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File name : spawnbase.py

Content :from io import StringIO, BytesIO import codecs import os import sys import re import errno from .exceptions import ExceptionPexpect, EOF, TIMEOUT from .expect import Expecter, searcher_string, searcher_re PY3 = (sys.version_info[0] >= 3) text_type = str if PY3 else unicode class _NullCoder(object): """Pass bytes through unchanged.""" @staticmethod def encode(b, final=False): return b @staticmethod def decode(b, final=False): return b class SpawnBase(object): """A base class providing the backwards-compatible spawn API for Pexpect. This should not be instantiated directly: use :class:`pexpect.spawn` or :class:`pexpect.fdpexpect.fdspawn`. """ encoding = None pid = None flag_eof = False def __init__(self, timeout=30, maxread=2000, searchwindowsize=None, logfile=None, encoding=None, codec_errors='strict'): 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 # status returned by os.waitpid self.status = None # the child file descriptor is initially closed self.child_fd = -1 self.timeout = timeout self.delimiter = EOF self.logfile = logfile # input from child (read_nonblocking) self.logfile_read = None # output to send (send, sendline) self.logfile_send = None # max bytes to read at one time into buffer self.maxread = maxread # Data before searchwindowsize point is preserved, but not searched. self.searchwindowsize = searchwindowsize # Delay used before sending data to child. Time in seconds. # Set this to None to skip the time.sleep() call completely. self.delaybeforesend = 0.05 # Used by close() to give kernel time to update process status. # Time in seconds. self.delayafterclose = 0.1 # Used by terminate() to give kernel time to update process status. # Time in seconds. self.delayafterterminate = 0.1 # Delay in seconds to sleep after each call to read_nonblocking(). # Set this to None to skip the time.sleep() call completely: that # would restore the behavior from pexpect-2.0 (for performance # reasons or because you don't want to release Python's global # interpreter lock). self.delayafterread = 0.0001 self.softspace = False self.name = '<' + repr(self) + '>' self.closed = True # Unicode interface self.encoding = encoding self.codec_errors = codec_errors if encoding is None: # bytes mode (accepts some unicode for backwards compatibility) self._encoder = self._decoder = _NullCoder() self.string_type = bytes self.buffer_type = BytesIO self.crlf = b'\r\n' if PY3: self.allowed_string_types = (bytes, str) self.linesep = os.linesep.encode('ascii') def write_to_stdout(b): try: return sys.stdout.buffer.write(b) except AttributeError: # If stdout has been replaced, it may not have .buffer return sys.stdout.write(b.decode('ascii', 'replace')) self.write_to_stdout = write_to_stdout else: self.allowed_string_types = (basestring,) # analysis:ignore self.linesep = os.linesep self.write_to_stdout = sys.stdout.write else: # unicode mode self._encoder = codecs.getincrementalencoder(encoding)(codec_errors) self._decoder = codecs.getincrementaldecoder(encoding)(codec_errors) self.string_type = text_type self.buffer_type = StringIO self.crlf = u'\r\n' self.allowed_string_types = (text_type, ) if PY3: self.linesep = os.linesep else: self.linesep = os.linesep.decode('ascii') # This can handle unicode in both Python 2 and 3 self.write_to_stdout = sys.stdout.write # storage for async transport self.async_pw_transport = None # This is the read buffer. See maxread. self._buffer = self.buffer_type() def _log(self, s, direction): if self.logfile is not None: self.logfile.write(s) self.logfile.flush() second_log = self.logfile_send if (direction=='send') else self.logfile_read if second_log is not None: second_log.write(s) second_log.flush() # For backwards compatibility, in bytes mode (when encoding is None) # unicode is accepted for send and expect. Unicode mode is strictly unicode # only. def _coerce_expect_string(self, s): if self.encoding is None and not isinstance(s, bytes): return s.encode('ascii') return s def _coerce_send_string(self, s): if self.encoding is None and not isinstance(s, bytes): return s.encode('utf-8') return s def _get_buffer(self): return self._buffer.getvalue() def _set_buffer(self, value): self._buffer = self.buffer_type() self._buffer.write(value) # This property is provided for backwards compatability (self.buffer used # to be a string/bytes object) buffer = property(_get_buffer, _set_buffer) def read_nonblocking(self, size=1, timeout=None): """This reads data from the file descriptor. This is a simple implementation suitable for a regular file. Subclasses using ptys or pipes should override it. The timeout parameter is ignored. """ try: s = os.read(self.child_fd, size) except OSError as err: if err.args[0] == errno.EIO: # Linux-style EOF self.flag_eof = True raise EOF('End Of File (EOF). Exception style platform.') raise if s == b'': # BSD-style EOF self.flag_eof = True raise EOF('End Of File (EOF). Empty string style platform.') s = self._decoder.decode(s, final=False) self._log(s, 'read') return s def _pattern_type_err(self, pattern): raise TypeError('got {badtype} ({badobj!r}) as pattern, must be one' ' of: {goodtypes}, pexpect.EOF, pexpect.TIMEOUT'\ .format(badtype=type(pattern), badobj=pattern, goodtypes=', '.join([str(ast)\ for ast in self.allowed_string_types]) ) ) 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(cpl, timeout) ... ''' if patterns is None: return [] if not isinstance(patterns, list): patterns = [patterns] # Allow dot to match \n compile_flags = re.DOTALL if self.ignorecase: compile_flags = compile_flags | re.IGNORECASE compiled_pattern_list = [] for idx, p in enumerate(patterns): if isinstance(p, self.allowed_string_types): p = self._coerce_expect_string(p) 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 isinstance(p, type(re.compile(''))): compiled_pattern_list.append(p) else: self._pattern_type_err(p) return compiled_pattern_list def expect(self, pattern, timeout=-1, searchwindowsize=-1, async_=False, **kw): '''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 returns 1('foo') if parts of the final 'bar' arrive late When a match is found for the given pattern, the class instance attribute *match* becomes an re.MatchObject result. Should an EOF or TIMEOUT pattern match, then the match attribute will be an instance of that exception class. The pairing before and after class instance attributes are views of the data preceding and following the matching pattern. On general exception, class attribute *before* is all data received up to the exception, while *match* and *after* attributes are value None. When the keyword argument timeout is -1 (default), then TIMEOUT will raise after the default value specified by the class timeout attribute. When None, TIMEOUT will not be raised and may block indefinitely until match. When the keyword argument searchwindowsize is -1 (default), then the value specified by the class maxread attribute is used. 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(). On Python 3.4, or Python 3.3 with asyncio installed, passing ``async_=True`` will make this return an :mod:`asyncio` coroutine, which you can yield from to get the same result that this method would normally give directly. So, inside a coroutine, you can replace this code:: index = p.expect(patterns) With this non-blocking form:: index = yield from p.expect(patterns, async_=True) ''' if 'async' in kw: async_ = kw.pop('async') if kw: raise TypeError("Unknown keyword arguments: {}".format(kw)) compiled_pattern_list = self.compile_pattern_list(pattern) return self.expect_list(compiled_pattern_list, timeout, searchwindowsize, async_) def expect_list(self, pattern_list, timeout=-1, searchwindowsize=-1, async_=False, **kw): '''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(). Like :meth:`expect`, passing ``async_=True`` will make this return an asyncio coroutine. ''' if timeout == -1: timeout = self.timeout if 'async' in kw: async_ = kw.pop('async') if kw: raise TypeError("Unknown keyword arguments: {}".format(kw)) exp = Expecter(self, searcher_re(pattern_list), searchwindowsize) if async_: from ._async import expect_async return expect_async(exp, timeout) else: return exp.expect_loop(timeout) def expect_exact(self, pattern_list, timeout=-1, searchwindowsize=-1, async_=False, **kw): '''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. Like :meth:`expect`, passing ``async_=True`` will make this return an asyncio coroutine. ''' if timeout == -1: timeout = self.timeout if 'async' in kw: async_ = kw.pop('async') if kw: raise TypeError("Unknown keyword arguments: {}".format(kw)) if (isinstance(pattern_list, self.allowed_string_types) or pattern_list in (TIMEOUT, EOF)): pattern_list = [pattern_list] def prepare_pattern(pattern): if pattern in (TIMEOUT, EOF): return pattern if isinstance(pattern, self.allowed_string_types): return self._coerce_expect_string(pattern) self._pattern_type_err(pattern) try: pattern_list = iter(pattern_list) except TypeError: self._pattern_type_err(pattern_list) pattern_list = [prepare_pattern(p) for p in pattern_list] exp = Expecter(self, searcher_string(pattern_list), searchwindowsize) if async_: from ._async import expect_async return expect_async(exp, timeout) else: return exp.expect_loop(timeout) 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. ''' exp = Expecter(self, searcher, searchwindowsize) return exp.expect_loop(timeout) def read(self, size=-1): '''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 self.string_type() if size < 0: # delimiter default is EOF self.expect(self.delimiter) 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 consistent 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(self._coerce_expect_string('.{%d}' % size), re.DOTALL) # delimiter default is EOF index = self.expect([cre, self.delimiter]) if index == 0: ### FIXME self.before should be ''. Should I assert this? return self.after return self.before def readline(self, size=-1): '''This reads and returns one entire line. The newline at the end of line is returned as part of the string, unless the file ends without a newline. An empty string is returned if EOF is encountered immediately. This looks for a newline as a CR/LF pair (\\r\\n) even on UNIX because this is what the pseudotty device returns. So contrary to what you may expect you will receive newlines as \\r\\n. If the size argument is 0 then an empty string is returned. In all other cases the size argument is ignored, which is not standard behavior for a file-like object. ''' if size == 0: return self.string_type() # delimiter default is EOF index = self.expect([self.crlf, self.delimiter]) if index == 0: return self.before + self.crlf else: return self.before def __iter__(self): '''This is to support iterators over a file-like object. ''' return iter(self.readline, self.string_type()) def readlines(self, sizehint=-1): '''This reads until EOF using readline() and returns a list containing the lines thus read. The optional 'sizehint' argument is ignored. Remember, because this reads until EOF that means the child process should have closed its stdout. If you run this method on a child that is still running with its stdout open then this method will block until it timesout.''' lines = [] while True: line = self.readline() if not line: break lines.append(line) return lines def fileno(self): '''Expose file descriptor for a file-like interface ''' return self.child_fd def flush(self): '''This does nothing. It is here to support the interface for a File-like object. ''' pass def isatty(self): """Overridden in subclass using tty""" return False # For 'with spawn(...) as child:' def __enter__(self): return self def __exit__(self, etype, evalue, tb): # We rely on subclasses to implement close(). If they don't, it's not # clear what a context manager should do. self.close()

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