Xorg+dummy: set resolution to first size in list

remoting/host/linux/linux_me2me_host.py

 #!/usr/bin/python
 # Copyright (c) 2012 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 # Virtual Me2Me implementation.  This script runs and manages the processes
 # required for a Virtual Me2Me desktop, which are: X server, X desktop
 # session, and Host process.
 # This script is intended to run continuously as a background daemon
 # process, running under an ordinary (non-root) user account.
@@ skipping 500 matching lines @@
          "-config", config_file.name
         ] + extra_x_args, env=self.child_env)
     if not self.x_proc.pid:
       raise Exception("Could not start Xorg.")
 
   def _launch_x_server(self, extra_x_args):
     x_auth_file = os.path.expanduser("~/.Xauthority")
     self.child_env["XAUTHORITY"] = x_auth_file
     devnull = open(os.devnull, "r+")
     display = self.get_unused_display_number()
+    use_xorg = USE_XORG_ENV_VAR in os.environ
 
     # Run "xauth add" with |child_env| so that it modifies the same XAUTHORITY
     # file which will be used for the X session.
     ret_code = subprocess.call("xauth add :%d . `mcookie`" % display,
                                env=self.child_env, shell=True)
     if ret_code != 0:
       raise Exception("xauth failed with code %d" % ret_code)
 
     # Disable the Composite extension iff the X session is the default
     # Unity-2D, since it uses Metacity which fails to generate DAMAGE
     # notifications correctly. See crbug.com/166468.
     x_session = choose_x_session()
     if (len(x_session) == 2 and
         x_session[1] == "/usr/bin/gnome-session --session=ubuntu-2d"):
       extra_x_args.extend(["-extension", "Composite"])
 
-    if USE_XORG_ENV_VAR in os.environ:
+    if use_xorg:
       self._launch_xorg(display, x_auth_file, extra_x_args)
     else:
       self._launch_xvfb(display, x_auth_file, extra_x_args)
 
     self.child_env["DISPLAY"] = ":%d" % display
     self.child_env["CHROME_REMOTE_DESKTOP_SESSION"] = "1"
 
     # Use a separate profile for any instances of Chrome that are started in
     # the virtual session. Chrome doesn't support sharing a profile between
     # multiple DISPLAYs, but Chrome Sync allows for a reasonable compromise.
@@ skipping 19 matching lines @@
     # starts configured to use the "base" ruleset, resulting in XKB configuring
     # for "xfree86" keycodes, and screwing up some keys. See crbug.com/119013.
     # Reconfigure the X server to use "evdev" keymap rules.  The X server must
     # be started with -noreset otherwise it'll reset as soon as the command
     # completes, since there are no other X clients running yet.
     retcode = subprocess.call("setxkbmap -rules evdev", env=self.child_env,
                               shell=True)
     if retcode != 0:
       logging.error("Failed to set XKB to 'evdev'")
 
+    # Xorg+dummy will default to a resolution that is the maximum of all
+    # specified widths by the maximum of all the specified heights (which might
+    # even be a mode that wasn't specified by the user). Instead, we want to
+    # mimic the behavior we have with Xvfb, where the first size in the list is
+    # used as the initial size. Note: The session's settings daemon might change
+    # to a different resolution when it starts.
+    if use_xorg:
+      subprocess.call(["xrandr", "--size", "%dx%d" % self.sizes[0]],
+                      env=self.child_env)

[Lambros, 2016/05/17 00:08:14]

Should redirect stdout/stderr (as in the code below).

[rkjnsn, 2016/05/17 21:58:45]

Is there a reason we wouldn't want an error message here to show up in the log
file?

[Lambros, 2016/05/18 00:13:49]

I suppressed the errors originally because Xvfb-randr always whines about some
"CRT" problem, which is a false alarm.

You could show the errors, I suppose. There is already lots of noise in the
session logs anyway. But be consistent with all the xrandr commands (feel free
to punt to a separate CL).

+
     if not self.server_supports_exact_resize:

[Lambros, 2016/05/17 00:08:14]

You currently set this to False for Xorg+dummy, which means this will
early-return. But the code you added above is the same as line 608 below.

Maybe refactor this a little? 'server_supports_exact_resize' feels like the
wrong thing to test. We should be testing the level of XRANDR support. For
example, xrandr -s will work just fine with Xorg+dummy, but the
--newmode/--addmode commands might not work properly?

[rkjnsn, 2016/05/17 21:58:45]

I agree that ‘server_supports_exact_resize’ probably isn't the right test in the
long run, but testing the level of RandR would definitely be wrong. Even once we
have a version of dummy that supports exact resize, we will still be providing
the initial resolutions through the config file, and won't want to do the
--newmode/--addmode commands. Maybe we should have a
"self.server_supports_randr" flag that controls setting the initial size,
setting DPI, and spawning the watch-resolution logic, and separate logic that
only runs in the Xvfb-randr case to handle adding resolutions.

[Lambros, 2016/05/18 00:13:49]

Sounds good.

       return
 
     # Register the screen sizes if the X server's RANDR extension supports it.
     # Errors here are non-fatal; the X server will continue to run with the
     # dimensions from the "-screen" option.
     for width, height in self.sizes:
       label = "%dx%d" % (width, height)
       args = ["xrandr", "--newmode", label, "0", str(width), "0", "0", "0",
               str(height), "0", "0", "0"]
       subprocess.call(args, env=self.child_env, stdout=devnull, stderr=devnull)
@@ skipping 930 matching lines @@
         else:
           logging.info("Host exited with status %s." % os.WEXITSTATUS(status))
       elif os.WIFSIGNALED(status):
         logging.info("Host terminated by signal %s." % os.WTERMSIG(status))
 
 
 if __name__ == "__main__":
   logging.basicConfig(level=logging.DEBUG,
                       format="%(asctime)s:%(levelname)s:%(message)s")
   sys.exit(main())