From 24b0d7ec0075e5be6ebad0a2f603f9f42670d871 Mon Sep 17 00:00:00 2001
From: Florian Schmaus <flow@gentoo.org>
Date: Tue, 14 Mar 2023 11:02:59 +0100
Subject: [PATCH] Add 'update' action to kernel module

The 'update' action attempts to update the /usr/src/linux symlink to
point to the sources of the running kernel.

Signed-off-by: Florian Schmaus <flow@gentoo.org>
---
 modules/kernel.eselect | 64 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 64 insertions(+)

diff --git a/modules/kernel.eselect b/modules/kernel.eselect
index 64b5e773d68d..fbbf7a95d797 100644
--- a/modules/kernel.eselect
+++ b/modules/kernel.eselect
@@ -125,3 +125,67 @@ do_set() {
 
 	set_symlink "$1" || die -q "Couldn't set a new symlink"
 }
+
+### update action ###
+
+describe_update() {
+	echo "Update the kernel symlink to running kernel"
+}
+
+describe_update_options() {
+	echo "ifunset: Do not override currently set version"
+}
+
+do_update() {
+	[[ -z $1 || $1 == ifunset ]] || die -q "Usage error"
+	[[ $# -gt 1 ]] && die -q "Too many parameters"
+	test_for_root
+
+	if [[ -e ${EROOT}/usr/src/linux && ! -L ${EROOT}/usr/src/linux ]]; then
+		# we have something strange
+		die -q "${EROOT}/usr/src/linux exists but is not a symlink"
+	fi
+
+	if [[ $1 == ifunset \
+			  && -L ${EROOT}/usr/src/linux \
+			  && -e ${EROOT}/usr/src/linux ]]; then
+		# The /usr/src/linux symlink exists, points to a path that
+		# exists, and 'ifunset' is provided. Nothing to do.
+		return
+	fi
+
+	local targets=( $(find_targets) )
+	local running_kernel_release=$(uname --kernel-release)
+	local running_kernel_symlink_target="linux-${running_kernel_release}"
+
+	if [[ -L ${EROOT}/usr/src/linux ]]; then
+		local current_target
+		current_target=$(basename "$(canonicalise "${EROOT}/usr/src/linux")")
+		if [[ ${current_target} == ${running_kernel_symlink_target} ]]; then
+			# The /usr/src/linux symlink already points to the running
+			# kernel's sources. Nothing to do.
+			return
+		fi
+	fi
+
+	local target
+	local target_list=()
+	for target in ${targets[@]}; do
+		if [[ ${target} == ${current_kernel_symlink_target} ]]; then
+			set_symlink "${target}"
+			return
+		fi
+		target_list+=("- ${target}\n")
+	done
+
+	local msg
+	msg="No kernel sources for running kernel ${running_kernel_release} found."
+	msg+=" Available sources:\n${target_list[@]}"
+	die -q "${msg}"
+}
+
+### helper functions ###
+
+test_for_root() {
+	[[ -w ${EROOT}/usr/src ]] || die -q "${EROOT}/usr/src not writeable by current user. Are you root?"
+}
-- 
2.39.2