Use hardlinks, bind mount and systemd-tmpfiles to simplify the logic

.SRCINFO

@@ -3,20 +3,17 @@ pkgbase = kernel-modules-hook
 	pkgver = 0.1.7
 	pkgrel = 1
 	url = https://github.com/saber-nyan/kernel-modules-hook
-	install = kernel-modules-hook.install
 	arch = any
-	license = UNLICENSE
-	depends = rsync
+	license = Unlicense
 	source = linux-modules-cleanup.conf
-	source = linux-modules-cleanup.service
 	source = 10-linux-modules-post.hook
 	source = 10-linux-modules-pre.hook
-	source = UNLICENSE
-	sha256sums = 4169b44c297ddb7aad2220c6eba7c7942e3396f92528c59617955ab5560cb4cf
-	sha256sums = 5d947290ef8c94b33c79c531e5615f4c9bea38e7649092d34af3bf0af5b1ca24
-	sha256sums = 900502d030e925fca6188b9448fbaf6562d6e23cd5c50938cdf00522825f76c2
-	sha256sums = f7ea2947c3fbe1510b3ea5cc5793b8197f0718dcb12daea3da9b27b3cf1c4116
-	sha256sums = 7e12e5df4bae12cb21581ba157ced20e1986a0508dd10d0e8a4ab9a4cf94e85c
+	source = linux-modules-restore
+	source = linux-modules-save
+	sha256sums = 950f851eba08dac4d0b93ff62b3fb16ddacd4f8ebb98a2435f80bf05f2ea5a29
+	sha256sums = fc4d53dec520c80fe97dfda65b238c7d678e7ef26aaebffc5b43f924477ea4f4
+	sha256sums = 087e5ed70b2fc512d814fbded9e873955b1da5b6bf1e31975174d704ad143156
+	sha256sums = 7cf080b0d0d5a07ccb414ffb793525e554ca95447201f22b917f0be04ff48d2a
+	sha256sums = 3168ea6c2740dbde4229d718e44f6262f2d10aef529fb446cdb4f1778b8b6424
 
 pkgname = kernel-modules-hook
-

.gitignore

@@ -1,20 +1 @@
-# ignore everything
-*
-!.gitignore
-
-# except PKGBUILD needed files
-!PKGBUILD
-!.SRCINFO
-!*.install
-
-# common wing-man files
-!*.diff
-!*.patch
-
-# add files that don't have an online source
-kernel-modules-hook.install
-linux-modules-cleanup.conf
-linux-modules-cleanup.service
-10-linux-modules-post.hook
-10-linux-modules-pre.hook
-UNLICENSE
+*pkg.tar*

10-linux-modules-post.hook

@@ -1,12 +1,10 @@
 [Trigger]
-Operation = Install
-Operation = Upgrade
+Operation = Remove
 Type = Path
 Target = usr/lib/modules/*/vmlinuz
 
 [Action]
 Description = Restoring Linux kernel modules...
 When = PostTransaction
-Depends = coreutils
-Depends = rsync
-Exec = /bin/sh -xc 'KVER="${KVER:-$(uname -r)}"; if test -e "/usr/lib/modules/backup/${KVER}"; then rsync -AHXal --ignore-existing "/usr/lib/modules/backup/${KVER}" /usr/lib/modules/; fi; rm -rf /usr/lib/modules/backup'
+Exec = /usr/share/libalpm/scripts/linux-modules-restore
+NeedsTargets

10-linux-modules-pre.hook

@@ -1,11 +1,11 @@
 [Trigger]
 Operation = Install
-Operation = Upgrade
+Operation = Remove
 Type = Path
 Target = usr/lib/modules/*/vmlinuz
 
 [Action]
-Description = Saving Linux kernel modules...
+Description = Saving Linux kernel modules directory (hardlinks)...
 When = PreTransaction
-Depends = rsync
-Exec = /bin/sh -c 'KVER="${KVER:-$(uname -r)}"; if test -e "/usr/lib/modules/${KVER}"; then rsync -AHXal --delete-after "/usr/lib/modules/${KVER}" /usr/lib/modules/backup/; fi'
+Exec = /usr/share/libalpm/scripts/linux-modules-save
+NeedsTargets

PKGBUILD

@@ -1,29 +1,26 @@
 # Maintainer: Artoria Pendragon <[email protected]>
 # Hooks: https://www.reddit.com/r/archlinux/comments/4zrsc3/keep_your_system_fully_functional_after_a_kernel/d6yin0r/
 pkgname=kernel-modules-hook
-pkgver=0.1.7
+pkgver=0.2.0
 pkgrel=1
 pkgdesc="Keeps your system fully functional after a kernel upgrade"
 arch=('any')
 url="https://github.com/saber-nyan/kernel-modules-hook"
-license=('UNLICENSE')
-depends=('rsync')
-install="${pkgname}.install"
+license=('Unlicense')
 source=("linux-modules-cleanup.conf"
-		"linux-modules-cleanup.service"
-		"10-linux-modules-post.hook"
-		"10-linux-modules-pre.hook"
-		"UNLICENSE")
-sha256sums=('4169b44c297ddb7aad2220c6eba7c7942e3396f92528c59617955ab5560cb4cf'
-            '5d947290ef8c94b33c79c531e5615f4c9bea38e7649092d34af3bf0af5b1ca24'
-            '900502d030e925fca6188b9448fbaf6562d6e23cd5c50938cdf00522825f76c2'
-            'f7ea2947c3fbe1510b3ea5cc5793b8197f0718dcb12daea3da9b27b3cf1c4116'
-            '7e12e5df4bae12cb21581ba157ced20e1986a0508dd10d0e8a4ab9a4cf94e85c')
+        "10-linux-modules-post.hook"
+        "10-linux-modules-pre.hook"
+        "linux-modules-restore"
+        "linux-modules-save"
+)
+sha256sums=('950f851eba08dac4d0b93ff62b3fb16ddacd4f8ebb98a2435f80bf05f2ea5a29'
+            'fc4d53dec520c80fe97dfda65b238c7d678e7ef26aaebffc5b43f924477ea4f4'
+            '087e5ed70b2fc512d814fbded9e873955b1da5b6bf1e31975174d704ad143156'
+            '7cf080b0d0d5a07ccb414ffb793525e554ca95447201f22b917f0be04ff48d2a'
+            '3168ea6c2740dbde4229d718e44f6262f2d10aef529fb446cdb4f1778b8b6424')
 
 package() {
 	install -Dm644 'linux-modules-cleanup.conf' "${pkgdir}/usr/lib/tmpfiles.d/linux-modules-cleanup.conf"
-	install -Dm644 'linux-modules-cleanup.service' "${pkgdir}/usr/lib/systemd/system/linux-modules-cleanup.service"
-	install -Dm644 '10-linux-modules-post.hook' "${pkgdir}/usr/share/libalpm/hooks/10-linux-modules-post.hook"
-	install -Dm644 '10-linux-modules-pre.hook' "${pkgdir}/usr/share/libalpm/hooks/10-linux-modules-pre.hook"
-	install -Dm644 'UNLICENSE' "${pkgdir}/usr/share/licenses/${pkgname}/UNLICENSE"
+	install -Dm644 10-linux-modules-{pre,post}.hook -t "${pkgdir}/usr/share/libalpm/hooks/"
+	install -Dm755 linux-modules-{save,restore} -t "${pkgdir}/usr/share/libalpm/scripts/"
 }

linux-modules-cleanup.conf

@@ -1 +1,2 @@
-R! /usr/lib/modules/.old/* - - - 4w
+R! /usr/lib/modules/running-kernel
+r /usr/lib/modules/*

linux-modules-restore

@@ -0,0 +1,11 @@
+#!/bin/bash -e
+
+kver = $(uname -r)
+while read -r line; do
+    # We only care about the running kernel
+    if [[ "$line" == usr/lib/modules/$kver/vmlinuz && -d "${line/$kver/running-kernel}" ]];then
+        mount --mkdir --bind --options ro /usr/lib/modules/{running-kernel,$kver}
+        # Mounting read-only since the only modification here should be unmounting
+        # when rebooting or reinstalling the running kernel
+    fi
+done

linux-modules-save

@@ -0,0 +1,24 @@
+#!/bin/bash -e
+
+kver = $(uname -r)
+while read -r line; do
+    # We only care about the running kernel
+    if [[ "$line" == "usr/lib/modules/$kver/vmlinuz" ]];then
+        if [[ mountpoint --nofollow --quiet ${line%vmlinuz} ]];then
+            # Mount point is already present
+            # This means we already ran that hook during 'remove case'
+            #
+            # Remove the mount so we can reinstall the kernel
+            umount ${line%vmlinuz}
+        elif [[ -f "$line" && ! -d "/usr/lib/modules/running-kernel/" ]];then
+            # Kernel install is present and we do not have a copy
+            #
+            # This is the removal case, so we save the kernel
+            mkdir /usr/lib/modules/running-kernel
+            cp --archive --link /usr/lib/modules/{$kver}/{kernel,modules*} \
+                /usr/lib/modules/running-kernel/
+        fi
+        # If we are re-removing the running kernel, (after removing + reinstalling),
+        # we already have a backup and this hook is a no-op
+    fi
+done