virtme-ng: allow to run long commands in graphic mode

Use the same syntax to run commands also in graphic mode, for example:

  $ vng -g -- glxgears

This will start glxgears in a graphic session, using the same syntax to
run regular (non-graphic) commands.

Signed-off-by: Andrea Righi <andrea.righi@canonical.com>

Author: Andrea Righi

README.md

@@ -219,23 +219,23 @@ Examples
 
  - Run `glxgears` inside a kernel recompiled in the current directory:
 ```
-   $ vng -g glxgears
+   $ vng -g -- glxgears
 
    (virtme-ng is started in graphical mode)
 ```
 
  - Execute an `awesome` window manager session with kernel
    6.2.0-1003-lowlatency (installed in the system):
 ```
-   $ vng -r 6.2.0-1003-lowlatency -g awesome
+   $ vng -r 6.2.0-1003-lowlatency -g -- awesome
 
    (virtme-ng is started in graphical mode)
 ```
 
  - Run the `steam` snap (tested in Ubuntu) inside a virtme-ng instance using
    the 6.2.0-1003-lowlatency kernel:
 ```
-   $ vng -r 6.2.0-1003-lowlatency --snaps --net user -g /snap/bin/steam
+   $ vng -r 6.2.0-1003-lowlatency --snaps --net user -g -- /snap/bin/steam
 
    (virtme-ng is started in graphical mode)
 ```

virtme/commands/run.py

@@ -1007,11 +1007,9 @@ def do_it() -> int:
             )
 
     def do_script(shellcmd: str, show_boot_console=False) -> None:
-        if args.graphics is not None:
-            arg_fail("scripts and --graphics are mutually exclusive")
-
-        # Turn off default I/O
-        qemuargs.extend(arch.qemu_nodisplay_args())
+        if args.graphics is None:
+            # Turn off default I/O
+            qemuargs.extend(arch.qemu_nodisplay_args())
 
         # Configure kernel console output
         if show_boot_console:
@@ -1063,13 +1061,6 @@ def do_script(shellcmd: str, show_boot_console=False) -> None:
         # Scripts shouldn't reboot
         qemuargs.extend(["-no-reboot"])
 
-        # Encode the shell command to base64 to handle special characters (such
-        # as quotes, double quotes, etc.).
-        shellcmd = b64encode(shellcmd.encode('utf-8')).decode('utf-8')
-
-        # Ask virtme-init to run the script
-        kernelargs.append(f"virtme.exec=`{shellcmd}`")
-
         # Nasty issue: QEMU will set O_NONBLOCK on fds 0, 1, and 2.
         # This isn't inherently bad, but it can cause a problem if
         # another process is reading from 1 or writing to 0, which is
@@ -1087,6 +1078,20 @@ def do_script(shellcmd: str, show_boot_console=False) -> None:
                     os.dup2(newfd, oldfd)
                     os.close(newfd)
 
+        # Encode the shell command to base64 to handle special characters (such
+        # as quotes, double quotes, etc.).
+        shellcmd = b64encode(shellcmd.encode('utf-8')).decode('utf-8')
+
+        if args.graphics is not None:
+            kernelargs.append("virtme_graphics=1")
+
+        # Ask virtme-init to run the script
+        kernelargs.append(f"virtme.exec=`{shellcmd}`")
+
+    # Do not break old syntax "-g command"
+    if args.graphics is not None and args.script_sh is None:
+        args.script_sh = args.graphics
+
     if args.script_sh is not None:
         do_script(args.script_sh, show_boot_console=args.show_boot_console)
 
@@ -1100,8 +1105,6 @@ def do_script(shellcmd: str, show_boot_console=False) -> None:
         video_args = arch.qemu_display_args()
         if video_args:
             qemuargs.extend(video_args)
-        if args.graphics != "":
-            kernelargs.append("virtme_graphics=%s" % args.graphics)
 
     if args.net:
         qemuargs.extend(["-device", "%s,netdev=n0" % arch.virtio_dev_type("net")])

virtme/guest/virtme-init

@@ -253,15 +253,17 @@ if [[ -n "${user_cmd}" ]]; then
     # Decode shell command (base64) and dump it to a script
     echo $user_cmd | base64 -d > /tmp/.virtme-script
 
-    # Start the script
-    log 'starting script'
-    setsid bash /tmp/.virtme-script </dev/virtio-ports/virtme.stdin >/dev/virtio-ports/virtme.stdout 2>/dev/virtio-ports/virtme.stderr
-    log "script returned $?"
-
-    # Hmm.  We should expose the return value somehow.
-    sync
-    poweroff -f
-    exit 0
+    if [[ ! -n "${virtme_graphics}" ]]; then
+        # Start the script
+        log 'starting script'
+        setsid bash /tmp/.virtme-script </dev/virtio-ports/virtme.stdin >/dev/virtio-ports/virtme.stdout 2>/dev/virtio-ports/virtme.stderr
+        log "script returned $?"
+
+        # Hmm.  We should expose the return value somehow.
+        sync
+        poweroff -f
+        exit 0
+    fi
 fi
 
 # Figure out what the main console is
@@ -330,7 +332,8 @@ if [[ -n "${virtme_graphics}" ]]; then
 
     # Create a .xinitrc to start the requested graphical application.
     xinit_rc=/tmp/.xinitrc
-    echo -e "${pre_exec_cmd}\nexec ${virtme_graphics}" > ${xinit_rc}
+    echo -e "${pre_exec_cmd}\nexec /tmp/.virtme-script" > ${xinit_rc}
+    chmod +x /tmp/.virtme-script
     if [[ -n "${virtme_user}" ]]; then
         chown ${virtme_user}:${virtme_user} $XDG_RUNTIME_DIR
         chown ${virtme_user}:${virtme_user} ${xinit_rc}

virtme_ng/run.py

@@ -329,12 +329,8 @@ def make_parser():
     parser.add_argument(
         "--graphics",
         "-g",
-        action="store",
-        nargs="?",
-        const="",
-        metavar="BINARY",
-        help="Show graphical output instead of using a console. "
-        + "An argument can be optionally specified to start a graphical application.",
+        action="store_true",
+        help="Show graphical output instead of using a console.",
     )
 
     parser.add_argument(
@@ -829,8 +825,8 @@ def _get_virtme_initramfs(self, args):
             self.virtme_param["force_initramfs"] = ""
 
     def _get_virtme_graphics(self, args):
-        if args.graphics is not None:
-            self.virtme_param["graphics"] = f'--graphics "{args.graphics}"'
+        if args.graphics:
+            self.virtme_param["graphics"] = '--graphics'
         else:
             self.virtme_param["graphics"] = ""