"""Pseudo terminal utilities."""
# Bugs: No signal handling. Doesn't set slave termios and window size.
# Only tested on Linux.
# 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, FCNTL
import tty
STDIN_FILENO = 0
STDOUT_FILENO = 1
STDERR_FILENO = 2
CHILD = 0
def master_open():
"""Open pty master and return (master_fd, tty_name).
SGI and Linux/BSD version."""
try:
import sgi
except ImportError:
pass
else:
try:
tty_name, master_fd = sgi._getpty(FCNTL.O_RDWR, 0666, 0)
except IOError, msg:
raise os.error, msg
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, FCNTL.O_RDWR)
except os.error:
continue
return (fd, '/dev/tty' + x + y)
raise os.error, 'out of pty devices'
def slave_open(tty_name):
"""Open the pty slave and acquire the controlling terminal.
Return the file descriptor. Linux version."""
# (Should be universal? --Guido)
return os.open(tty_name, FCNTL.O_RDWR)
def fork():
"""Fork and make the child a session leader with a controlling terminal.
Return (pid, master_fd)."""
master_fd, tty_name = master_open()
pid = os.fork()
if pid == CHILD:
# Establish a new session.
os.setsid()
# Acquire controlling terminal.
slave_fd = slave_open(tty_name)
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)
# Parent and child process.
return pid, master_fd
def writen(fd, data):
"""Write all the data to a descriptor."""
while data != '':
n = os.write(fd, data)
data = data[n:]
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)"""
while 1:
rfds, wfds, xfds = select(
[master_fd, STDIN_FILENO], [], [])
if master_fd in rfds:
data = master_read(master_fd)
os.write(STDOUT_FILENO, data)
if STDIN_FILENO in rfds:
data = stdin_read(STDIN_FILENO)
writen(master_fd, data)
def spawn(argv, master_read=read, stdin_read=read):
"""Create a spawned process."""
if type(argv) == type(''):
argv = (argv,)
pid, master_fd = fork()
if pid == CHILD:
apply(os.execlp, (argv[0],) + argv)
mode = tty.tcgetattr(STDIN_FILENO)
tty.setraw(STDIN_FILENO)
try:
copy(master_fd, master_read, stdin_read)
except:
tty.tcsetattr(STDIN_FILENO, tty.TCSAFLUSH, mode)
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