shell: pty: pack shell.output args in RFC 24 data event format

Problem: The shell.output plugin topic args (currently only used
in the job shell pty plugin) is mostly in RFC 24 data event format,
except that the rank is encoded as an integer instead of a string. This
means the plugin args have to be unpacked and repacked into a context
suitable for use with iodecode().

Pack shell.output args with a string rank so the object can be passed
directly to iodecode(). This will remove unnecessary decode and encode
plus memory allocation in the output plugin.

Author: grondo

src/shell/output.c

@@ -726,21 +726,13 @@ static int shell_output_handler (flux_plugin_t *p,
                                  void *arg)
 {
     struct shell_output *out = arg;
-    int rank;
-    const char *stream;
-    const void *data;
-    size_t len;
+    json_t *context;
 
-    if (flux_plugin_arg_unpack (args,
-                                FLUX_PLUGIN_ARG_IN,
-                                "{s:s s:i s:s%}",
-                                "stream", &stream,
-                                "rank", &rank,
-                                "data", &data, &len) < 0) {
+    if (flux_plugin_arg_unpack (args, FLUX_PLUGIN_ARG_IN, "o", &context) < 0) {
         shell_log_errno ("shell.output: flux_plugin_arg_unpack");
         return -1;
     }
-    return shell_output_write (out, rank, stream, data, len, len == 0);
+    return shell_output_write_type (out, "data", context);
 }
 
 static void shell_output_type_file_cleanup (struct shell_output_type_file *ofp)

src/shell/pty.c

@@ -69,7 +69,7 @@ shell_terminus_server_start (flux_shell_t *shell, const char *shell_service)
 static void pty_monitor (struct flux_pty *pty, void *data, int len)
 {
     flux_plugin_arg_t *args;
-    int rank;
+    const char *rank;
 
     /*  len == 0 indicates pty is closed. If there's a reference on
      *  stdout, release it here
@@ -81,10 +81,11 @@ static void pty_monitor (struct flux_pty *pty, void *data, int len)
         return;
     }
 
-    rank = ptr2int (flux_pty_aux_get (pty, "rank"));
+    rank = flux_pty_aux_get (pty, "rank");
     if (!(args = flux_plugin_arg_create ())
-        || flux_plugin_arg_pack (args, FLUX_PLUGIN_ARG_IN,
-                                 "{s:s s:i s:s#}",
+        || flux_plugin_arg_pack (args,
+                                 FLUX_PLUGIN_ARG_IN,
+                                 "{s:s s:s s:s#}",
                                  "stream", "stdout",
                                  "rank", rank,
                                  "data", data, len) < 0) {
@@ -371,12 +372,16 @@ static int pty_init (flux_plugin_t *p,
          *   ranks do not support interactive attach.
          */
         if (capture || rank != 0) {
-            if (flux_pty_aux_set (pty, "shell", shell, NULL) < 0
-                || flux_pty_aux_set (pty, "rank", int2ptr (rank), NULL) < 0
+            char *rankstr = NULL;
+
+            if (asprintf (&rankstr, "%d", rank) < 0
+                || flux_pty_aux_set (pty, "shell", shell, NULL) < 0
+                || flux_pty_aux_set (pty, "rank", rankstr, free) < 0
                 || flux_pty_aux_set (pty,
                                      "capture",
                                      int2ptr (capture),
                                      NULL) < 0) {
+                free (rankstr);
                 shell_log_errno ("flux_pty_aux_set");
                 goto error;
             }