mu-init: insist that --maildir is absolute

lib/mu-store.cc

@@ -89,8 +89,12 @@ struct Store::Private {
 	Config make_config(XapianDb& xapian_db, const std::string& root_maildir,
 			   Option<const Config&> conf) {
 
-		Config config{xapian_db};
+		if (!g_path_is_absolute(root_maildir.c_str()))
+			throw Error{Error::Code::File,
+					"root maildir path is not absolute ({})",
+					root_maildir};
 
+		Config config{xapian_db};
 		if (conf)
 			config.import_configurable(*conf);
 

lib/mu-store.hh

@@ -77,8 +77,8 @@ public:
 	 * Construct a store for a not-yet-existing document database
 	 *
 	 * @param path path to the database
-	 * @param root_maildir maildir to use for this store
-	 * @param config a configuration object
+	 * @param root_maildir absolute path to maildir to use for this store
+	 * @param conf a configuration object
 	 *
 	 * @return a store or an error
 	 */

man/mu-init.1.org

@@ -22,7 +22,8 @@ use =<maildir>= as the root-maildir.
 
 By default, *mu* uses the *MAILDIR* environment; if it is not set, it uses =~/Maildir=
 if it is an existing directory. If neither of those can be used, the ~--maildir~
-option is required.
+option is required; it must be an absolute path (but ~~/~ expansion is
+performed).
 
 ** --my-address=<email-address-or-regex>
 

mu/mu-cmd-init.cc

@@ -45,6 +45,9 @@ Mu::mu_cmd_init(const Options& opts)
 			return Err(Error::Code::InvalidArgument,
 				   "missing --maildir parameter and could "
 				   "not determine default");
+		else if (!g_path_is_absolute(opts.init.maildir.c_str()))
+			return Err(Error{Error::Code::File,
+					"--maildir is not absolute"});
 
 		MemDb mdb;
 		Config conf{mdb};