From 61ea83cbc019db5c000baf4debf873be59528e63 Mon Sep 17 00:00:00 2001
From: Florian Dold <florian@dold.me>
Date: Mon, 4 Oct 2021 18:08:34 +0200
Subject: report reducer error instead of crashing

---
 src/reducer/anastasis_api_redux.c | 61 +++++++++++++++++++++++++++++++++++----
 1 file changed, 55 insertions(+), 6 deletions(-)

diff --git a/src/reducer/anastasis_api_redux.c b/src/reducer/anastasis_api_redux.c
index 796e60d..92801f4 100644
--- a/src/reducer/anastasis_api_redux.c
+++ b/src/reducer/anastasis_api_redux.c
@@ -1490,6 +1490,31 @@ dummy_cleanup (void *cls)
 }
 
 
+/**
+ * Closure for external_redux_done.
+ */
+struct ExternalReduxCls
+{
+  ANASTASIS_ActionCallback cb;
+  void *cb_cls;
+  json_t *new_state;
+};
+
+
+/**
+ * Callback called when the redux action has been processed by
+ * the external reducer.
+ */
+static void
+external_redux_done (void *cls)
+{
+  struct ExternalReduxCls *erc = cls;
+  erc->cb (erc->cb_cls,
+           TALER_EC_NONE,
+           erc->new_state);
+}
+
+
 /**
  * Handle an action using an external reducer, i.e.
  * by shelling out to another process.
@@ -1563,9 +1588,26 @@ redux_action_external (const char *ext_reducer,
   GNUNET_log (GNUNET_ERROR_TYPE_INFO,
               "Wrote old state to reducer stdin.\n");
 
-  next_state = json_loadf (reducer_stdout,
-                           0,
-                           NULL);
+  {
+    json_error_t err;
+
+    next_state = json_loadf (reducer_stdout,
+                             0,
+                             &err);
+
+    if (NULL == next_state)
+    {
+      GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
+                  "External reducer did not output valid JSON: %s:%d:%d %s\n",
+                  err.source,
+                  err.line,
+                  err.column,
+                  err.text);
+      GNUNET_assert (0 == fclose (reducer_stdout));
+      waitpid (pid, &status, 0);
+      return NULL;
+    }
+  }
 
   /* FIXME: report error instead! */
   GNUNET_assert (NULL != next_state);
@@ -1584,9 +1626,16 @@ redux_action_external (const char *ext_reducer,
   /* Callback is called immediately, cleanup must never be called */
   act->cleanup = &dummy_cleanup;
 
-  cb (cb_cls,
-      TALER_EC_NONE,
-      next_state);
+  {
+    struct ExternalReduxCls *sched_cls = GNUNET_new (struct ExternalReduxCls);
+
+    sched_cls->cb = cb;
+    sched_cls->cb_cls = cb_cls;
+    sched_cls->new_state = next_state;
+    GNUNET_SCHEDULER_add_now (external_redux_done,
+                              sched_cls);
+  }
+
   return act;
 }
 
-- 
cgit v1.2.3