_process_posix.py
225 lines
| 8.7 KiB
| text/x-python
|
PythonLexer
Fernando Perez
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r2908 | """Posix-specific implementation of process utilities. | ||
This file is only meant to be imported by process.py, not by end-users. | ||||
""" | ||||
#----------------------------------------------------------------------------- | ||||
Matthias BUSSONNIER
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r5390 | # Copyright (C) 2010-2011 The IPython Development Team | ||
Fernando Perez
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r2908 | # | ||
# Distributed under the terms of the BSD License. The full license is in | ||||
# the file COPYING, distributed as part of this software. | ||||
#----------------------------------------------------------------------------- | ||||
#----------------------------------------------------------------------------- | ||||
# Imports | ||||
#----------------------------------------------------------------------------- | ||||
# Stdlib | ||||
Thomas Kluyver
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r17181 | import errno | ||
import os | ||||
Fernando Perez
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r2908 | import subprocess as sp | ||
import sys | ||||
MinRK
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r20815 | import pexpect | ||
Fernando Perez
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r2908 | |||
# Our own | ||||
Jörgen Stenarson
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r5537 | from ._process_common import getoutput, arg_split | ||
Thomas Kluyver
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r4896 | from IPython.utils import py3compat | ||
Brandon Parsons
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r6716 | from IPython.utils.encoding import DEFAULT_ENCODING | ||
Fernando Perez
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r2908 | |||
#----------------------------------------------------------------------------- | ||||
# Function definitions | ||||
#----------------------------------------------------------------------------- | ||||
def _find_cmd(cmd): | ||||
"""Find the full path to a command using which.""" | ||||
Thomas Kluyver
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r4896 | path = sp.Popen(['/usr/bin/env', 'which', cmd], | ||
MinRK
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r7547 | stdout=sp.PIPE, stderr=sp.PIPE).communicate()[0] | ||
Hugo
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r24010 | return py3compat.decode(path) | ||
Fernando Perez
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r2908 | |||
class ProcessHandler(object): | ||||
"""Execute subprocesses under the control of pexpect. | ||||
""" | ||||
# Timeout in seconds to wait on each reading of the subprocess' output. | ||||
# This should not be set too low to avoid cpu overusage from our side, | ||||
# since we read in a loop whose period is controlled by this timeout. | ||||
read_timeout = 0.05 | ||||
# Timeout to give a process if we receive SIGINT, between sending the | ||||
# SIGINT to the process and forcefully terminating it. | ||||
terminate_timeout = 0.2 | ||||
# File object where stdout and stderr of the subprocess will be written | ||||
logfile = None | ||||
# Shell to call for subprocesses to execute | ||||
Thomas Kluyver
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r9472 | _sh = None | ||
Fernando Perez
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r2908 | |||
Thomas Kluyver
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r9485 | @property | ||
Fernando Perez
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r2908 | def sh(self): | ||
Min RK
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r25796 | if self._sh is None: | ||
shell_name = os.environ.get("SHELL", "sh") | ||||
self._sh = pexpect.which(shell_name) | ||||
Thomas Kluyver
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r9472 | if self._sh is None: | ||
Min RK
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r25796 | raise OSError('"{}" shell not found'.format(shell_name)) | ||
Thomas Kluyver
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r9472 | return self._sh | ||
Fernando Perez
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r2908 | |||
def __init__(self, logfile=None, read_timeout=None, terminate_timeout=None): | ||||
"""Arguments are used for pexpect calls.""" | ||||
self.read_timeout = (ProcessHandler.read_timeout if read_timeout is | ||||
None else read_timeout) | ||||
self.terminate_timeout = (ProcessHandler.terminate_timeout if | ||||
terminate_timeout is None else | ||||
terminate_timeout) | ||||
self.logfile = sys.stdout if logfile is None else logfile | ||||
def getoutput(self, cmd): | ||||
"""Run a command and return its stdout/stderr as a string. | ||||
Parameters | ||||
---------- | ||||
cmd : str | ||||
Matthias Bussonnier
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r26419 | A command to be executed in the system shell. | ||
Fernando Perez
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r2908 | |||
Returns | ||||
------- | ||||
output : str | ||||
Matthias Bussonnier
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r26419 | A string containing the combination of stdout and stderr from the | ||
Fernando Perez
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r2908 | subprocess, in whatever order the subprocess originally wrote to its | ||
file descriptors (so the order of the information in this string is the | ||||
correct order as would be seen if running the command in a terminal). | ||||
""" | ||||
try: | ||||
MinRK
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r5296 | return pexpect.run(self.sh, args=['-c', cmd]).replace('\r\n', '\n') | ||
Fernando Perez
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r2908 | except KeyboardInterrupt: | ||
print('^C', file=sys.stderr, end='') | ||||
Fernando Perez
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r3002 | def getoutput_pexpect(self, cmd): | ||
"""Run a command and return its stdout/stderr as a string. | ||||
Parameters | ||||
---------- | ||||
cmd : str | ||||
Matthias Bussonnier
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r26419 | A command to be executed in the system shell. | ||
Fernando Perez
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r3002 | |||
Returns | ||||
------- | ||||
output : str | ||||
Matthias Bussonnier
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r26419 | A string containing the combination of stdout and stderr from the | ||
Fernando Perez
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r3002 | subprocess, in whatever order the subprocess originally wrote to its | ||
file descriptors (so the order of the information in this string is the | ||||
correct order as would be seen if running the command in a terminal). | ||||
""" | ||||
try: | ||||
MinRK
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r5296 | return pexpect.run(self.sh, args=['-c', cmd]).replace('\r\n', '\n') | ||
Fernando Perez
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r3002 | except KeyboardInterrupt: | ||
print('^C', file=sys.stderr, end='') | ||||
Fernando Perez
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r2908 | def system(self, cmd): | ||
"""Execute a command in a subshell. | ||||
Parameters | ||||
---------- | ||||
cmd : str | ||||
Matthias Bussonnier
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r26419 | A command to be executed in the system shell. | ||
Fernando Perez
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r2908 | |||
Returns | ||||
------- | ||||
MinRK
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r3910 | int : child's exitstatus | ||
Fernando Perez
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r2908 | """ | ||
Thomas Kluyver
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r4836 | # Get likely encoding for the output. | ||
Brandon Parsons
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r6716 | enc = DEFAULT_ENCODING | ||
Thomas Kluyver
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r4836 | |||
Fernando Perez
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r2908 | # Patterns to match on the output, for pexpect. We read input and | ||
# allow either a short timeout or EOF | ||||
patterns = [pexpect.TIMEOUT, pexpect.EOF] | ||||
# the index of the EOF pattern in the list. | ||||
MinRK
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r5296 | # even though we know it's 1, this call means we don't have to worry if | ||
# we change the above list, and forget to change this value: | ||||
EOF_index = patterns.index(pexpect.EOF) | ||||
Fernando Perez
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r2908 | # The size of the output stored so far in the process output buffer. | ||
# Since pexpect only appends to this buffer, each time we print we | ||||
# record how far we've printed, so that next time we only print *new* | ||||
# content from the buffer. | ||||
out_size = 0 | ||||
try: | ||||
# Since we're not really searching the buffer for text patterns, we | ||||
# can set pexpect's search window to be tiny and it won't matter. | ||||
# We only search for the 'patterns' timeout or EOF, which aren't in | ||||
# the text itself. | ||||
Thomas Kluyver
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r5433 | #child = pexpect.spawn(pcmd, searchwindowsize=1) | ||
Thomas Kluyver
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r5434 | if hasattr(pexpect, 'spawnb'): | ||
child = pexpect.spawnb(self.sh, args=['-c', cmd]) # Pexpect-U | ||||
else: | ||||
child = pexpect.spawn(self.sh, args=['-c', cmd]) # Vanilla Pexpect | ||||
Fernando Perez
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r2908 | flush = sys.stdout.flush | ||
while True: | ||||
# res is the index of the pattern that caused the match, so we | ||||
# know whether we've finished (if we matched EOF) or not | ||||
res_idx = child.expect_list(patterns, self.read_timeout) | ||||
Thomas Kluyver
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r5434 | print(child.before[out_size:].decode(enc, 'replace'), end='') | ||
Fernando Perez
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r2908 | flush() | ||
if res_idx==EOF_index: | ||||
break | ||||
Fernando Perez
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r3075 | # Update the pointer to what we've already printed | ||
out_size = len(child.before) | ||||
Fernando Perez
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r2908 | except KeyboardInterrupt: | ||
# We need to send ^C to the process. The ascii code for '^C' is 3 | ||||
# (the character is known as ETX for 'End of Text', see | ||||
# curses.ascii.ETX). | ||||
child.sendline(chr(3)) | ||||
# Read and print any more output the program might produce on its | ||||
# way out. | ||||
try: | ||||
out_size = len(child.before) | ||||
child.expect_list(patterns, self.terminate_timeout) | ||||
Thomas Kluyver
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r5434 | print(child.before[out_size:].decode(enc, 'replace'), end='') | ||
Fernando Perez
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r3075 | sys.stdout.flush() | ||
Fernando Perez
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r2908 | except KeyboardInterrupt: | ||
# Impatient users tend to type it multiple times | ||||
pass | ||||
finally: | ||||
# Ensure the subprocess really is terminated | ||||
child.terminate(force=True) | ||||
MinRK
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r5296 | # add isalive check, to ensure exitstatus is set: | ||
child.isalive() | ||||
Thomas Kluyver
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r12766 | |||
# We follow the subprocess pattern, returning either the exit status | ||||
# as a positive number, or the terminating signal as a negative | ||||
MinRK
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r13421 | # number. | ||
# on Linux, sh returns 128+n for signals terminating child processes on Linux | ||||
# on BSD (OS X), the signal code is set instead | ||||
MinRK
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r13420 | if child.exitstatus is None: | ||
# on WIFSIGNALED, pexpect sets signalstatus, leaving exitstatus=None | ||||
if child.signalstatus is None: | ||||
# this condition may never occur, | ||||
# but let's be certain we always return an integer. | ||||
return 0 | ||||
return -child.signalstatus | ||||
Thomas Kluyver
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r12774 | if child.exitstatus > 128: | ||
return -(child.exitstatus - 128) | ||||
MinRK
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r3910 | return child.exitstatus | ||
Fernando Perez
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r2908 | |||
Fernando Perez
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r3002 | # Make system() with a functional interface for outside use. Note that we use | ||
# getoutput() from the _common utils, which is built on top of popen(). Using | ||||
# pexpect to get subprocess output produces difficult to parse output, since | ||||
# programs think they are talking to a tty and produce highly formatted output | ||||
# (ls is a good example) that makes them hard. | ||||
system = ProcessHandler().system | ||||
Jörgen Stenarson
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r5517 | |||
Thomas Kluyver
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r17181 | def check_pid(pid): | ||
try: | ||||
os.kill(pid, 0) | ||||
except OSError as err: | ||||
if err.errno == errno.ESRCH: | ||||
return False | ||||
elif err.errno == errno.EPERM: | ||||
# Don't have permission to signal the process - probably means it exists | ||||
return True | ||||
raise | ||||
else: | ||||
return True | ||||