hookcheck.py.template

#!/usr/bin/env python3

"""
This template file goes into /etc/grub.d/99_matter
It checks that the theme is still hooked to grub-mkconfig.
Hooks it back again if not.

This is a template file, be careful of your use of curly braces. Use {{ and }} instead.

# About /etc/grub.d
Files in /etc/grub.d run in the order of their prefix number.
We use the 99 number because the hook should be run after the entire grub.cfg file is generated.
Everything echoed to stdout is written to /boot/grub/grub.cfg after the previous files.
Everything echoed to stderr is shown to the user wherever there is a grub update.
This script does not write to stdout.
More @ https://www.gnu.org/software/grub/manual/grub/grub.html#Simple-configuration

# Why this script exists?
Files in /etc/grub.d are not erased after your distro upgrades the grub package.
As this theme relies on being hooked to the grub-mkconfig file (i.e. executed by it)
and grub package upgrades restore the mkconfig file, this file detects
when the grub-mkconfig file has been restored and then hook the theme back onto it.
"""

import re
from subprocess import run
from sys import stderr

GRUB_MKCONFIG_PATH = "{GRUB_MKCONFIG_PATH}"
THEME_NAME = "{THEME_NAME}"
THEME_OVERRIDES_TITLE = "{THEME_OVERRIDES_TITLE}"
BEGIN_THEME_OVERRIDES = "{BEGIN_THEME_OVERRIDES}"
END_THEME_OVERRIDES = "{END_THEME_OVERRIDES}"
SETICONS_CALL = "{SETICONS_CALL}"

cyan = "\033[36m"
pink = "\033[38;5;206m"
endcolor ="\033[0m"
def info(msg):
    # info with cyan [I]
    print(f"{{cyan}}[I]{{endcolor}} {{msg}}", file=stderr)


def sh(command):
    "Executes command in shell and returns its exit status"
    return run(command, shell=True).returncode

info(f"{{pink}}[Matter]{{endcolor}} Setting entry icons")

with open(GRUB_MKCONFIG_PATH, "r", newline="") as f:
    grub_mkconfig = f.read()

theme_overrides = f"\n*{{BEGIN_THEME_OVERRIDES}}.*{{END_THEME_OVERRIDES}}\n*"
theme_hooked = re.search(theme_overrides, grub_mkconfig, flags=re.DOTALL) is not None

if theme_hooked:
    info(f"Found {{GRUB_MKCONFIG_PATH}} hook")
    exit(0)

info(f"Hook back onto {{GRUB_MKCONFIG_PATH}}")

grub_mkconfig += (
    f"\n\n{{BEGIN_THEME_OVERRIDES}}\n{{SETICONS_CALL}}\n{{END_THEME_OVERRIDES}}\n\n"
)

with open(GRUB_MKCONFIG_PATH, "w") as f:
    f.write(grub_mkconfig)

info(
    f"{{GRUB_MKCONFIG_PATH}} successfully patched, icons will now persist between grub updates."
)


# Lastly call the hook as mkconfig is currently running and should be loaded in memory.
# NOTE: Some bash interpreters seem to not load the entire script in memory
# so appending commands to the end of the script at runtime will indeed make
# mkconfig run them. That's what's happening is you see the
# 'grub.cfg icons patched' message twice
sh(SETICONS_CALL)