diff mbox series

[1/1] scripts/package/builddeb: allow hooks also in /usr/share/kernel

Message ID 20241128062940.1708257-2-josch@mister-muffin.de (mailing list archive)
State New
Headers show
Series scripts/package/builddeb: allow hooks also in /usr/share/kernel | expand

Commit Message

Johannes Schauer Marin Rodrigues Nov. 28, 2024, 6:29 a.m. UTC
By passing an additional directory to run-parts, allow Debian and its
derivatives an easy way to ship maintainer scripts in /usr while at the
same time allowing the local admin to easily override or disable them by
placing hooks of the same name in /etc. This adds support for the
mechanism described in the UAPI Configuration Files Specification for
kernel hooks:
https://uapi-group.org/specifications/specs/configuration_files_specification/

This functionality relies on run-parts 5.21 or later.  It is the
responsibility of packages installing hooks into /usr/share/kernel to
also declare a Depends: debianutils (>= 5.21).

KDEB_HOOKDIR can be used to change the list of directories that is
searched. By default, /etc/kernel and /usr/share/kernel are hook
directories.

Signed-off-by: Johannes Schauer Marin Rodrigues <josch@mister-muffin.de>
---
 scripts/package/builddeb | 44 ++++++++++++++++++++++++++++++++--------
 1 file changed, 36 insertions(+), 8 deletions(-)
diff mbox series

Patch

diff --git a/scripts/package/builddeb b/scripts/package/builddeb
index 441b0bb66e0d..2772146a76ce 100755
--- a/scripts/package/builddeb
+++ b/scripts/package/builddeb
@@ -5,10 +5,12 @@ 
 #
 # Simple script to generate a deb package for a Linux kernel. All the
 # complexity of what to do with a kernel after it is installed or removed
-# is left to other scripts and packages: they can install scripts in the
-# /etc/kernel/{pre,post}{inst,rm}.d/ directories (or an alternative location
-# specified in KDEB_HOOKDIR) that will be called on package install and
-# removal.
+# is left to other scripts and packages. Scripts can be placed into the
+# preinst, postinst, prerm and postrm directories in /etc/kernel or
+# /usr/share/kernel. A different list of search directories can be given
+# via KDEB_HOOKDIR. Scripts in directories earlier in the list will
+# override scripts of the same name in later directories.  The script will
+# be called on package installation and removal.
 
 set -eu
 
@@ -68,11 +70,18 @@  install_linux_image () {
 	# kernel packages, as well as kernel packages built using make-kpkg.
 	# make-kpkg sets $INITRD to indicate whether an initramfs is wanted, and
 	# so do we; recent versions of dracut and initramfs-tools will obey this.
-	debhookdir=${KDEB_HOOKDIR:-/etc/kernel}
+	debhookdir=${KDEB_HOOKDIR:-/etc/kernel /usr/share/kernel}
+
+	# Only pre-create the first hook directory. Support for more than one hook
+	# directory requires run-parts 5.21 and it is the responsibility of packages
+	# creating additional hook directories to declare that dependency.
+	firsthookdir=${debhookdir%% *}
 	for script in postinst postrm preinst prerm; do
-		mkdir -p "${pdir}${debhookdir}/${script}.d"
+		mkdir -p "${pdir}${firsthookdir}/${script}.d"
+	done
 
-		mkdir -p "${pdir}/DEBIAN"
+	mkdir -p "${pdir}/DEBIAN"
+	for script in postinst postrm preinst prerm; do
 		cat <<-EOF > "${pdir}/DEBIAN/${script}"
 		#!/bin/sh
 
@@ -84,7 +93,26 @@  install_linux_image () {
 		# Tell initramfs builder whether it's wanted
 		export INITRD=$(if_enabled_echo CONFIG_BLK_DEV_INITRD Yes No)
 
-		test -d ${debhookdir}/${script}.d && run-parts --arg="${KERNELRELEASE}" --arg="/${installed_image_path}" ${debhookdir}/${script}.d
+		# run-parts will error out if one of its directory arguments does not
+		# exist, so filter the list of hook directories accordingly.
+		hookdirs=
+		for dir in ${debhookdir}; do
+			test -d "\$dir/${script}.d" || continue
+			hookdirs="\$hookdirs \$dir/${script}.d"
+		done
+		hookdirs="\${hookdirs# }"
+		test -n "\$hookdirs" || exit 0
+
+		# If more than one hook directory remained, check version of run-parts. If
+		# run-parts is too old, fall back to only processing the first.
+		case \$hookdirs in *" "*) if ! run-parts --help 2>&1 \
+				| grep -Fxq "Usage: run-parts [OPTION]... DIRECTORY [DIRECTORY ...]"; then
+				echo "E: run-parts >=5.21 is required for multiple hook directories, falling back to $firsthookdir" >&2
+				test -d "${firsthookdir}/${script}.d" || exit 0
+				hookdirs="${firsthookdir}/${script}.d"
+			fi
+		esac
+		run-parts --arg="${KERNELRELEASE}" --arg="/${installed_image_path}" \$hookdirs
 		exit 0
 		EOF
 		chmod 755 "${pdir}/DEBIAN/${script}"