lib: add notmuch_message_has_maildir_flag_st

Initially the new function is mainly tested indirectly via the
wrapper.

lib/message.cc

@@ -1717,7 +1717,7 @@ _filename_is_in_maildir (const char *filename)
     return NULL;
 }
 
-static void
+static notmuch_status_t
 _ensure_maildir_flags (notmuch_message_t *message, bool force)
 {
     const char *flags;
@@ -1732,9 +1732,10 @@ _ensure_maildir_flags (notmuch_message_t *message, bool force)
 	    message->maildir_flags = NULL;
 	}
     }
-    /* n_m_get_filenames returns NULL for errors, which terminates the
-     * loop */
-    for (filenames = notmuch_message_get_filenames (message);
+    filenames = notmuch_message_get_filenames (message);
+    if (! filenames)
+	return NOTMUCH_STATUS_XAPIAN_EXCEPTION;
+    for (;
 	 notmuch_filenames_valid (filenames);
 	 notmuch_filenames_move_to_next (filenames)) {
 	filename = notmuch_filenames_get (filenames);
@@ -1760,13 +1761,37 @@ _ensure_maildir_flags (notmuch_message_t *message, bool force)
     }
     if (seen_maildir_info)
 	message->maildir_flags = combined_flags;
+    return NOTMUCH_STATUS_SUCCESS;
 }
 
 notmuch_bool_t
 notmuch_message_has_maildir_flag (notmuch_message_t *message, char flag)
 {
-    _ensure_maildir_flags (message, false);
-    return message->maildir_flags && (strchr (message->maildir_flags, flag) != NULL);
+    notmuch_status_t status;
+    notmuch_bool_t ret;
+    status = notmuch_message_has_maildir_flag_st (message, flag, &ret);
+    if (status)
+	return FALSE;
+
+    return ret;
+}
+
+notmuch_status_t
+notmuch_message_has_maildir_flag_st (notmuch_message_t *message,
+				     char flag,
+				     notmuch_bool_t *is_set)
+{
+    notmuch_status_t status;
+    
+    if (! is_set)
+	return NOTMUCH_STATUS_NULL_POINTER;
+
+    status = _ensure_maildir_flags (message, false);
+    if (status)
+	return status;
+    
+    *is_set =  message->maildir_flags && (strchr (message->maildir_flags, flag) != NULL);
+    return NOTMUCH_STATUS_SUCCESS;
 }
 
 notmuch_status_t
@@ -1775,7 +1800,9 @@ notmuch_message_maildir_flags_to_tags (notmuch_message_t *message)
     notmuch_status_t status;
     unsigned i;
 
-    _ensure_maildir_flags (message, true);
+    status = _ensure_maildir_flags (message, true);
+    if (status)
+	return status;
     /* If none of the filenames have any maildir info field (not even
      * an empty info with no flags set) then there's no information to
      * go on, so do nothing. */

lib/notmuch.h

@@ -1680,10 +1680,32 @@ notmuch_message_maildir_flags_to_tags (notmuch_message_t *message);
  * return TRUE if any filename of 'message' has maildir flag 'flag',
  * FALSE otherwise.
  *
+ * Deprecated wrapper for notmuch_message_has_maildir_flag_st
+ *
+ * @returns FALSE in case of error
+ * @deprecated libnotmuch 5.3 (notmuch 0.31)
  */
+NOTMUCH_DEPRECATED(5, 3)
 notmuch_bool_t
 notmuch_message_has_maildir_flag (notmuch_message_t *message, char flag);
 
+/**
+ * check message for maildir flag
+ *
+ * @param [in,out]	message message to check
+ * @param [in] flag	flag to check for
+ * @param [out] is_set  pointer to boolean
+ *
+ * @retval #NOTMUCH_STATUS_SUCCESS
+ * @retval #NOTMUCH_STATUS_NULL_POINTER is_set is NULL
+ * @retval #NOTMUCH_STATUS_XAPIAN_EXCEPTION Accessing the database
+ * triggered an exception.
+ */
+notmuch_status_t
+notmuch_message_has_maildir_flag_st (notmuch_message_t *message,
+				     char flag,
+				     notmuch_bool_t *is_set);
+
 /**
  * Rename message filename(s) to encode tags as maildir flags.
  *

test/T560-lib-error.sh

@@ -549,4 +549,21 @@ cat <<EOF > EXPECTED
 EOF
 test_expect_equal_file EXPECTED OUTPUT
 
+test_begin_subtest "Handle checking maildir flag with closed db (new API)"
+cat c_head2 - c_tail <<'EOF' | test_C ${MAIL_DIR}
+    {
+        notmuch_status_t status;
+        notmuch_bool_t out;
+        status = notmuch_message_has_maildir_flag_st (message, 'S', &out);
+        printf("%d\n%d\n", message != NULL,  status == NOTMUCH_STATUS_XAPIAN_EXCEPTION);
+    }
+EOF
+cat <<EOF > EXPECTED
+== stdout ==
+1
+1
+== stderr ==
+EOF
+test_expect_equal_file EXPECTED OUTPUT
+
 test_done