/*
 * Copyright (C) 2016 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.
 */

package android.hidl.base@1.0;

/*
 * The ancestor for all interfaces.
 *
 * All HAL files will have this interface implicitly imported. If an interface
 * does not explicitly extend from another interface, it will implicitly extend
 * from IBase. (This is like java.lang.Object in Java.)
 *
 * Methods defined here are shared by all interfaces (this is like
 * java.lang.Object.notify(), for example.) However, the behavior of these
 * functions cannot be overridden (with the exception of the "debug" method).
 */
interface IBase {

    /*
     * Provides way to determine if interface is running without requesting
     * any functionality.
     */
    ping();

    /*
     * Provides run-time type information for this object.
     * For example, for the following interface definition:
     *     package android.hardware.foo@1.0;
     *     interface IParent {};
     *     interface IChild extends IParent {};
     * Calling interfaceChain on an IChild object must yield the following:
     *     ["android.hardware.foo@1.0::IChild",
     *      "android.hardware.foo@1.0::IParent"
     *      "android.hidl.base@1.0::IBase"]
     *
     * @return descriptors a vector of descriptors of the run-time type of the
     *         object.
     */
    interfaceChain() generates (vec<string> descriptors);

    /*
     * Provides run-time type information for this object.
     * For example, for the following interface definition:
     *     package android.hardware.foo@1.0;
     *     interface IParent {};
     *     interface IChild extends IParent {};
     * Calling interfaceDescriptor on an IChild object must yield
     *     "android.hardware.foo@1.0::IChild"
     *
     * @return descriptor a descriptor of the run-time type of the
     *         object (the first element of the vector returned by
     *         interfaceChain())
     */
    interfaceDescriptor() generates (string descriptor);

    /*
     * This method notifies the interface that one or more system properties
     * have changed. The default implementation calls
     * (C++)  report_sysprop_change() in libcutils or
     * (Java) android.os.SystemProperties.reportSyspropChanged,
     * which in turn calls a set of registered callbacks (eg to update trace
     * tags).
     */
    oneway notifySyspropsChanged();

    /*
     * Registers a death recipient, to be called when the process hosting this
     * interface dies.
     *
     * @param recipient a hidl_death_recipient callback object
     * @param cookie a cookie that must be returned with the callback
     * @return success whether the death recipient was registered successfully.
     */
    linkToDeath(death_recipient recipient, uint64_t cookie) generates (bool success);

    /*
     * Unregisters the registered death recipient. If this service was registered
     * multiple times with the same exact death recipient, this unlinks the most
     * recently registered one.
     *
     * @param recipient a previously registered hidl_death_recipient callback
     * @return success whether the death recipient was unregistered successfully.
     */
    unlinkToDeath(death_recipient recipient) generates (bool success);

    /*
     * This method trigger the interface to enable/disable instrumentation based
     * on system property hal.instrumentation.enable.
     */
    oneway setHALInstrumentation();

    /*
     * Get debug information on references on this interface.
     * @return info debugging information. See comments of DebugInfo.
     */
    getDebugInfo() generates (DebugInfo info);

    /*
     * Emit diagnostic information to the given file.
     *
     * Optionally overriden.
     *
     * @param fd      File descriptor to dump data to.
     *                Must only be used for the duration of this call.
     * @param options Arguments for debugging.
     *                Must support empty for default debug information.
     */
    debug(handle fd, vec<string> options);

    /*
     * Returns hashes of the source HAL files that define the interfaces of the
     * runtime type information on the object.
     * For example, for the following interface definition:
     *     package android.hardware.foo@1.0;
     *     interface IParent {};
     *     interface IChild extends IParent {};
     * Calling interfaceChain on an IChild object must yield the following:
     *     [(hash of IChild.hal),
     *      (hash of IParent.hal)
     *      (hash of IBase.hal)].
     *
     * SHA-256 is used as the hashing algorithm. Each hash has 32 bytes
     * according to SHA-256 standard.
     *
     * @return hashchain a vector of SHA-1 digests
     */
    getHashChain() generates (vec<uint8_t[32]> hashchain);
};