150 lines
3.6 KiB
Python
150 lines
3.6 KiB
Python
"""Pseudo terminal utilities."""
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# Bugs: No signal handling. Doesn't set slave termios and window size.
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# Only tested on Linux.
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# See: W. Richard Stevens. 1992. Advanced Programming in the
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# UNIX Environment. Chapter 19.
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# Author: Steen Lumholt -- with additions by Guido.
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from select import select
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import os, FCNTL
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import tty
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STDIN_FILENO = 0
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STDOUT_FILENO = 1
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STDERR_FILENO = 2
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CHILD = 0
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def openpty():
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"""openpty() -> (master_fd, slave_fd)
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Open a pty master/slave pair, using os.openpty() if possible."""
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try:
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return os.openpty()
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except (AttributeError, OSError):
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pass
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master_fd, slave_name = _open_terminal()
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slave_fd = slave_open(slave_name)
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return master_fd, slave_fd
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def master_open():
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"""master_open() -> (master_fd, slave_name)
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Open a pty master and return the fd, and the filename of the slave end.
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Deprecated, use openpty() instead."""
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try:
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master_fd, slave_fd = os.openpty()
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except (AttributeError, OSError):
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pass
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else:
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slave_name = os.ttyname(slave_fd)
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os.close(slave_fd)
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return master_fd, slave_name
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return _open_terminal()
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def _open_terminal():
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"""Open pty master and return (master_fd, tty_name).
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SGI and generic BSD version, for when openpty() fails."""
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try:
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import sgi
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except ImportError:
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pass
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else:
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try:
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tty_name, master_fd = sgi._getpty(FCNTL.O_RDWR, 0666, 0)
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except IOError, msg:
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raise os.error, msg
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return master_fd, tty_name
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for x in 'pqrstuvwxyzPQRST':
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for y in '0123456789abcdef':
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pty_name = '/dev/pty' + x + y
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try:
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fd = os.open(pty_name, FCNTL.O_RDWR)
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except os.error:
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continue
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return (fd, '/dev/tty' + x + y)
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raise os.error, 'out of pty devices'
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def slave_open(tty_name):
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"""slave_open(tty_name) -> slave_fd
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Open the pty slave and acquire the controlling terminal, returning
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opened filedescriptor.
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Deprecated, use openpty() instead."""
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return os.open(tty_name, FCNTL.O_RDWR)
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def fork():
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"""fork() -> (pid, master_fd)
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Fork and make the child a session leader with a controlling terminal."""
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try:
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pid, fd = os.forkpty()
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except (AttributeError, OSError):
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pass
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else:
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if pid == CHILD:
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try:
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os.setsid()
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except OSError:
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# os.forkpty() already set us session leader
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pass
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return pid, fd
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master_fd, slave_fd = openpty()
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pid = os.fork()
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if pid == CHILD:
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# Establish a new session.
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os.setsid()
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os.close(master_fd)
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# Slave becomes stdin/stdout/stderr of child.
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os.dup2(slave_fd, STDIN_FILENO)
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os.dup2(slave_fd, STDOUT_FILENO)
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os.dup2(slave_fd, STDERR_FILENO)
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if (slave_fd > STDERR_FILENO):
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os.close (slave_fd)
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# Parent and child process.
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return pid, master_fd
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def _writen(fd, data):
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"""Write all the data to a descriptor."""
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while data != '':
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n = os.write(fd, data)
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data = data[n:]
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def _read(fd):
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"""Default read function."""
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return os.read(fd, 1024)
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def _copy(master_fd, master_read=_read, stdin_read=_read):
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"""Parent copy loop.
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Copies
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pty master -> standard output (master_read)
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standard input -> pty master (stdin_read)"""
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while 1:
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rfds, wfds, xfds = select(
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[master_fd, STDIN_FILENO], [], [])
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if master_fd in rfds:
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data = master_read(master_fd)
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os.write(STDOUT_FILENO, data)
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if STDIN_FILENO in rfds:
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data = stdin_read(STDIN_FILENO)
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_writen(master_fd, data)
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def spawn(argv, master_read=_read, stdin_read=_read):
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"""Create a spawned process."""
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if type(argv) == type(''):
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argv = (argv,)
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pid, master_fd = fork()
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if pid == CHILD:
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apply(os.execlp, (argv[0],) + argv)
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mode = tty.tcgetattr(STDIN_FILENO)
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tty.setraw(STDIN_FILENO)
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try:
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_copy(master_fd, master_read, stdin_read)
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except:
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tty.tcsetattr(STDIN_FILENO, tty.TCSAFLUSH, mode)
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