text: /*
   * Copyright (C) 2019 The Android Open Source Project
   *
   * 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.
   */
  
  //#define LOG_NDEBUG 0
  #define LOG_TAG "MediaTranscodingService"
  #include <MediaTranscodingService.h>
  #include <android/binder_manager.h>
  #include <android/binder_process.h>
  #include <private/android_filesystem_config.h>
  #include <utils/Log.h>
  #include <utils/Vector.h>
  
  namespace android {
  
  // Convenience methods for constructing binder::Status objects for error returns
  #define STATUS_ERROR_FMT(errorCode, errorString, ...) \
      Status::fromServiceSpecificErrorWithMessage(      \
              errorCode,                                \
              String8::format("%s:%d: " errorString, __FUNCTION__, __LINE__, ##__VA_ARGS__))
  
  // Can MediaTranscoding service trust the caller based on the calling UID?
  // TODO(hkuang): Add MediaProvider's UID.
  static bool isTrustedCallingUid(uid_t uid) {
      switch (uid) {
      case AID_ROOT:  // root user
      case AID_SYSTEM:
      case AID_SHELL:
      case AID_MEDIA:  // mediaserver
          return true;
      default:
          return false;
      }
  }
  
  MediaTranscodingService::MediaTranscodingService()
        : mTranscodingClientManager(TranscodingClientManager::getInstance()) {
      ALOGV("MediaTranscodingService is created");
  }
  
  MediaTranscodingService::~MediaTranscodingService() {
      ALOGE("Should not be in ~MediaTranscodingService");
  }
  
  binder_status_t MediaTranscodingService::dump(int fd, const char** /*args*/, uint32_t /*numArgs*/) {
      String8 result;
      const size_t SIZE = 256;
      char buffer[SIZE];
  
      snprintf(buffer, SIZE, "MediaTranscodingService: %p\n", this);
      result.append(buffer);
      write(fd, result.string(), result.size());
  
      Vector<String16> args;
      mTranscodingClientManager.dumpAllClients(fd, args);
      return OK;
  }
  
  //static
  void MediaTranscodingService::instantiate() {
      std::shared_ptr<MediaTranscodingService> service =
              ::ndk::SharedRefBase::make<MediaTranscodingService>();
      binder_status_t status =
              AServiceManager_addService(service->asBinder().get(), getServiceName());
      if (status != STATUS_OK) {
          return;
      }
  }
  
  Status MediaTranscodingService::registerClient(
          const std::shared_ptr<ITranscodingServiceClient>& in_client,
          const std::string& in_opPackageName, int32_t in_clientUid, int32_t in_clientPid,
          int32_t* _aidl_return) {
      if (in_client == nullptr) {
          ALOGE("Client can not be null");
          *_aidl_return = kInvalidJobId;
          return Status::fromServiceSpecificError(ERROR_ILLEGAL_ARGUMENT);
      }
  
      int32_t callingPid = AIBinder_getCallingPid();
      int32_t callingUid = AIBinder_getCallingUid();
  
      // Check if we can trust clientUid. Only privilege caller could forward the uid on app client's behalf.
      if (in_clientUid == USE_CALLING_UID) {
          in_clientUid = callingUid;
      } else if (!isTrustedCallingUid(callingUid)) {
          ALOGE("MediaTranscodingService::registerClient failed (calling PID %d, calling UID %d) "
                "rejected "
                "(don't trust clientUid %d)",
                in_clientPid, in_clientUid, in_clientUid);
          return STATUS_ERROR_FMT(ERROR_PERMISSION_DENIED,
                                  "Untrusted caller (calling PID %d, UID %d) trying to "
                                  "register client",
                                  in_clientPid, in_clientUid);
      }
  
      // Check if we can trust clientPid. Only privilege caller could forward the pid on app client's behalf.
      if (in_clientPid == USE_CALLING_PID) {
          in_clientPid = callingPid;
      } else if (!isTrustedCallingUid(callingUid)) {
          ALOGE("MediaTranscodingService::registerClient client failed (calling PID %d, calling UID "
                "%d) rejected "
                "(don't trust clientPid %d)",
                in_clientPid, in_clientUid, in_clientPid);
          return STATUS_ERROR_FMT(ERROR_PERMISSION_DENIED,
                                  "Untrusted caller (calling PID %d, UID %d) trying to "
                                  "register client",
                                  in_clientPid, in_clientUid);
      }
  
      // We know the clientId must be equal to its pid as we assigned client's pid as its clientId.
      int32_t clientId = in_clientPid;
  
      // Checks if the client already registers.
      if (mTranscodingClientManager.isClientIdRegistered(clientId)) {
          return Status::fromServiceSpecificError(ERROR_ALREADY_EXISTS);
      }
  
      // Creates the client and uses its process id as client id.
      std::unique_ptr<TranscodingClientManager::ClientInfo> newClient =
              std::make_unique<TranscodingClientManager::ClientInfo>(
                      in_client, clientId, in_clientPid, in_clientUid, in_opPackageName);
      status_t err = mTranscodingClientManager.addClient(std::move(newClient));
      if (err != OK) {
          *_aidl_return = kInvalidClientId;
          return STATUS_ERROR_FMT(err, "Failed to add client to TranscodingClientManager");
      }
  
      ALOGD("Assign client: %s pid: %d, uid: %d with id: %d", in_opPackageName.c_str(), in_clientPid,
            in_clientUid, clientId);
  
      *_aidl_return = clientId;
      return Status::ok();
  }
  
  Status MediaTranscodingService::unregisterClient(int32_t clientId, bool* _aidl_return) {
      ALOGD("unregisterClient id: %d", clientId);
      int32_t callingUid = AIBinder_getCallingUid();
      int32_t callingPid = AIBinder_getCallingPid();
  
      // Only the client with clientId or the trusted caller could unregister the client.
      if (callingPid != clientId) {
          if (!isTrustedCallingUid(callingUid)) {
              ALOGE("Untrusted caller (calling PID %d, UID %d) trying to "
                    "unregister client with id: %d",
                    callingUid, callingPid, clientId);
              *_aidl_return = true;
              return STATUS_ERROR_FMT(ERROR_PERMISSION_DENIED,
                                      "Untrusted caller (calling PID %d, UID %d) trying to "
                                      "unregister client with id: %d",
                                      callingUid, callingPid, clientId);
          }
      }
  
      *_aidl_return = (mTranscodingClientManager.removeClient(clientId) == OK);
      return Status::ok();
  }
  
  Status MediaTranscodingService::getNumOfClients(int32_t* _aidl_return) {
      ALOGD("MediaTranscodingService::getNumOfClients");
      *_aidl_return = mTranscodingClientManager.getNumOfClients();
      return Status::ok();
  }
  
  Status MediaTranscodingService::submitRequest(int32_t /*clientId*/,
                                                const TranscodingRequestParcel& /*request*/,
                                                TranscodingJobParcel* /*job*/,
                                                int32_t* /*_aidl_return*/) {
      // TODO(hkuang): Add implementation.
      return Status::ok();
  }
  
  Status MediaTranscodingService::cancelJob(int32_t /*in_clientId*/, int32_t /*in_jobId*/,
                                            bool* /*_aidl_return*/) {
      // TODO(hkuang): Add implementation.
      return Status::ok();
  }
  
  Status MediaTranscodingService::getJobWithId(int32_t /*in_jobId*/,
                                               TranscodingJobParcel* /*out_job*/,
                                               bool* /*_aidl_return*/) {
      // TODO(hkuang): Add implementation.
      return Status::ok();
  }
  
  }  // namespace android
  