lib/open: load default values for known configuration keys.

This emulates the behaviour of notmuch_config_open defined in the CLI,
in that it fills in default values if they are not otherwise defined.

lib/config.cc

@@ -31,6 +31,8 @@ struct _notmuch_config_list {
     char *current_val;
 };
 
+static const char * _notmuch_config_key_to_string (notmuch_config_key_t key);
+
 static int
 _notmuch_config_list_destroy (notmuch_config_list_t *list)
 {
@@ -280,7 +282,7 @@ _notmuch_config_load_from_file (notmuch_database_t *notmuch,
     return status;
 }
 
-const char *
+static const char *
 _notmuch_config_key_to_string (notmuch_config_key_t key) {
     switch (key) {
     case NOTMUCH_CONFIG_DATABASE_PATH:
@@ -302,6 +304,52 @@ _notmuch_config_key_to_string (notmuch_config_key_t key) {
     }
 }
 
+static const char *
+_notmuch_config_default (void *ctx, notmuch_config_key_t key) {
+    char *path;
+
+    switch (key) {
+    case NOTMUCH_CONFIG_DATABASE_PATH:
+	path = getenv ("MAILDIR");
+	if (path)
+	    path = talloc_strdup (ctx, path);
+	else
+	    path = talloc_asprintf (ctx, "%s/mail",
+				    getenv ("HOME"));
+	return path;
+    case NOTMUCH_CONFIG_EXCLUDE_TAGS:
+	return "";
+    case NOTMUCH_CONFIG_NEW_TAGS:
+	return "inbox;unread";
+    case NOTMUCH_CONFIG_SYNC_MAILDIR_FLAGS:
+	return "true";
+    case NOTMUCH_CONFIG_USER_NAME:
+    case NOTMUCH_CONFIG_PRIMARY_EMAIL:
+    case NOTMUCH_CONFIG_OTHER_EMAIL:
+	return NULL;
+    default:
+    case NOTMUCH_CONFIG_LAST:
+	INTERNAL_ERROR ("illegal key enum %d", key);
+   }
+}
+
+notmuch_status_t
+_notmuch_config_load_defaults (notmuch_database_t *notmuch) {
+    notmuch_config_key_t key;
+    for (key = NOTMUCH_CONFIG_FIRST;
+	 key < NOTMUCH_CONFIG_LAST;
+	 key = notmuch_config_key_t(key + 1)) {
+	const char *val = notmuch_config_get (notmuch, key);
+	const char *key_string = _notmuch_config_key_to_string (key);
+
+	val = _notmuch_string_map_get (notmuch->config, key_string);
+	if (! val) {
+	    _notmuch_string_map_set (notmuch->config, key_string, _notmuch_config_default (notmuch, key));
+	}
+    }
+    return NOTMUCH_STATUS_SUCCESS;
+}
+
 const char *
 notmuch_config_get (notmuch_database_t *notmuch, notmuch_config_key_t key) {
 

lib/notmuch-private.h

@@ -710,6 +710,9 @@ _notmuch_config_load_from_database (notmuch_database_t * db);
 
 notmuch_status_t
 _notmuch_config_load_from_file (notmuch_database_t * db, GKeyFile *file);
+
+notmuch_status_t
+_notmuch_config_load_defaults (notmuch_database_t * db);
 NOTMUCH_END_DECLS
 
 #ifdef __cplusplus

lib/open.cc

@@ -289,6 +289,10 @@ notmuch_database_open_with_config (const char *database_path,
 	if (status)
 	    goto DONE;
 
+	status = _notmuch_config_load_defaults (notmuch);
+	if (status)
+	    goto DONE;
+
 	status = _notmuch_database_setup_standard_query_fields (notmuch);
 	if (status)
 	    goto DONE;

test/T590-libconfig.sh

@@ -239,6 +239,33 @@ EOF
 test_expect_equal_file EXPECTED OUTPUT
 restore_database
 
+test_begin_subtest "load default values"
+export MAILDIR=${MAIL_DIR}
+cat c_head - c_tail <<'EOF' | test_C ${MAIL_DIR} '' %NULL%
+{
+    notmuch_config_key_t key;
+    for (key = NOTMUCH_CONFIG_FIRST;
+	 key < NOTMUCH_CONFIG_LAST;
+	 key = (notmuch_config_key_t)(key + 1)) {
+	const char *val = notmuch_config_get (db, key);
+        printf("%s\n", val ? val : "NULL" );
+    }
+}
+EOF
+cat <<'EOF' >EXPECTED
+== stdout ==
+MAIL_DIR
+
+inbox;unread
+true
+NULL
+NULL
+NULL
+== stderr ==
+EOF
+unset MAILDIR
+test_expect_equal_file EXPECTED OUTPUT
+
 backup_database
 test_begin_subtest "override config from \${NOTMUCH_CONFIG}"
 notmuch config set test.key1 overridden