lib: add notmuch_threads_status()

While a number of errors can happen when iterating over threads
(DatabaseModifiedError, memory allocation errors, etc.), the API
currently cannot signal them to the caller, and either triggers an
internal error (aborting the caller) or returns NULL from
notmuch_threads_get() with no information on what actually went wrong.

Add a new public function notmuch_threads_status() - similar to
previously added notmuch_messages_status() - that allows propagating
those errors to the caller.

Use this to remove the INTERNAL_ERROR() in _notmuch_thread_create()
(triggered by T642).

Fixes: https://github.com/pazz/alot/issues/1460

Amended-By: db. Resolved whitespace disagreement between emacs and
uncrustify in favour of uncrustify.

1 files changed, 15 insertions, 9 deletions

diff --git a/lib/thread.cc b/lib/thread.cc
index 168a9e8b..75b0f188 100644
--- a/lib/thread.cc
+++ b/lib/thread.cc
@@ -544,16 +544,17 @@ _resolve_thread_relationships (notmuch_thread_t *thread)
  *
  * Here, 'ctx' is talloc context for the resulting thread object.
  *
- * This function returns NULL in the case of any error.
+ * This function write NULL in the case of any error.
  */
-notmuch_thread_t *
+notmuch_private_status_t
 _notmuch_thread_create (void *ctx,
 			notmuch_database_t *notmuch,
 			unsigned int seed_doc_id,
 			notmuch_doc_id_set_t *match_set,
 			notmuch_string_list_t *exclude_terms,
 			notmuch_exclude_t omit_excluded,
-			notmuch_sort_t sort)
+			notmuch_sort_t sort,
+			notmuch_thread_t **pthread)
 {
     void *local = talloc_new (ctx);
     notmuch_thread_t *thread = NULL;
@@ -564,11 +565,13 @@ _notmuch_thread_create (void *ctx,
 
     notmuch_messages_t *messages;
     notmuch_message_t *message;
-    notmuch_status_t status;
+    notmuch_private_status_t status;
 
-    seed_message = _notmuch_message_create (local, notmuch, seed_doc_id, NULL);
-    if (! seed_message)
-	INTERNAL_ERROR ("Thread seed message %u does not exist", seed_doc_id);
+    *pthread = NULL;
+
+    seed_message = _notmuch_message_create (local, notmuch, seed_doc_id, &status);
+    if (status)
+	return status;
 
     thread_id = notmuch_message_get_thread_id (seed_message);
     thread_id_query_string = talloc_asprintf (local, "thread:%s", thread_id);
@@ -623,7 +626,7 @@ _notmuch_thread_create (void *ctx,
      * oldest or newest subject is desired. */
     notmuch_query_set_sort (thread_id_query, NOTMUCH_SORT_OLDEST_FIRST);
 
-    status = notmuch_query_search_messages (thread_id_query, &messages);
+    status = (notmuch_private_status_t) notmuch_query_search_messages (thread_id_query, &messages);
     if (status)
 	goto DONE;
 
@@ -656,10 +659,13 @@ _notmuch_thread_create (void *ctx,
 
     /* Commit to returning thread. */
     (void) talloc_steal (ctx, thread);
+    *pthread = thread;
 
   DONE:
     talloc_free (local);
-    return thread;
+    if (! *pthread && ! status)
+	status = NOTMUCH_PRIVATE_STATUS_OUT_OF_MEMORY;
+    return status;
 }
 
 notmuch_messages_t *