[taler-anastasis] branch master updated: allow external reducer binary to process actions

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dold pushed a commit to branch master
in repository anastasis.

The following commit(s) were added to refs/heads/master by this push:
     new a4b3524  allow external reducer binary to process actions
a4b3524 is described below

commit a4b3524111d176d7374db1340f0d996eecfadff1
Author: Florian Dold <florian@dold.me>
AuthorDate: Mon Oct 4 17:26:30 2021 +0200

    allow external reducer binary to process actions
---
 contrib/gana                      |   2 +-
 src/reducer/anastasis_api_redux.c | 120 ++++++++++++++++++++++++++++++++++++++
 2 files changed, 121 insertions(+), 1 deletion(-)

diff --git a/contrib/gana b/contrib/gana
index 3b63803..90aee6a 160000
--- a/contrib/gana
+++ b/contrib/gana
@@ -1 +1 @@
-Subproject commit 3b638032297cfed132912dfe82a1c47033eff03b
+Subproject commit 90aee6a0ba5c9e3e52074a2dabe1b3b9421ad165
diff --git a/src/reducer/anastasis_api_redux.c 
b/src/reducer/anastasis_api_redux.c
index 851be12..796e60d 100644
--- a/src/reducer/anastasis_api_redux.c
+++ b/src/reducer/anastasis_api_redux.c
@@ -1480,6 +1480,116 @@ typedef struct ANASTASIS_ReduxAction *
                    ANASTASIS_ActionCallback cb,
                    void *cb_cls);
 
+/**
+ * Dummy cleanup function.
+ */
+static void
+dummy_cleanup (void *cls)
+{
+  GNUNET_assert (0);
+}
+
+
+/**
+ * Handle an action using an external reducer, i.e.
+ * by shelling out to another process.
+ */
+static struct ANASTASIS_ReduxAction *
+redux_action_external (const char *ext_reducer,
+                       const json_t *state,
+                       const char *action,
+                       const json_t *arguments,
+                       ANASTASIS_ActionCallback cb,
+                       void *cb_cls)
+{
+  struct ANASTASIS_ReduxAction *act = NULL;
+  int pipefd_stdout[2];
+  int pipefd_stdin[2];
+  pid_t pid = 0;
+  int status;
+  FILE *reducer_stdout;
+  FILE *reducer_stdin;
+  json_t *next_state;
+
+  GNUNET_log (GNUNET_ERROR_TYPE_INFO,
+              "Using external reducer '%s'\n",
+              ext_reducer);
+
+  GNUNET_assert (0 == pipe (pipefd_stdout));
+  GNUNET_assert (0 == pipe (pipefd_stdin));
+  pid = fork ();
+  if (pid == 0)
+  {
+    /* Child */
+
+    char *arg_str = json_dumps (arguments, JSON_COMPACT);
+
+    close (pipefd_stdout[0]);
+    dup2 (pipefd_stdout[1], STDOUT_FILENO);
+
+    close (pipefd_stdin[1]);
+    dup2 (pipefd_stdin[0], STDIN_FILENO);
+
+    /* Unset environment variable, otherwise anastasis-reducer
+       would recursively shell out to itself. */
+    unsetenv ("ANASTASIS_EXTERNAL_REDUCER");
+
+    execlp (ext_reducer,
+            ext_reducer,
+            "-a",
+            arg_str,
+            action,
+            NULL);
+    GNUNET_assert (0);
+  }
+
+  /* Only parent reaches here */
+
+  close (pipefd_stdout[1]);
+  close (pipefd_stdin[0]);
+
+  reducer_stdout = fdopen (pipefd_stdout[0],
+                           "r");
+  reducer_stdin = fdopen (pipefd_stdin[1],
+                          "w");
+
+  GNUNET_assert (0 == json_dumpf (state,
+                                  reducer_stdin,
+                                  JSON_COMPACT));
+
+  GNUNET_assert (0 == fclose (reducer_stdin));
+  reducer_stdin = NULL;
+
+  GNUNET_log (GNUNET_ERROR_TYPE_INFO,
+              "Wrote old state to reducer stdin.\n");
+
+  next_state = json_loadf (reducer_stdout,
+                           0,
+                           NULL);
+
+  /* FIXME: report error instead! */
+  GNUNET_assert (NULL != next_state);
+
+  GNUNET_log (GNUNET_ERROR_TYPE_INFO,
+              "Waiting for external reducer to terminate.\n");
+  GNUNET_assert (0 == fclose (reducer_stdout));
+  reducer_stdout = NULL;
+  waitpid (pid, &status, 0);
+
+  GNUNET_log (GNUNET_ERROR_TYPE_INFO,
+              "External reducer finished with exit status '%d'\n",
+              status);
+
+  act = GNUNET_new (struct ANASTASIS_ReduxAction);
+  /* Callback is called immediately, cleanup must never be called */
+  act->cleanup = &dummy_cleanup;
+
+  cb (cb_cls,
+      TALER_EC_NONE,
+      next_state);
+  return act;
+}
+
 
 struct ANASTASIS_ReduxAction *
 ANASTASIS_redux_action (const json_t *state,
@@ -1540,6 +1650,16 @@ ANASTASIS_redux_action (const json_t *state,
   const char *s = json_string_value (json_object_get (state,
                                                       "backup_state"));
   enum ANASTASIS_GenericState gs;
+  const char *ext_reducer = getenv ("ANASTASIS_EXTERNAL_REDUCER");
+
+  /* If requested, handle action with external reducer, used for testing. */
+  if (NULL != ext_reducer)
+    return redux_action_external (ext_reducer,
+                                  state,
+                                  action,
+                                  arguments,
+                                  cb,
+                                  cb_cls);
 
   if (NULL == s)
   {

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