image-tools: T5923: update system_console.py for new GRUB file structure

Add util function to set serial console speed in accordance with revised
GRUB file structure; in keeping with the intentions of the config_mode
script, adjust the GRUB var 'console_speed' to only modify ttyS0.

(cherry picked from commit 5ceaff2ef970cb9c567ac317bafbffca5b073f4a)

1 files changed, 42 insertions, 0 deletions

diff --git a/python/vyos/system/grub_util.py b/python/vyos/system/grub_util.py
new file mode 100644
index 000000000..9e79d41d4
--- /dev/null
+++ b/python/vyos/system/grub_util.py
@@ -0,0 +1,42 @@
+# Copyright 2024 VyOS maintainers and contributors <maintainers@vyos.io>
+#
+# This library is free software; you can redistribute it and/or
+# modify it under the terms of the GNU Lesser General Public
+# License as published by the Free Software Foundation; either
+# version 2.1 of the License, or (at your option) any later version.
+#
+# This library 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
+# Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public License
+# along with this library.  If not, see <http://www.gnu.org/licenses/>.
+
+from vyos.system import disk, grub, compat
+
+@compat.grub_cfg_update
+def set_console_speed(console_speed: str, root_dir: str = '') -> None:
+    """Write default console speed to GRUB configuration
+
+    Args:
+        console_speed (str): default console speed
+        root_dir (str, optional): an optional path to the root directory.
+        Defaults to empty.
+    """
+    if not root_dir:
+        root_dir = disk.find_persistence()
+
+    grub.set_console_speed(console_speed, root_dir)
+
+def update_console_speed(console_speed: str, root_dir: str = '') -> None:
+    """Update console_speed if different from current value"""
+
+    if not root_dir:
+        root_dir = disk.find_persistence()
+
+    vars_file: str = f'{root_dir}/{grub.CFG_VYOS_VARS}'
+    vars_current: dict[str, str] = grub.vars_read(vars_file)
+    console_speed_current = vars_current.get('console_speed', None)
+    if console_speed != console_speed_current:
+        set_console_speed(console_speed, root_dir)