put the terminal into raw mode

For whatever reason, urwid puts the terminal into cbreak mode during
initialization. If we put the terminal into raw mode instead, then we
don't have to ignore SIGINT and SIGQUIT, which is good, because when we
support dropping to a subshell we don't want to run that subshell with
those signals ignored, because that is extremely confusing.

This also lets me dump the code that puts the terminal into raw mode
during keyboard detection.

console_conf/cmd/tui.py

@@ -17,7 +17,6 @@
 import argparse
 import sys
 import logging
-import signal
 from subiquitycore.log import setup_logger
 from subiquitycore import __version__ as VERSION
 from console_conf.core import ConsoleConf
@@ -83,9 +82,6 @@ def main():
     logger.info("Starting console-conf v{}".format(VERSION))
     logger.info("Arguments passed: {}".format(sys.argv))
 
-    signal.signal(signal.SIGINT, signal.SIG_IGN)
-    signal.signal(signal.SIGQUIT, signal.SIG_IGN)
-
     env_ok = environment_check(ENVIRONMENT)
     if env_ok is False and not opts.dry_run:
         print('Failed environment check.  '

subiquity/cmd/tui.py

@@ -18,7 +18,6 @@ import argparse
 import logging
 import os
 import fcntl
-import signal
 import sys
 
 from subiquitycore.log import setup_logger
@@ -126,9 +125,6 @@ def main():
     logging.getLogger('curtin').addHandler(handler)
     logging.getLogger('block-discover').addHandler(handler)
 
-    signal.signal(signal.SIGINT, signal.SIG_IGN)
-    signal.signal(signal.SIGQUIT, signal.SIG_IGN)
-
     env_ok = environment_check(ENVIRONMENT)
     if env_ok is False and not opts.dry_run:
         print('Failed environment check.  '

subiquitycore/core.py

@@ -20,7 +20,6 @@ import logging
 import os
 import struct
 import sys
-import termios
 import tty
 
 import urwid
@@ -156,25 +155,13 @@ class KeyCodesFilter:
     def enter_keycodes_mode(self):
         log.debug("enter_keycodes_mode")
         self.filtering = True
-        # Read the old keyboard mode (it will proably always be
-        # K_UNICODE but well).
+        # Read the old keyboard mode (it will proably always be K_UNICODE but
+        # well).
         o = bytearray(4)
         fcntl.ioctl(self._fd, KDGKBMODE, o)
         self._old_mode = struct.unpack('i', o)[0]
-        # Make some changes to the terminal settings.
-        # If you don't do this, sometimes writes to the terminal hang (and no,
-        # I don't know exactly why).
-        self._old_settings = termios.tcgetattr(self._fd)
-        new_settings = termios.tcgetattr(self._fd)
-        new_settings[tty.IFLAG] = 0
-        new_settings[tty.LFLAG] = new_settings[tty.LFLAG] & ~(termios.ECHO |
-                                                              termios.ICANON |
-                                                              termios.ISIG)
-        new_settings[tty.CC][termios.VMIN] = 0
-        new_settings[tty.CC][termios.VTIME] = 0
-        termios.tcsetattr(self._fd, termios.TCSAFLUSH, new_settings)
-        # Finally, set the keyboard mode to K_MEDIUMRAW, which causes
-        # the keyboard driver in the kernel to pass us keycodes.
+        # Set the keyboard mode to K_MEDIUMRAW, which causes the keyboard
+        # driver in the kernel to pass us keycodes.
         log.debug("old mode was %s, setting mode to %s",
                   self._old_mode, K_MEDIUMRAW)
         fcntl.ioctl(self._fd, KDSKBMODE, K_MEDIUMRAW)
@@ -184,7 +171,6 @@ class KeyCodesFilter:
         self.filtering = False
         log.debug("setting mode back to %s", self._old_mode)
         fcntl.ioctl(self._fd, KDSKBMODE, self._old_mode)
-        termios.tcsetattr(self._fd, termios.TCSANOW, self._old_settings)
 
     def filter(self, keys, codes):
         # Luckily urwid passes us the raw results from read() we can
@@ -526,6 +512,8 @@ class Application:
                 except Skip:
                     self.next_screen()
 
+            self.common['loop'].set_alarm_in(
+                0.00, lambda loop, ud: tty.setraw(0))
             self.common['loop'].set_alarm_in(
                 0.05, select_initial_screen, initial_controller_index)
             self._connect_base_signals()