text: /*
   *
   * Copyright 2015 gRPC authors.
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *     http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   *
   */
  
  #include <stdio.h>
  #include <string.h>
  
  #include <grpc/grpc.h>
  #include <grpc/grpc_security.h>
  #include <grpc/slice.h>
  #include <grpc/support/alloc.h>
  #include <grpc/support/log.h>
  #include <grpc/support/sync.h>
  
  #include "src/core/lib/iomgr/load_file.h"
  #include "src/core/lib/security/credentials/credentials.h"
  #include "test/core/security/oauth2_utils.h"
  #include "test/core/util/cmdline.h"
  
  static grpc_call_credentials* create_refresh_token_creds(
      const char* json_refresh_token_file_path) {
    grpc_slice refresh_token;
    GPR_ASSERT(GRPC_LOG_IF_ERROR(
        "load_file",
        grpc_load_file(json_refresh_token_file_path, 1, &refresh_token)));
    return grpc_google_refresh_token_credentials_create(
        reinterpret_cast<const char*> GRPC_SLICE_START_PTR(refresh_token),
        nullptr);
  }
  
  int main(int argc, char** argv) {
    grpc_call_credentials* creds = nullptr;
    char* json_key_file_path = nullptr;
    const char* json_refresh_token_file_path = nullptr;
    char* token = nullptr;
    int use_gce = 0;
    char* scope = nullptr;
    gpr_cmdline* cl = gpr_cmdline_create("fetch_oauth2");
    gpr_cmdline_add_string(cl, "json_refresh_token",
                           "File path of the json refresh token.",
                           &json_refresh_token_file_path);
    gpr_cmdline_add_flag(
        cl, "gce",
        "Get a token from the GCE metadata server (only works in GCE).",
        &use_gce);
    gpr_cmdline_parse(cl, argc, argv);
  
    grpc_init();
  
    if (json_key_file_path != nullptr &&
        json_refresh_token_file_path != nullptr) {
      gpr_log(GPR_ERROR,
              "--json_key and --json_refresh_token are mutually exclusive.");
      exit(1);
    }
  
    if (use_gce) {
      if (json_key_file_path != nullptr || scope != nullptr) {
        gpr_log(GPR_INFO,
                "Ignoring json key and scope to get a token from the GCE "
                "metadata server.");
      }
      creds = grpc_google_compute_engine_credentials_create(nullptr);
      if (creds == nullptr) {
        gpr_log(GPR_ERROR, "Could not create gce credentials.");
        exit(1);
      }
    } else if (json_refresh_token_file_path != nullptr) {
      creds = create_refresh_token_creds(json_refresh_token_file_path);
      if (creds == nullptr) {
        gpr_log(GPR_ERROR,
                "Could not create refresh token creds. %s does probably not "
                "contain a valid json refresh token.",
                json_refresh_token_file_path);
        exit(1);
      }
    } else {
      gpr_log(GPR_ERROR, "Missing --gce or --json_refresh_token option.");
      exit(1);
    }
    GPR_ASSERT(creds != nullptr);
  
    token = grpc_test_fetch_oauth2_token_with_credentials(creds);
    if (token != nullptr) {
      printf("Got token: %s.\n", token);
      gpr_free(token);
    }
    grpc_call_credentials_release(creds);
    gpr_cmdline_destroy(cl);
    grpc_shutdown();
    return 0;
  }
  