1 """Pseudo terminal utilities."""
3 # Bugs: No signal handling. Doesn't set slave termios and window size.
4 # Only tested on Linux.
5 # See: W. Richard Stevens. 1992. Advanced Programming in the
6 # UNIX Environment. Chapter 19.
7 # Author: Steen Lumholt -- with additions by Guido.
9 from select import select
13 __all__ = ["openpty","fork","spawn"]
22 """openpty() -> (master_fd, slave_fd)
23 Open a pty master/slave pair, using os.openpty() if possible."""
27 except (AttributeError, OSError):
29 master_fd, slave_name = _open_terminal()
30 slave_fd = slave_open(slave_name)
31 return master_fd, slave_fd
34 """master_open() -> (master_fd, slave_name)
35 Open a pty master and return the fd, and the filename of the slave end.
36 Deprecated, use openpty() instead."""
39 master_fd, slave_fd = os.openpty()
40 except (AttributeError, OSError):
43 slave_name = os.ttyname(slave_fd)
45 return master_fd, slave_name
47 return _open_terminal()
50 """Open pty master and return (master_fd, tty_name).
51 SGI and generic BSD version, for when openpty() fails."""
58 tty_name, master_fd = sgi._getpty(os.O_RDWR, 0666, 0)
61 return master_fd, tty_name
62 for x in 'pqrstuvwxyzPQRST':
63 for y in '0123456789abcdef':
64 pty_name = '/dev/pty' + x + y
66 fd = os.open(pty_name, os.O_RDWR)
69 return (fd, '/dev/tty' + x + y)
70 raise os.error, 'out of pty devices'
72 def slave_open(tty_name):
73 """slave_open(tty_name) -> slave_fd
74 Open the pty slave and acquire the controlling terminal, returning
75 opened filedescriptor.
76 Deprecated, use openpty() instead."""
78 result = os.open(tty_name, os.O_RDWR)
80 from fcntl import ioctl, I_PUSH
84 ioctl(result, I_PUSH, "ptem")
85 ioctl(result, I_PUSH, "ldterm")
91 """fork() -> (pid, master_fd)
92 Fork and make the child a session leader with a controlling terminal."""
95 pid, fd = os.forkpty()
96 except (AttributeError, OSError):
103 # os.forkpty() already set us session leader
107 master_fd, slave_fd = openpty()
110 # Establish a new session.
114 # Slave becomes stdin/stdout/stderr of child.
115 os.dup2(slave_fd, STDIN_FILENO)
116 os.dup2(slave_fd, STDOUT_FILENO)
117 os.dup2(slave_fd, STDERR_FILENO)
118 if (slave_fd > STDERR_FILENO):
121 # Explicitly open the tty to make it become a controlling tty.
122 tmp_fd = os.open(os.ttyname(STDOUT_FILENO), os.O_RDWR)
127 # Parent and child process.
128 return pid, master_fd
130 def _writen(fd, data):
131 """Write all the data to a descriptor."""
133 n = os.write(fd, data)
137 """Default read function."""
138 return os.read(fd, 1024)
140 def _copy(master_fd, master_read=_read, stdin_read=_read):
143 pty master -> standard output (master_read)
144 standard input -> pty master (stdin_read)"""
146 rfds, wfds, xfds = select(
147 [master_fd, STDIN_FILENO], [], [])
148 if master_fd in rfds:
149 data = master_read(master_fd)
150 os.write(STDOUT_FILENO, data)
151 if STDIN_FILENO in rfds:
152 data = stdin_read(STDIN_FILENO)
153 _writen(master_fd, data)
155 def spawn(argv, master_read=_read, stdin_read=_read):
156 """Create a spawned process."""
157 if type(argv) == type(''):
159 pid, master_fd = fork()
161 os.execlp(argv[0], *argv)
163 mode = tty.tcgetattr(STDIN_FILENO)
164 tty.setraw(STDIN_FILENO)
166 except tty.error: # This is the same as termios.error
169 _copy(master_fd, master_read, stdin_read)
170 except (IOError, OSError):
172 tty.tcsetattr(STDIN_FILENO, tty.TCSAFLUSH, mode)