grpc_channel_credentials *grpc_google_default_credentials_create(void) {
  grpc_channel_credentials *result = NULL;
  grpc_call_credentials *call_creds = NULL;

  GRPC_API_TRACE("grpc_google_default_credentials_create(void)", 0, ());

  gpr_once_init(&g_once, init_default_credentials);

  gpr_mu_lock(&g_mu);

  if (default_credentials != NULL) {
    result = grpc_channel_credentials_ref(default_credentials);
    goto end;
  }

  /* First, try the environment variable. */
  call_creds = create_default_creds_from_path(
      gpr_getenv(GRPC_GOOGLE_CREDENTIALS_ENV_VAR));
  if (call_creds != NULL) goto end;

  /* Then the well-known file. */
  call_creds = create_default_creds_from_path(
      grpc_get_well_known_google_credentials_file_path());
  if (call_creds != NULL) goto end;

  /* At last try to see if we're on compute engine (do the detection only once
     since it requires a network test). */
  if (!compute_engine_detection_done) {
    int need_compute_engine_creds = is_stack_running_on_compute_engine();
    compute_engine_detection_done = 1;
    if (need_compute_engine_creds) {
      call_creds = grpc_google_compute_engine_credentials_create(NULL);
    }
  }

end:
  if (result == NULL) {
    if (call_creds != NULL) {
      /* Blend with default ssl credentials and add a global reference so that
         it
         can be cached and re-served. */
      grpc_channel_credentials *ssl_creds =
          grpc_ssl_credentials_create(NULL, NULL, NULL);
      default_credentials = grpc_channel_credentials_ref(
          grpc_composite_channel_credentials_create(ssl_creds, call_creds,
                                                    NULL));
      GPR_ASSERT(default_credentials != NULL);
      grpc_channel_credentials_unref(ssl_creds);
      grpc_call_credentials_unref(call_creds);
      result = default_credentials;
    } else {
      gpr_log(GPR_ERROR, "Could not create google default credentials.");
    }
  }
  gpr_mu_unlock(&g_mu);
  return result;
}
grpc_credentials *grpc_google_default_credentials_create(void) {
  grpc_credentials *result = NULL;
  int serving_cached_credentials = 0;
  gpr_once_init(&g_once, init_default_credentials);

  gpr_mu_lock(&g_mu);

  if (default_credentials != NULL) {
    result = grpc_credentials_ref(default_credentials);
    serving_cached_credentials = 1;
    goto end;
  }

  /* First, try the environment variable. */
  result =
      create_jwt_creds_from_path(gpr_getenv(GRPC_GOOGLE_CREDENTIALS_ENV_VAR));
  if (result != NULL) goto end;

  /* Then the well-known file. */
  result = create_refresh_token_creds_from_path(
      grpc_get_well_known_google_credentials_file_path());
  if (result != NULL) goto end;

  /* At last try to see if we're on compute engine (do the detection only once
     since it requires a network test). */
  if (!compute_engine_detection_done) {
    int need_compute_engine_creds = is_stack_running_on_compute_engine();
    compute_engine_detection_done = 1;
    if (need_compute_engine_creds) {
      result = grpc_compute_engine_credentials_create();
    }
  }

end:
  if (!serving_cached_credentials && result != NULL) {
    /* Blend with default ssl credentials and add a global reference so that it
       can be cached and re-served. */
    result = grpc_composite_credentials_create(
        grpc_ssl_credentials_create(NULL, NULL), result);
    GPR_ASSERT(result != NULL);
    default_credentials = grpc_credentials_ref(result);
  }
  gpr_mu_unlock(&g_mu);
  return result;
}
grpc_channel_credentials *grpc_google_default_credentials_create(void) {
  grpc_channel_credentials *result = NULL;
  grpc_call_credentials *call_creds = NULL;
  grpc_error *error = GRPC_ERROR_CREATE("Failed to create Google credentials");
  grpc_error *err;
  grpc_exec_ctx exec_ctx = GRPC_EXEC_CTX_INIT;

  GRPC_API_TRACE("grpc_google_default_credentials_create(void)", 0, ());

  gpr_once_init(&g_once, init_default_credentials);

  gpr_mu_lock(&g_state_mu);

  if (default_credentials != NULL) {
    result = grpc_channel_credentials_ref(default_credentials);
    goto end;
  }

  /* First, try the environment variable. */
  err = create_default_creds_from_path(
      &exec_ctx, gpr_getenv(GRPC_GOOGLE_CREDENTIALS_ENV_VAR), &call_creds);
  if (err == GRPC_ERROR_NONE) goto end;
  error = grpc_error_add_child(error, err);

  /* Then the well-known file. */
  err = create_default_creds_from_path(
      &exec_ctx, grpc_get_well_known_google_credentials_file_path(),
      &call_creds);
  if (err == GRPC_ERROR_NONE) goto end;
  error = grpc_error_add_child(error, err);

  /* At last try to see if we're on compute engine (do the detection only once
     since it requires a network test). */
  if (!compute_engine_detection_done) {
    int need_compute_engine_creds =
        is_stack_running_on_compute_engine(&exec_ctx);
    compute_engine_detection_done = 1;
    if (need_compute_engine_creds) {
      call_creds = grpc_google_compute_engine_credentials_create(NULL);
      if (call_creds == NULL) {
        error = grpc_error_add_child(
            error, GRPC_ERROR_CREATE("Failed to get credentials from network"));
      }
    }
  }

end:
  if (result == NULL) {
    if (call_creds != NULL) {
      /* Blend with default ssl credentials and add a global reference so that
         it
         can be cached and re-served. */
      grpc_channel_credentials *ssl_creds =
          grpc_ssl_credentials_create(NULL, NULL, NULL);
      default_credentials = grpc_channel_credentials_ref(
          grpc_composite_channel_credentials_create(ssl_creds, call_creds,
                                                    NULL));
      GPR_ASSERT(default_credentials != NULL);
      grpc_channel_credentials_unref(&exec_ctx, ssl_creds);
      grpc_call_credentials_unref(&exec_ctx, call_creds);
      result = default_credentials;
    } else {
      gpr_log(GPR_ERROR, "Could not create google default credentials.");
    }
  }
  gpr_mu_unlock(&g_state_mu);
  if (result == NULL) {
    GRPC_LOG_IF_ERROR("grpc_google_default_credentials_create", error);
  } else {
    GRPC_ERROR_UNREF(error);
  }
  grpc_exec_ctx_finish(&exec_ctx);
  return result;
}