[PATCH 2/3] scripts/runfvp: add Screen support

Add support for Screen the GNU terminal multiplexer. The -t/--terminal
option now accepts "screen" as a terminal type. When selected, the tool
must be run from within an existing Screen session, and each FVP
terminal is opened in a new Screen window.

Signed-off-by: Gyorgy Szing <[email protected]>
---
 documentation/runfvp.md      |  3 +++
 meta-arm/lib/fvp/terminal.py | 17 ++++++++++++++++-
 2 files changed, 19 insertions(+), 1 deletion(-)

diff --git a/documentation/runfvp.md b/documentation/runfvp.md
index aed99971..8c9b5f40 100644
--- a/documentation/runfvp.md
+++ b/documentation/runfvp.md
@@ -33,6 +33,8 @@ The tool attempts to automatically select a suitable te=
rminal type. To see which
 `runfvp` determines availability by checking for required executables in=
 your PATH as well as environment variables specific to each terminal typ=
e. If any of these checks fail, the corresponding terminal type is disabl=
ed.
 The --help output also lists all currently available terminal types.
=20
+When using `-terminals=3Dscreen`, `runfvp` must be launched from within =
an existing [`screen`][screen] session. Normally, screen sets the `STY` e=
nvironment variable to reference the current session. However, if the ses=
sion is renamed or if `kas` is started from within the screen session, th=
is value may become invalid or be lost. In such cases, `STY` must be set =
manually. Use `screen -ls` to view the list of currently attached session=
s.
+
 The default terminal can also be configured by writing a [INI-style][INI=
] configuration file to `~/.config/runfvp.conf`:
=20
 ```
@@ -144,3 +146,4 @@ FVP_ENV_PASSTHROUGH =3D "ARMLMD_LICENSE_FILE FM_TRACE=
_PLUGINS"
 [FVP]: https://developer.arm.com/tools-and-software/simulation-models/fi=
xed-virtual-platforms
 [tmux]: https://tmux.github.io/
 [INI]: https://docs.python.org/3/library/configparser.html
+[screen]: https://www.gnu.org/software/screen/
diff --git a/meta-arm/lib/fvp/terminal.py b/meta-arm/lib/fvp/terminal.py
index c0087fa1..fb6050d6 100644
--- a/meta-arm/lib/fvp/terminal.py
+++ b/meta-arm/lib/fvp/terminal.py
@@ -1,4 +1,3 @@
-import shutil
 import collections
 import pathlib
 import os
@@ -37,6 +36,20 @@ def check_executable(*cmd) -> bool:
     return exitcode =3D=3D 0
=20
=20
+def screen_is_ready(*, silent: bool =3D False) -> bool:
+    log_print =3D (lambda *_args, **_kwargs: None) if silent else logger=
.error
+
+    if not check_executable("screen", "--version"):
+        log_print("--terminal screen requires screen to be available and=
 runnable, but startup failed.")
+        return False
+
+    if not os.environ.get("STY"):
+        log_print("--terminal screen requires runfvp to be started from =
a screen session.\n\tEnsure $STY is set in the environment.")
+        return False
+
+    return True
+
+
 def tmux_is_ready(*, silent: bool =3D False) -> bool:
     log_print =3D (lambda *_args, **_kwargs: None) if silent else logger=
.error
=20
@@ -126,6 +139,8 @@ class Terminals:
 terminals =3D Terminals()
 # TODO: option to switch between telnet and netcat
 connect_command =3D "telnet localhost %port"
+sty =3D os.environ.get("STY")
+terminals.add_terminal(2, "screen", f'screen -S "{sty}" -X screen -t "{{=
name}} - %title" -L {connect_command}', screen_is_ready)
 terminals.add_terminal(2, "tmux", f'tmux new-window -n "{{name}}" "{conn=
ect_command}"', tmux_is_ready)
 terminals.add_terminal(2, "gnome-terminal", f'gnome-terminal --window --=
title "{{name}} - %title" --command "{connect_command}"', gterm_is_ready)
 terminals.add_terminal(1, "xterm", f'xterm -title "{{name}} - %title" -e=
 {connect_command}', xterm_is_ready)
--=20
2.43.0