text: /*
   *
   * Copyright 2015, Google Inc.
   * All rights reserved.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions are
   * met:
   *
   *     * Redistributions of source code must retain the above copyright
   * notice, this list of conditions and the following disclaimer.
   *     * Redistributions in binary form must reproduce the above
   * copyright notice, this list of conditions and the following disclaimer
   * in the documentation and/or other materials provided with the
   * distribution.
   *     * Neither the name of Google Inc. nor the names of its
   * contributors may be used to endorse or promote products derived from
   * this software without specific prior written permission.
   *
   * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
   * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
   * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
   * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
   * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
   * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
   * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
   * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
   * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
   * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
   * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   *
   */
  
  #include "test/core/security/oauth2_utils.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/security/credentials/credentials.h"
  
  typedef struct {
    gpr_mu *mu;
    grpc_polling_entity pops;
    int is_done;
    char *token;
  } oauth2_request;
  
  static void on_oauth2_response(grpc_exec_ctx *exec_ctx, void *user_data,
                                 grpc_credentials_md *md_elems, size_t num_md,
                                 grpc_credentials_status status,
                                 const char *error_details) {
    oauth2_request *request = user_data;
    char *token = NULL;
    grpc_slice token_slice;
    if (status == GRPC_CREDENTIALS_ERROR) {
      gpr_log(GPR_ERROR, "Fetching token failed.");
    } else {
      GPR_ASSERT(num_md == 1);
      token_slice = md_elems[0].value;
      token = gpr_malloc(GRPC_SLICE_LENGTH(token_slice) + 1);
      memcpy(token, GRPC_SLICE_START_PTR(token_slice),
             GRPC_SLICE_LENGTH(token_slice));
      token[GRPC_SLICE_LENGTH(token_slice)] = '\0';
    }
    gpr_mu_lock(request->mu);
    request->is_done = 1;
    request->token = token;
    GRPC_LOG_IF_ERROR(
        "pollset_kick",
        grpc_pollset_kick(grpc_polling_entity_pollset(&request->pops), NULL));
    gpr_mu_unlock(request->mu);
  }
  
  static void do_nothing(grpc_exec_ctx *exec_ctx, void *unused,
                         grpc_error *error) {}
  
  char *grpc_test_fetch_oauth2_token_with_credentials(
      grpc_call_credentials *creds) {
    oauth2_request request;
    grpc_exec_ctx exec_ctx = GRPC_EXEC_CTX_INIT;
    grpc_closure do_nothing_closure;
    grpc_auth_metadata_context null_ctx = {"", "", NULL, NULL};
  
    grpc_pollset *pollset = gpr_malloc(grpc_pollset_size());
    grpc_pollset_init(pollset, &request.mu);
    request.pops = grpc_polling_entity_create_from_pollset(pollset);
    request.is_done = 0;
  
    grpc_closure_init(&do_nothing_closure, do_nothing, NULL);
  
    grpc_call_credentials_get_request_metadata(
        &exec_ctx, creds, &request.pops, null_ctx, on_oauth2_response, &request);
  
    grpc_exec_ctx_finish(&exec_ctx);
  
    gpr_mu_lock(request.mu);
    while (!request.is_done) {
      grpc_pollset_worker *worker = NULL;
      if (!GRPC_LOG_IF_ERROR(
              "pollset_work",
              grpc_pollset_work(&exec_ctx,
                                grpc_polling_entity_pollset(&request.pops),
                                &worker, gpr_now(GPR_CLOCK_MONOTONIC),
                                gpr_inf_future(GPR_CLOCK_MONOTONIC)))) {
        request.is_done = 1;
      }
    }
    gpr_mu_unlock(request.mu);
  
    grpc_pollset_shutdown(&exec_ctx, grpc_polling_entity_pollset(&request.pops),
                          &do_nothing_closure);
    grpc_exec_ctx_finish(&exec_ctx);
    gpr_free(grpc_polling_entity_pollset(&request.pops));
    return request.token;
  }
  