From b9eb737f279128c62aefe6d76ece41996367a376 Mon Sep 17 00:00:00 2001
From: Julien Falque <julien.falque@gmail.com>
Date: Thu, 25 Aug 2022 20:24:58 +0200
Subject: [PATCH] Improve pacman hook

The hook now reacts on updated files instead of updated packages, like
the `mkinitcpio` hook does.

This allows it to be triggered each time a kernel image is updated:
 - when a kernel package is updated (e.g. `linux`);
 - when a dependency is updated (e.g. `systemd`).

This also allows to only rebuild the kernel images that were actually
updated instead of always rebuilding all. The main script now accepts
kernel names as arguments for that.

Files have been renamed to be more consistent with the AUR package.
---
 README.md                               |  8 +++----
 build_kernel.sh => build_efi_kernels.sh | 29 +++++++++++++++++++------
 hook/efi-kernel-update.hook             | 12 ++++++++++
 hook/efi-kernel-update.sh               | 17 +++++++++++++++
 install.sh                              |  4 ++--
 kernel-update.hook                      | 11 ----------
 6 files changed, 57 insertions(+), 24 deletions(-)
 rename build_kernel.sh => build_efi_kernels.sh (64%)
 create mode 100644 hook/efi-kernel-update.hook
 create mode 100755 hook/efi-kernel-update.sh
 delete mode 100644 kernel-update.hook

diff --git a/README.md b/README.md
index c82d57e..6bc04f0 100644
--- a/README.md
+++ b/README.md
@@ -32,12 +32,12 @@ If your EFI partition is mounted as /boot and your kernels are installed there,
 sudo install.sh
 ```
 
-If not, please edit build_kernel.sh and install it manually. You can do it by running
+If not, please edit build_efi_kernel.sh and install it manually. You can do it by running
 
 ```
-cp build_kernel.sh to /opt
-mkdir -p /etc/pacman.d/hooks/
-cp kernel-update.hook /etc/pacman.d/hooks
+cp build_efi_kernel.sh to /opt
+mkdir -p /etc/pacman.d/hooks
+cp hook/* /etc/pacman.d/hooks/
 ```
 
 ## EFI boot entries
diff --git a/build_kernel.sh b/build_efi_kernels.sh
similarity index 64%
rename from build_kernel.sh
rename to build_efi_kernels.sh
index 26af513..5084202 100755
--- a/build_kernel.sh
+++ b/build_efi_kernels.sh
@@ -1,15 +1,30 @@
-#!/bin/bash
+#!/bin/bash -e
 
 TARGET=/boot
 BOOTDIR=/boot
 UCODE=$BOOTDIR/intel-ucode.img
 EFISTUB=/usr/lib/systemd/boot/efi/linuxx64.efi.stub
 
-echo "Updating EFI kernels..."
+if [[ $# -gt 0 ]]; then
+	KERNEL_IMAGES=()
+	for KERNEL in "$@"; do
+		KERNEL_IMAGE="${BOOTDIR}/vmlinuz-${KERNEL}"
 
-for k in $BOOTDIR/vmlinuz*; do
+		if [ ! -f "${KERNEL_IMAGE}" ]; then
+			echo "Kernel \"${KERNEL}\" not available."
+
+			exit 1;
+		fi
+
+		KERNEL_IMAGES+=("${KERNEL_IMAGE}")
+	done
+else
+	KERNEL_IMAGES=($BOOTDIR/vmlinuz*)
+fi
+
+for k in "${KERNEL_IMAGES[@]}"; do
 	NAME=$(basename $k|sed 's/vmlinuz-//')
-	echo "  Building $NAME"
+	echo "Updating EFI kernel $NAME..."
 	INITRD="$BOOTDIR/initramfs-$NAME.img"
 
 	if [ -f "$UCODE" ]; then
@@ -17,18 +32,18 @@ for k in $BOOTDIR/vmlinuz*; do
 		INITRDFILE=/tmp/initrd.bin
 	else
 		# Do not fail on AMD systems
-		echo "    Intel microcode not found. Skipping."
+		echo "  Intel microcode not found. Skipping."
 		INITRDFILE="$INITRD"
 	fi
 
 	# Check for custom command line for the kernel.
 	CMDLINE="$BOOTDIR/cmdline-$NAME.txt"
 	if [ -f "$CMDLINE" ]; then
-		echo "    Using custom command line $CMDLINE"
+		echo "  Using custom command line $CMDLINE"
 	else
 		CMDLINE="$BOOTDIR/cmdline.txt"
 		if [ ! -f "$CMDLINE" ]; then
-			echo "CMDLINE missing. Extracting from running kernel..."
+			echo "  CMDLINE missing. Extracting from running kernel..."
 			cat /proc/cmdline |sed 's/BOOT_IMAGE=[^ ]* \?//' > "$CMDLINE"
 		fi
 	fi
diff --git a/hook/efi-kernel-update.hook b/hook/efi-kernel-update.hook
new file mode 100644
index 0000000..600d120
--- /dev/null
+++ b/hook/efi-kernel-update.hook
@@ -0,0 +1,12 @@
+[Trigger]
+Type = Path
+Operation = Install
+Operation = Upgrade
+Target = usr/lib/modules/*/vmlinuz
+Target = usr/lib/initcpio/*
+
+[Action]
+Description = Updating EFI kernel images
+When = PostTransaction
+Exec = /etc/pacman.d/hooks/efi-kernel-update.sh
+NeedsTargets
diff --git a/hook/efi-kernel-update.sh b/hook/efi-kernel-update.sh
new file mode 100755
index 0000000..e7a80c7
--- /dev/null
+++ b/hook/efi-kernel-update.sh
@@ -0,0 +1,17 @@
+#!/bin/bash -e
+
+while read -r updated_file; do
+	if [[ $updated_file == usr/lib/initcpio/* ]]; then
+		# all kernels images have been updated
+		build_efi_kernels
+
+		break
+	fi
+
+	pkgbase_file="${updated_file%/vmlinuz}/pkgbase"
+	if ! read -r kernel > /dev/null 2>&1 < "${pkgbase_file}"; then
+		continue
+	fi
+
+	build_efi_kernels "${kernel}"
+done
diff --git a/install.sh b/install.sh
index 558e9cd..24e79ce 100755
--- a/install.sh
+++ b/install.sh
@@ -10,9 +10,9 @@ if [ "$(id -u)" -ne 0 ]; then
 	exit 1
 fi
 
-cp build_kernel.sh /opt/
+cp build_efi_kernels.sh /opt/
 mkdir -p /etc/pacman.d/hooks
-cp kernel-update.hook /etc/pacman.d/hooks/
+cp hooks/* /etc/pacman.d/hooks/
 
 echo "Install completed. Building kernels..."
 
diff --git a/kernel-update.hook b/kernel-update.hook
deleted file mode 100644
index 6eadebf..0000000
--- a/kernel-update.hook
+++ /dev/null
@@ -1,11 +0,0 @@
-[Trigger]
-Type = Package
-Operation = Upgrade
-Operation = Install
-Target = linux*
-Target = intel-ucode
-
-[Action]
-Description = Updating EFI kernel images
-When = PostTransaction
-Exec = /bin/bash /opt/build_kernel.sh