Add a load_status callback hook that is invoked at the end of chrome LoadApp.

src/trusted/service_runtime/sel_main_chrome.c

 /*
  * Copyright (c) 2012 The Native Client Authors. All rights reserved.
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "native_client/src/public/chrome_main.h"
 
 #include "native_client/src/include/build_config.h"
 #include "native_client/src/include/portability.h"
@@ skipping 89 matching lines @@
 #endif
 #if NACL_WINDOWS
   args->debug_stub_server_port_selected_handler_func = NULL;
 #endif
   args->create_memory_object_func = NULL;
   args->validation_cache = NULL;
 #if NACL_WINDOWS
   args->broker_duplicate_handle_func = NULL;
   args->attach_debug_exception_handler_func = NULL;
 #endif
+  args->load_status_handler_func = NULL;
 #if NACL_LINUX || NACL_OSX
   args->number_of_cores = -1;  /* unknown */
 #endif
 #if NACL_LINUX
   args->prereserved_sandbox_size = 0;
 #endif
   args->nexe_desc = NULL;
 
   args->argc = default_argc;
   args->argv = (char **) default_argv;
@@ skipping 244 matching lines @@
     if (!NaClDebugInit(nap)) {
       goto done;
     }
 #if NACL_WINDOWS
     if (NULL != args->debug_stub_server_port_selected_handler_func) {
       args->debug_stub_server_port_selected_handler_func(nap->debug_stub_port);
     }
 #endif
   }
 
+  if (args->load_status_handler_func != NULL) {
+    args->load_status_handler_func(LOAD_OK);
+  }
   return LOAD_OK;
 
 done:
   fflush(stdout);
 
   /*
+   * If there is a load status callback, call that now and transfer logs
+   * in preparation for process exit.
+   */
+  if (args->load_status_handler_func != NULL) {
+    /* Don't return LOAD_OK if we had some failure loading. */
+    if (LOAD_OK == errcode) {
+      errcode = LOAD_INTERNAL;
+    }
+    args->load_status_handler_func(errcode);
+    NaClLog(LOG_ERROR, "NaCl LoadApp failed. Transferring logs before exit.\n");
+    NaClLogRunAbortBehavior();
+    /*
+     * Fall through and run NaClBlockIfCommandChannelExists.
+     * TODO(jvoung): remove NaClBlockIfCommandChannelExists() and use the
+     * callback to indicate the load_status after Chromium no longer calls
+     * start_module. We also need to change Chromium so that it does not
+     * attempt to set up the command channel if there is a known load error.
+     * Otherwise there is a race between this process's exit / load error
+     * reporting, and the command channel setup on the Chromium side (plus
+     * the associated reporting). Thus this could end up with two different
+     * load errors being reported (1) the real load error from here, and
+     * (2) the command channel setup failure because the process exited in
+     * the middle of setting up the command channel.
+     */
+  }
+  /*
    * If there is a secure command channel, we sent an RPC reply with
    * the reason that the nexe was rejected.  If we exit now, that
    * reply may still be in-flight and the various channel closure (esp
    * reverse channel) may be detected first.  This would result in a
    * crash being reported, rather than the error in the RPC reply.
    * Instead, we wait for the hard-shutdown on the command channel.
    */
   if (LOAD_OK != errcode) {
     NaClBlockIfCommandChannelExists(nap);
   } else {
@@ skipping 48 matching lines @@
 int NaClChromeMainStart(struct NaClApp *nap,
                         struct NaClChromeMainArgs *args,
                         int *exit_status) {
   int load_ok = LOAD_OK == LoadApp(nap, args);
   if (load_ok) {
     *exit_status = StartApp(nap, args);
   }
   free(args);
   return load_ok;
 }