Benchmark tools: Android memtrack_helper meaningful errors.

tools/android/memtrack_helper/memtrack_helper.c

 /*
  * Copyright 2015 The Chromium 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 "tools/android/memtrack_helper/memtrack_helper.h"
 
 #include <dlfcn.h>
 #include <errno.h>
@@ skipping 193 matching lines @@
     }
     break;
   }
 
   if (res)
     exit_with_failure("bind");
 
   if (argc > 1 && strcmp(argv[1], "-d") == 0)
     daemonize();
 
-  if(memtrack_init())
-    exit_with_failure("memtrack_init() returned non-zero");
+  res = memtrack_init();
+  if (res == -ENOENT) {
+    exit_with_failure("Unable to load memtrack module in libhardware. "
+                      "Probably implementation is missing in this ROM.");
+  } else if (res != 0) {
+    exit_with_failure("memtrack_init() returned non-zero status.");
+  }
 
   if (listen(server_fd, 128 /* max number of queued requests */))
     exit_with_failure("listen");
 
   for (;;) {
     struct sockaddr_un client_addr;
     socklen_t len = sizeof(client_addr);
     int client_sock = accept(server_fd, (struct sockaddr*)&client_addr, &len);
     handle_one_request(client_sock);
     close(client_sock);
   }
 
   return EXIT_SUCCESS;
 }