build/version.sh: Move version calculation here

Author: tavianator

Makefile

@@ -68,13 +68,7 @@ ${OBJS}: gen/config.mk
 # Save the version number to this file, but only update version.c if it changes
 gen/version.i.new::
 	@${MKDIR} ${@D}
-	@if [ "$$VERSION" ]; then \
-	    printf '%s' "$$VERSION"; \
-	elif test -e src/../.git && command -v git >/dev/null 2>&1; then \
-	    git -C src/.. describe --always --dirty; \
-	else \
-	    echo "4.0.1"; \
-	fi | tr -d '\n' | build/embed.sh >$@
+	@build/version.sh | tr -d '\n' | build/embed.sh >$@
 
 gen/version.i: gen/version.i.new
 	@test -e $@ && cmp -s $@ ${.ALLSRC} && ${RM} ${.ALLSRC} || mv ${.ALLSRC} $@

build/version.sh

@@ -0,0 +1,18 @@
+#!/bin/sh
+
+# Copyright © Tavian Barnes <tavianator@tavianator.com>
+# SPDX-License-Identifier: 0BSD
+
+# Print the version number
+
+set -eu
+
+DIR="$(dirname -- "$0")/.."
+
+if [ "${VERSION-}" ]; then
+    printf '%s' "$VERSION"
+elif [ -e "$DIR/.git" ] && command -v git >/dev/null 2>&1; then
+    git -C "$DIR" describe --always --dirty
+else
+    echo "4.0.1"
+fi