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
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
|
"""Pseudo terminal utilities."""
# Bugs: No signal handling. Doesn't set slave termios and window size.
# Only tested on Linux, FreeBSD, and macOS.
# See: W. Richard Stevens. 1992. Advanced Programming in the
# UNIX Environment. Chapter 19.
# Author: Steen Lumholt -- with additions by Guido.
from select import select
import os
import sys
import tty
# names imported directly for test mocking purposes
from os import close, waitpid
from tty import setraw, tcgetattr, tcsetattr
__all__ = ["openpty", "fork", "spawn"]
STDIN_FILENO = 0
STDOUT_FILENO = 1
STDERR_FILENO = 2
CHILD = 0
def openpty():
"""openpty() -> (master_fd, slave_fd)
Open a pty master/slave pair, using os.openpty() if possible."""
try:
return os.openpty()
except (AttributeError, OSError):
pass
master_fd, slave_name = _open_terminal()
slave_fd = slave_open(slave_name)
return master_fd, slave_fd
def master_open():
"""master_open() -> (master_fd, slave_name)
Open a pty master and return the fd, and the filename of the slave end.
Deprecated, use openpty() instead."""
try:
master_fd, slave_fd = os.openpty()
except (AttributeError, OSError):
pass
else:
slave_name = os.ttyname(slave_fd)
os.close(slave_fd)
return master_fd, slave_name
return _open_terminal()
def _open_terminal():
"""Open pty master and return (master_fd, tty_name)."""
for x in 'pqrstuvwxyzPQRST':
for y in '0123456789abcdef':
pty_name = '/dev/pty' + x + y
try:
fd = os.open(pty_name, os.O_RDWR)
except OSError:
continue
return (fd, '/dev/tty' + x + y)
raise OSError('out of pty devices')
def slave_open(tty_name):
"""slave_open(tty_name) -> slave_fd
Open the pty slave and acquire the controlling terminal, returning
opened filedescriptor.
Deprecated, use openpty() instead."""
result = os.open(tty_name, os.O_RDWR)
try:
from fcntl import ioctl, I_PUSH
except ImportError:
return result
try:
ioctl(result, I_PUSH, "ptem")
ioctl(result, I_PUSH, "ldterm")
except OSError:
pass
return result
def fork():
"""fork() -> (pid, master_fd)
Fork and make the child a session leader with a controlling terminal."""
try:
pid, fd = os.forkpty()
except (AttributeError, OSError):
pass
else:
if pid == CHILD:
try:
os.setsid()
except OSError:
# os.forkpty() already set us session leader
pass
return pid, fd
master_fd, slave_fd = openpty()
pid = os.fork()
if pid == CHILD:
# Establish a new session.
os.setsid()
os.close(master_fd)
# Slave becomes stdin/stdout/stderr of child.
os.dup2(slave_fd, STDIN_FILENO)
os.dup2(slave_fd, STDOUT_FILENO)
os.dup2(slave_fd, STDERR_FILENO)
if slave_fd > STDERR_FILENO:
os.close(slave_fd)
# Explicitly open the tty to make it become a controlling tty.
tmp_fd = os.open(os.ttyname(STDOUT_FILENO), os.O_RDWR)
os.close(tmp_fd)
else:
os.close(slave_fd)
# Parent and child process.
return pid, master_fd
def _read(fd):
"""Default read function."""
return os.read(fd, 1024)
def _copy(master_fd, master_read=_read, stdin_read=_read):
"""Parent copy loop.
Copies
pty master -> standard output (master_read)
standard input -> pty master (stdin_read)"""
if os.get_blocking(master_fd):
# If we write more than tty/ndisc is willing to buffer, we may block
# indefinitely. So we set master_fd to non-blocking temporarily during
# the copy operation.
os.set_blocking(master_fd, False)
try:
_copy(master_fd, master_read=master_read, stdin_read=stdin_read)
finally:
# restore blocking mode for backwards compatibility
os.set_blocking(master_fd, True)
return
high_waterlevel = 4096
stdin_avail = master_fd != STDIN_FILENO
stdout_avail = master_fd != STDOUT_FILENO
i_buf = b''
o_buf = b''
while 1:
rfds = []
wfds = []
if stdin_avail and len(i_buf) < high_waterlevel:
rfds.append(STDIN_FILENO)
if stdout_avail and len(o_buf) < high_waterlevel:
rfds.append(master_fd)
if stdout_avail and len(o_buf) > 0:
wfds.append(STDOUT_FILENO)
if len(i_buf) > 0:
wfds.append(master_fd)
rfds, wfds, _xfds = select(rfds, wfds, [])
if STDOUT_FILENO in wfds:
try:
n = os.write(STDOUT_FILENO, o_buf)
o_buf = o_buf[n:]
except OSError:
stdout_avail = False
if master_fd in rfds:
# Some OSes signal EOF by returning an empty byte string,
# some throw OSErrors.
try:
data = master_read(master_fd)
except OSError:
data = b""
if not data: # Reached EOF.
return # Assume the child process has exited and is
# unreachable, so we clean up.
o_buf += data
if master_fd in wfds:
n = os.write(master_fd, i_buf)
i_buf = i_buf[n:]
if stdin_avail and STDIN_FILENO in rfds:
data = stdin_read(STDIN_FILENO)
if not data:
stdin_avail = False
else:
i_buf += data
def spawn(argv, master_read=_read, stdin_read=_read):
"""Create a spawned process."""
if type(argv) == type(''):
argv = (argv,)
sys.audit('pty.spawn', argv)
pid, master_fd = fork()
if pid == CHILD:
os.execlp(argv[0], *argv)
try:
mode = tcgetattr(STDIN_FILENO)
setraw(STDIN_FILENO)
restore = True
except tty.error: # This is the same as termios.error
restore = False
try:
_copy(master_fd, master_read, stdin_read)
finally:
if restore:
tcsetattr(STDIN_FILENO, tty.TCSAFLUSH, mode)
close(master_fd)
return waitpid(pid, 0)[1]
|
