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 "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/string_util.h>
  #include <grpc/support/sync.h>
  
  #include "src/core/lib/iomgr/exec_ctx.h"
  #include "src/core/lib/promise/exec_ctx_wakeup_scheduler.h"
  #include "src/core/lib/promise/map.h"
  #include "src/core/lib/resource_quota/resource_quota.h"
  #include "src/core/lib/security/context/security_context.h"
  #include "src/core/lib/security/credentials/credentials.h"
  
  static auto* g_memory_allocator = new grpc_core::MemoryAllocator(
      grpc_core::ResourceQuota::Default()->memory_quota()->CreateMemoryAllocator(
          "test"));
  
  char* grpc_test_fetch_oauth2_token_with_credentials(
      grpc_call_credentials* creds) {
    grpc_core::ExecCtx exec_ctx;
    grpc_call_credentials::GetRequestMetadataArgs get_request_metadata_args;
  
    grpc_pollset* pollset =
        static_cast<grpc_pollset*>(gpr_zalloc(grpc_pollset_size()));
    gpr_mu* mu = nullptr;
    grpc_pollset_init(pollset, &mu);
    auto pops = grpc_polling_entity_create_from_pollset(pollset);
    bool is_done = false;
  
    auto arena = grpc_core::MakeScopedArena(1024, g_memory_allocator);
    grpc_metadata_batch initial_metadata{arena.get()};
    char* token = nullptr;
  
    auto activity = grpc_core::MakeActivity(
        [creds, &initial_metadata, &get_request_metadata_args]() {
          return grpc_core::Map(
              creds->GetRequestMetadata(
                  grpc_core::ClientMetadataHandle::TestOnlyWrap(
                      &initial_metadata),
                  &get_request_metadata_args),
              [](const absl::StatusOr<grpc_core::ClientMetadataHandle>& s) {
                return s.status();
              });
        },
        grpc_core::ExecCtxWakeupScheduler(),
        [&is_done, &token, &initial_metadata](absl::Status result) {
          is_done = true;
          if (!result.ok()) {
            gpr_log(GPR_ERROR, "Fetching token failed: %s",
                    result.ToString().c_str());
          } else {
            std::string buffer;
            token = gpr_strdup(
                std::string(
                    initial_metadata
                        .GetStringValue(GRPC_AUTHORIZATION_METADATA_KEY, &buffer)
                        .value_or(""))
                    .c_str());
          }
        },
        arena.get(), &pops);
  
    grpc_core::ExecCtx::Get()->Flush();
  
    gpr_mu_lock(mu);
    while (!is_done) {
      grpc_pollset_worker* worker = nullptr;
      if (!GRPC_LOG_IF_ERROR(
              "pollset_work",
              grpc_pollset_work(grpc_polling_entity_pollset(&pops), &worker,
                                grpc_core::Timestamp::InfFuture()))) {
        is_done = true;
      }
    }
    gpr_mu_unlock(mu);
  
    grpc_pollset_shutdown(
        grpc_polling_entity_pollset(&pops),
        GRPC_CLOSURE_CREATE([](void*, grpc_error_handle) {}, nullptr, nullptr));
    grpc_core::ExecCtx::Get()->Flush();
    grpc_pollset_destroy(grpc_polling_entity_pollset(&pops));
    gpr_free(pollset);
  
    return token;
  }
  