forked from ipython/ipython
-
Notifications
You must be signed in to change notification settings - Fork 4
/
_process_posix.py
198 lines (166 loc) · 7.66 KB
/
_process_posix.py
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
"""Posix-specific implementation of process utilities.
This file is only meant to be imported by process.py, not by end-users.
"""
#-----------------------------------------------------------------------------
# Copyright (C) 2010-2011 The IPython Development Team
#
# Distributed under the terms of the BSD License. The full license is in
# the file COPYING, distributed as part of this software.
#-----------------------------------------------------------------------------
#-----------------------------------------------------------------------------
# Imports
#-----------------------------------------------------------------------------
from __future__ import print_function
# Stdlib
import subprocess as sp
import sys
from IPython.external import pexpect
# Our own
from ._process_common import getoutput, arg_split
from IPython.utils import py3compat
from IPython.utils.encoding import DEFAULT_ENCODING
#-----------------------------------------------------------------------------
# Function definitions
#-----------------------------------------------------------------------------
def _find_cmd(cmd):
"""Find the full path to a command using which."""
path = sp.Popen(['/usr/bin/env', 'which', cmd],
stdout=sp.PIPE, stderr=sp.PIPE).communicate()[0]
return py3compat.bytes_to_str(path)
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
_sh = None
@property
def sh(self):
if self._sh is None:
self._sh = pexpect.which('sh')
if self._sh is None:
raise OSError('"sh" shell not found')
return self._sh
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
A command to be executed in the system shell.
Returns
-------
output : str
A string containing the combination of stdout and stderr from the
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:
return pexpect.run(self.sh, args=['-c', cmd]).replace('\r\n', '\n')
except KeyboardInterrupt:
print('^C', file=sys.stderr, end='')
def getoutput_pexpect(self, cmd):
"""Run a command and return its stdout/stderr as a string.
Parameters
----------
cmd : str
A command to be executed in the system shell.
Returns
-------
output : str
A string containing the combination of stdout and stderr from the
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:
return pexpect.run(self.sh, args=['-c', cmd]).replace('\r\n', '\n')
except KeyboardInterrupt:
print('^C', file=sys.stderr, end='')
def system(self, cmd):
"""Execute a command in a subshell.
Parameters
----------
cmd : str
A command to be executed in the system shell.
Returns
-------
int : child's exitstatus
"""
# Get likely encoding for the output.
enc = DEFAULT_ENCODING
# 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.
# 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)
# 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.
#child = pexpect.spawn(pcmd, searchwindowsize=1)
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
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)
print(child.before[out_size:].decode(enc, 'replace'), end='')
flush()
if res_idx==EOF_index:
break
# Update the pointer to what we've already printed
out_size = len(child.before)
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)
print(child.before[out_size:].decode(enc, 'replace'), end='')
sys.stdout.flush()
except KeyboardInterrupt:
# Impatient users tend to type it multiple times
pass
finally:
# Ensure the subprocess really is terminated
child.terminate(force=True)
# add isalive check, to ensure exitstatus is set:
child.isalive()
return child.exitstatus
# 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