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oasis-root

Compiled tree of Oasis Linux based on own branch at <https://hacktivis.me/git/oasis/> git clone https://anongit.hacktivis.me/git/oasis-root.git

pty.py (5213B)


  1. """Pseudo terminal utilities."""
  2. # Bugs: No signal handling. Doesn't set slave termios and window size.
  3. # Only tested on Linux, FreeBSD, and macOS.
  4. # See: W. Richard Stevens. 1992. Advanced Programming in the
  5. # UNIX Environment. Chapter 19.
  6. # Author: Steen Lumholt -- with additions by Guido.
  7. from select import select
  8. import os
  9. import sys
  10. import tty
  11. # names imported directly for test mocking purposes
  12. from os import close, waitpid
  13. from tty import setraw, tcgetattr, tcsetattr
  14. __all__ = ["openpty", "fork", "spawn"]
  15. STDIN_FILENO = 0
  16. STDOUT_FILENO = 1
  17. STDERR_FILENO = 2
  18. CHILD = 0
  19. def openpty():
  20. """openpty() -> (master_fd, slave_fd)
  21. Open a pty master/slave pair, using os.openpty() if possible."""
  22. try:
  23. return os.openpty()
  24. except (AttributeError, OSError):
  25. pass
  26. master_fd, slave_name = _open_terminal()
  27. slave_fd = slave_open(slave_name)
  28. return master_fd, slave_fd
  29. def master_open():
  30. """master_open() -> (master_fd, slave_name)
  31. Open a pty master and return the fd, and the filename of the slave end.
  32. Deprecated, use openpty() instead."""
  33. try:
  34. master_fd, slave_fd = os.openpty()
  35. except (AttributeError, OSError):
  36. pass
  37. else:
  38. slave_name = os.ttyname(slave_fd)
  39. os.close(slave_fd)
  40. return master_fd, slave_name
  41. return _open_terminal()
  42. def _open_terminal():
  43. """Open pty master and return (master_fd, tty_name)."""
  44. for x in 'pqrstuvwxyzPQRST':
  45. for y in '0123456789abcdef':
  46. pty_name = '/dev/pty' + x + y
  47. try:
  48. fd = os.open(pty_name, os.O_RDWR)
  49. except OSError:
  50. continue
  51. return (fd, '/dev/tty' + x + y)
  52. raise OSError('out of pty devices')
  53. def slave_open(tty_name):
  54. """slave_open(tty_name) -> slave_fd
  55. Open the pty slave and acquire the controlling terminal, returning
  56. opened filedescriptor.
  57. Deprecated, use openpty() instead."""
  58. result = os.open(tty_name, os.O_RDWR)
  59. try:
  60. from fcntl import ioctl, I_PUSH
  61. except ImportError:
  62. return result
  63. try:
  64. ioctl(result, I_PUSH, "ptem")
  65. ioctl(result, I_PUSH, "ldterm")
  66. except OSError:
  67. pass
  68. return result
  69. def fork():
  70. """fork() -> (pid, master_fd)
  71. Fork and make the child a session leader with a controlling terminal."""
  72. try:
  73. pid, fd = os.forkpty()
  74. except (AttributeError, OSError):
  75. pass
  76. else:
  77. if pid == CHILD:
  78. try:
  79. os.setsid()
  80. except OSError:
  81. # os.forkpty() already set us session leader
  82. pass
  83. return pid, fd
  84. master_fd, slave_fd = openpty()
  85. pid = os.fork()
  86. if pid == CHILD:
  87. # Establish a new session.
  88. os.setsid()
  89. os.close(master_fd)
  90. # Slave becomes stdin/stdout/stderr of child.
  91. os.dup2(slave_fd, STDIN_FILENO)
  92. os.dup2(slave_fd, STDOUT_FILENO)
  93. os.dup2(slave_fd, STDERR_FILENO)
  94. if slave_fd > STDERR_FILENO:
  95. os.close(slave_fd)
  96. # Explicitly open the tty to make it become a controlling tty.
  97. tmp_fd = os.open(os.ttyname(STDOUT_FILENO), os.O_RDWR)
  98. os.close(tmp_fd)
  99. else:
  100. os.close(slave_fd)
  101. # Parent and child process.
  102. return pid, master_fd
  103. def _writen(fd, data):
  104. """Write all the data to a descriptor."""
  105. while data:
  106. n = os.write(fd, data)
  107. data = data[n:]
  108. def _read(fd):
  109. """Default read function."""
  110. return os.read(fd, 1024)
  111. def _copy(master_fd, master_read=_read, stdin_read=_read):
  112. """Parent copy loop.
  113. Copies
  114. pty master -> standard output (master_read)
  115. standard input -> pty master (stdin_read)"""
  116. fds = [master_fd, STDIN_FILENO]
  117. while fds:
  118. rfds, _wfds, _xfds = select(fds, [], [])
  119. if master_fd in rfds:
  120. # Some OSes signal EOF by returning an empty byte string,
  121. # some throw OSErrors.
  122. try:
  123. data = master_read(master_fd)
  124. except OSError:
  125. data = b""
  126. if not data: # Reached EOF.
  127. return # Assume the child process has exited and is
  128. # unreachable, so we clean up.
  129. else:
  130. os.write(STDOUT_FILENO, data)
  131. if STDIN_FILENO in rfds:
  132. data = stdin_read(STDIN_FILENO)
  133. if not data:
  134. fds.remove(STDIN_FILENO)
  135. else:
  136. _writen(master_fd, data)
  137. def spawn(argv, master_read=_read, stdin_read=_read):
  138. """Create a spawned process."""
  139. if type(argv) == type(''):
  140. argv = (argv,)
  141. sys.audit('pty.spawn', argv)
  142. pid, master_fd = fork()
  143. if pid == CHILD:
  144. os.execlp(argv[0], *argv)
  145. try:
  146. mode = tcgetattr(STDIN_FILENO)
  147. setraw(STDIN_FILENO)
  148. restore = True
  149. except tty.error: # This is the same as termios.error
  150. restore = False
  151. try:
  152. _copy(master_fd, master_read, stdin_read)
  153. finally:
  154. if restore:
  155. tcsetattr(STDIN_FILENO, tty.TCSAFLUSH, mode)
  156. close(master_fd)
  157. return waitpid(pid, 0)[1]