Current File : //snap/core22/current/usr/share/subiquity/subiquitycore/screen.py
# Copyright 2020 Canonical, Ltd.
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, version 3.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
import fcntl
import logging
import os
import sys
import tty
import urwid
from subiquitycore.palette import COLORS, urwid_8_names
log = logging.getLogger('subiquitycore.screen')
# From uapi/linux/kd.h:
KDGKBTYPE = 0x4B33 # get keyboard type
GIO_CMAP = 0x4B70 # gets colour palette on VGA+
PIO_CMAP = 0x4B71 # sets colour palette on VGA+
UO_R, UO_G, UO_B = 0xe9, 0x54, 0x20
class SubiquityScreen(urwid.raw_display.Screen):
# This class fixes a bug in urwid's screen:
#
# Calling screen.stop() sends the INPUT_DESCRIPTORS_CHANGED signal. This
# calls _reset_input_descriptors() which calls unhook_event_loop /
# hook_event_loop on the screen. But this all happens before _started is
# set to False on the screen and so this does not actually do anything. If
# we call stop and then, for example, run bash, we end up attempting to
# read from stdin while in a background process group and that gets the
# kernel upset at us.
#
# The cleanest fix seems to be to just send the signal again once stop()
# has returned which, now that screen._started is False, correctly stops
# listening from stdin.
#
# There is an exactly analagous problem with screen.start() except there
# the symptom is that we are running in the foreground but not listening to
# stdin! The fix is the same.
def start(self):
super().start()
urwid.emit_signal(self, urwid.display_common.INPUT_DESCRIPTORS_CHANGED)
# We run the terminal in raw, not cbreak mode.
fd = self._term_input_file.fileno()
if os.isatty(fd):
tty.setraw(fd)
def stop(self):
super().stop()
urwid.emit_signal(self, urwid.display_common.INPUT_DESCRIPTORS_CHANGED)
class LinuxScreen(SubiquityScreen):
def __init__(self, colors, **kwargs):
self._colors = colors
super().__init__(**kwargs)
def start(self):
self.curpal = bytearray(16*3)
fcntl.ioctl(sys.stdout.fileno(), GIO_CMAP, self.curpal)
newpal = self.curpal.copy()
for i in range(8):
for j in range(3):
newpal[i*3+j] = self._colors[i][1][j]
fcntl.ioctl(self._term_input_file.fileno(), PIO_CMAP, newpal)
super().start()
def stop(self):
fcntl.ioctl(self._term_input_file.fileno(), PIO_CMAP, self.curpal)
super().stop()
class TwentyFourBitScreen(SubiquityScreen):
def __init__(self, colors, **kwargs):
self._urwid_name_to_rgb = {
n: colors[i][1] for i, n in enumerate(urwid_8_names)}
super().__init__(**kwargs)
def _cc(self, color):
"""Return the "SGR" parameter for selecting color.
See https://en.wikipedia.org/wiki/ANSI_escape_code#SGR for an
explanation. We use the basic codes for black/white/default for
maximum compatibility; they are the only colors used when the
mono palette is selected.
"""
if color == 'white':
return '7'
elif color == 'black':
return '0'
elif color == 'default':
return '9'
else:
# This is almost but not quite a ISO 8613-3 code -- that
# would use colons to separate the rgb values instead. But
# it's what xterm, and hence everything else, supports.
return '8;2;{};{};{}'.format(*self._urwid_name_to_rgb[color])
def _attrspec_to_escape(self, a):
return '\x1b[0;3{};4{}m'.format(
self._cc(a.foreground),
self._cc(a.background))
_is_linux_tty = None
def is_linux_tty():
global _is_linux_tty
if _is_linux_tty is None:
try:
r = fcntl.ioctl(sys.stdout.fileno(), KDGKBTYPE, ' ')
except IOError as e:
log.debug("KDGKBTYPE failed %r", e)
return False
log.debug("KDGKBTYPE returned %r, is_linux_tty %s", r, r == b'\x02')
_is_linux_tty = r == b'\x02'
return _is_linux_tty
def make_screen(ascii=False, inputf=None, outputf=None):
""" """
if inputf is None:
inputf = sys.stdin
if outputf is None:
outputf = sys.stdout
if is_linux_tty():
return LinuxScreen(COLORS, input=inputf, output=outputf)
elif ascii:
return SubiquityScreen(input=inputf, output=outputf)
else:
return TwentyFourBitScreen(COLORS, input=inputf, output=outputf)
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