--- cpython/Lib/pty.py	2020-08-07 19:08:16.285101146 -0500
+++ pty.py	2020-08-07 19:04:51.012271815 -0500
@@ -1,6 +1,6 @@
 """Pseudo terminal utilities."""
 
-# Bugs: No signal handling.  Doesn't set slave termios and window size.
+# Bugs: No signal handling.  Doesn't set slave termios.
 #       Only tested on Linux.
 # See:  W. Richard Stevens. 1992.  Advanced Programming in the
 #       UNIX Environment.  Chapter 19.
@@ -10,8 +10,13 @@
 import os
 import sys
 import tty
+import signal
+import struct
+import fcntl
+import termios
+import time
 
-__all__ = ["openpty","fork","spawn"]
+__all__ = ["openpty","fork","spawn","wspawn"]
 
 STDIN_FILENO = 0
 STDOUT_FILENO = 1
@@ -170,3 +175,128 @@
 
     os.close(master_fd)
     return os.waitpid(pid, 0)[1]
+
+# Author: Soumendra Ganguly.
+SIGWINCH = signal.SIGWINCH
+
+def _login_pty(master_fd, slave_fd):
+    """Given a pty, makes the calling process a session leader, makes the pty slave
+    its controlling terminal, stdin, stdout, and stderr. Closes both pty ends."""
+    # Establish a new session.
+    os.setsid()
+    os.close(master_fd)
+
+    try:
+        fcntl.ioctl(slave_fd, termios.TIOCSCTTY) # Make the pty slave the controlling terminal.
+    except:
+        os.close(slave_fd)
+        raise
+
+    # Slave becomes stdin/stdout/stderr.
+    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)
+
+def _winresz(pty_slave):
+    """Resize window."""
+    w = struct.pack('HHHH', 0, 0, 0, 0)
+    s = fcntl.ioctl(STDIN_FILENO, termios.TIOCGWINSZ, w)
+    fcntl.ioctl(pty_slave, termios.TIOCSWINSZ, s)
+
+def _create_hwinch(pty_slave):
+    """Creates SIGWINCH handler."""
+    def _hwinch(signum, frame):
+        try:
+            _winresz(pty_slave)
+        except:
+            pass
+    return _hwinch
+
+def _cleanup(master_fd, slave_fd, old_hwinch, tty_mode):
+    """Performs cleanup in wspawn."""
+
+    # Close both pty ends.
+    os.close(master_fd)
+    os.close(slave_fd)
+
+    # Restore original tty attributes.
+    if tty_mode != None:
+        tty.tcsetattr(STDIN_FILENO, tty.TCSAFLUSH, tty_mode)
+
+    # Restore original SIGWINCH signal handler.
+    try:
+        signal.signal(SIGWINCH, old_hwinch)
+    except:
+        pass
+
+def _ekill(child_pid):
+    """Kill spawned process due to exception."""
+    try:
+        os.kill(child_pid, signal.SIGTERM)
+        time.sleep(1)
+        os.kill(child_pid, signal.SIGKILL)
+    except:
+        pass
+    try:
+        os.waitpid(child_pid, 0)
+    except:
+        pass
+
+def _wcopy(master_fd, child_pid, master_read=_read, stdin_read=_read, timeout=0.01):
+    """Parent copy loop for wspawn."""
+    fds = [master_fd, STDIN_FILENO]
+    ret = (0,0)
+    while True:
+        rfds, wfds, xfds = select(fds, [], [], timeout)
+        if ret == (0,0):
+            ret = os.waitpid(child_pid, os.WNOHANG)
+        elif len(rfds) == 0:
+            break;
+        if master_fd in rfds:
+            data = master_read(master_fd)
+            if not data:  # Reached EOF.
+                fds.remove(master_fd)
+            else:
+                os.write(STDOUT_FILENO, data)
+        if STDIN_FILENO in rfds:
+            data = stdin_read(STDIN_FILENO)
+            if not data:
+                fds.remove(STDIN_FILENO)
+            else:
+                _writen(master_fd, data)
+    return ret
+
+def wspawn(argv, master_read=_read, stdin_read=_read, timeout=0.01):
+    """Create a spawned process with
+    terminal window resizing enabled."""
+    if type(argv) == type(''):
+        argv = (argv,)
+    sys.audit('pty.wspawn', argv)
+    bk_hwinch = signal.getsignal(SIGWINCH)
+    master_fd, slave_fd = openpty()
+    try:
+        _winresz(slave_fd)
+        signal.signal(SIGWINCH, _create_hwinch(slave_fd))
+    except:     # User should handle exception and try spawn instead.
+        _cleanup(master_fd, slave_fd, bk_hwinch, None)
+        raise
+    pid = os.fork()
+    if pid == CHILD:
+        _login_pty(master_fd, slave_fd)
+        os.execlp(argv[0], *argv)
+    try:
+        mode = tty.tcgetattr(STDIN_FILENO)
+        tty.setraw(STDIN_FILENO)
+    except tty.error:    # This is the same as termios.error
+        mode = None
+    try:
+        ret = _wcopy(master_fd, pid, master_read, stdin_read, timeout)[1]
+    except:
+        _ekill(pid)
+        _cleanup(master_fd, slave_fd, bk_hwinch, mode)
+        raise
+
+    _cleanup(master_fd, slave_fd, bk_hwinch, mode)
+    return ret