Binder.cpp revision 23eb1e20cf59e1238b65cc108f31dfbfd85b2337 
1/*
2 * Copyright (C) 2005 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
17#include <binder/Binder.h>
18
19#include <atomic>
20#include <utils/misc.h>
21#include <binder/BpBinder.h>
22#include <binder/IInterface.h>
23#include <binder/IResultReceiver.h>
24#include <binder/Parcel.h>
25
26#include <stdio.h>
27
28namespace android {
29
30// ---------------------------------------------------------------------------
31
32IBinder::IBinder()
33    : RefBase()
34{
35}
36
37IBinder::~IBinder()
38{
39}
40
41// ---------------------------------------------------------------------------
42
43sp<IInterface>  IBinder::queryLocalInterface(const String16& /*descriptor*/)
44{
45    return NULL;
46}
47
48BBinder* IBinder::localBinder()
49{
50    return NULL;
51}
52
53BpBinder* IBinder::remoteBinder()
54{
55    return NULL;
56}
57
58bool IBinder::checkSubclass(const void* /*subclassID*/) const
59{
60    return false;
61}
62
63
64status_t IBinder::shellCommand(int /*in*/, int out, int /*err*/, Vector<String16>& /*args*/,
65    const sp<IResultReceiver>& resultReceiver)
66{
67    if (out >= 0) {
68        dprintf(out, "Shell commands not supported.\n");
69    }
70    if (resultReceiver != NULL) {
71        resultReceiver->send(INVALID_OPERATION);
72    }
73    return NO_ERROR;
74}
75
76// ---------------------------------------------------------------------------
77
78class BBinder::Extras
79{
80public:
81    Mutex mLock;
82    BpBinder::ObjectManager mObjects;
83};
84
85// ---------------------------------------------------------------------------
86
87BBinder::BBinder() : mExtras(nullptr)
88{
89}
90
91bool BBinder::isBinderAlive() const
92{
93    return true;
94}
95
96status_t BBinder::pingBinder()
97{
98    return NO_ERROR;
99}
100
101const String16& BBinder::getInterfaceDescriptor() const
102{
103    // This is a local static rather than a global static,
104    // to avoid static initializer ordering issues.
105    static String16 sEmptyDescriptor;
106    ALOGW("reached BBinder::getInterfaceDescriptor (this=%p)", this);
107    return sEmptyDescriptor;
108}
109
110status_t BBinder::transact(
111    uint32_t code, const Parcel& data, Parcel* reply, uint32_t flags)
112{
113    data.setDataPosition(0);
114
115    status_t err = NO_ERROR;
116    switch (code) {
117        case PING_TRANSACTION:
118            reply->writeInt32(pingBinder());
119            break;
120        default:
121            err = onTransact(code, data, reply, flags);
122            break;
123    }
124
125    if (reply != NULL) {
126        reply->setDataPosition(0);
127    }
128
129    return err;
130}
131
132status_t BBinder::linkToDeath(
133    const sp<DeathRecipient>& /*recipient*/, void* /*cookie*/,
134    uint32_t /*flags*/)
135{
136    return INVALID_OPERATION;
137}
138
139status_t BBinder::unlinkToDeath(
140    const wp<DeathRecipient>& /*recipient*/, void* /*cookie*/,
141    uint32_t /*flags*/, wp<DeathRecipient>* /*outRecipient*/)
142{
143    return INVALID_OPERATION;
144}
145
146status_t BBinder::dump(int /*fd*/, const Vector<String16>& /*args*/)
147{
148    return NO_ERROR;
149}
150
151void BBinder::attachObject(
152    const void* objectID, void* object, void* cleanupCookie,
153    object_cleanup_func func)
154{
155    Extras* e = mExtras.load(std::memory_order_acquire);
156
157    if (!e) {
158        e = new Extras;
159        Extras* expected = nullptr;
160        if (!mExtras.compare_exchange_strong(expected, e,
161                                             std::memory_order_release,
162                                             std::memory_order_acquire)) {
163            delete e;
164            e = expected;  // Filled in by CAS
165        }
166        if (e == 0) return; // out of memory
167    }
168
169    AutoMutex _l(e->mLock);
170    e->mObjects.attach(objectID, object, cleanupCookie, func);
171}
172
173void* BBinder::findObject(const void* objectID) const
174{
175    Extras* e = mExtras.load(std::memory_order_acquire);
176    if (!e) return NULL;
177
178    AutoMutex _l(e->mLock);
179    return e->mObjects.find(objectID);
180}
181
182void BBinder::detachObject(const void* objectID)
183{
184    Extras* e = mExtras.load(std::memory_order_acquire);
185    if (!e) return;
186
187    AutoMutex _l(e->mLock);
188    e->mObjects.detach(objectID);
189}
190
191BBinder* BBinder::localBinder()
192{
193    return this;
194}
195
196BBinder::~BBinder()
197{
198    Extras* e = mExtras.load(std::memory_order_relaxed);
199    if (e) delete e;
200}
201
202
203status_t BBinder::onTransact(
204    uint32_t code, const Parcel& data, Parcel* reply, uint32_t /*flags*/)
205{
206    switch (code) {
207        case INTERFACE_TRANSACTION:
208            reply->writeString16(getInterfaceDescriptor());
209            return NO_ERROR;
210
211        case DUMP_TRANSACTION: {
212            int fd = data.readFileDescriptor();
213            int argc = data.readInt32();
214            Vector<String16> args;
215            for (int i = 0; i < argc && data.dataAvail() > 0; i++) {
216               args.add(data.readString16());
217            }
218            return dump(fd, args);
219        }
220
221        case SHELL_COMMAND_TRANSACTION: {
222            int in = data.readFileDescriptor();
223            int out = data.readFileDescriptor();
224            int err = data.readFileDescriptor();
225            int argc = data.readInt32();
226            Vector<String16> args;
227            for (int i = 0; i < argc && data.dataAvail() > 0; i++) {
228               args.add(data.readString16());
229            }
230            sp<IResultReceiver> resultReceiver = IResultReceiver::asInterface(
231                    data.readStrongBinder());
232
233            return shellCommand(in, out, err, args, resultReceiver);
234        }
235
236        case SYSPROPS_TRANSACTION: {
237            report_sysprop_change();
238            return NO_ERROR;
239        }
240
241        default:
242            return UNKNOWN_TRANSACTION;
243    }
244}
245
246// ---------------------------------------------------------------------------
247
248enum {
249    // This is used to transfer ownership of the remote binder from
250    // the BpRefBase object holding it (when it is constructed), to the
251    // owner of the BpRefBase object when it first acquires that BpRefBase.
252    kRemoteAcquired = 0x00000001
253};
254
255BpRefBase::BpRefBase(const sp<IBinder>& o)
256    : mRemote(o.get()), mRefs(NULL), mState(0)
257{
258    extendObjectLifetime(OBJECT_LIFETIME_WEAK);
259
260    if (mRemote) {
261        mRemote->incStrong(this);           // Removed on first IncStrong().
262        mRefs = mRemote->createWeak(this);  // Held for our entire lifetime.
263    }
264}
265
266BpRefBase::~BpRefBase()
267{
268    if (mRemote) {
269        if (!(mState.load(std::memory_order_relaxed)&kRemoteAcquired)) {
270            mRemote->decStrong(this);
271        }
272        mRefs->decWeak(this);
273    }
274}
275
276void BpRefBase::onFirstRef()
277{
278    mState.fetch_or(kRemoteAcquired, std::memory_order_relaxed);
279}
280
281void BpRefBase::onLastStrongRef(const void* /*id*/)
282{
283    if (mRemote) {
284        mRemote->decStrong(this);
285    }
286}
287
288bool BpRefBase::onIncStrongAttempted(uint32_t /*flags*/, const void* /*id*/)
289{
290    return mRemote ? mRefs->attemptIncStrong(this) : false;
291}
292
293// ---------------------------------------------------------------------------
294
295}; // namespace android
296