary of patterns and responses.
Whenever one of the patterns is seen in the command out run() will send the
associated response string. Note that you should put newlines in your
string if Enter is necessary. The responses may also contain callback
functions. Any callback is function that takes a dictionary as an argument.
The dictionary contains all the locals from the run() function, so you can
access the child spawn object or any other variable defined in run()
(event_count, child, and extra_args are the most useful). A callback may
return True to stop the current run process otherwise run() continues until
the next event. A callback may also return a string which will be sent to
the child. 'extra_args' is not used by directly run(). It provides a way to
pass data to a callback function through run() through the locals
dictionary passed to a callback. """
if timeout == -1:
child = spawn(command, maxread=2000, logfile=logfile, cwd=cwd, env=env)
else:
child = spawn(command, timeout=timeout, maxread=2000, logfile=logfile, cwd=cwd, env=env)
if events is not None:
patterns = list(events.keys())
responses = list(events.values())
else:
patterns=None # We assume that EOF or TIMEOUT will save us.
responses=None
child_result_list = []
event_count = 0
while 1:
try:
index = child.expect (patterns)
if type(child.after) in (str,):
child_result_list.append(child.before + child.after)
else: # child.after may have been a TIMEOUT or EOF, so don't cat those.
child_result_list.append(child.before)
if type(responses[index]) in (str,):
child.send(responses[index])
elif type(responses[index]) is types.FunctionType:
callback_result = responses[index](locals())
sys.stdout.flush()
if type(callback_result) in (str,):
child.send(callback_result)
elif callback_result:
break
else:
logger.info('TypeError: The callback must be a string or function type.')
raise TypeError ('The callback must be a string or function type.')
event_count = event_count + 1
except TIMEOUT:
child_result_list.append(child.before)
break
except EOF:
child_result_list.append(child.before)
break
child_result = ''.join(child_result_list)
if withexitstatus:
child.close()
return (child_result, child.exitstatus)
else:
return child_result
def spawn(command, args=[], timeout=30, maxread=2000, searchwindowsize=None, logfile=None, cwd=None,
env=None, codepage=None, echo=True, **kwargs):
"""This is the most essential function. The command parameter may be a string that
includes a command and any arguments to the command. For example::
child = wexpect.spawn ('/usr/bin/ftp')
child = wexpect.spawn ('/usr/bin/ssh [email protected]')
child = wexpect.spawn ('ls -latr /tmp')
You may also construct it with a list of arguments like so::
child = wexpect.spawn ('/usr/bin/ftp', [])
child = wexpect.spawn ('/usr/bin/ssh', ['[email protected]'])
child = wexpect.spawn ('ls', ['-latr', '/tmp'])
After this the child application will be created and will be ready to
talk to. For normal use, see expect() and send() and sendline().
Remember that Wexpect does NOT interpret shell meta characters such as
redirect, pipe, or wild cards (>, |, or *). This is a common mistake.
If you want to run a command and pipe it through another command then
you must also start a shell. For example::
child = wexpect.spawn('/bin/bash -c "ls -l | grep LOG > log_list.txt"')
child.expect(wexpect.EOF)
The second form of spawn (where you pass a list of arguments) is useful
in situations where you wish to spawn a command and pass it its own
argument list. This can make syntax more clear. For example, the
following is equivalent to the previous example::
shell_cmd = 'ls -l | grep LOG > log_list.txt'
child = wexpect.spawn('/bin/bash', ['-c', shell_cmd])
child.expect(wexpect.EOF)
The maxread attribute sets the read buffer size. This is maximum number
of bytes that Wexpect will try to read from a TTY at one time. Setting
the maxread size to 1 will turn off buffering. Setting the maxread
value higher may help performance in cases where large amounts of
output are read back from the child. This feature is useful in
conjunction with searchwindowsize.
The searchwindowsize attribute sets the how far back in the incomming
seach buffer Wexpect will search for pattern matches. Every time
Wexpect reads some data from the child it will append the data to the
incomming buffer. The default is to search from the beginning of the
imcomming buffer each time new data is read from the child. But this is
very inefficient if you are running a command that generates a large
amount of data where you want to match The searchwindowsize does not
effect the size of the incomming data buffer. You will still have
access to the full buffer after expect() returns.
The delaybeforesend helps overcome a weird behavior that many users
were experiencing. The typical problem was that a user would expect() a
"Password:" prompt and then immediately call sendline() to send the
password. The user would then see that their password was echoed back
to them. Passwords don't normally echo. The problem is caused by the
fact that most applications print out the "Password" prompt and then
turn off stdin echo, but if you send your password before the
application turned off echo, then you get your password echoed.
Normally this wouldn't be a problem when interacting with a human at a
real keyboard. If you introduce a slight delay just before writing then
this seems to clear up the problem. This was such a common problem for
many users that I decided that the default wexpect behavior should be
to sleep just before writing to the child application. 1/20th of a
second (50 ms) seems to be enough to clear up the problem. You can set
delaybeforesend to 0 to return to the old behavior. Most Linux machines
don't like this to be below 0.03. I don't know why.
Note that spawn is clever about finding commands on your path.
It uses the same logic that "which" uses to find executables.
If you wish to get the exit status of the child you must call the
close() method. The exit status of the child will be stored in self.exitstatus.
If the child exited normally then exitstatus will store the exit return code.
"""
logger.debug('=' * 80)
logger.debug('Buffer size: %s' % maxread)
if searchwindowsize:
logger.debug('Search window size: %s' % searchwindowsize)
logger.debug('Timeout: %ss' % timeout)
if env:
logger.debug('Environment:')
for name in env:
logger.debug('\t%s=%s' % (name, env[name]))
if cwd:
logger.debug('Working directory: %s' % cwd)
return spawn_windows(command, args, timeout, maxread, searchwindowsize, logfile, cwd, env,
codepage, echo=echo)
class spawn_windows ():
"""This is the main class interface for Wexpect. Use this class to start
and control child applications. """
def __init__(self, command, args=[], timeout=30, maxread=60000, searchwindowsize=None,
logfile=None, cwd=None, env=None, codepage=None, echo=True):
""" The spawn_windows constructor. Do not call it directly. Use spawn(), or run() instead.
"""
self.codepage = codepage
self.stdin = sys.stdin
self.stdout = sys.stdout
self.stderr = sys.stderr
self.searcher = None
self.ignorecase = False
self.before = None
self.after = None
self.match = None
self.match_index = None
self.terminated = True
self.exitstatus = None
self.status = None # status returned by os.waitpid
self.flag_eof = False
self.flag_child_finished = False
self.pid = None
self.child_fd = -1 # initially closed
self.timeout = timeout
self.delimiter = EOF
self.logfile = logfile
self.logfile_read = None # input from child (read_nonblocking)
self.logfile_send = None # output to send (send, sendline)
self.maxread = maxread # max bytes to read at one time into buffer
self.buffer = '' # This is the read buffer. See maxread.
self.searchwindowsize = searchwindowsize # Anything before searchwindowsize point is preserved, but not searched.
self.delaybeforesend = 0.05 # Sets sleep time used just before sending data to child. Time in seconds.
self.delayafterterminate = 0.1 # Sets delay in terminate() method to allow kernel time to update process status. Time in seconds.
self.name = '<' + repr(self) + '>' # File-like object.
self.closed = True # File-like object.
self.ocwd = os.getcwd()
self.cwd = cwd
self.env = env
# allow dummy instances for subclasses that may not use command or args.
if command is None:
self.command = None
self.args = None
self.name = '<wexpect factory incomplete>'
else:
self._spawn(command, args, echo=echo)
def __del__(self):
"""This makes sure that no system resources are left open. Python only
garbage collects Python objects, not the child console."""
try:
self.wtty.terminate_child()
except:
pass
def __str__(self):
"""This returns a human-readable string that represents the state of
the object. """
s = []
s.append(repr(self))
s.append('command: ' + str(self.command))
s.append('args: ' + str(self.args))
s.append('searcher: ' + str(self.searcher))
s.append('buffer (last 100 chars): ' + str(self.buffer)[-100:])
s.append('before (last 100 chars): ' + str(self.before)[-100:])
s.append('after: ' + str(self.after))
s.append('match: ' + str(self.match))
s.append('match_index: ' + str(self.match_index))
s.append('exitstatus: ' + str(self.exitstatus))
s.append('flag_eof: ' + str(self.flag_eof))
s.append('pid: ' + str(self.pid))
s.append('child_fd: ' + str(self.child_fd))
s.append('closed: ' + str(self.closed))
s.append('timeout: ' + str(self.timeout))
s.append('delimiter: ' + str(self.delimiter))
s.append('logfile: ' + str(self.logfile))
s.append('logfile_read: ' + str(self.logfile_read))
s.append('logfile_send: ' + str(self.logfile_send))
s.append('maxread: ' + str(self.maxread))
s.append('ignorecase: ' + str(self.ignorecase))
s.append('searchwindowsize: ' + str(self.searchwindowsize))
s.append('delaybeforesend: ' + str(self.delaybeforesend))
s.append('delayafterterminate: ' + str(self.delayafterterminate))
return '\n'.join(s)
def _spawn(self,command,args=[], echo=True):
"""This starts the given command in a child process. This does all the
fork/exec type of stuff for a pty. This is called by __init__. If args
is empty then command will be parsed (split on spaces) and args will be
set to parsed arguments. """
# The pid and child_fd of this object get set by this method.
# Note that it is difficult for this method to fail.
# You cannot detect if the child process cannot start.
# So the only way you can tell if the child process started
# or not is to try to read from the file descriptor. If you get
# EOF immediately then it means that the child is already dead.
# That may not necessarily be bad because you may haved spawned a child
# that performs some task; creates no stdout output; and then dies.
# If command is an int type then it may represent a file descriptor.
if type(command) == type(0):
logger.info('ExceptionPexpect: Command is an int type. If this is a file descriptor then maybe you want to use fdpexpect.fdspawn which takes an existing file descriptor instead of a command string.')
raise ExceptionPexpect ('Command is an int type. If this is a file descriptor then maybe you want to use fdpexpect.fdspawn which takes an existing file descriptor instead of a command string.')
if type (args) != type([]):
logger.info('TypeError: The argument, args, must be a list.')
raise TypeError ('The argument, args, must be a list.')
if args == []:
self.args = split_command_line(command)
self.command = self.args[0]
else:
self.args = args[:] # work with a copy
self.args.insert (0, command)
self.command = command
command_with_path = shutil.which(self.command)
if command_with_path is None:
logger.info('ExceptionPexpect: The command was not found or was not executable: %s.' % self.command)
raise ExceptionPexpect ('The command was not found or was not executable: %s.' % self.command)
self.command = command_with_path
self.args[0] = self.command
self.name = '<' + ' '.join (self.args) + '>'
#assert self.pid is None, 'The pid member should be None.'
#assert self.command is not None, 'The command member should not be None.'
self.wtty = Wtty(codepage=self.codepage, echo=echo)
if self.cwd is not None:
os.chdir(self.cwd)
self.child_fd = self.wtty.spawn(self.command, self.args, self.env)
if self.cwd is not None:
# Restore the original working dir
os.chdir(self.ocwd)
self.terminated = False
self.closed = False
self.pid = self.wtty.pid
def fileno (self): # File-like object.
"""There is no child fd."""
return 0
def close(self, force=True): # File-like object.
""" Closes the child console."""
self.closed = self.terminate(force)
if not self.closed:
logger.info('ExceptionPexpect: close() could not terminate the child using terminate()')
raise ExceptionPexpect ('close() could not terminate the child using terminate()')
self.closed = True
def isatty(self): # File-like object.
"""The child is always created with a console."""
return True
def waitnoecho (self, timeout=-1):
"""This waits until the terminal ECHO flag is set False. This returns
True if the echo mode is off. This returns False if the ECHO flag was
not set False before the timeout. This can be used to detect when the
child is waiting for a password. Usually a child application will turn
off echo mode when it is waiting for the user to enter a password. For
example, instead of expecting the "password:" prompt you can wait for
the child to set ECHO off::
p = wexpect.spawn ('ssh [email protected]')
p.waitnoecho()
p.sendline(mypassword)
If timeout is None then this method to block forever until ECHO flag is
False.
"""
if timeout == -1:
timeout = self.timeout
if timeout is not None:
end_time = time.time() + timeout
while True:
if not self.getecho():
return True
if timeout < 0 and timeout is not None:
return False
if timeout is not None:
timeout = end_time - time.time()
time.sleep(0.1)
def getecho (self):
"""This returns the terminal echo mode. This returns True if echo is
on or False if echo is off. Child applications that are expecting you
to enter a password often set ECHO False. See waitnoecho()."""
return self.wtty.getecho()
def setecho (self, state):
"""This sets the terminal echo mode on or off."""
self.wtty.setecho(state)
def read (self, size = -1): # File-like object.
"""This reads at most "size" bytes from the file (less if the read hits
EOF before obtaining size bytes). If the size argument is negative or
omitted, read all data until EOF is reached. The bytes are returned as
a string object. An empty string is returned when EOF is encountered
immediately. """
if size == 0:
return ''
if size < 0:
self.expect (self.delimiter) # delimiter default is EOF
return self.before
# I could have done this more directly by not using expect(), but
# I deliberately decided to couple read() to expect() so that
# I would catch any bugs early and ensure consistant behavior.
# It's a little less efficient, but there is less for me to
# worry about if I have to later modify read() or expect().
# Note, it's OK if size==-1 in the regex. That just means it
# will never match anything in which case we stop only on EOF.
cre = re.compile('.{%d}' % size, re.DOTALL)
index = self.expect ([cre, self.delimiter]) # delimiter default is EOF
if index == 0:
return self.after ### self.before should be ''. Should I assert this?
return self.before
def readline (self, size = -1): # File-like object.
"""This reads and returns one entire line. A trailing newline is kept
in the string, but may be absent when a file ends with an incomplete
line. Note: This readline() looks for a \\r\\n pair even on UNIX
because this is what the pseudo tty device returns. So contrary to what
you may expect you will receive the newline as \\r\\n. An empty string
is returned when EOF is hit immediately. Currently, the size argument is
mostly ignored, so this behavior is not standard for a file-like
object. If size is 0 then an empty string is returned. """
if size == 0:
return ''
index = self.expect (['\r\n', self.delimiter]) # delimiter default is EOF
if index == 0:
return self.before + '\r\n'
else:
return self.before
def __iter__ (self): # File-like object.
"""This is to support iterators over a file-like object.
"""
return self
def __next__ (self): # File-like object.
"""This is to support iterators over a file-like object.
"""
result = self.readline()
if self.after == self.delimiter:
raise StopIteration
return result
def __enter__(self):
return self
def __exit__(self, exc_type, exc_val, exc_tb):
self.terminate()
def readlines (self, sizehint = -1): # File-like object.
"""This reads until EOF using readline() and returns a list containing
the lines thus read. The optional "sizehint" argument is ignored. """
lines = []
while True:
line = self.readline()
if not line:
break
lines.append(line)
return lines
def read_nonblocking (self, size = 1):
"""This reads at most size characters from the child application. If
the end of file is read then an EOF exception will be raised.
This is not effected by the 'size' parameter, so if you call
read_nonblocking(size=100, timeout=30) and only one character is
available right away then one character will be returned immediately.
It will not wait for 30 seconds for another 99 characters to come in.
This is a wrapper around Wtty.read(). """
if self.closed:
logger.info('ValueError: I/O operation on closed file in read_nonblocking().')
raise ValueError ('I/O operation on closed file in read_nonblocking().')
try:
# The real child and it's console are two different process. The console dies 0.1 sec
# later to be able to read the child's last output (before EOF). So here we check
# isalive() (which checks the real child.) and try a last read on the console. To catch
# the last output.
# The flag_child_finished flag shows that this is the second trial, where we raise the EOF.
if self.flag_child_finished:
logger.info('EOF: self.flag_child_finished')
raise EOF('self.flag_child_finished')
if not self.isalive():
self.flag_child_finished = True
s = self.wtty.read_nonblocking(size)
except EOF:
self.flag_eof = True
raise
if self.logfile is not None:
self.logfile.write (s)
self.logfile.flush()
if self.logfile_read is not None:
self.logfile_read.write (s)
self.logfile_read.flush()
return s
def write(self, s): # File-like object.
"""This is similar to send() except that there is no return value.
"""
self.send (s)
def writelines (self, sequence): # File-like object.
"""This calls write() for each element in the sequence. The sequence
can be any iterable object producing strings, typically a list of
strings. This does not add line separators There is no return value.
"""
for s in sequence:
self.write (s)
def sendline(self, s=''):
"""This is like send(), but it adds a line feed (os.linesep). This
returns the number of bytes written. """
n = self.send(s)
n = n + self.send (os.linesep)
return n
def sendeof(self):
"""This sends an EOF to the child. This sends a character which causes
the pending parent output buffer to be sent to the waiting child
program without waiting for end-of-line. If it is the first character
of the line, the read() in the user program returns 0, which signifies
end-of-file. This means to work as expected a sendeof() has to be
called at the beginning of a line. This method does not send a newline.
It is the responsibility of the caller to ensure the eof is sent at the
beginning of a line. """
# platform does not define VEOF so assume CTRL-D
char = chr(4)
self.send(char)
def send(self, s):
"""This sends a string to the child process. This returns the number of
bytes written. If a log file was set then the data is also written to
the log. """
(self.delaybeforesend)
if self.logfile is not None:
self.logfile.write (s)
self.logfile.flush()
if self.logfile_send is not None:
self.logfile_send.write (s)
self.logfile_send.flush()
c = self.wtty.write(s)
return c
def sendintr(self):
"""This sends a SIGINT to the child. It does not require
the SIGINT to be the first character on a line. """
self.wtty.sendintr()
def eof (self):
"""This returns True if the EOF exception was ever raised.
"""
return self.flag_eof
def terminate(self, force=False):
"""Terminate the child. Force not used. """
if not self.isalive():
return True
self.wtty.terminate_child()
time.sleep(self.delayafterterminate)
if not self.isalive():
return True
return False
def kill(self, sig=signal.SIGTERM):
"""Sig == sigint for ctrl-c otherwise the child is terminated."""
if not self.isalive():
return
if sig == signal.SIGINT:
self.wtty.sendintr()
else:
self.wtty.terminate_child()
def wait(self):
"""This waits until the child exits. This is a blocking call. This will
not read any data from the child, so this will block forever if the
child has unread output and has terminated. In other words, the child
may have printed output then called exit(); but, technically, the child
is still alive until its output is read."""
# We can't use os.waitpid under Windows because of 'permission denied'
# exception? Perhaps if not running as admin (or UAC enabled under
# Vista/7). Simply loop and wait for child to exit.
while self.isalive():
time.sleep(.05) # Keep CPU utilization down
return self.exitstatus
def isalive(self):
"""Determines if the child is still alive."""
if self.terminated:
logger.debug('self.terminated is true')
return False
if self.wtty.isalive():
return True
else:
logger.debug('self.wtty.isalive() is false')
self.exitstatus = win32process.GetExitCodeProcess(self.wtty.getchild())
self.status = (self.pid, self.exitstatus << 8) # left-shift exit status by 8 bits like os.waitpid
self.terminated = True
return False
def compile_pattern_list(self, patterns):
"""This compiles a pattern-string or a list of pattern-strings.
Patterns must be a StringType, EOF, TIMEOUT, SRE_Pattern, or a list of
those. Patterns may also be None which results in an empty list (you
might do this if waiting for an EOF or TIMEOUT condition without
expecting any pattern).
This is used by expect() when calling expect_list(). Thus expect() is
nothing more than::
cpl = self.compile_pattern_list(pl)
return self.expect_list(cpl, timeout)
If you are using expect() within a loop it may be more
efficient to compile the patterns first and then call expect_list().
This avoid calls in a loop to compile_pattern_list()::
cpl = self.compile_pattern_list(my_pattern)
while some_condition:
...
i = self.expect_list(clp, timeout)
...
"""
if patterns is None:
return []
if type(patterns) is not list:
patterns = [patterns]
compile_flags = re.DOTALL # Allow dot to match \n
if self.ignorecase:
compile_flags = compile_flags | re.IGNORECASE
compiled_pattern_list = []
for p in patterns:
if type(p) in (str,):
compiled_pattern_list.append(re.compile(p, compile_flags))
elif p is EOF:
compiled_pattern_list.append(EOF)
elif p is TIMEOUT:
compiled_pattern_list.append(TIMEOUT)
elif type(p) is type(re.compile('')):
compiled_pattern_list.append(p)
else:
logger.info('TypeError: Argument must be one of StringTypes, EOF, TIMEOUT, SRE_Pattern, or a list of those type. %s' % str(type(p)))
raise TypeError ('Argument must be one of StringTypes, EOF, TIMEOUT, SRE_Pattern, or a list of those type. %s' % str(type(p)))
return compiled_pattern_list
def expect(self, pattern, timeout = -1, searchwindowsize=None):
"""This seeks through the stream until a pattern is matched. The
pattern is overloaded and may take several types. The pattern can be a
StringType, EOF, a compiled re, or a list of any of those types.
Strings will be compiled to re types. This returns the index into the
pattern list. If the pattern was not a list this returns index 0 on a
successful match. This may raise exceptions for EOF or TIMEOUT. To
avoid the EOF or TIMEOUT exceptions add EOF or TIMEOUT to the pattern
list. That will cause expect to match an EOF or TIMEOUT condition
instead of raising an exception.
If you pass a list of patterns and more than one matches, the first match
in the stream is chosen. If more than one pattern matches at that point,
the leftmost in the pattern list is chosen. For example::
# the input is 'foobar'
index = p.expect (['bar', 'foo', 'foobar'])
# returns 1 ('foo') even though 'foobar' is a "better" match
Please note, however, that buffering can affect this behavior, since
input arrives in unpredictable chunks. For example::
# the input is 'foobar'
index = p.expect (['foobar', 'foo'])
# returns 0 ('foobar') if all input is available at once,
# but returs 1 ('foo') if parts of the final 'bar' arrive late
After a match is found the instance attributes 'before', 'after' and
'match' will be set. You can see all the data read before the match in
'before'. You can see the data that was matched in 'after'. The
re.MatchObject used in the re match will be in 'match'. If an error
occurred then 'before' will be set to all the data read so far and
'after' and 'match' will be None.
If timeout is -1 then timeout will be set to the self.timeout value.
A list entry may be EOF or TIMEOUT instead of a string. This will
catch these exceptions and return the index of the list entry instead
of raising the exception. The attribute 'after' will be set to the
exception type. The attribute 'match' will be None. This allows you to
write code like this::
index = p.expect (['good', 'bad', wexpect.EOF, wexpect.TIMEOUT])
if index == 0:
do_something()
elif index == 1:
do_something_else()
elif index == 2:
do_some_other_thing()
elif index == 3:
do_something_completely_different()
instead of code like this::
try:
index = p.expect (['good', 'bad'])
if index == 0:
do_something()
elif index == 1:
do_something_else()
except EOF:
do_some_other_thing()
except TIMEOUT:
do_something_completely_different()
These two forms are equivalent. It all depends on what you want. You
can also just expect the EOF if you are waiting for all output of a
child to finish. For example::
p = wexpect.spawn('/bin/ls')
p.expect (wexpect.EOF)
print p.before
If you are trying to optimize for speed then see expect_list().
"""
compiled_pattern_list = self.compile_pattern_list(pattern)
return self.expect_list(compiled_pattern_list, timeout, searchwindowsize)
def expect_list(self, pattern_list, timeout = -1, searchwindowsize = -1):
"""This takes a list of compiled regular expressions and returns the
index into the pattern_list that matched the child output. The list may
also contain EOF or TIMEOUT (which are not compiled regular
expressions). This method is similar to the expect() method except that
expect_list() does not recompile the pattern list on every call. This
may help if you are trying to optimize for speed, otherwise just use
the expect() method. This is called by expect(). If timeout==-1 then
the self.timeout value is used. If searchwindowsize==-1 then the
self.searchwindowsize value is used. """
return self.expect_loop(searcher_re(pattern_list), timeout, searchwindowsize)
def expect_exact(self, pattern_list, timeout = -1, searchwindowsize = -1):
"""This is similar to expect(), but uses plain string matching instead
of compiled regular expressions in 'pattern_list'. The 'pattern_list'
may be a string; a list or other sequence of strings; or TIMEOUT and
EOF.
This call might be faster than expect() for two reasons: string
searching is faster than RE matching and it is possible to limit the
search to just the end of the input buffer.
This method is also useful when you don't want to have to worry about
escaping regular expression characters that you want to match."""
if not isinstance(pattern_list, list):
pattern_list = [pattern_list]
for p in pattern_list:
if type(p) not in (str,) and p not in (TIMEOUT, EOF):
logger.info('TypeError: Argument must be one of StringTypes, EOF, TIMEOUT, or a list of those type. %s' % str(type(p)))
raise TypeError ('Argument must be one of StringTypes, EOF, TIMEOUT, or a list of those type. %s' % str(type(p)))
return self.expect_loop(searcher_string(pattern_list), timeout, searchwindowsize)
def expect_loop(self, searcher, timeout = -1, searchwindowsize = -1):
"""This is the common loop used inside expect. The 'searcher' should be
an instance of searcher_re or searcher_string, which describes how and what
to search for in the input.
See expect() for other arguments, return value and exceptions. """
self.searcher = searcher
if timeout == -1:
timeout = self.timeout
if timeout is not None:
end_time = time.time() + timeout
if searchwindowsize == -1:
searchwindowsize = self.searchwindowsize
try:
incoming = self.buffer
freshlen = len(incoming)
while True: # Keep reading until exception or return.
index = searcher.search(incoming, freshlen, searchwindowsize)
if index >= 0:
self.buffer = incoming[searcher.end : ]
self.before = incoming[ : searcher.start]
self.after = incoming[searcher.start : searcher.end]
self.match = searcher.match
self.match_index = index