|
| 1 | +"""Pseudo terminal utilities.""" |
| 2 | + |
| 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. |
| 8 | + |
| 9 | +from select import select |
| 10 | +import os |
| 11 | +import sys |
| 12 | +import tty |
| 13 | + |
| 14 | +__all__ = ["openpty","fork","spawn"] |
| 15 | + |
| 16 | +STDIN_FILENO = 0 |
| 17 | +STDOUT_FILENO = 1 |
| 18 | +STDERR_FILENO = 2 |
| 19 | + |
| 20 | +CHILD = 0 |
| 21 | + |
| 22 | +def openpty(): |
| 23 | + """openpty() -> (master_fd, slave_fd) |
| 24 | + Open a pty master/slave pair, using os.openpty() if possible.""" |
| 25 | + |
| 26 | + try: |
| 27 | + return os.openpty() |
| 28 | + except (AttributeError, OSError): |
| 29 | + pass |
| 30 | + master_fd, slave_name = _open_terminal() |
| 31 | + slave_fd = slave_open(slave_name) |
| 32 | + return master_fd, slave_fd |
| 33 | + |
| 34 | +def master_open(): |
| 35 | + """master_open() -> (master_fd, slave_name) |
| 36 | + Open a pty master and return the fd, and the filename of the slave end. |
| 37 | + Deprecated, use openpty() instead.""" |
| 38 | + |
| 39 | + try: |
| 40 | + master_fd, slave_fd = os.openpty() |
| 41 | + except (AttributeError, OSError): |
| 42 | + pass |
| 43 | + else: |
| 44 | + slave_name = os.ttyname(slave_fd) |
| 45 | + os.close(slave_fd) |
| 46 | + return master_fd, slave_name |
| 47 | + |
| 48 | + return _open_terminal() |
| 49 | + |
| 50 | +def _open_terminal(): |
| 51 | + """Open pty master and return (master_fd, tty_name).""" |
| 52 | + for x in 'pqrstuvwxyzPQRST': |
| 53 | + for y in '0123456789abcdef': |
| 54 | + pty_name = '/dev/pty' + x + y |
| 55 | + try: |
| 56 | + fd = os.open(pty_name, os.O_RDWR) |
| 57 | + except OSError: |
| 58 | + continue |
| 59 | + return (fd, '/dev/tty' + x + y) |
| 60 | + raise OSError('out of pty devices') |
| 61 | + |
| 62 | +def slave_open(tty_name): |
| 63 | + """slave_open(tty_name) -> slave_fd |
| 64 | + Open the pty slave and acquire the controlling terminal, returning |
| 65 | + opened filedescriptor. |
| 66 | + Deprecated, use openpty() instead.""" |
| 67 | + |
| 68 | + result = os.open(tty_name, os.O_RDWR) |
| 69 | + try: |
| 70 | + from fcntl import ioctl, I_PUSH |
| 71 | + except ImportError: |
| 72 | + return result |
| 73 | + try: |
| 74 | + ioctl(result, I_PUSH, "ptem") |
| 75 | + ioctl(result, I_PUSH, "ldterm") |
| 76 | + except OSError: |
| 77 | + pass |
| 78 | + return result |
| 79 | + |
| 80 | +def fork(): |
| 81 | + """fork() -> (pid, master_fd) |
| 82 | + Fork and make the child a session leader with a controlling terminal.""" |
| 83 | + |
| 84 | + try: |
| 85 | + pid, fd = os.forkpty() |
| 86 | + except (AttributeError, OSError): |
| 87 | + pass |
| 88 | + else: |
| 89 | + if pid == CHILD: |
| 90 | + try: |
| 91 | + os.setsid() |
| 92 | + except OSError: |
| 93 | + # os.forkpty() already set us session leader |
| 94 | + pass |
| 95 | + return pid, fd |
| 96 | + |
| 97 | + master_fd, slave_fd = openpty() |
| 98 | + pid = os.fork() |
| 99 | + if pid == CHILD: |
| 100 | + # Establish a new session. |
| 101 | + os.setsid() |
| 102 | + os.close(master_fd) |
| 103 | + |
| 104 | + # Slave becomes stdin/stdout/stderr of child. |
| 105 | + os.dup2(slave_fd, STDIN_FILENO) |
| 106 | + os.dup2(slave_fd, STDOUT_FILENO) |
| 107 | + os.dup2(slave_fd, STDERR_FILENO) |
| 108 | + if (slave_fd > STDERR_FILENO): |
| 109 | + os.close (slave_fd) |
| 110 | + |
| 111 | + # Explicitly open the tty to make it become a controlling tty. |
| 112 | + tmp_fd = os.open(os.ttyname(STDOUT_FILENO), os.O_RDWR) |
| 113 | + os.close(tmp_fd) |
| 114 | + else: |
| 115 | + os.close(slave_fd) |
| 116 | + |
| 117 | + # Parent and child process. |
| 118 | + return pid, master_fd |
| 119 | + |
| 120 | +def _writen(fd, data): |
| 121 | + """Write all the data to a descriptor.""" |
| 122 | + while data: |
| 123 | + n = os.write(fd, data) |
| 124 | + data = data[n:] |
| 125 | + |
| 126 | +def _read(fd): |
| 127 | + """Default read function.""" |
| 128 | + return os.read(fd, 1024) |
| 129 | + |
| 130 | +def _copy(master_fd, master_read=_read, stdin_read=_read): |
| 131 | + """Parent copy loop. |
| 132 | + Copies |
| 133 | + pty master -> standard output (master_read) |
| 134 | + standard input -> pty master (stdin_read)""" |
| 135 | + fds = [master_fd, STDIN_FILENO] |
| 136 | + while True: |
| 137 | + rfds, wfds, xfds = select(fds, [], []) |
| 138 | + if master_fd in rfds: |
| 139 | + data = master_read(master_fd) |
| 140 | + if not data: # Reached EOF. |
| 141 | + fds.remove(master_fd) |
| 142 | + else: |
| 143 | + os.write(STDOUT_FILENO, data) |
| 144 | + if STDIN_FILENO in rfds: |
| 145 | + data = stdin_read(STDIN_FILENO) |
| 146 | + if not data: |
| 147 | + fds.remove(STDIN_FILENO) |
| 148 | + else: |
| 149 | + _writen(master_fd, data) |
| 150 | + |
| 151 | +def spawn(argv, master_read=_read, stdin_read=_read): |
| 152 | + """Create a spawned process.""" |
| 153 | + if type(argv) == type(''): |
| 154 | + argv = (argv,) |
| 155 | + sys.audit('pty.spawn', argv) |
| 156 | + pid, master_fd = fork() |
| 157 | + if pid == CHILD: |
| 158 | + os.execlp(argv[0], *argv) |
| 159 | + try: |
| 160 | + mode = tty.tcgetattr(STDIN_FILENO) |
| 161 | + tty.setraw(STDIN_FILENO) |
| 162 | + restore = 1 |
| 163 | + except tty.error: # This is the same as termios.error |
| 164 | + restore = 0 |
| 165 | + try: |
| 166 | + _copy(master_fd, master_read, stdin_read) |
| 167 | + except OSError: |
| 168 | + if restore: |
| 169 | + tty.tcsetattr(STDIN_FILENO, tty.TCSAFLUSH, mode) |
| 170 | + |
| 171 | + os.close(master_fd) |
| 172 | + return os.waitpid(pid, 0)[1] |
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