home *** CD-ROM | disk | FTP | other *** search
"""Pexpect is a Python module for spawning child applications and controlling them automatically. Pexpect 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. Pexpect is in the spirit of Don Libes' Expect, but Pexpect is pure Python. Other Expect-like modules for Python require TCL and Expect or require C extensions to be compiled. Pexpect does not use C, Expect, or TCL extensions. It should work on any platform that supports the standard Python pty module. The Pexpect interface focuses on ease of use so that simple tasks are easy. There are two main interfaces to Pexpect -- 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:: pexpect.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 = pexpect.spawn('scp foo myname@host.example.com:.') child.expect ('Password:') child.sendline (mypassword) This works even for commands that ask for passwords or other input outside of the normal stdio streams. Credits: Noah Spurrier, Richard Holden, Marco Molteni, Kimberley Burchett, Robert Stone, Hartmut Goebel, Chad Schroeder, Erick Tryzelaar, Dave Kirby, Ids vander Molen, George Todd, Noel Taylor, Nicolas D. Cesar, Alexander Gattin, Geoffrey Marshall, Francisco Lourenco, Glen Mabey, Karthik Gurusamy, Fernando Perez, Corey Minyard, Jon Cohen, Guillaume Chazarain, Andrew Ryan, Nick Craig-Wood, Andrew Stone, Jorgen Grahn (Let me know if I forgot anyone.) Free, open source, and all that good stuff. Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions: The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software. THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. Pexpect Copyright (c) 2008 Noah Spurrier http://pexpect.sourceforge.net/ $Id: pexpect.py 507 2007-12-27 02:40:52Z noah $ """ try: import os, sys, time import select import string import re import struct import resource import types import pty import tty import termios import fcntl import errno import traceback import signal except ImportError, e: raise ImportError (str(e) + """ A critical module was not found. Probably this operating system does not support it. Pexpect is intended for UNIX-like operating systems.""") __version__ = '2.3' __revision__ = '$Revision: 399 $' __all__ = ['ExceptionPexpect', 'EOF', 'TIMEOUT', 'spawn', 'run', 'which', 'split_command_line', '__version__', '__revision__'] # Exception classes used by this module. 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 Pexpect module is not included. """ tblist = traceback.extract_tb(sys.exc_info()[2]) #tblist = filter(self.__filter_not_pexpect, tblist) tblist = [item for item in tblist if self.__filter_not_pexpect(item)] tblist = traceback.format_list(tblist) return ''.join(tblist) def __filter_not_pexpect(self, trace_list_item): """This returns True if list item 0 the string 'pexpect.py' in it. """ if trace_list_item[0].find('pexpect.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.""" class TIMEOUT(ExceptionPexpect): """Raised when a read time exceeds the timeout. """ ##class TIMEOUT_PATTERN(TIMEOUT): ## """Raised when the pattern match time exceeds the timeout. ## This is different than a read TIMEOUT because the child process may ## give output, thus never give a TIMEOUT, but the output ## may never match a pattern. ## """ ##class MAXBUFFER(ExceptionPexpect): ## """Raised when a scan buffer fills before matching an expected pattern.""" def run (command, timeout=-1, withexitstatus=False, events=None, extra_args=None, logfile=None, cwd=None, env=None): """ 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:: from pexpect import * child = spawn('scp foo myname@host.example.com:.') child.expect ('(?i)password') child.sendline (mypassword) The previous code can be replace with the following:: from pexpect import * run ('scp foo myname@host.example.com:.', events={'(?i)password': mypassword}) Examples ======== Start the apache daemon on the local machine:: from pexpect import * run ("/usr/local/apache/bin/apachectl start") Check in a file using SVN:: from pexpect import * run ("svn ci -m 'automatic commit' my_file.py") Run a command and capture exit status:: from pexpect import * (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 username@machine.example.com 'ls -l'", events={'(?i)password':'secret\\n'}) This will start mencoder to rip a video from DVD. This will also display progress ticks every 5 seconds as it runs. For example:: from pexpect import * def print_ticks(d): print d['event_count'], run ("mencoder dvd://1 -o video.avi -oac copy -ovc copy", events={TIMEOUT:print_ticks}, timeout=5) 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 = events.keys() responses = 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 types.StringTypes: 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 types.StringTypes: child.send(responses[index]) elif type(responses[index]) is types.FunctionType: callback_result = responses[index](locals()) sys.stdout.flush() if type(callback_result) in types.StringTypes: child.send(callback_result) elif callback_result: break else: raise TypeError ('The callback must be a string or function type.') event_count = event_count + 1 except TIMEOUT, e: child_result_list.append(child.before) break except EOF, e: 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 class spawn (object): """This is the main class interface for Pexpect. Use this class to start and control child applications. """ def __init__(self, command, args=[], timeout=30, maxread=2000, searchwindowsize=None, logfile=None, cwd=None, env=None): """This is the constructor. The command parameter may be a string that includes a command and any arguments to the command. For example:: child = pexpect.spawn ('/usr/bin/ftp') child = pexpect.spawn ('/usr/bin/ssh user@example.com') child = pexpect.spawn ('ls -latr /tmp') You may also construct it with a list of arguments like so:: child = pexpect.spawn ('/usr/bin/ftp', []) child = pexpect.spawn ('/usr/bin/ssh', ['user@example.com']) child = pexpect.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 Pexpect 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 = pexpect.spawn('/bin/bash -c "ls -l | grep LOG > log_list.txt"') child.expect(pexpect.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 = pexpect.spawn('/bin/bash', ['-c', shell_cmd]) child.expect(pexpect.EOF) The maxread attribute sets the read buffer size. This is maximum number of bytes that Pexpect 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 Pexpect will search for pattern matches. Every time Pexpect 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 logfile member turns on or off logging. All input and output will be copied to the given file object. Set logfile to None to stop logging. This is the default. Set logfile to sys.stdout to echo everything to standard output. The logfile is flushed after each write. Example log input and output to a file:: child = pexpect.spawn('some_command') fout = file('mylog.txt','w') child.logfile = fout Example log to stdout:: child = pexpect.spawn('some_command') child.logfile = sys.stdout The logfile_read and logfile_send members can be used to separately log the input from the child and output sent to the child. Sometimes you don't want to see everything you write to the child. You only want to log what the child sends back. For example:: child = pexpect.spawn('some_command') child.logfile_read = sys.stdout To separately log output sent to the child use logfile_send:: self.logfile_send = fout 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 pexpect 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 or signal status of the child will be stored in self.exitstatus or self.signalstatus. If the child exited normally then exitstatus will store the exit return code and signalstatus will be None. If the child was terminated abnormally with a signal then signalstatus will store the signal value and exitstatus will be None. If you need more detail you can also read the self.status member which stores the status returned by os.waitpid. You can interpret this using os.WIFEXITED/os.WEXITSTATUS or os.WIFSIGNALED/os.TERMSIG. """ self.STDIN_FILENO = pty.STDIN_FILENO self.STDOUT_FILENO = pty.STDOUT_FILENO self.STDERR_FILENO = pty.STDERR_FILENO 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.signalstatus = None self.status = None # status returned by os.waitpid self.flag_eof = 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. # Most Linux machines don't like delaybeforesend to be below 0.03 (30 ms). self.delaybeforesend = 0.05 # Sets sleep time used just before sending data to child. Time in seconds. self.delayafterclose = 0.1 # Sets delay in close() method to allow kernel time to update process status. Time in seconds. self.delayafterterminate = 0.1 # Sets delay in terminate() method to allow kernel time to update process status. Time in seconds. self.softspace = False # File-like object. self.name = '<' + repr(self) + '>' # File-like object. self.encoding = None # File-like object. self.closed = True # File-like object. self.cwd = cwd self.env = env self.__irix_hack = (sys.platform.lower().find('irix')>=0) # This flags if we are running on irix # Solaris uses internal __fork_pty(). All others use pty.fork(). if (sys.platform.lower().find('solaris')>=0) or (sys.platform.lower().find('sunos5')>=0): self.use_native_pty_fork = False else: self.use_native_pty_fork = True # allow dummy instances for subclasses that may not use command or args. if command is None: self.command = None self.args = None self.name = '<pexpect factory incomplete>' else: self._spawn (command, args) def __del__(self): """This makes sure that no system resources are left open. Python only garbage collects Python objects. OS file descriptors are not Python objects, so they must be handled explicitly. If the child file descriptor was opened outside of this class (passed to the constructor) then this does not close it. """ if not self.closed: # It is possible for __del__ methods to execute during the # teardown of the Python VM itself. Thus self.close() may # trigger an exception because os.close may be None. # -- Fernando Perez try: self.close() except AttributeError: pass def __str__(self): """This returns a human-readable string that represents the state of the object. """ s = [] s.append(repr(self)) s.append('version: ' + __version__ + ' (' + __revision__ + ')') 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('delayafterclose: ' + str(self.delayafterclose)) s.append('delayafterterminate: ' + str(self.delayafterterminate)) return '\n'.join(s) def _spawn(self,command,args=[]): """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): 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([]): 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 = which(self.command) if command_with_path is None: 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.' if self.use_native_pty_fork: try: self.pid, self.child_fd = pty.fork() except OSError, e: raise ExceptionPexpect('Error! pty.fork() failed: ' + str(e)) else: # Use internal __fork_pty self.pid, self.child_fd = self.__fork_pty() if self.pid == 0: # Child try: self.child_fd = sys.stdout.fileno() # used by setwinsize() self.setwinsize(24, 80) except: # Some platforms do not like setwinsize (Cygwin). # This will cause problem when running applications that # are very picky about window size. # This is a serious limitation, but not a show stopper. pass # Do not allow child to inherit open file descriptors from parent. max_fd = resource.getrlimit(resource.RLIMIT_NOFILE)[0] for i in range (3, max_fd): try: os.close (i) except OSError: pass # I don't know why this works, but ignoring SIGHUP fixes a # problem when trying to start a Java daemon with sudo # (specifically, Tomcat). signal.signal(signal.SIGHUP, signal.SIG_IGN) if self.cwd is not None: os.chdir(self.cwd) if self.env is None: os.execv(self.command, self.args) else: os.execvpe(self.command, self.args, self.env) # Parent self.terminated = False self.closed = False def __fork_pty(self): """This implements a substitute for the forkpty system call. This should be more portable than the pty.fork() function. Specifically, this should work on Solaris. Modified 10.06.05 by Geoff Marshall: Implemented __fork_pty() method to resolve the issue with Python's pty.fork() not supporting Solaris, particularly ssh. Based on patch to posixmodule.c authored by Noah Spurrier:: http://mail.python.org/pipermail/python-dev/2003-May/035281.html """ parent_fd, child_fd = os.openpty() if parent_fd < 0 or child_fd < 0: raise ExceptionPexpect, "Error! Could not open pty with os.openpty()." pid = os.fork() if pid < 0: raise ExceptionPexpect, "Error! Failed os.fork()." elif pid == 0: # Child. os.close(parent_fd) self.__pty_make_controlling_tty(child_fd) os.dup2(child_fd, 0) os.dup2(child_fd, 1) os.dup2(child_fd, 2) if child_fd > 2: os.close(child_fd) else: # Parent. os.close(child_fd) return pid, parent_fd def __pty_make_controlling_tty(self, tty_fd): """This makes the pseudo-terminal the controlling tty. This should be more portable than the pty.fork() function. Specifically, this should work on Solaris. """ child_name = os.ttyname(tty_fd) # Disconnect from controlling tty if still connected. fd = os.open("/dev/tty", os.O_RDWR | os.O_NOCTTY); if fd >= 0: os.close(fd) os.setsid() # Verify we are disconnected from controlling tty try: fd = os.open("/dev/tty", os.O_RDWR | os.O_NOCTTY); if fd >= 0: os.close(fd) raise ExceptionPexpect, "Error! We are not disconnected from a controlling tty." except: # Good! We are disconnected from a controlling tty. pass # Verify we can open child pty. fd = os.open(child_name, os.O_RDWR); if fd < 0: raise ExceptionPexpect, "Error! Could not open child pty, " + child_name else: os.close(fd) # Verify we now have a controlling tty. fd = os.open("/dev/tty", os.O_WRONLY) if fd < 0: raise ExceptionPexpect, "Error! Could not open controlling tty, /dev/tty" else: os.close(fd) def fileno (self): # File-like object. """This returns the file descriptor of the pty for the child. """ return self.child_fd def close (self, force=True): # File-like object. """This closes the connection with the child application. Note that calling close() more than once is valid. This emulates standard Python behavior with files. Set force to True if you want to make sure that the child is terminated (SIGKILL is sent if the child ignores SIGHUP and SIGINT). """ if not self.closed: self.flush() os.close (self.child_fd) time.sleep(self.delayafterclose) # Give kernel time to update process status. if self.isalive(): if not self.terminate(force): raise ExceptionPexpect ('close() could not terminate the child using terminate()') self.child_fd = -1 self.closed = True #self.pid = None def flush (self): # File-like object. """This does nothing. It is here to support the interface for a File-like object. """ pass def isatty (self): # File-like object. """This returns True if the file descriptor is open and connected to a tty(-like) device, else False. """ return os.isatty(self.child_fd) 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 = pexpect.spawn ('ssh user@example.com') 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(). """ attr = termios.tcgetattr(self.child_fd) if attr[3] & termios.ECHO: return True return False def setecho (self, state): """This sets the terminal echo mode on or off. Note that anything the child sent before the echo will be lost, so you should be sure that your input buffer is empty before you call setecho(). For example, the following will work as expected:: p = pexpect.spawn('cat') p.sendline ('1234') # We will see this twice (once from tty echo and again from cat). p.expect (['1234']) p.expect (['1234']) p.setecho(False) # Turn off tty echo p.sendline ('abcd') # We will set this only once (echoed by cat). p.sendline ('wxyz') # We will set this only once (echoed by cat) p.expect (['abcd']) p.expect (['wxyz']) The following WILL NOT WORK because the lines sent before the setecho will be lost:: p = pexpect.spawn('cat') p.sendline ('1234') # We will see this twice (once from tty echo and again from cat). p.setecho(False) # Turn off tty echo p.sendline ('abcd') # We will set this only once (echoed by cat). p.sendline ('wxyz') # We will set this only once (echoed by cat) p.expect (['1234']) p.expect (['1234']) p.expect (['abcd']) p.expect (['wxyz']) """ self.child_fd attr = termios.tcgetattr(self.child_fd) if state: attr[3] = attr[3] | termios.ECHO else: attr[3] = attr[3] & ~termios.ECHO # I tried TCSADRAIN and TCSAFLUSH, but these were inconsistent # and blocked on some platforms. TCSADRAIN is probably ideal if it worked. termios.tcsetattr(self.child_fd, termios.TCSANOW, attr) def read_nonblocking (self, size = 1, timeout = -1): """This reads at most size characters from the child application. It includes a timeout. If the read does not complete within the timeout period then a TIMEOUT exception is raised. If the end of file is read then an EOF exception will be raised. If a log file was set using setlog() then all data will also be written to the log file. If timeout is None then the read may block indefinitely. If timeout is -1 then the self.timeout value is used. If timeout is 0 then the child is polled and if there was no data immediately ready then this will raise a TIMEOUT exception. The timeout refers only to the amount of time to read at least one character. 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 os.read(). It uses select.select() to implement the timeout. """ if self.closed: raise ValueError ('I/O operation on closed file in read_nonblocking().') if timeout == -1: timeout = self.timeout # Note that some systems such as Solaris do not give an EOF when # the child dies. In fact, you can still try to read # from the child_fd -- it will block forever or until TIMEOUT. # For this case, I test isalive() before doing any reading. # If isalive() is false, then I pretend that this is the same as EOF. if not self.isalive(): r,w,e = self.__select([self.child_fd], [], [], 0) # timeout of 0 means "poll" if not r: self.flag_eof = True raise EOF ('End Of File (EOF) in read_nonblocking(). Braindead platform.') elif self.__irix_hack: # This is a hack for Irix. It seems that Irix requires a long delay before checking isalive. # This adds a 2 second delay, but only when the child is terminated. r, w, e = self.__select([self.child_fd], [], [], 2) if not r and not self.isalive(): self.flag_eof = True raise EOF ('End Of File (EOF) in read_nonblocking(). Pokey platform.') r,w,e = self.__select([self.child_fd], [], [], timeout) if not r: if not self.isalive(): # Some platforms, such as Irix, will claim that their processes are alive; # then timeout on the select; and then finally admit that they are not alive. self.flag_eof = True raise EOF ('End of File (EOF) in read_nonblocking(). Very pokey platform.') else: raise TIMEOUT ('Timeout exceeded in read_nonblocking().') if self.child_fd in r: try: s = os.read(self.child_fd, size) except OSError, e: # Linux does this self.flag_eof = True raise EOF ('End Of File (EOF) in read_nonblocking(). Exception style platform.') if s == '': # BSD style self.flag_eof = True raise EOF ('End Of File (EOF) in read_nonblocking(). Empty string style platform.') 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 raise ExceptionPexpect ('Reached an unexpected state in read_nonblocking().') 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 result == "": raise StopIteration return result 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 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 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. """ time.sleep(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 = os.write(self.child_fd, s) return c 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 sendcontrol(self, char): """This sends a control character to the child such as Ctrl-C or Ctrl-D. For example, to send a Ctrl-G (ASCII 7):: child.sendcontrol('g') See also, sendintr() and sendeof(). """ char = char.lower() a = ord(char) if a>=97 and a<=122: a = a - ord('a') + 1 return self.send (chr(a)) d = {'@':0, '`':0, '[':27, '{':27, '\\':28, '|':28, ']':29, '}': 29, '^':30, '~':30, '_':31, '?':127} if char not in d: return 0 return self.send (chr(d[char])) 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. """ ### Hmmm... how do I send an EOF? ###C if ((m = write(pty, *buf, p - *buf)) < 0) ###C return (errno == EWOULDBLOCK) ? n : -1; #fd = sys.stdin.fileno() #old = termios.tcgetattr(fd) # remember current state #attr = termios.tcgetattr(fd) #attr[3] = attr[3] | termios.ICANON # ICANON must be set to recognize EOF #try: # use try/finally to ensure state gets restored # termios.tcsetattr(fd, termios.TCSADRAIN, attr) # if hasattr(termios, 'CEOF'): # os.write (self.child_fd, '%c' % termios.CEOF) # else: # # Silly platform does not define CEOF so assume CTRL-D # os.write (self.child_fd, '%c' % 4) #finally: # restore state # termios.tcsetattr(fd, termios.TCSADRAIN, old) if hasattr(termios, 'VEOF'): char = termios.tcgetattr(self.child_fd)[6][termios.VEOF] else: # platform does not define VEOF so assume CTRL-D char = chr(4) self.send(char) def sendintr(self): """This sends a SIGINT to the child. It does not require the SIGINT to be the first character on a line. """ if hasattr(termios, 'VINTR'): char = termios.tcgetattr(self.child_fd)[6][termios.VINTR] else: # platform does not define VINTR so assume CTRL-C char = chr(3) self.send (char) def eof (self): """This returns True if the EOF exception was ever raised. """ return self.flag_eof def terminate(self, force=False): """This forces a child process to terminate. It starts nicely with SIGHUP and SIGINT. If "force" is True then moves onto SIGKILL. This returns True if the child was terminated. This returns False if the child could not be terminated. """ if not self.isalive(): return True try: self.kill(signal.SIGHUP) time.sleep(self.delayafterterminate) if not self.isalive(): return True self.kill(signal.SIGCONT) time.sleep(self.delayafterterminate) if not self.isalive(): return True self.kill(signal.SIGINT) time.sleep(self.delayafterterminate) if not self.isalive(): return True if force: self.kill(signal.SIGKILL) time.sleep(self.delayafterterminate) if not self.isalive(): return True else: return False return False except OSError, e: # I think there are kernel timing issues that sometimes cause # this to happen. I think isalive() reports True, but the # process is dead to the kernel. # Make one last attempt to see if the kernel is up to date. time.sleep(self.delayafterterminate) if not self.isalive(): return True else: return False 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. """ if self.isalive(): pid, status = os.waitpid(self.pid, 0) else: raise ExceptionPexpect ('Cannot wait for dead child process.') self.exitstatus = os.WEXITSTATUS(status) if os.WIFEXITED (status): self.status = status self.exitstatus = os.WEXITSTATUS(status) self.signalstatus = None self.terminated = True elif os.WIFSIGNALED (status): self.status = status self.exitstatus = None self.signalstatus = os.WTERMSIG(status) self.terminated = True elif os.WIFSTOPPED (status): raise ExceptionPexpect ('Wait was called for a child process that is stopped. This is not supported. Is some other process attempting job control with our child pid?') return self.exitstatus def isalive(self): """This tests if the child process is running or not. This is non-blocking. If the child was terminated then this will read the exitstatus or signalstatus of the child. This returns True if the child process appears to be running or False if not. It can take literally SECONDS for Solaris to return the right status. """ if self.terminated: return False if self.flag_eof: # This is for Linux, which requires the blocking form of waitpid to get # status of a defunct process. This is super-lame. The flag_eof would have # been set in read_nonblocking(), so this should be safe. waitpid_options = 0 else: waitpid_options = os.WNOHANG try: pid, status = os.waitpid(self.pid, waitpid_options) except OSError, e: # No child processes if e[0] == errno.ECHILD: raise ExceptionPexpect ('isalive() encountered condition where "terminated" is 0, but there was no child process. Did someone else call waitpid() on our process?') else: raise e # I have to do this twice for Solaris. I can't even believe that I figured this out... # If waitpid() returns 0 it means that no child process wishes to # report, and the value of status is undefined. if pid == 0: try: pid, status = os.waitpid(self.pid, waitpid_options) ### os.WNOHANG) # Solaris! except OSError, e: # This should never happen... if e[0] == errno.ECHILD: raise ExceptionPexpect ('isalive() encountered condition that should never happen. There was no child process. Did someone else call waitpid() on our process?') else: raise e # If pid is still 0 after two calls to waitpid() then # the process really is alive. This seems to work on all platforms, except # for Irix which seems to require a blocking call on waitpid or select, so I let read_nonblocking # take care of this situation (unfortunately, this requires waiting through the timeout). if pid == 0: return True if pid == 0: return True if os.WIFEXITED (status): self.status = status self.exitstatus = os.WEXITSTATUS(status) self.signalstatus = None self.terminated = True elif os.WIFSIGNALED (status): self.status = status self.exitstatus = None self.signalstatus = os.WTERMSIG(status) self.terminated = True elif os.WIFSTOPPED (status): raise ExceptionPexpect ('isalive() encountered condition where child process is stopped. This is not supported. Is some other process attempting job control with our child pid?') return False def kill(self, sig): """This sends the given signal to the child application. In keeping with UNIX tradition it has a misleading name. It does not necessarily kill the child unless you send the right signal. """ # Same as os.kill, but the pid is given for you. if self.isalive(): os.kill(self.pid, sig) 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 types.ListType: 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 types.StringTypes: 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: 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', pexpect.EOF, pexpect.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 = pexpect.spawn('/bin/ls') p.expect (pexpect.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 type(pattern_list) in types.StringTypes or pattern_list in (TIMEOUT, EOF): pattern_list = [pattern_list] 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 return self.match_index # No match at this point if timeout < 0 and timeout is not None: raise TIMEOUT ('Timeout exceeded in expect_any().') # Still have time left, so read more data c = self.read_nonblocking (self.maxread, timeout) freshlen = len(c) time.sleep (0.0001) incoming = incoming + c if timeout is not None: timeout = end_time - time.time() except EOF, e: self.buffer = '' self.before = incoming self.after = EOF index = searcher.eof_index if index >= 0: self.match = EOF self.match_index = index return self.match_index else: self.match = None self.match_index = None raise EOF (str(e) + '\n' + str(self)) except TIMEOUT, e: self.buffer = incoming self.before = incoming self.after = TIMEOUT index = searcher.timeout_index if index >= 0: self.match = TIMEOUT self.match_index = index return self.match_index else: self.match = None self.match_index = None raise TIMEOUT (str(e) + '\n' + str(self)) except: self.before = incoming self.after = None self.match = None self.match_index = None raise def getwinsize(self): """This returns the terminal window size of the child tty. The return value is a tuple of (rows, cols). """ TIOCGWINSZ = getattr(termios, 'TIOCGWINSZ', 1074295912L) s = struct.pack('HHHH', 0, 0, 0, 0) x = fcntl.ioctl(self.fileno(), TIOCGWINSZ, s) return struct.unpack('HHHH', x)[0:2] def setwinsize(self, r, c): """This sets the terminal window size of the child tty. This will cause a SIGWINCH signal to be sent to the child. This does not change the physical window size. It changes the size reported to TTY-aware applications like vi or curses -- applications that respond to the SIGWINCH signal. """ # Check for buggy platforms. Some Python versions on some platforms # (notably OSF1 Alpha and RedHat 7.1) truncate the value for # termios.TIOCSWINSZ. It is not clear why this happens. # These platforms don't seem to handle the signed int very well; # yet other platforms like OpenBSD have a large negative value for # TIOCSWINSZ and they don't have a truncate problem. # Newer versions of Linux have totally different values for TIOCSWINSZ. # Note that this fix is a hack. TIOCSWINSZ = getattr(termios, 'TIOCSWINSZ', -2146929561) if TIOCSWINSZ == 2148037735L: # L is not required in Python >= 2.2. TIOCSWINSZ = -2146929561 # Same bits, but with sign. # Note, assume ws_xpixel and ws_ypixel are zero. s = struct.pack('HHHH', r, c, 0, 0) fcntl.ioctl(self.fileno(), TIOCSWINSZ, s) def interact(self, escape_character = chr(29), input_filter = None, output_filter = None): """This gives control of the child process to the interactive user (the human at the keyboard). Keystrokes are sent to the child process, and the stdout and stderr output of the child process is printed. This simply echos the child stdout and child stderr to the real stdout and it echos the real stdin to the child stdin. When the user types the escape_character this method will stop. The default for escape_character is ^]. This should not be confused with ASCII 27 -- the ESC character. ASCII 29 was chosen for historical merit because this is the character used by 'telnet' as the escape character. The escape_character will not be sent to the child process. You may pass in optional input and output filter functions. These functions should take a string and return a string. The output_filter will be passed all the output from the child process. The input_filter will be passed all the keyboard input from the user. The input_filter is run BEFORE the check for the escape_character. Note that if you change the window size of the parent the SIGWINCH signal will not be passed through to the child. If you want the child window size to change when the parent's window size changes then do something like the following example:: import pexpect, struct, fcntl, termios, signal, sys def sigwinch_passthrough (sig, data): s = struct.pack("HHHH", 0, 0, 0, 0) a = struct.unpack('hhhh', fcntl.ioctl(sys.stdout.fileno(), termios.TIOCGWINSZ , s)) global p p.setwinsize(a[0],a[1]) p = pexpect.spawn('/bin/bash') # Note this is global and used in sigwinch_passthrough. signal.signal(signal.SIGWINCH, sigwinch_passthrough) p.interact() """ # Flush the buffer. self.stdout.write (self.buffer) self.stdout.flush() self.buffer = '' mode = tty.tcgetattr(self.STDIN_FILENO) tty.setraw(self.STDIN_FILENO) try: self.__interact_copy(escape_character, input_filter, output_filter) finally: tty.tcsetattr(self.STDIN_FILENO, tty.TCSAFLUSH, mode) def __interact_writen(self, fd, data): """This is used by the interact() method. """ while data != '' and self.isalive(): n = os.write(fd, data) data = data[n:] def __interact_read(self, fd): """This is used by the interact() method. """ return os.read(fd, 1000) def __interact_copy(self, escape_character = None, input_filter = None, output_filter = None): """This is used by the interact() method. """ while self.isalive(): r,w,e = self.__select([self.child_fd, self.STDIN_FILENO], [], []) if self.child_fd in r: data = self.__interact_read(self.child_fd) if output_filter: data = output_filter(data) if self.logfile is not None: self.logfile.write (data) self.logfile.flush() os.write(self.STDOUT_FILENO, data) if self.STDIN_FILENO in r: data = self.__interact_read(self.STDIN_FILENO) if input_filter: data = input_filter(data) i = data.rfind(escape_character) if i != -1: data = data[:i] self.__interact_writen(self.child_fd, data) break self.__interact_writen(self.child_fd, data) def __select (self, iwtd, owtd, ewtd, timeout=None): """This is a wrapper around select.select() that ignores signals. If select.select raises a select.error exception and errno is an EINTR error then it is ignored. Mainly this is used to ignore sigwinch (terminal resize). """ # if select() is interrupted by a signal (errno==EINTR) then # we loop back and enter the select() again. if timeout is not None: end_time = time.time() + timeout while True: try: return select.select (iwtd, owtd, ewtd, timeout) except select.error, e: if e[0] == errno.EINTR: # if we loop back we have to subtract the amount of time we already waited. if timeout is not None: timeout = end_time - time.time() if timeout < 0: return ([],[],[]) else: # something else caused the select.error, so this really is an exception raise ############################################################################## # The following methods are no longer supported or allowed. def setmaxread (self, maxread): """This method is no longer supported or allowed. I don't like getters and setters without a good reason. """ raise ExceptionPexpect ('This method is no longer supported or allowed. Just assign a value to the maxread member variable.') def setlog (self, fileobject): """This method is no longer supported or allowed. """ raise ExceptionPexpect ('This method is no longer supported or allowed. Just assign a value to the logfile member variable.') ############################################################################## # End of spawn class ############################################################################## class searcher_string (object): """This is a plain string search helper for the spawn.expect_any() method. Attributes: eof_index - index of EOF, or -1 timeout_index - index of TIMEOUT, or -1 After a successful match by the search() method the following attributes are available: start - index into the buffer, first byte of match end - index into the buffer, first byte after match match - the matching string itself """ def __init__(self, strings): """This creates an instance of searcher_string. This argument 'strings' may be a list; a sequence of strings; or the EOF or TIMEOUT types. """ self.eof_index = -1 self.timeout_index = -1 self._strings = [] for n, s in zip(range(len(strings)), strings): if s is EOF: self.eof_index = n continue if s is TIMEOUT: self.timeout_index = n continue self._strings.append((n, s)) def __str__(self): """This returns a human-readable string that represents the state of the object.""" ss = [ (ns[0],' %d: "%s"' % ns) for ns in self._strings ] ss.append((-1,'searcher_string:')) if self.eof_index >= 0: ss.append ((self.eof_index,' %d: EOF' % self.eof_index)) if self.timeout_index >= 0: ss.append ((self.timeout_index,' %d: TIMEOUT' % self.timeout_index)) ss.sort() ss = zip(*ss)[1] return '\n'.join(ss) def search(self, buffer, freshlen, searchwindowsize=None): """This searches 'buffer' for the first occurence of one of the search strings. 'freshlen' must indicate the number of bytes at the end of 'buffer' which have not been searched before. It helps to avoid searching the same, possibly big, buffer over and over again. See class spawn for the 'searchwindowsize' argument. If there is a match this returns the index of that string, and sets 'start', 'end' and 'match'. Otherwise, this returns -1. """ absurd_match = len(buffer) first_match = absurd_match # 'freshlen' helps a lot here. Further optimizations could # possibly include: # # using something like the Boyer-Moore Fast String Searching # Algorithm; pre-compiling the search through a list of # strings into something that can scan the input once to # search for all N strings; realize that if we search for # ['bar', 'baz'] and the input is '...foo' we need not bother # rescanning until we've read three more bytes. # # Sadly, I don't know enough about this interesting topic. /grahn for index, s in self._strings: if searchwindowsize is None: # the match, if any, can only be in the fresh data, # or at the very end of the old data offset = -(freshlen+len(s)) else: # better obey searchwindowsize offset = -searchwindowsize n = buffer.find(s, offset) if n >= 0 and n < first_match: first_match = n best_index, best_match = index, s if first_match == absurd_match: return -1 self.match = best_match self.start = first_match self.end = self.start + len(self.match) return best_index class searcher_re (object): """This is regular expression string search helper for the spawn.expect_any() method. Attributes: eof_index - index of EOF, or -1 timeout_index - index of TIMEOUT, or -1 After a successful match by the search() method the following attributes are available: start - index into the buffer, first byte of match end - index into the buffer, first byte after match match - the re.match object returned by a succesful re.search """ def __init__(self, patterns): """This creates an instance that searches for 'patterns' Where 'patterns' may be a list or other sequence of compiled regular expressions, or the EOF or TIMEOUT types.""" self.eof_index = -1 self.timeout_index = -1 self._searches = [] for n, s in zip(range(len(patterns)), patterns): if s is EOF: self.eof_index = n continue if s is TIMEOUT: self.timeout_index = n continue self._searches.append((n, s)) def __str__(self): """This returns a human-readable string that represents the state of the object.""" ss = [ (n,' %d: re.compile("%s")' % (n,str(s.pattern))) for n,s in self._searches] ss.append((-1,'searcher_re:')) if self.eof_index >= 0: ss.append ((self.eof_index,' %d: EOF' % self.eof_index)) if self.timeout_index >= 0: ss.append ((self.timeout_index,' %d: TIMEOUT' % self.timeout_index)) ss.sort() ss = zip(*ss)[1] return '\n'.join(ss) def search(self, buffer, freshlen, searchwindowsize=None): """This searches 'buffer' for the first occurence of one of the regular expressions. 'freshlen' must indicate the number of bytes at the end of 'buffer' which have not been searched before. See class spawn for the 'searchwindowsize' argument. If there is a match this returns the index of that string, and sets 'start', 'end' and 'match'. Otherwise, returns -1.""" absurd_match = len(buffer) first_match = absurd_match # 'freshlen' doesn't help here -- we cannot predict the # length of a match, and the re module provides no help. if searchwindowsize is None: searchstart = 0 else: searchstart = max(0, len(buffer)-searchwindowsize) for index, s in self._searches: match = s.search(buffer, searchstart) if match is None: continue n = match.start() if n < first_match: first_match = n the_match = match best_index = index if first_match == absurd_match: return -1 self.start = first_match self.match = the_match self.end = self.match.end() return best_index def which (filename): """This takes a given filename; tries to find it in the environment path; then checks if it is executable. This returns the full path to the filename if found and executable. Otherwise this returns None.""" # Special case where filename already contains a path. if os.path.dirname(filename) != '': if os.access (filename, os.X_OK): return filename if not os.environ.has_key('PATH') or os.environ['PATH'] == '': p = os.defpath else: p = os.environ['PATH'] # Oddly enough this was the one line that made Pexpect # incompatible with Python 1.5.2. #pathlist = p.split (os.pathsep) pathlist = string.split (p, os.pathsep) for path in pathlist: f = os.path.join(path, filename) if os.access(f, os.X_OK): return f return None def split_command_line(command_line): """This splits a command line into a list of arguments. It splits arguments on spaces, but handles embedded quotes, doublequotes, and escaped characters. It's impossible to do this with a regular expression, so I wrote a little state machine to parse the command line. """ arg_list = [] arg = '' # Constants to name the states we can be in. state_basic = 0 state_esc = 1 state_singlequote = 2 state_doublequote = 3 state_whitespace = 4 # The state of consuming whitespace between commands. state = state_basic for c in command_line: if state == state_basic or state == state_whitespace: if c == '\\': # Escape the next character state = state_esc elif c == r"'": # Handle single quote state = state_singlequote elif c == r'"': # Handle double quote state = state_doublequote elif c.isspace(): # Add arg to arg_list if we aren't in the middle of whitespace. if state == state_whitespace: None # Do nothing. else: arg_list.append(arg) arg = '' state = state_whitespace else: arg = arg + c state = state_basic elif state == state_esc: arg = arg + c state = state_basic elif state == state_singlequote: if c == r"'": state = state_basic else: arg = arg + c elif state == state_doublequote: if c == r'"': state = state_basic else: arg = arg + c if arg != '': arg_list.append(arg) return arg_list # vi:ts=4:sw=4:expandtab:ft=python: 
