Disallow running as root without --user-data-dir

This commit adds the --user-data-dir argument which allows a custom data dir
for Chromium's user data. This is useful when running as root on Linux since
the root user does not have read or write permissions for the ~/.config/Code
dir.

Part of #3068

resources/linux/bin/code.sh

@@ -3,6 +3,23 @@
 # Copyright (c) Microsoft Corporation. All rights reserved.
 # Licensed under the MIT License. See License.txt in the project root for license information.
 
+ARGS=$@
+
+# If root, ensure that --user-data-dir is specified
+if [ "$(id -u)" = "0" ]; then
+	while test $# -gt 0
+	do
+		if [[ $1 == --user-data-dir=* ]]; then
+			DATA_DIR_SET=1
+		fi
+		shift
+	done
+	if [ -z $DATA_DIR_SET ]; then
+		echo "It is recommended to start vscode as a normal user. To run as root, you must specify an alternate user data directory with the --user-data-dir argument." 1>&2
+		exit 1
+	fi
+fi
+
 if [ ! -L $0 ]; then
 	# if path is not a symlink, find relatively
 	VSCODE_PATH="$(dirname $0)/.."
@@ -15,7 +32,8 @@ else
 		VSCODE_PATH="/usr/share/@@NAME@@"
 	fi
 fi
+
 ELECTRON="$VSCODE_PATH/@@NAME@@"
 CLI="$VSCODE_PATH/resources/app/out/cli.js"
-ATOM_SHELL_INTERNAL_RUN_AS_NODE=1 "$ELECTRON" "$CLI" "$@"
+ATOM_SHELL_INTERNAL_RUN_AS_NODE=1 "$ELECTRON" "$CLI" $ARGS
 exit $?