build_library: Fix depmod issues with sysext kmods

OS-dependent sysexts that ship kernel modules, usually also ship the
files in /usr/lib/modules/*-flatcar/modules.XXX When multiple such
sysexts get activated, depmod files from just one sysext win and other
kernel modules cannot be loaded using modprobe. We get around this by
removing the depmod files from every sysext with kernel modules.
Instead, we set up modprobe hook, which dynamically runs depmod in a
temporary directory on every sysext kernel module activation.

Signed-off-by: Daniel Zatovic <daniel.zatovic@gmail.com>

build_library/sysext_mangle_flatcar-nvidia-drivers-535

@@ -0,0 +1,14 @@
+#!/bin/bash
+
+set -euo pipefail
+
+SCRIPT_NAME=$(basename "$(realpath "${BASH_SOURCE[0]}")")
+SYSEXT_NAME=${SCRIPT_NAME#sysext_mangle_}
+SYSEXT_NAME=${SYSEXT_NAME%.sh}
+DIR=$(dirname "$(realpath "${BASH_SOURCE[0]}")")
+. "$DIR/sysext_mangle_kmod"
+
+rootfs="${1}"
+
+cd "${rootfs}"
+configure_modprobe "$SYSEXT_NAME"

build_library/sysext_mangle_flatcar-nvidia-drivers-535-open

@@ -0,0 +1 @@
+sysext_mangle_flatcar-nvidia-drivers-535

build_library/sysext_mangle_flatcar-nvidia-drivers-550

@@ -0,0 +1 @@
+sysext_mangle_flatcar-nvidia-drivers-535

build_library/sysext_mangle_flatcar-nvidia-drivers-550-open

@@ -0,0 +1 @@
+sysext_mangle_flatcar-nvidia-drivers-535

build_library/sysext_mangle_flatcar-nvidia-drivers-570

@@ -0,0 +1 @@
+sysext_mangle_flatcar-nvidia-drivers-535

build_library/sysext_mangle_flatcar-nvidia-drivers-570-open

@@ -0,0 +1 @@
+sysext_mangle_flatcar-nvidia-drivers-535

build_library/sysext_mangle_flatcar-zfs

@@ -3,6 +3,9 @@
 set -euo pipefail
 rootfs="${1}"
 
+DIR="$(dirname "$(realpath "${BASH_SOURCE[0]}")")"
+. "$DIR/sysext_mangle_kmod"
+
 pushd "${rootfs}"
 
 rm -rf ./usr/{lib/debug/,lib64/cmake/,include/}
@@ -40,4 +43,5 @@ cat <<EOF >./usr/lib/systemd/system/systemd-udevd.service.d/10-zfs.conf
 [Unit]
 After=systemd-sysext.service
 EOF
+configure_modprobe flatcar-zfs
 popd

build_library/sysext_mangle_kmod

@@ -0,0 +1,48 @@
+#!/bin/bash
+
+configure_modprobe() {
+  local sysext_name="${1}"
+  shift
+
+  local module_directories=(./usr/lib/modules/*-flatcar/)
+
+  mkdir -p ./usr/lib/modprobe.d/
+  for module_name in $(find "${module_directories[@]}" -type f \( -name "*.ko" -o -name "*.ko.*" \) -printf "%f\n" | sed -E 's/\.ko(\.\w+)?$//'); do
+    cat <<EOF >> "./usr/lib/modprobe.d/10-${sysext_name}-kmod-sysext.conf"
+install $module_name     /usr/local/bin/_${sysext_name}_modprobe_helper $module_name
+remove  $module_name     /usr/local/bin/_${sysext_name}_modprobe_helper -r $module_name
+EOF
+  done
+
+  mkdir -p ./usr/local/bin/
+  install -m0755 -D /dev/stdin "./usr/local/bin/_${sysext_name}_modprobe_helper" <<'EOF'
+#!/bin/bash
+
+set -euo pipefail
+
+action="Loading"
+for arg in "$@"; do
+    if [[ $arg == "-r" ]]; then
+        action="Unloading"
+    fi
+done
+echo "$action kernel module from a sysext..."
+
+KMOD_PATH=/usr/lib/modules/$(uname -r)
+TMP_DIR=$(mktemp -d)
+trap "rm -rf -- '${TMP_DIR}'" EXIT
+mkdir "${TMP_DIR}"/{upper,work}
+
+unshare -m bash -s -- "${@}" <<FOE
+set -euo pipefail
+if ! mountpoint -q "${KMOD_PATH}"; then
+    mount -t overlay overlay -o lowerdir="${KMOD_PATH}",upperdir="${TMP_DIR}"/upper,workdir="${TMP_DIR}"/work "${KMOD_PATH}"
+    depmod
+fi
+modprobe --ignore-install "\${@}"
+FOE
+EOF
+
+  # prevent the sysext from masking /usr/lib/modules/*-flatcar/modules.XXX
+  find "${module_directories[@]}" -maxdepth 1 -mindepth 1 -type f -delete
+}