1/*
2 * Copyright (C) 2016 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17package [email protected];
18
19/*
20 * The ancestor for all interfaces.
21 *
22 * All HAL files will have this interface implicitly imported. If an interface
23 * does not explicitly extend from another interface, it will implicitly extend
24 * from IBase. (This is like java.lang.Object in Java.)
25 *
26 * Methods defined here are shared by all interfaces (this is like
27 * java.lang.Object.notify(), for example.) However, the behavior of these
28 * functions cannot be overridden (with the exception of the "debug" method).
29 */
30interface IBase {
31
32    /*
33     * Provides way to determine if interface is running without requesting
34     * any functionality.
35     */
36    ping();
37
38    /*
39     * Provides run-time type information for this object.
40     * For example, for the following interface definition:
41     *     package [email protected];
42     *     interface IParent {};
43     *     interface IChild extends IParent {};
44     * Calling interfaceChain on an IChild object must yield the following:
45     *     ["[email protected]::IChild",
46     *      "[email protected]::IParent"
47     *      "[email protected]::IBase"]
48     *
49     * @return descriptors a vector of descriptors of the run-time type of the
50     *         object.
51     */
52    interfaceChain() generates (vec<string> descriptors);
53
54    /*
55     * Provides run-time type information for this object.
56     * For example, for the following interface definition:
57     *     package [email protected];
58     *     interface IParent {};
59     *     interface IChild extends IParent {};
60     * Calling interfaceDescriptor on an IChild object must yield
61     *     "[email protected]::IChild"
62     *
63     * @return descriptor a descriptor of the run-time type of the
64     *         object (the first element of the vector returned by
65     *         interfaceChain())
66     */
67    interfaceDescriptor() generates (string descriptor);
68
69    /*
70     * This method notifies the interface that one or more system properties
71     * have changed. The default implementation calls
72     * (C++)  report_sysprop_change() in libcutils or
73     * (Java) android.os.SystemProperties.reportSyspropChanged,
74     * which in turn calls a set of registered callbacks (eg to update trace
75     * tags).
76     */
77    oneway notifySyspropsChanged();
78
79    /*
80     * Registers a death recipient, to be called when the process hosting this
81     * interface dies.
82     *
83     * @param recipient a hidl_death_recipient callback object
84     * @param cookie a cookie that must be returned with the callback
85     * @return success whether the death recipient was registered successfully.
86     */
87    linkToDeath(death_recipient recipient, uint64_t cookie) generates (bool success);
88
89    /*
90     * Unregisters the registered death recipient. If this service was registered
91     * multiple times with the same exact death recipient, this unlinks the most
92     * recently registered one.
93     *
94     * @param recipient a previously registered hidl_death_recipient callback
95     * @return success whether the death recipient was unregistered successfully.
96     */
97    unlinkToDeath(death_recipient recipient) generates (bool success);
98
99    /*
100     * This method trigger the interface to enable/disable instrumentation based
101     * on system property hal.instrumentation.enable.
102     */
103    oneway setHALInstrumentation();
104
105    /*
106     * Get debug information on references on this interface.
107     * @return info debugging information. See comments of DebugInfo.
108     */
109    getDebugInfo() generates (DebugInfo info);
110
111    /*
112     * Emit diagnostic information to the given file.
113     *
114     * Optionally overriden.
115     *
116     * @param fd      File descriptor to dump data to.
117     *                Must only be used for the duration of this call.
118     * @param options Arguments for debugging.
119     *                Must support empty for default debug information.
120     */
121    debug(handle fd, vec<string> options);
122
123    /*
124     * Returns hashes of the source HAL files that define the interfaces of the
125     * runtime type information on the object.
126     * For example, for the following interface definition:
127     *     package [email protected];
128     *     interface IParent {};
129     *     interface IChild extends IParent {};
130     * Calling interfaceChain on an IChild object must yield the following:
131     *     [(hash of IChild.hal),
132     *      (hash of IParent.hal)
133     *      (hash of IBase.hal)].
134     *
135     * SHA-256 is used as the hashing algorithm. Each hash has 32 bytes
136     * according to SHA-256 standard.
137     *
138     * @return hashchain a vector of SHA-1 digests
139     */
140    getHashChain() generates (vec<uint8_t[32]> hashchain);
141};
142