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bpo-41541: Make pty.spawn set window size #21861

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bpo-41541: Make pty.spawn set window size #21861

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0244838
📜🤖 Added by blurb_it.
blurb-it[bot] Aug 13, 2020
5ebf0f3
Make pty.spawn set window size
8vasu Aug 19, 2020
efca4a1
Minor modification to _setwinsz()
8vasu Sep 19, 2020
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60 changes: 46 additions & 14 deletions Lib/pty.py
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Original file line number Diff line number Diff line change
Expand Up @@ -77,6 +77,27 @@ def slave_open(tty_name):
pass
return result

def login_tty(fd):
"""Makes the calling process a session leader, makes fd its
controlling terminal, stdin, stdout, and stderr. Closes fd."""
# Establish a new session.
os.setsid()

# Make fd the controlling terminal.
try:
from fcntl import ioctl
ioctl(fd, tty.TIOCSCTTY)
except (ImportError, AttributeError, OSError):
tmp_fd = os.open(os.ttyname(fd), os.O_RDWR)
os.close(tmp_fd)

# fd becomes stdin/stdout/stderr.
os.dup2(fd, STDIN_FILENO)
os.dup2(fd, STDOUT_FILENO)
os.dup2(fd, STDERR_FILENO)
if (fd > STDERR_FILENO):
os.close(fd)

def fork():
"""fork() -> (pid, master_fd)
Fork and make the child a session leader with a controlling terminal."""
Expand All @@ -97,20 +118,8 @@ def fork():
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)
login_tty(slave_fd)
else:
os.close(slave_fd)

Expand Down Expand Up @@ -148,14 +157,37 @@ def _copy(master_fd, master_read=_read, stdin_read=_read):
else:
_writen(master_fd, data)

def _setwinsz(fd):
"""Sets window size.
If both stdin and fd are terminals,
then set fd's window size to be the
same as that of stdin's."""
try:
from struct import pack
from fcntl import ioctl
except ImportError:
return

strct = pack('HHHH', 0, 0, 0, 0)
try:
winsz = ioctl(STDIN_FILENO, tty.TIOCGWINSZ, strct)
ioctl(fd, tty.TIOCSWINSZ, winsz)
except (AttributeError, OSError):
pass

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()
master_fd, slave_fd = openpty()
_setwinsz(slave_fd)
pid = os.fork()
if pid == CHILD:
os.close(master_fd)
login_tty(slave_fd)
os.execlp(argv[0], *argv)
os.close(slave_fd)
try:
mode = tty.tcgetattr(STDIN_FILENO)
tty.setraw(STDIN_FILENO)
Expand Down
1 change: 1 addition & 0 deletions Misc/NEWS.d/next/Library/2020-08-13-17-48-58.bpo-41541.vKJSeV.rst
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Original file line number Diff line number Diff line change
@@ -0,0 +1 @@
Make pty.spawn set window size.