include/hwbinder/IPCThreadState.h

/*
 * Copyright (C) 2005 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.
 */

#ifndef ANDROID_HARDWARE_IPC_THREAD_STATE_H
#define ANDROID_HARDWARE_IPC_THREAD_STATE_H

#include <utils/Errors.h>
#include <hwbinder/Parcel.h>
#include <hwbinder/ProcessState.h>
#include <utils/Vector.h>

#include <functional>

// WARNING: this code is part of libhwbinder, a fork of libbinder. Generally,
// this means that it is only relevant to HIDL. Any AIDL- or libbinder-specific
// code should not try to use these things.

#if defined(_WIN32)
typedef  int  uid_t;
#endif

// ---------------------------------------------------------------------------
namespace android {

namespace hardware {

class IPCThreadState
{
public:
    static  IPCThreadState*     self();
    static  IPCThreadState*     selfOrNull();  // self(), but won't instantiate

            sp<ProcessState>    process();

            status_t            clearLastError();

            pid_t               getCallingPid() const;
            // nullptr if unavailable
            //
            // this can't be restored once it's cleared, and it does not return the
            // context of the current process when not in a binder call.
            const char*         getCallingSid() const;
            uid_t               getCallingUid() const;

            void                setStrictModePolicy(int32_t policy);
            int32_t             getStrictModePolicy() const;

            void                setLastTransactionBinderFlags(int32_t flags);
            int32_t             getLastTransactionBinderFlags() const;

            int64_t             clearCallingIdentity();
            // Restores PID/UID (not SID)
            void                restoreCallingIdentity(int64_t token);

            int                 setupPolling(int* fd);
            status_t            handlePolledCommands();
            void                flushCommands();

            void                joinThreadPool(bool isMain = true);

            // Stop the local process.
            void                stopProcess(bool immediate = true);

            status_t            transact(int32_t handle,
                                         uint32_t code, const Parcel& data,
                                         Parcel* reply, uint32_t flags);

            void                incStrongHandle(int32_t handle, BpHwBinder *proxy);
            void                decStrongHandle(int32_t handle);
            void                incWeakHandle(int32_t handle, BpHwBinder *proxy);
            void                decWeakHandle(int32_t handle);
            status_t            attemptIncStrongHandle(int32_t handle);
    static  void                expungeHandle(int32_t handle, IBinder* binder);
            status_t            requestDeathNotification(   int32_t handle,
                                                            BpHwBinder* proxy);
            status_t            clearDeathNotification( int32_t handle,
                                                        BpHwBinder* proxy);

    static  void                shutdown();

            // Service manager registration
            void                setTheContextObject(sp<BHwBinder> obj);

            bool                isLooperThread();
            bool                isOnlyBinderThread();

            // WARNING: DO NOT USE THIS API
            //
            // Returns a pointer to the stack from the last time a transaction
            // was initiated by the kernel. Used to compare when making nested
            // calls between multiple different transports.
            const void*         getServingStackPointer() const;

            // Tasks which are done on the binder thread after the thread returns to the
            // threadpool.
            void addPostCommandTask(const std::function<void(void)>& task);

           private:
            IPCThreadState();
            ~IPCThreadState();

            status_t            sendReply(const Parcel& reply, uint32_t flags);
            status_t            waitForResponse(Parcel *reply,
                                                status_t *acquireResult=nullptr);
            status_t            talkWithDriver(bool doReceive=true);
            status_t            writeTransactionData(int32_t cmd,
                                                     uint32_t binderFlags,
                                                     int32_t handle,
                                                     uint32_t code,
                                                     const Parcel& data,
                                                     status_t* statusBuffer);
            status_t            getAndExecuteCommand();
            status_t            executeCommand(int32_t command);
            void                processPendingDerefs();
            void                processPostWriteDerefs();

            void                clearCaller();

    static  void                threadDestructor(void *st);
    static  void                freeBuffer(Parcel* parcel,
                                           const uint8_t* data, size_t dataSize,
                                           const binder_size_t* objects, size_t objectsSize,
                                           void* cookie);

    const   sp<ProcessState>    mProcess;
            Vector<BHwBinder*>    mPendingStrongDerefs;
            Vector<RefBase::weakref_type*> mPendingWeakDerefs;
            Vector<RefBase*>    mPostWriteStrongDerefs;
            Vector<RefBase::weakref_type*> mPostWriteWeakDerefs;
            Parcel              mIn;
            Parcel              mOut;
            status_t            mLastError;
            const void*         mServingStackPointer;
            pid_t               mCallingPid;
            const char*         mCallingSid;
            uid_t               mCallingUid;
            int32_t             mStrictModePolicy;
            int32_t             mLastTransactionBinderFlags;
            bool                mIsLooper;
            bool mIsPollingThread;

            std::vector<std::function<void(void)>> mPostCommandTasks;

            ProcessState::CallRestriction mCallRestriction;
};

} // namespace hardware
} // namespace android

// ---------------------------------------------------------------------------

#endif // ANDROID_HARDWARE_IPC_THREAD_STATE_H