Add auto-update script

Signed-off-by: Knut Ahlers <knut@ahlers.me>

.gitignore

@@ -2,6 +2,7 @@
 !.gitignore
 !PKGBUILD
 !.SRCINFO
+!update_version.sh
 !vault.hcl
 !vault.install
 !vault.service

update_version.sh

@@ -0,0 +1,37 @@
+#!/bin/bash
+set -euxo pipefail
+
+# Read pkg name
+PKG=$(awk -F '=' '/pkgname=/{ print $2 }' PKGBUILD)
+
+# Get latest version
+VER=$(
+	curl -sSf "https://lv.luzifer.io/catalog-api/vault/latest.txt?p=version"
+)
+[[ -n $VER ]] || exit 1
+
+# Insert latest version into PKGBUILD
+sed -i \
+	-e "s/^pkgver=.*/pkgver=${VER}/" \
+	PKGBUILD
+
+# Check whether this changed anything
+if (git diff --exit-code PKGBUILD); then
+	echo "Package ${PKG} has most recent version ${VER}"
+	exit 0
+fi
+
+# Reset pkgrel
+sed -i \
+	-e 's/pkgrel=.*/pkgrel=1/' \
+	PKGBUILD
+
+# Update source hashes
+updpkgsums
+
+# Update .SRCINFO
+makepkg --printsrcinfo >.SRCINFO
+
+# Commit changes
+git add PKGBUILD .SRCINFO
+git commit -m "${PKG} v${VER}"