Android中的Parcel机制(上)

Android技术篇 尼古拉斯.赵四 5422℃ 0评论

一.先从Serialize说起

         我们都知道JAVA中的Serialize机制,译成串行化、序列化……,其作用是能将数据对象存入字节流当中,在需要时重新生成对象。主要应用是利用外部存储设备保存对象状态,以及通过网络传输对象等。

 

二.Android中的新的序列化机制

         在Android系统中,定位为针对内存受限的设备,因此对性能要求更高,另外系统中采用了新的IPC(进程间通信)机制,必然要求使用性能更出色的对象传输方式。在这样的环境下,Parcel被设计出来,其定位就是轻量级的高效的对象序列化和反序列化机制。

 

三.Parcel类的背后

在Framework中有parcel类,源码路径是:

Frameworks/base/core/java/android/os/Parcel.java

典型的源码片断如下:

 

/** 
 * Write an integer value into the parcel at the current dataPosition(), 
 * growing dataCapacity() if needed. 
 */  
public final native void writeInt(int val);  
  
/** 
 * Write a long integer value into the parcel at the current dataPosition(), 
 * growing dataCapacity() if needed. 
 */  
public final native void writeLong(long val);

 

从中我们看到,从这个源程序文件中我们看不到真正的功能是如何实现的,必须透过JNI往下走了。于是,Frameworks/base/core/jni/android_util_Binder.cpp中找到了线索

static void android_os_Parcel_writeInt(JNIEnv* env, jobject clazz, jint val)  
{  
    Parcel* parcel = parcelForJavaObject(env, clazz);  
    if (parcel != NULL) {  
        const status_t err = parcel->writeInt32(val);  
        if (err != NO_ERROR) {  
            jniThrowException(env, "java/lang/OutOfMemoryError", NULL);  
        }  
    }  
}  
  
static void android_os_Parcel_writeLong(JNIEnv* env, jobject clazz, jlong val)  
{  
    Parcel* parcel = parcelForJavaObject(env, clazz);  
    if (parcel != NULL) {  
        const status_t err = parcel->writeInt64(val);  
        if (err != NO_ERROR) {  
            jniThrowException(env, "java/lang/OutOfMemoryError", NULL);  
        }  
    }  
}

 

从这里我们可以得到的信息是函数的实现依赖于Parcel指针,因此还需要找到Parcel的类定义,注意,这里的类已经是用C++语言实现的了。

找到Frameworks/base/include/binder/parcel.h和Frameworks/base/libs/binder/parcel.cpp。终于找到了最终的实现代码了。

有兴趣的朋友可以自己读一下,不难理解,这里把基本的思路总结一下:

1.       整个读写全是在内存中进行,主要是通过malloc()、realloc()、memcpy()等内存操作进行,所以效率比JAVA序列化中使用外部存储器会高很多;

2.       读写时是4字节对齐的,可以看到#define PAD_SIZE(s) (((s)+3)&~3)这句宏定义就是在做这件事情;

3.       如果预分配的空间不够时newSize = ((mDataSize+len)*3)/2;会一次多分配50%;

4.       对于普通数据,使用的是mData内存地址,对于IBinder类型的数据以及FileDescriptor使用的是mObjects内存地址。后者是通过flatten_binder()和unflatten_binder()实现的,目的是反序列化时读出的对象就是原对象而不用重新new一个新对象。

 

好了,这就是Parcel背后的动作,全是在一块内存里进行读写操作,就不啰嗦了,把parcel的代码贴在这供没有源码的朋友参考吧。接下来我会用一个小DEMO演示一下Parcel类在应用程序中的使用,详见《Android中的Parcel机制(下)》。

/* 
 * 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_PARCEL_H  
#define ANDROID_PARCEL_H  
  
#include <cutils/native_handle.h>  
#include <utils/Errors.h>  
#include <utils/RefBase.h>  
#include <utils/String16.h>  
#include <utils/Vector.h>  
  
// ---------------------------------------------------------------------------  
namespace android {  
  
class IBinder;  
class ProcessState;  
class String8;  
class TextOutput;  
class Flattenable;  
  
struct flat_binder_object;  // defined in support_p/binder_module.h  
  
class Parcel  
{  
public:  
                        Parcel();  
                        ~Parcel();  
      
    const uint8_t*      data() const;  
    size_t              dataSize() const;  
    size_t              dataAvail() const;  
    size_t              dataPosition() const;  
    size_t              dataCapacity() const;  
      
    status_t            setDataSize(size_t size);  
    void                setDataPosition(size_t pos) const;  
    status_t            setDataCapacity(size_t size);  
      
    status_t            setData(const uint8_t* buffer, size_t len);  
  
    status_t            appendFrom(Parcel *parcel, size_t start, size_t len);  
  
    bool                hasFileDescriptors() const;  
  
    status_t            writeInterfaceToken(const String16& interface);  
    bool                enforceInterface(const String16& interface) const;  
    bool                checkInterface(IBinder*) const;      
  
    void                freeData();  
  
    const size_t*       objects() const;  
    size_t              objectsCount() const;  
      
    status_t            errorCheck() const;  
    void                setError(status_t err);  
      
    status_t            write(const void* data, size_t len);  
    void*               writeInplace(size_t len);  
    status_t            writeUnpadded(const void* data, size_t len);  
    status_t            writeInt32(int32_t val);  
    status_t            writeInt64(int64_t val);  
    status_t            writeFloat(float val);  
    status_t            writeDouble(double val);  
    status_t            writeIntPtr(intptr_t val);  
    status_t            writeCString(const char* str);  
    status_t            writeString8(const String8& str);  
    status_t            writeString16(const String16& str);  
    status_t            writeString16(const char16_t* str, size_t len);  
    status_t            writeStrongBinder(const sp<IBinder>& val);  
    status_t            writeWeakBinder(const wp<IBinder>& val);  
    status_t            write(const Flattenable& val);  
  
    // Place a native_handle into the parcel (the native_handle's file-  
    // descriptors are dup'ed, so it is safe to delete the native_handle  
    // when this function returns).   
    // Doesn't take ownership of the native_handle.  
    status_t            writeNativeHandle(const native_handle* handle);  
      
    // Place a file descriptor into the parcel.  The given fd must remain  
    // valid for the lifetime of the parcel.  
    status_t            writeFileDescriptor(int fd);  
      
    // Place a file descriptor into the parcel.  A dup of the fd is made, which  
    // will be closed once the parcel is destroyed.  
    status_t            writeDupFileDescriptor(int fd);  
      
    status_t            writeObject(const flat_binder_object& val, bool nullMetaData);  
  
    void                remove(size_t start, size_t amt);  
      
    status_t            read(void* outData, size_t len) const;  
    const void*         readInplace(size_t len) const;  
    int32_t             readInt32() const;  
    status_t            readInt32(int32_t *pArg) const;  
    int64_t             readInt64() const;  
    status_t            readInt64(int64_t *pArg) const;  
    float               readFloat() const;  
    status_t            readFloat(float *pArg) const;  
    double              readDouble() const;  
    status_t            readDouble(double *pArg) const;  
    intptr_t            readIntPtr() const;  
    status_t            readIntPtr(intptr_t *pArg) const;  
  
    const char*         readCString() const;  
    String8             readString8() const;  
    String16            readString16() const;  
    const char16_t*     readString16Inplace(size_t* outLen) const;  
    sp<IBinder>         readStrongBinder() const;  
    wp<IBinder>         readWeakBinder() const;  
    status_t            read(Flattenable& val) const;  
      
    // Retrieve native_handle from the parcel. This returns a copy of the  
    // parcel's native_handle (the caller takes ownership). The caller  
    // must free the native_handle with native_handle_close() and   
    // native_handle_delete().  
    native_handle*     readNativeHandle() const;  
  
      
    // Retrieve a file descriptor from the parcel.  This returns the raw fd  
    // in the parcel, which you do not own -- use dup() to get your own copy.  
    int                 readFileDescriptor() const;  
      
    const flat_binder_object* readObject(bool nullMetaData) const;  
  
    // Explicitly close all file descriptors in the parcel.  
    void                closeFileDescriptors();  
      
    typedef void        (*release_func)(Parcel* parcel,  
                                        const uint8_t* data, size_t dataSize,  
                                        const size_t* objects, size_t objectsSize,  
                                        void* cookie);  
                          
    const uint8_t*      ipcData() const;  
    size_t              ipcDataSize() const;  
    const size_t*       ipcObjects() const;  
    size_t              ipcObjectsCount() const;  
    void                ipcSetDataReference(const uint8_t* data, size_t dataSize,  
                                            const size_t* objects, size_t objectsCount,  
                                            release_func relFunc, void* relCookie);  
      
    void                print(TextOutput& to, uint32_t flags = 0) const;  
          
private:  
                        Parcel(const Parcel& o);  
    Parcel&             operator=(const Parcel& o);  
      
    status_t            finishWrite(size_t len);  
    void                releaseObjects();  
    void                acquireObjects();  
    status_t            growData(size_t len);  
    status_t            restartWrite(size_t desired);  
    status_t            continueWrite(size_t desired);  
    void                freeDataNoInit();  
    void                initState();  
    void                scanForFds() const;  
                          
    template<class T>  
    status_t            readAligned(T *pArg) const;  
  
    template<class T>   T readAligned() const;  
  
    template<class T>  
    status_t            writeAligned(T val);  
  
    status_t            mError;  
    uint8_t*            mData;  
    size_t              mDataSize;  
    size_t              mDataCapacity;  
    mutable size_t      mDataPos;  
    size_t*             mObjects;  
    size_t              mObjectsSize;  
    size_t              mObjectsCapacity;  
    mutable size_t      mNextObjectHint;  
  
    mutable bool        mFdsKnown;  
    mutable bool        mHasFds;  
      
    release_func        mOwner;  
    void*               mOwnerCookie;  
};  
  
// ---------------------------------------------------------------------------  
  
inline TextOutput& operator<<(TextOutput& to, const Parcel& parcel)  
{  
    parcel.print(to);  
    return to;  
}  
  
// ---------------------------------------------------------------------------  
  
// Generic acquire and release of objects.  
void acquire_object(const sp<ProcessState>& proc,  
                    const flat_binder_object& obj, const void* who);  
void release_object(const sp<ProcessState>& proc,  
                    const flat_binder_object& obj, const void* who);  
  
void flatten_binder(const sp<ProcessState>& proc,  
                    const sp<IBinder>& binder, flat_binder_object* out);  
void flatten_binder(const sp<ProcessState>& proc,  
                    const wp<IBinder>& binder, flat_binder_object* out);  
status_t unflatten_binder(const sp<ProcessState>& proc,  
                          const flat_binder_object& flat, sp<IBinder>* out);  
status_t unflatten_binder(const sp<ProcessState>& proc,  
                          const flat_binder_object& flat, wp<IBinder>* out);  
  
}; // namespace android  
  
// ---------------------------------------------------------------------------  
  
#endif // ANDROID_PARCEL_H

下面是函数的实现

/* 
 * 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. 
 */  
  
#define LOG_TAG "Parcel"  
//#define LOG_NDEBUG 0  
  
#include <binder/Parcel.h>  
  
#include <binder/Binder.h>  
#include <binder/BpBinder.h>  
#include <utils/Debug.h>  
#include <binder/ProcessState.h>  
#include <utils/Log.h>  
#include <utils/String8.h>  
#include <utils/String16.h>  
#include <utils/TextOutput.h>  
#include <utils/misc.h>  
#include <utils/Flattenable.h>  
  
#include <private/binder/binder_module.h>  
  
#include <stdio.h>  
#include <stdlib.h>  
#include <stdint.h>  
  
#ifndef INT32_MAX  
#define INT32_MAX ((int32_t)(2147483647))  
#endif  
  
#define LOG_REFS(...)  
//#define LOG_REFS(...) LOG(LOG_DEBUG, "Parcel", __VA_ARGS__)  
  
// ---------------------------------------------------------------------------  
  
#define PAD_SIZE(s) (((s)+3)&~3)  
  
// XXX This can be made public if we want to provide  
// support for typed data.  
struct small_flat_data  
{  
    uint32_t type;  
    uint32_t data;  
};  
  
namespace android {  
  
void acquire_object(const sp<ProcessState>& proc,  
    const flat_binder_object& obj, const void* who)  
{  
    switch (obj.type) {  
        case BINDER_TYPE_BINDER:  
            if (obj.binder) {  
                LOG_REFS("Parcel %p acquiring reference on local %p", who, obj.cookie);  
                static_cast<IBinder*>(obj.cookie)->incStrong(who);  
            }  
            return;  
        case BINDER_TYPE_WEAK_BINDER:  
            if (obj.binder)  
                static_cast<RefBase::weakref_type*>(obj.binder)->incWeak(who);  
            return;  
        case BINDER_TYPE_HANDLE: {  
            const sp<IBinder> b = proc->getStrongProxyForHandle(obj.handle);  
            if (b != NULL) {  
                LOG_REFS("Parcel %p acquiring reference on remote %p", who, b.get());  
                b->incStrong(who);  
            }  
            return;  
        }  
        case BINDER_TYPE_WEAK_HANDLE: {  
            const wp<IBinder> b = proc->getWeakProxyForHandle(obj.handle);  
            if (b != NULL) b.get_refs()->incWeak(who);  
            return;  
        }  
        case BINDER_TYPE_FD: {  
            // intentionally blank -- nothing to do to acquire this, but we do  
            // recognize it as a legitimate object type.  
            return;  
        }  
    }  
  
    LOGD("Invalid object type 0x%08lx", obj.type);  
}  
  
void release_object(const sp<ProcessState>& proc,  
    const flat_binder_object& obj, const void* who)  
{  
    switch (obj.type) {  
        case BINDER_TYPE_BINDER:  
            if (obj.binder) {  
                LOG_REFS("Parcel %p releasing reference on local %p", who, obj.cookie);  
                static_cast<IBinder*>(obj.cookie)->decStrong(who);  
            }  
            return;  
        case BINDER_TYPE_WEAK_BINDER:  
            if (obj.binder)  
                static_cast<RefBase::weakref_type*>(obj.binder)->decWeak(who);  
            return;  
        case BINDER_TYPE_HANDLE: {  
            const sp<IBinder> b = proc->getStrongProxyForHandle(obj.handle);  
            if (b != NULL) {  
                LOG_REFS("Parcel %p releasing reference on remote %p", who, b.get());  
                b->decStrong(who);  
            }  
            return;  
        }  
        case BINDER_TYPE_WEAK_HANDLE: {  
            const wp<IBinder> b = proc->getWeakProxyForHandle(obj.handle);  
            if (b != NULL) b.get_refs()->decWeak(who);  
            return;  
        }  
        case BINDER_TYPE_FD: {  
            if (obj.cookie != (void*)0) close(obj.handle);  
            return;  
        }  
    }  
  
    LOGE("Invalid object type 0x%08lx", obj.type);  
}  
  
inline static status_t finish_flatten_binder(  
    const sp<IBinder>& binder, const flat_binder_object& flat, Parcel* out)  
{  
    return out->writeObject(flat, false);  
}  
  
status_t flatten_binder(const sp<ProcessState>& proc,  
    const sp<IBinder>& binder, Parcel* out)  
{  
    flat_binder_object obj;  
      
    obj.flags = 0x7f | FLAT_BINDER_FLAG_ACCEPTS_FDS;  
    if (binder != NULL) {  
        IBinder *local = binder->localBinder();  
        if (!local) {  
            BpBinder *proxy = binder->remoteBinder();  
            if (proxy == NULL) {  
                LOGE("null proxy");  
            }  
            const int32_t handle = proxy ? proxy->handle() : 0;  
            obj.type = BINDER_TYPE_HANDLE;  
            obj.handle = handle;  
            obj.cookie = NULL;  
        } else {  
            obj.type = BINDER_TYPE_BINDER;  
            obj.binder = local->getWeakRefs();  
            obj.cookie = local;  
        }  
    } else {  
        obj.type = BINDER_TYPE_BINDER;  
        obj.binder = NULL;  
        obj.cookie = NULL;  
    }  
      
    return finish_flatten_binder(binder, obj, out);  
}  
  
status_t flatten_binder(const sp<ProcessState>& proc,  
    const wp<IBinder>& binder, Parcel* out)  
{  
    flat_binder_object obj;  
      
    obj.flags = 0x7f | FLAT_BINDER_FLAG_ACCEPTS_FDS;  
    if (binder != NULL) {  
        sp<IBinder> real = binder.promote();  
        if (real != NULL) {  
            IBinder *local = real->localBinder();  
            if (!local) {  
                BpBinder *proxy = real->remoteBinder();  
                if (proxy == NULL) {  
                    LOGE("null proxy");  
                }  
                const int32_t handle = proxy ? proxy->handle() : 0;  
                obj.type = BINDER_TYPE_WEAK_HANDLE;  
                obj.handle = handle;  
                obj.cookie = NULL;  
            } else {  
                obj.type = BINDER_TYPE_WEAK_BINDER;  
                obj.binder = binder.get_refs();  
                obj.cookie = binder.unsafe_get();  
            }  
            return finish_flatten_binder(real, obj, out);  
        }  
          
        // XXX How to deal?  In order to flatten the given binder,  
        // we need to probe it for information, which requires a primary  
        // reference...  but we don't have one.  
        //  
        // The OpenBinder implementation uses a dynamic_cast<> here,  
        // but we can't do that with the different reference counting  
        // implementation we are using.  
        LOGE("Unable to unflatten Binder weak reference!");  
        obj.type = BINDER_TYPE_BINDER;  
        obj.binder = NULL;  
        obj.cookie = NULL;  
        return finish_flatten_binder(NULL, obj, out);  
      
    } else {  
        obj.type = BINDER_TYPE_BINDER;  
        obj.binder = NULL;  
        obj.cookie = NULL;  
        return finish_flatten_binder(NULL, obj, out);  
    }  
}  
  
inline static status_t finish_unflatten_binder(  
    BpBinder* proxy, const flat_binder_object& flat, const Parcel& in)  
{  
    return NO_ERROR;  
}  
      
status_t unflatten_binder(const sp<ProcessState>& proc,  
    const Parcel& in, sp<IBinder>* out)  
{  
    const flat_binder_object* flat = in.readObject(false);  
      
    if (flat) {  
        switch (flat->type) {  
            case BINDER_TYPE_BINDER:  
                *out = static_cast<IBinder*>(flat->cookie);  
                return finish_unflatten_binder(NULL, *flat, in);  
            case BINDER_TYPE_HANDLE:  
                *out = proc->getStrongProxyForHandle(flat->handle);  
                return finish_unflatten_binder(  
                    static_cast<BpBinder*>(out->get()), *flat, in);  
        }          
    }  
    return BAD_TYPE;  
}  
  
status_t unflatten_binder(const sp<ProcessState>& proc,  
    const Parcel& in, wp<IBinder>* out)  
{  
    const flat_binder_object* flat = in.readObject(false);  
      
    if (flat) {  
        switch (flat->type) {  
            case BINDER_TYPE_BINDER:  
                *out = static_cast<IBinder*>(flat->cookie);  
                return finish_unflatten_binder(NULL, *flat, in);  
            case BINDER_TYPE_WEAK_BINDER:  
                if (flat->binder != NULL) {  
                    out->set_object_and_refs(  
                        static_cast<IBinder*>(flat->cookie),  
                        static_cast<RefBase::weakref_type*>(flat->binder));  
                } else {  
                    *out = NULL;  
                }  
                return finish_unflatten_binder(NULL, *flat, in);  
            case BINDER_TYPE_HANDLE:  
            case BINDER_TYPE_WEAK_HANDLE:  
                *out = proc->getWeakProxyForHandle(flat->handle);  
                return finish_unflatten_binder(  
                    static_cast<BpBinder*>(out->unsafe_get()), *flat, in);  
        }  
    }  
    return BAD_TYPE;  
}  
  
// ---------------------------------------------------------------------------  
  
Parcel::Parcel()  
{  
    initState();  
}  
  
Parcel::~Parcel()  
{  
    freeDataNoInit();  
}  
  
const uint8_t* Parcel::data() const  
{  
    return mData;  
}  
  
size_t Parcel::dataSize() const  
{  
    return (mDataSize > mDataPos ? mDataSize : mDataPos);  
}  
  
size_t Parcel::dataAvail() const  
{  
    // TODO: decide what to do about the possibility that this can  
    // report an available-data size that exceeds a Java int's max  
    // positive value, causing havoc.  Fortunately this will only  
    // happen if someone constructs a Parcel containing more than two  
    // gigabytes of data, which on typical phone hardware is simply  
    // not possible.  
    return dataSize() - dataPosition();  
}  
  
size_t Parcel::dataPosition() const  
{  
    return mDataPos;  
}  
  
size_t Parcel::dataCapacity() const  
{  
    return mDataCapacity;  
}  
  
status_t Parcel::setDataSize(size_t size)  
{  
    status_t err;  
    err = continueWrite(size);  
    if (err == NO_ERROR) {  
        mDataSize = size;  
        LOGV("setDataSize Setting data size of %p to %d/n", this, mDataSize);  
    }  
    return err;  
}  
  
void Parcel::setDataPosition(size_t pos) const  
{  
    mDataPos = pos;  
    mNextObjectHint = 0;  
}  
  
status_t Parcel::setDataCapacity(size_t size)  
{  
    if (size > mDataSize) return continueWrite(size);  
    return NO_ERROR;  
}  
  
status_t Parcel::setData(const uint8_t* buffer, size_t len)  
{  
    status_t err = restartWrite(len);  
    if (err == NO_ERROR) {  
        memcpy(const_cast<uint8_t*>(data()), buffer, len);  
        mDataSize = len;  
        mFdsKnown = false;  
    }  
    return err;  
}  
  
status_t Parcel::appendFrom(Parcel *parcel, size_t offset, size_t len)  
{  
    const sp<ProcessState> proc(ProcessState::self());  
    status_t err;  
    uint8_t *data = parcel->mData;  
    size_t *objects = parcel->mObjects;  
    size_t size = parcel->mObjectsSize;  
    int startPos = mDataPos;  
    int firstIndex = -1, lastIndex = -2;  
  
    if (len == 0) {  
        return NO_ERROR;  
    }  
  
    // range checks against the source parcel size  
    if ((offset > parcel->mDataSize)  
            || (len > parcel->mDataSize)  
            || (offset + len > parcel->mDataSize)) {  
        return BAD_VALUE;  
    }  
  
    // Count objects in range  
    for (int i = 0; i < (int) size; i++) {  
        size_t off = objects[i];  
        if ((off >= offset) && (off < offset + len)) {  
            if (firstIndex == -1) {  
                firstIndex = i;  
            }  
            lastIndex = i;  
        }  
    }  
    int numObjects = lastIndex - firstIndex + 1;  
  
    // grow data  
    err = growData(len);  
    if (err != NO_ERROR) {  
        return err;  
    }  
  
    // append data  
    memcpy(mData + mDataPos, data + offset, len);  
    mDataPos += len;  
    mDataSize += len;  
  
    if (numObjects > 0) {  
        // grow objects  
        if (mObjectsCapacity < mObjectsSize + numObjects) {  
            int newSize = ((mObjectsSize + numObjects)*3)/2;  
            size_t *objects =  
                (size_t*)realloc(mObjects, newSize*sizeof(size_t));  
            if (objects == (size_t*)0) {  
                return NO_MEMORY;  
            }  
            mObjects = objects;  
            mObjectsCapacity = newSize;  
        }  
          
        // append and acquire objects  
        int idx = mObjectsSize;  
        for (int i = firstIndex; i <= lastIndex; i++) {  
            size_t off = objects[i] - offset + startPos;  
            mObjects[idx++] = off;  
            mObjectsSize++;  
  
            flat_binder_object* flat  
                = reinterpret_cast<flat_binder_object*>(mData + off);  
            acquire_object(proc, *flat, this);  
  
            if (flat->type == BINDER_TYPE_FD) {  
                // If this is a file descriptor, we need to dup it so the  
                // new Parcel now owns its own fd, and can declare that we  
                // officially know we have fds.  
                flat->handle = dup(flat->handle);  
                flat->cookie = (void*)1;  
                mHasFds = mFdsKnown = true;  
            }  
        }  
    }  
  
    return NO_ERROR;  
}  
  
bool Parcel::hasFileDescriptors() const  
{  
    if (!mFdsKnown) {  
        scanForFds();  
    }  
    return mHasFds;  
}  
  
status_t Parcel::writeInterfaceToken(const String16& interface)  
{  
    // currently the interface identification token is just its name as a string  
    return writeString16(interface);  
}  
  
bool Parcel::checkInterface(IBinder* binder) const  
{  
    return enforceInterface(binder->getInterfaceDescriptor());   
}  
  
bool Parcel::enforceInterface(const String16& interface) const  
{  
    const String16 str(readString16());  
    if (str == interface) {  
        return true;  
    } else {  
        LOGW("**** enforceInterface() expected '%s' but read '%s'/n",  
                String8(interface).string(), String8(str).string());  
        return false;  
    }  
}   
  
const size_t* Parcel::objects() const  
{  
    return mObjects;  
}  
  
size_t Parcel::objectsCount() const  
{  
    return mObjectsSize;  
}  
  
status_t Parcel::errorCheck() const  
{  
    return mError;  
}  
  
void Parcel::setError(status_t err)  
{  
    mError = err;  
}  
  
status_t Parcel::finishWrite(size_t len)  
{  
    //printf("Finish write of %d/n", len);  
    mDataPos += len;  
    LOGV("finishWrite Setting data pos of %p to %d/n", this, mDataPos);  
    if (mDataPos > mDataSize) {  
        mDataSize = mDataPos;  
        LOGV("finishWrite Setting data size of %p to %d/n", this, mDataSize);  
    }  
    //printf("New pos=%d, size=%d/n", mDataPos, mDataSize);  
    return NO_ERROR;  
}  
  
status_t Parcel::writeUnpadded(const void* data, size_t len)  
{  
    size_t end = mDataPos + len;  
    if (end < mDataPos) {  
        // integer overflow  
        return BAD_VALUE;  
    }  
  
    if (end <= mDataCapacity) {  
restart_write:  
        memcpy(mData+mDataPos, data, len);  
        return finishWrite(len);  
    }  
  
    status_t err = growData(len);  
    if (err == NO_ERROR) goto restart_write;  
    return err;  
}  
  
status_t Parcel::write(const void* data, size_t len)  
{  
    void* const d = writeInplace(len);  
    if (d) {  
        memcpy(d, data, len);  
        return NO_ERROR;  
    }  
    return mError;  
}  
  
void* Parcel::writeInplace(size_t len)  
{  
    const size_t padded = PAD_SIZE(len);  
  
    // sanity check for integer overflow  
    if (mDataPos+padded < mDataPos) {  
        return NULL;  
    }  
  
    if ((mDataPos+padded) <= mDataCapacity) {  
restart_write:  
        //printf("Writing %ld bytes, padded to %ld/n", len, padded);  
        uint8_t* const data = mData+mDataPos;  
  
        // Need to pad at end?  
        if (padded != len) {  
#if BYTE_ORDER == BIG_ENDIAN  
            static const uint32_t mask[4] = {  
                0x00000000, 0xffffff00, 0xffff0000, 0xff000000  
            };  
#endif  
#if BYTE_ORDER == LITTLE_ENDIAN  
            static const uint32_t mask[4] = {  
                0x00000000, 0x00ffffff, 0x0000ffff, 0x000000ff  
            };  
#endif  
            //printf("Applying pad mask: %p to %p/n", (void*)mask[padded-len],  
            //    *reinterpret_cast<void**>(data+padded-4));  
            *reinterpret_cast<uint32_t*>(data+padded-4) &= mask[padded-len];  
        }  
  
        finishWrite(padded);  
        return data;  
    }  
  
    status_t err = growData(padded);  
    if (err == NO_ERROR) goto restart_write;  
    return NULL;  
}  
  
status_t Parcel::writeInt32(int32_t val)  
{  
    return writeAligned(val);  
}  
  
status_t Parcel::writeInt64(int64_t val)  
{  
    return writeAligned(val);  
}  
  
status_t Parcel::writeFloat(float val)  
{  
    return writeAligned(val);  
}  
  
status_t Parcel::writeDouble(double val)  
{  
    return writeAligned(val);  
}  
  
status_t Parcel::writeIntPtr(intptr_t val)  
{  
    return writeAligned(val);  
}  
  
status_t Parcel::writeCString(const char* str)  
{  
    return write(str, strlen(str)+1);  
}  
  
status_t Parcel::writeString8(const String8& str)  
{  
    status_t err = writeInt32(str.bytes());  
    if (err == NO_ERROR) {  
        err = write(str.string(), str.bytes()+1);  
    }  
    return err;  
}  
  
status_t Parcel::writeString16(const String16& str)  
{  
    return writeString16(str.string(), str.size());  
}  
  
status_t Parcel::writeString16(const char16_t* str, size_t len)  
{  
    if (str == NULL) return writeInt32(-1);  
      
    status_t err = writeInt32(len);  
    if (err == NO_ERROR) {  
        len *= sizeof(char16_t);  
        uint8_t* data = (uint8_t*)writeInplace(len+sizeof(char16_t));  
        if (data) {  
            memcpy(data, str, len);  
            *reinterpret_cast<char16_t*>(data+len) = 0;  
            return NO_ERROR;  
        }  
        err = mError;  
    }  
    return err;  
}  
  
status_t Parcel::writeStrongBinder(const sp<IBinder>& val)  
{  
    return flatten_binder(ProcessState::self(), val, this);  
}  
  
status_t Parcel::writeWeakBinder(const wp<IBinder>& val)  
{  
    return flatten_binder(ProcessState::self(), val, this);  
}  
  
status_t Parcel::writeNativeHandle(const native_handle* handle)  
{  
    if (!handle || handle->version != sizeof(native_handle))  
        return BAD_TYPE;  
  
    status_t err;  
    err = writeInt32(handle->numFds);  
    if (err != NO_ERROR) return err;  
  
    err = writeInt32(handle->numInts);  
    if (err != NO_ERROR) return err;  
  
    for (int i=0 ; err==NO_ERROR && i<handle->numFds ; i++)  
        err = writeDupFileDescriptor(handle->data[i]);  
  
    if (err != NO_ERROR) {  
        LOGD("write native handle, write dup fd failed");  
        return err;  
    }  
    err = write(handle->data + handle->numFds, sizeof(int)*handle->numInts);  
    return err;  
}  
  
status_t Parcel::writeFileDescriptor(int fd)  
{  
    flat_binder_object obj;  
    obj.type = BINDER_TYPE_FD;  
    obj.flags = 0x7f | FLAT_BINDER_FLAG_ACCEPTS_FDS;  
    obj.handle = fd;  
    obj.cookie = (void*)0;  
    return writeObject(obj, true);  
}  
  
status_t Parcel::writeDupFileDescriptor(int fd)  
{  
    flat_binder_object obj;  
    obj.type = BINDER_TYPE_FD;  
    obj.flags = 0x7f | FLAT_BINDER_FLAG_ACCEPTS_FDS;  
    obj.handle = dup(fd);  
    obj.cookie = (void*)1;  
    return writeObject(obj, true);  
}  
  
status_t Parcel::write(const Flattenable& val)  
{  
    status_t err;  
  
    // size if needed  
    size_t len = val.getFlattenedSize();  
    size_t fd_count = val.getFdCount();  
  
    err = this->writeInt32(len);  
    if (err) return err;  
  
    err = this->writeInt32(fd_count);  
    if (err) return err;  
  
    // payload  
    void* buf = this->writeInplace(PAD_SIZE(len));  
    if (buf == NULL)  
        return BAD_VALUE;  
  
    int* fds = NULL;  
    if (fd_count) {  
        fds = new int[fd_count];  
    }  
  
    err = val.flatten(buf, len, fds, fd_count);  
    for (size_t i=0 ; i<fd_count && err==NO_ERROR ; i++) {  
        err = this->writeDupFileDescriptor( fds[i] );  
    }  
  
    if (fd_count) {  
        delete [] fds;  
    }  
  
    return err;  
}  
  
status_t Parcel::writeObject(const flat_binder_object& val, bool nullMetaData)  
{  
    const bool enoughData = (mDataPos+sizeof(val)) <= mDataCapacity;  
    const bool enoughObjects = mObjectsSize < mObjectsCapacity;  
    if (enoughData && enoughObjects) {  
restart_write:  
        *reinterpret_cast<flat_binder_object*>(mData+mDataPos) = val;  
          
        // Need to write meta-data?  
        if (nullMetaData || val.binder != NULL) {  
            mObjects[mObjectsSize] = mDataPos;  
            acquire_object(ProcessState::self(), val, this);  
            mObjectsSize++;  
        }  
          
        // remember if it's a file descriptor  
        if (val.type == BINDER_TYPE_FD) {  
            mHasFds = mFdsKnown = true;  
        }  
  
        return finishWrite(sizeof(flat_binder_object));  
    }  
  
    if (!enoughData) {  
        const status_t err = growData(sizeof(val));  
        if (err != NO_ERROR) return err;  
    }  
    if (!enoughObjects) {  
        size_t newSize = ((mObjectsSize+2)*3)/2;  
        size_t* objects = (size_t*)realloc(mObjects, newSize*sizeof(size_t));  
        if (objects == NULL) return NO_MEMORY;  
        mObjects = objects;  
        mObjectsCapacity = newSize;  
    }  
      
    goto restart_write;  
}  
  
void Parcel::remove(size_t start, size_t amt)  
{  
    LOG_ALWAYS_FATAL("Parcel::remove() not yet implemented!");  
}  
  
status_t Parcel::read(void* outData, size_t len) const  
{  
    if ((mDataPos+PAD_SIZE(len)) >= mDataPos && (mDataPos+PAD_SIZE(len)) <= mDataSize) {  
        memcpy(outData, mData+mDataPos, len);  
        mDataPos += PAD_SIZE(len);  
        LOGV("read Setting data pos of %p to %d/n", this, mDataPos);  
        return NO_ERROR;  
    }  
    return NOT_ENOUGH_DATA;  
}  
  
const void* Parcel::readInplace(size_t len) const  
{  
    if ((mDataPos+PAD_SIZE(len)) >= mDataPos && (mDataPos+PAD_SIZE(len)) <= mDataSize) {  
        const void* data = mData+mDataPos;  
        mDataPos += PAD_SIZE(len);  
        LOGV("readInplace Setting data pos of %p to %d/n", this, mDataPos);  
        return data;  
    }  
    return NULL;  
}  
  
template<class T>  
status_t Parcel::readAligned(T *pArg) const {  
    COMPILE_TIME_ASSERT_FUNCTION_SCOPE(PAD_SIZE(sizeof(T)) == sizeof(T));  
  
    if ((mDataPos+sizeof(T)) <= mDataSize) {  
        const void* data = mData+mDataPos;  
        mDataPos += sizeof(T);  
        *pArg =  *reinterpret_cast<const T*>(data);  
        return NO_ERROR;  
    } else {  
        return NOT_ENOUGH_DATA;  
    }  
}  
  
template<class T>  
T Parcel::readAligned() const {  
    T result;  
    if (readAligned(&result) != NO_ERROR) {  
        result = 0;  
    }  
  
    return result;  
}  
  
template<class T>  
status_t Parcel::writeAligned(T val) {  
    COMPILE_TIME_ASSERT_FUNCTION_SCOPE(PAD_SIZE(sizeof(T)) == sizeof(T));  
  
    if ((mDataPos+sizeof(val)) <= mDataCapacity) {  
restart_write:  
        *reinterpret_cast<T*>(mData+mDataPos) = val;  
        return finishWrite(sizeof(val));  
    }  
  
    status_t err = growData(sizeof(val));  
    if (err == NO_ERROR) goto restart_write;  
    return err;  
}  
  
status_t Parcel::readInt32(int32_t *pArg) const  
{  
    return readAligned(pArg);  
}  
  
int32_t Parcel::readInt32() const  
{  
    return readAligned<int32_t>();  
}  
  
  
status_t Parcel::readInt64(int64_t *pArg) const  
{  
    return readAligned(pArg);  
}  
  
  
int64_t Parcel::readInt64() const  
{  
    return readAligned<int64_t>();  
}  
  
status_t Parcel::readFloat(float *pArg) const  
{  
    return readAligned(pArg);  
}  
  
  
float Parcel::readFloat() const  
{  
    return readAligned<float>();  
}  
  
status_t Parcel::readDouble(double *pArg) const  
{  
    return readAligned(pArg);  
}  
  
  
double Parcel::readDouble() const  
{  
    return readAligned<double>();  
}  
  
status_t Parcel::readIntPtr(intptr_t *pArg) const  
{  
    return readAligned(pArg);  
}  
  
  
intptr_t Parcel::readIntPtr() const  
{  
    return readAligned<intptr_t>();  
}  
  
  
const char* Parcel::readCString() const  
{  
    const size_t avail = mDataSize-mDataPos;  
    if (avail > 0) {  
        const char* str = reinterpret_cast<const char*>(mData+mDataPos);  
        // is the string's trailing NUL within the parcel's valid bounds?  
        const char* eos = reinterpret_cast<const char*>(memchr(str, 0, avail));  
        if (eos) {  
            const size_t len = eos - str;  
            mDataPos += PAD_SIZE(len+1);  
            LOGV("readCString Setting data pos of %p to %d/n", this, mDataPos);  
            return str;  
        }  
    }  
    return NULL;  
}  
  
String8 Parcel::readString8() const  
{  
    int32_t size = readInt32();  
    // watch for potential int overflow adding 1 for trailing NUL  
    if (size > 0 && size < INT32_MAX) {  
        const char* str = (const char*)readInplace(size+1);  
        if (str) return String8(str, size);  
    }  
    return String8();  
}  
  
String16 Parcel::readString16() const  
{  
    size_t len;  
    const char16_t* str = readString16Inplace(&len);  
    if (str) return String16(str, len);  
    LOGE("Reading a NULL string not supported here.");  
    return String16();  
}  
  
const char16_t* Parcel::readString16Inplace(size_t* outLen) const  
{  
    int32_t size = readInt32();  
    // watch for potential int overflow from size+1  
    if (size >= 0 && size < INT32_MAX) {  
        *outLen = size;  
        const char16_t* str = (const char16_t*)readInplace((size+1)*sizeof(char16_t));  
        if (str != NULL) {  
            return str;  
        }  
    }  
    *outLen = 0;  
    return NULL;  
}  
  
sp<IBinder> Parcel::readStrongBinder() const  
{  
    sp<IBinder> val;  
    unflatten_binder(ProcessState::self(), *this, &val);  
    return val;  
}  
  
wp<IBinder> Parcel::readWeakBinder() const  
{  
    wp<IBinder> val;  
    unflatten_binder(ProcessState::self(), *this, &val);  
    return val;  
}  
  
  
native_handle* Parcel::readNativeHandle() const  
{  
    int numFds, numInts;  
    status_t err;  
    err = readInt32(&numFds);  
    if (err != NO_ERROR) return 0;  
    err = readInt32(&numInts);  
    if (err != NO_ERROR) return 0;  
  
    native_handle* h = native_handle_create(numFds, numInts);  
    for (int i=0 ; err==NO_ERROR && i<numFds ; i++) {  
        h->data[i] = dup(readFileDescriptor());  
        if (h->data[i] < 0) err = BAD_VALUE;  
    }  
    err = read(h->data + numFds, sizeof(int)*numInts);  
    if (err != NO_ERROR) {  
        native_handle_close(h);  
        native_handle_delete(h);  
        h = 0;  
    }  
    return h;  
}  
  
  
int Parcel::readFileDescriptor() const  
{  
    const flat_binder_object* flat = readObject(true);  
    if (flat) {  
        switch (flat->type) {  
            case BINDER_TYPE_FD:  
                //LOGI("Returning file descriptor %ld from parcel %p/n", flat->handle, this);  
                return flat->handle;  
        }          
    }  
    return BAD_TYPE;  
}  
  
status_t Parcel::read(Flattenable& val) const  
{  
    // size  
    const size_t len = this->readInt32();  
    const size_t fd_count = this->readInt32();  
  
    // payload  
    void const* buf = this->readInplace(PAD_SIZE(len));  
    if (buf == NULL)  
        return BAD_VALUE;  
  
    int* fds = NULL;  
    if (fd_count) {  
        fds = new int[fd_count];  
    }  
  
    status_t err = NO_ERROR;  
    for (size_t i=0 ; i<fd_count && err==NO_ERROR ; i++) {  
        fds[i] = dup(this->readFileDescriptor());  
        if (fds[i] < 0) err = BAD_VALUE;  
    }  
  
    if (err == NO_ERROR) {  
        err = val.unflatten(buf, len, fds, fd_count);  
    }  
  
    if (fd_count) {  
        delete [] fds;  
    }  
  
    return err;  
}  
const flat_binder_object* Parcel::readObject(bool nullMetaData) const  
{  
    const size_t DPOS = mDataPos;  
    if ((DPOS+sizeof(flat_binder_object)) <= mDataSize) {  
        const flat_binder_object* obj  
                = reinterpret_cast<const flat_binder_object*>(mData+DPOS);  
        mDataPos = DPOS + sizeof(flat_binder_object);  
        if (!nullMetaData && (obj->cookie == NULL && obj->binder == NULL)) {  
            // When transferring a NULL object, we don't write it into  
            // the object list, so we don't want to check for it when  
            // reading.  
            LOGV("readObject Setting data pos of %p to %d/n", this, mDataPos);  
            return obj;  
        }  
          
        // Ensure that this object is valid...  
        size_t* const OBJS = mObjects;  
        const size_t N = mObjectsSize;  
        size_t opos = mNextObjectHint;  
          
        if (N > 0) {  
            LOGV("Parcel %p looking for obj at %d, hint=%d/n",  
                 this, DPOS, opos);  
              
            // Start at the current hint position, looking for an object at  
            // the current data position.  
            if (opos < N) {  
                while (opos < (N-1) && OBJS[opos] < DPOS) {  
                    opos++;  
                }  
            } else {  
                opos = N-1;  
            }  
            if (OBJS[opos] == DPOS) {  
                // Found it!  
                LOGV("Parcel found obj %d at index %d with forward search",  
                     this, DPOS, opos);  
                mNextObjectHint = opos+1;  
                LOGV("readObject Setting data pos of %p to %d/n", this, mDataPos);  
                return obj;  
            }  
          
            // Look backwards for it...  
            while (opos > 0 && OBJS[opos] > DPOS) {  
                opos--;  
            }  
            if (OBJS[opos] == DPOS) {  
                // Found it!  
                LOGV("Parcel found obj %d at index %d with backward search",  
                     this, DPOS, opos);  
                mNextObjectHint = opos+1;  
                LOGV("readObject Setting data pos of %p to %d/n", this, mDataPos);  
                return obj;  
            }  
        }  
        LOGW("Attempt to read object from Parcel %p at offset %d that is not in the object list",  
             this, DPOS);  
    }  
    return NULL;  
}  
  
void Parcel::closeFileDescriptors()  
{  
    size_t i = mObjectsSize;  
    if (i > 0) {  
        //LOGI("Closing file descriptors for %d objects...", mObjectsSize);  
    }  
    while (i > 0) {  
        i--;  
        const flat_binder_object* flat  
            = reinterpret_cast<flat_binder_object*>(mData+mObjects[i]);  
        if (flat->type == BINDER_TYPE_FD) {  
            //LOGI("Closing fd: %ld/n", flat->handle);  
            close(flat->handle);  
        }  
    }  
}  
  
const uint8_t* Parcel::ipcData() const  
{  
    return mData;  
}  
  
size_t Parcel::ipcDataSize() const  
{  
    return (mDataSize > mDataPos ? mDataSize : mDataPos);  
}  
  
const size_t* Parcel::ipcObjects() const  
{  
    return mObjects;  
}  
  
size_t Parcel::ipcObjectsCount() const  
{  
    return mObjectsSize;  
}  
  
void Parcel::ipcSetDataReference(const uint8_t* data, size_t dataSize,  
    const size_t* objects, size_t objectsCount, release_func relFunc, void* relCookie)  
{  
    freeDataNoInit();  
    mError = NO_ERROR;  
    mData = const_cast<uint8_t*>(data);  
    mDataSize = mDataCapacity = dataSize;  
    //LOGI("setDataReference Setting data size of %p to %lu (pid=%d)/n", this, mDataSize, getpid());  
    mDataPos = 0;  
    LOGV("setDataReference Setting data pos of %p to %d/n", this, mDataPos);  
    mObjects = const_cast<size_t*>(objects);  
    mObjectsSize = mObjectsCapacity = objectsCount;  
    mNextObjectHint = 0;  
    mOwner = relFunc;  
    mOwnerCookie = relCookie;  
    scanForFds();  
}  
  
void Parcel::print(TextOutput& to, uint32_t flags) const  
{  
    to << "Parcel(";  
      
    if (errorCheck() != NO_ERROR) {  
        const status_t err = errorCheck();  
        to << "Error: " << (void*)err << " /"" << strerror(-err) << "/"";  
    } else if (dataSize() > 0) {  
        const uint8_t* DATA = data();  
        to << indent << HexDump(DATA, dataSize()) << dedent;  
        const size_t* OBJS = objects();  
        const size_t N = objectsCount();  
        for (size_t i=0; i<N; i++) {  
            const flat_binder_object* flat  
                = reinterpret_cast<const flat_binder_object*>(DATA+OBJS[i]);  
            to << endl << "Object #" << i << " @ " << (void*)OBJS[i] << ": "  
                << TypeCode(flat->type & 0x7f7f7f00)  
                << " = " << flat->binder;  
        }  
    } else {  
        to << "NULL";  
    }  
      
    to << ")";  
}  
  
void Parcel::releaseObjects()  
{  
    const sp<ProcessState> proc(ProcessState::self());  
    size_t i = mObjectsSize;  
    uint8_t* const data = mData;  
    size_t* const objects = mObjects;  
    while (i > 0) {  
        i--;  
        const flat_binder_object* flat  
            = reinterpret_cast<flat_binder_object*>(data+objects[i]);  
        release_object(proc, *flat, this);  
    }  
}  
  
void Parcel::acquireObjects()  
{  
    const sp<ProcessState> proc(ProcessState::self());  
    size_t i = mObjectsSize;  
    uint8_t* const data = mData;  
    size_t* const objects = mObjects;  
    while (i > 0) {  
        i--;  
        const flat_binder_object* flat  
            = reinterpret_cast<flat_binder_object*>(data+objects[i]);  
        acquire_object(proc, *flat, this);  
    }  
}  
  
void Parcel::freeData()  
{  
    freeDataNoInit();  
    initState();  
}  
  
void Parcel::freeDataNoInit()  
{  
    if (mOwner) {  
        //LOGI("Freeing data ref of %p (pid=%d)/n", this, getpid());  
        mOwner(this, mData, mDataSize, mObjects, mObjectsSize, mOwnerCookie);  
    } else {  
        releaseObjects();  
        if (mData) free(mData);  
        if (mObjects) free(mObjects);  
    }  
}  
  
status_t Parcel::growData(size_t len)  
{  
    size_t newSize = ((mDataSize+len)*3)/2;  
    return (newSize <= mDataSize)  
            ? (status_t) NO_MEMORY  
            : continueWrite(newSize);  
}  
  
status_t Parcel::restartWrite(size_t desired)  
{  
    if (mOwner) {  
        freeData();  
        return continueWrite(desired);  
    }  
      
    uint8_t* data = (uint8_t*)realloc(mData, desired);  
    if (!data && desired > mDataCapacity) {  
        mError = NO_MEMORY;  
        return NO_MEMORY;  
    }  
      
    releaseObjects();  
      
    if (data) {  
        mData = data;  
        mDataCapacity = desired;  
    }  
      
    mDataSize = mDataPos = 0;  
    LOGV("restartWrite Setting data size of %p to %d/n", this, mDataSize);  
    LOGV("restartWrite Setting data pos of %p to %d/n", this, mDataPos);  
          
    free(mObjects);  
    mObjects = NULL;  
    mObjectsSize = mObjectsCapacity = 0;  
    mNextObjectHint = 0;  
    mHasFds = false;  
    mFdsKnown = true;  
      
    return NO_ERROR;  
}  
  
status_t Parcel::continueWrite(size_t desired)  
{  
    // If shrinking, first adjust for any objects that appear  
    // after the new data size.  
    size_t objectsSize = mObjectsSize;  
    if (desired < mDataSize) {  
        if (desired == 0) {  
            objectsSize = 0;  
        } else {  
            while (objectsSize > 0) {  
                if (mObjects[objectsSize-1] < desired)  
                    break;  
                objectsSize--;  
            }  
        }  
    }  
      
    if (mOwner) {  
        // If the size is going to zero, just release the owner's data.  
        if (desired == 0) {  
            freeData();  
            return NO_ERROR;  
        }  
  
        // If there is a different owner, we need to take  
        // posession.  
        uint8_t* data = (uint8_t*)malloc(desired);  
        if (!data) {  
            mError = NO_MEMORY;  
            return NO_MEMORY;  
        }  
        size_t* objects = NULL;  
          
        if (objectsSize) {  
            objects = (size_t*)malloc(objectsSize*sizeof(size_t));  
            if (!objects) {  
                mError = NO_MEMORY;  
                return NO_MEMORY;  
            }  
  
            // Little hack to only acquire references on objects  
            // we will be keeping.  
            size_t oldObjectsSize = mObjectsSize;  
            mObjectsSize = objectsSize;  
            acquireObjects();  
            mObjectsSize = oldObjectsSize;  
        }  
          
        if (mData) {  
            memcpy(data, mData, mDataSize < desired ? mDataSize : desired);  
        }  
        if (objects && mObjects) {  
            memcpy(objects, mObjects, objectsSize*sizeof(size_t));  
        }  
        //LOGI("Freeing data ref of %p (pid=%d)/n", this, getpid());  
        mOwner(this, mData, mDataSize, mObjects, mObjectsSize, mOwnerCookie);  
        mOwner = NULL;  
  
        mData = data;  
        mObjects = objects;  
        mDataSize = (mDataSize < desired) ? mDataSize : desired;  
        LOGV("continueWrite Setting data size of %p to %d/n", this, mDataSize);  
        mDataCapacity = desired;  
        mObjectsSize = mObjectsCapacity = objectsSize;  
        mNextObjectHint = 0;  
  
    } else if (mData) {  
        if (objectsSize < mObjectsSize) {  
            // Need to release refs on any objects we are dropping.  
            const sp<ProcessState> proc(ProcessState::self());  
            for (size_t i=objectsSize; i<mObjectsSize; i++) {  
                const flat_binder_object* flat  
                    = reinterpret_cast<flat_binder_object*>(mData+mObjects[i]);  
                if (flat->type == BINDER_TYPE_FD) {  
                    // will need to rescan because we may have lopped off the only FDs  
                    mFdsKnown = false;  
                }  
                release_object(proc, *flat, this);  
            }  
            size_t* objects =  
                (size_t*)realloc(mObjects, objectsSize*sizeof(size_t));  
            if (objects) {  
                mObjects = objects;  
            }  
            mObjectsSize = objectsSize;  
            mNextObjectHint = 0;  
        }  
  
        // We own the data, so we can just do a realloc().  
        if (desired > mDataCapacity) {  
            uint8_t* data = (uint8_t*)realloc(mData, desired);  
            if (data) {  
                mData = data;  
                mDataCapacity = desired;  
            } else if (desired > mDataCapacity) {  
                mError = NO_MEMORY;  
                return NO_MEMORY;  
            }  
        } else {  
            mDataSize = desired;  
            LOGV("continueWrite Setting data size of %p to %d/n", this, mDataSize);  
            if (mDataPos > desired) {  
                mDataPos = desired;  
                LOGV("continueWrite Setting data pos of %p to %d/n", this, mDataPos);  
            }  
        }  
          
    } else {  
        // This is the first data.  Easy!  
        uint8_t* data = (uint8_t*)malloc(desired);  
        if (!data) {  
            mError = NO_MEMORY;  
            return NO_MEMORY;  
        }  
          
        if(!(mDataCapacity == 0 && mObjects == NULL  
             && mObjectsCapacity == 0)) {  
            LOGE("continueWrite: %d/%p/%d/%d", mDataCapacity, mObjects, mObjectsCapacity, desired);  
        }  
          
        mData = data;  
        mDataSize = mDataPos = 0;  
        LOGV("continueWrite Setting data size of %p to %d/n", this, mDataSize);  
        LOGV("continueWrite Setting data pos of %p to %d/n", this, mDataPos);  
        mDataCapacity = desired;  
    }  
  
    return NO_ERROR;  
}  
  
void Parcel::initState()  
{  
    mError = NO_ERROR;  
    mData = 0;  
    mDataSize = 0;  
    mDataCapacity = 0;  
    mDataPos = 0;  
    LOGV("initState Setting data size of %p to %d/n", this, mDataSize);  
    LOGV("initState Setting data pos of %p to %d/n", this, mDataPos);  
    mObjects = NULL;  
    mObjectsSize = 0;  
    mObjectsCapacity = 0;  
    mNextObjectHint = 0;  
    mHasFds = false;  
    mFdsKnown = true;  
    mOwner = NULL;  
}  
  
void Parcel::scanForFds() const  
{  
    bool hasFds = false;  
    for (size_t i=0; i<mObjectsSize; i++) {  
        const flat_binder_object* flat  
            = reinterpret_cast<const flat_binder_object*>(mData + mObjects[i]);  
        if (flat->type == BINDER_TYPE_FD) {  
            hasFds = true;  
            break;  
        }  
    }  
    mHasFds = hasFds;  
    mFdsKnown = true;  
}  
  
}; // namespace android

 

本文的源码使用的是Android 2.1版本。

转载请注明:尼古拉斯.赵四 » Android中的Parcel机制(上)

喜欢 (0)or分享 (0)
发表我的评论
取消评论

表情

Hi,您需要填写昵称和邮箱!

  • 昵称 (必填)
  • 邮箱 (必填)
  • 网址