Makefile: install: add sanity checks

Prevent the user from installing to the wrong firefox dir, and give a
userfriendly message if install needs root rights.

Makefile

@@ -26,6 +26,7 @@ out/userContent.files: $(USERCONTENT_FILES) out
     done > $@
 
 install: all
+	src/prepare_install.sh "$(FIREFOX_DIR)" "$(DESTDIR)"
 	install -Dm644 src/policies.json \
 		"$(DESTDIR)/$(FIREFOX_CONFIG_DIR)/policies/policies.json"
 	install -Dm644 src/mobile-config-prefs.js \

src/prepare_install.sh

+#!/bin/sh
+FIREFOX_DIR="$1"
+DESTDIR="$2"
+
+if ! [ -d "$FIREFOX_DIR"/browser ]; then
+	if [ -d "$FIREFOX_DIR"-esr/browser ]; then
+		echo
+		echo "ERROR: Firefox ESR is installed, but FIREFOX_DIR points to"
+		echo "       regular Firefox."
+		echo
+		echo "Run this instead:"
+		echo "$ make"
+		echo "$ sudo make FIREFOX_DIR=$FIREFOX_DIR-esr install"
+		echo
+		exit 1
+	else
+		echo
+		echo "WARNING: FIREFOX_DIR does not exist: $FIREFOX_DIR"
+		echo "This should be fine during packaging. However if you just ran"
+		echo "'make install' manually, consider running 'make uninstall', then"
+		echo "adjusting FIREFOX_DIR (in the Makefile or via environment"
+		echo "variable) and running 'make install' again."
+		echo
+	fi
+fi
+
+if [ -z "$DESTDIR" ] && [ "$(id -u)" != 0 ]; then
+	echo
+	echo "ERROR: run make install as root!"
+	echo
+	echo "$ make"
+	echo "$ sudo make FIREFOX_DIR=$FIREFOX_DIR install"
+	echo
+	exit 1
+fi