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![Soumendra Ganguly](/assets/img/avatar_default.png)
Refactored the implementation of pty.fork to use os.login_tty. A DeprecationWarning is now raised by pty.master_open() and pty.slave_open(). They were undocumented and deprecated long long ago in the docstring in favor of pty.openpty. Signed-off-by: Soumendra Ganguly <soumendraganguly@gmail.com> Co-authored-by: blurb-it[bot] <43283697+blurb-it[bot]@users.noreply.github.com> Co-authored-by: Gregory P. Smith <greg@krypto.org>
182 lines
4.9 KiB
Python
182 lines
4.9 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, FreeBSD, and macOS.
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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
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import sys
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import tty
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# names imported directly for test mocking purposes
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from os import close, waitpid
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from tty import setraw, tcgetattr, tcsetattr
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__all__ = ["openpty", "fork", "spawn"]
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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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import warnings
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warnings.warn("Use pty.openpty() instead.", DeprecationWarning, stacklevel=2) # Remove API in 3.14
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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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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, os.O_RDWR)
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except OSError:
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continue
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return (fd, '/dev/tty' + x + y)
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raise OSError('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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import warnings
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warnings.warn("Use pty.openpty() instead.", DeprecationWarning, stacklevel=2) # Remove API in 3.14
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result = os.open(tty_name, os.O_RDWR)
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try:
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from fcntl import ioctl, I_PUSH
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except ImportError:
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return result
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try:
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ioctl(result, I_PUSH, "ptem")
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ioctl(result, I_PUSH, "ldterm")
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except OSError:
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pass
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return result
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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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os.close(master_fd)
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os.login_tty(slave_fd)
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else:
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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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fds = [master_fd, STDIN_FILENO]
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while fds:
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rfds, _wfds, _xfds = select(fds, [], [])
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if master_fd in rfds:
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# Some OSes signal EOF by returning an empty byte string,
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# some throw OSErrors.
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try:
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data = master_read(master_fd)
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except OSError:
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data = b""
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if not data: # Reached EOF.
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return # Assume the child process has exited and is
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# unreachable, so we clean up.
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else:
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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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if not data:
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fds.remove(STDIN_FILENO)
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else:
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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 isinstance(argv, str):
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argv = (argv,)
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sys.audit('pty.spawn', argv)
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pid, master_fd = fork()
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if pid == CHILD:
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os.execlp(argv[0], *argv)
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try:
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mode = tcgetattr(STDIN_FILENO)
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setraw(STDIN_FILENO)
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restore = True
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except tty.error: # This is the same as termios.error
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restore = False
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try:
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_copy(master_fd, master_read, stdin_read)
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finally:
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if restore:
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tcsetattr(STDIN_FILENO, tty.TCSAFLUSH, mode)
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close(master_fd)
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return waitpid(pid, 0)[1]
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