vm/Debugger.c

/*
 * Copyright (C) 2008 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.
 */

/*
 * Link between JDWP and the VM.  The code here only runs as a result of
 * requests from the debugger, so speed is not essential.  Maintaining
 * isolation of the JDWP code should make it easier to maintain and reuse.
 *
 * Collecting all debugger-related pieces here will also allow us to #ifdef
 * the JDWP code out of release builds.
 */
#include "Dalvik.h"

/*
Notes on garbage collection and object registration

JDWP does not allow the debugger to assume that objects passed to it
will not be garbage collected.  It specifies explicit commands (e.g.
ObjectReference.DisableCollection) to allow the debugger to manage
object lifetime.  It does, however, require that the VM not re-use an
object ID unless an explicit "dispose" call has been made, and if the
VM asks for a now-collected object we must return INVALID_OBJECT.

JDWP also requires that, while the VM is suspended, no garbage collection
occur.  The JDWP docs suggest that this is obvious, because no threads
can be running.  Unfortunately it's not entirely clear how to deal
with situations where the debugger itself allocates strings or executes
code as part of displaying variables.  The easiest way to enforce this,
short of disabling GC whenever the debugger is connected, is to ensure
that the debugger thread can't cause a GC: it has to expand the heap or
fail to allocate.  (Might want to make that "is debugger thread AND all
other threads are suspended" to avoid unnecessary heap expansion by a
poorly-timed JDWP request.)

We use an "object registry" so that we can separate our internal
representation from what we show the debugger.  This allows us to
return a registry table index instead of a pointer or handle.

There are various approaches we can take to achieve correct behavior:

(1) Disable garbage collection entirely while the debugger is attached.
This is very easy, but doesn't allow extended debugging sessions on
small devices.

(2) Keep a list of all object references requested by or sent to the
debugger, and include the list in the GC root set.  This ensures that
objects the debugger might care about don't go away.  This is straightforward,
but it can cause us to hold on to large objects and prevent finalizers from
being executed.

(3) Keep a list of what amount to weak object references.  This way we
don't interfere with the GC, and can support JDWP requests like
"ObjectReference.IsCollected".

The current implementation is #2.  The set should be reasonably small and
performance isn't critical, so a simple expanding array can be used.


Notes on threads:

The VM has a Thread struct associated with every active thread.  The
ThreadId we pass to the debugger is the ObjectId for the java/lang/Thread
object, so to retrieve the VM's Thread struct we have to scan through the
list looking for a match.

When a thread goes away, we lock the list and free the struct.  To
avoid having the thread list updated or Thread structs freed out from
under us, we want to acquire and hold the thread list lock while we're
performing operations on Threads.  Exceptions to this rule are noted in
a couple of places.

We can speed this up a bit by adding a Thread struct pointer to the
java/lang/Thread object, and ensuring that both are discarded at the
same time.
*/

#define THREAD_GROUP_ALL ((ObjectId) 0x12345)   // magic, internal-only value

#define kSlot0Sub   1000    // Eclipse workaround

/*
 * System init.  We don't allocate the registry until first use.
 * Make sure we do this before initializing JDWP.
 */
bool dvmDebuggerStartup(void)
{
    if (!dvmBreakpointStartup())
        return false;

    gDvm.dbgRegistry = dvmHashTableCreate(1000, NULL);
    return (gDvm.dbgRegistry != NULL);
}

/*
 * Free registry storage.
 */
void dvmDebuggerShutdown(void)
{
    dvmHashTableFree(gDvm.dbgRegistry);
    gDvm.dbgRegistry = NULL;
    dvmBreakpointShutdown();
}


/*
 * Pass these through to the VM functions.  Allows extended checking
 * (e.g. "errorcheck" mutexes).  If nothing else we can assert() success.
 */
void dvmDbgInitMutex(pthread_mutex_t* pMutex)
{
    dvmInitMutex(pMutex);
}
void dvmDbgLockMutex(pthread_mutex_t* pMutex)
{
    dvmLockMutex(pMutex);
}
void dvmDbgUnlockMutex(pthread_mutex_t* pMutex)
{
    dvmUnlockMutex(pMutex);
}
void dvmDbgInitCond(pthread_cond_t* pCond)
{
    pthread_cond_init(pCond, NULL);
}
void dvmDbgCondWait(pthread_cond_t* pCond, pthread_mutex_t* pMutex)
{
    int cc = pthread_cond_wait(pCond, pMutex);
    assert(cc == 0);
}
void dvmDbgCondSignal(pthread_cond_t* pCond)
{
    int cc = pthread_cond_signal(pCond);
    assert(cc == 0);
}
void dvmDbgCondBroadcast(pthread_cond_t* pCond)
{
    int cc = pthread_cond_broadcast(pCond);
    assert(cc == 0);
}


/* keep track of type, in case we need to distinguish them someday */
typedef enum RegistryType {
    kObjectId = 0xc1, kRefTypeId
} RegistryType;

/*
 * Hash function for object IDs.  Since objects are at least 8 bytes, and
 * could someday be allocated on 16-byte boundaries, we don't want to use
 * the low 4 bits in our hash.
 */
static inline u4 registryHash(u4 val)
{
    return val >> 4;
}

/*
 * (This is a dvmHashTableLookup() callback.)
 */
static int registryCompare(const void* obj1, const void* obj2)
{
    return (int) obj1 - (int) obj2;
}


/*
 * Determine if an id is already in the list.
 *
 * If the list doesn't yet exist, this creates it.
 *
 * Lock the registry before calling here.
 */
static bool lookupId(ObjectId id)
{
    void* found;

    found = dvmHashTableLookup(gDvm.dbgRegistry, registryHash((u4) id),
                (void*)(u4) id, registryCompare, false);
    if (found == NULL)
        return false;
    assert(found == (void*)(u4) id);
    return true;
}

/*
 * Register an object, if it hasn't already been.
 *
 * This is used for both ObjectId and RefTypeId.  In theory we don't have
 * to register RefTypeIds unless we're worried about classes unloading.
 *
 * Null references must be represented as zero, or the debugger will get
 * very confused.
 */
static ObjectId registerObject(const Object* obj, RegistryType type, bool reg)
{
    ObjectId id;

    if (obj == NULL)
        return 0;

    assert((u4) obj != 0xcccccccc);
    assert((u4) obj > 0x100);

    id = (ObjectId)(u4)obj | ((u8) type) << 32;
    if (!reg)
        return id;

    dvmHashTableLock(gDvm.dbgRegistry);
    if (!gDvm.debuggerConnected) {
        /* debugger has detached while we were doing stuff? */
        LOGI("ignoring registerObject request in thread=%d\n",
            dvmThreadSelf()->threadId);
        //dvmAbort();
        goto bail;
    }

    (void) dvmHashTableLookup(gDvm.dbgRegistry, registryHash((u4) id),
                (void*)(u4) id, registryCompare, true);

bail:
    dvmHashTableUnlock(gDvm.dbgRegistry);
    return id;
}

/*
 * (This is a HashForeachFunc callback.)
 */
static int markRef(void* data, void* arg)
{
    UNUSED_PARAMETER(arg);

    //LOGI("dbg mark %p\n", data);
    dvmMarkObjectNonNull(data);
    return 0;
}

/* Mark all of the registered debugger references so the
 * GC doesn't collect them.
 */
void dvmGcMarkDebuggerRefs()
{
    /* dvmDebuggerStartup() may not have been called before the first GC.
     */
    if (gDvm.dbgRegistry != NULL) {
        dvmHashTableLock(gDvm.dbgRegistry);
        dvmHashForeach(gDvm.dbgRegistry, markRef, NULL);
        dvmHashTableUnlock(gDvm.dbgRegistry);
    }
}

/*
 * Verify that an object has been registered.  If it hasn't, the debugger
 * is asking for something we didn't send it, which means something
 * somewhere is broken.
 *
 * If speed is an issue we can encode the registry index in the high
 * four bytes.  We could also just hard-wire this to "true".
 *
 * Note this actually takes both ObjectId and RefTypeId.
 */
static bool objectIsRegistered(ObjectId id, RegistryType type)
{
    UNUSED_PARAMETER(type);

    if (id == 0)        // null reference?
        return true;

    dvmHashTableLock(gDvm.dbgRegistry);
    bool result = lookupId(id);
    dvmHashTableUnlock(gDvm.dbgRegistry);
    return result;
}

/*
 * Convert to/from a RefTypeId.
 *
 * These are rarely NULL, but can be (e.g. java/lang/Object's superclass).
 */
static RefTypeId classObjectToRefTypeId(ClassObject* clazz)
{
    return (RefTypeId) registerObject((Object*) clazz, kRefTypeId, true);
}
static RefTypeId classObjectToRefTypeIdNoReg(ClassObject* clazz)
{
    return (RefTypeId) registerObject((Object*) clazz, kRefTypeId, false);
}
static ClassObject* refTypeIdToClassObject(RefTypeId id)
{
    assert(objectIsRegistered(id, kRefTypeId) || !gDvm.debuggerConnected);
    return (ClassObject*)(u4) id;
}

/*
 * Convert to/from an ObjectId.
 */
static ObjectId objectToObjectId(const Object* obj)
{
    return registerObject(obj, kObjectId, true);
}
static ObjectId objectToObjectIdNoReg(const Object* obj)
{
    return registerObject(obj, kObjectId, false);
}
static Object* objectIdToObject(ObjectId id)
{
    assert(objectIsRegistered(id, kObjectId) || !gDvm.debuggerConnected);
    return (Object*)(u4) id;
}

/*
 * Register an object ID that might not have been registered previously.
 *
 * Normally this wouldn't happen -- the conversion to an ObjectId would
 * have added the object to the registry -- but in some cases (e.g.
 * throwing exceptions) we really want to do the registration late.
 */
void dvmDbgRegisterObjectId(ObjectId id)
{
    Object* obj = (Object*)(u4) id;
    LOGV("+++ registering %p (%s)\n", obj, obj->clazz->descriptor);
    registerObject(obj, kObjectId, true);
}

/*
 * Convert to/from a MethodId.
 *
 * These IDs are only guaranteed unique within a class, so they could be
 * an enumeration index.  For now we just use the Method*.
 */
static MethodId methodToMethodId(const Method* meth)
{
    return (MethodId)(u4) meth;
}
static Method* methodIdToMethod(RefTypeId refTypeId, MethodId id)
{
    // TODO? verify "id" is actually a method in "refTypeId"
    return (Method*)(u4) id;
}

/*
 * Convert to/from a FieldId.
 *
 * These IDs are only guaranteed unique within a class, so they could be
 * an enumeration index.  For now we just use the Field*.
 */
static FieldId fieldToFieldId(const Field* field)
{
    return (FieldId)(u4) field;
}
static Field* fieldIdToField(RefTypeId refTypeId, FieldId id)
{
    // TODO? verify "id" is actually a field in "refTypeId"
    return (Field*)(u4) id;
}

/*
 * Convert to/from a FrameId.
 *
 * We just return a pointer to the stack frame.
 */
static FrameId frameToFrameId(const void* frame)
{
    return (FrameId)(u4) frame;
}
static void* frameIdToFrame(FrameId id)
{
    return (void*)(u4) id;
}


/*
 * Get the invocation request state.
 */
DebugInvokeReq* dvmDbgGetInvokeReq(void)
{
    return &dvmThreadSelf()->invokeReq;
}

/*
 * Enable the object registry, but don't enable debugging features yet.
 *
 * Only called from the JDWP handler thread.
 */
void dvmDbgConnected(void)
{
    assert(!gDvm.debuggerConnected);

    LOGV("JDWP has attached\n");
    assert(dvmHashTableNumEntries(gDvm.dbgRegistry) == 0);
    gDvm.debuggerConnected = true;
}

/*
 * Enable all debugging features, including scans for breakpoints.
 *
 * This is a no-op if we're already active.
 *
 * Only called from the JDWP handler thread.
 */
void dvmDbgActive(void)
{
    if (gDvm.debuggerActive)
        return;

    LOGI("Debugger is active\n");
    dvmInitBreakpoints();
    gDvm.debuggerActive = true;
}

/*
 * Disable debugging features.
 *
 * Set "debuggerConnected" to false, which disables use of the object
 * registry.
 *
 * Only called from the JDWP handler thread.
 */
void dvmDbgDisconnected(void)
{
    assert(gDvm.debuggerConnected);

    gDvm.debuggerActive = false;

    dvmHashTableLock(gDvm.dbgRegistry);
    gDvm.debuggerConnected = false;

    LOGD("Debugger has detached; object registry had %d entries\n",
        dvmHashTableNumEntries(gDvm.dbgRegistry));
    //int i;
    //for (i = 0; i < gDvm.dbgRegistryNext; i++)
    //    LOGVV("%4d: 0x%llx\n", i, gDvm.dbgRegistryTable[i]);

    dvmHashTableClear(gDvm.dbgRegistry);
    dvmHashTableUnlock(gDvm.dbgRegistry);
}

/*
 * Returns "true" if a debugger is connected.
 *
 * Does not return "true" if it's just a DDM server.
 */
bool dvmDbgIsDebuggerConnected(void)
{
    return gDvm.debuggerActive;
}

/*
 * Get time since last debugger activity.  Used when figuring out if the
 * debugger has finished configuring us.
 */
s8 dvmDbgLastDebuggerActivity(void)
{
    return dvmJdwpLastDebuggerActivity(gDvm.jdwpState);
}

/*
 * JDWP thread is running, don't allow GC.
 */
int dvmDbgThreadRunning(void)
{
    return dvmChangeStatus(NULL, THREAD_RUNNING);
}

/*
 * JDWP thread is idle, allow GC.
 */
int dvmDbgThreadWaiting(void)
{
    return dvmChangeStatus(NULL, THREAD_VMWAIT);
}

/*
 * Restore state returned by Running/Waiting calls.
 */
int dvmDbgThreadContinuing(int status)
{
    return dvmChangeStatus(NULL, status);
}

/*
 * The debugger wants us to exit.
 */
void dvmDbgExit(int status)
{
    // TODO? invoke System.exit() to perform exit processing; ends up
    // in System.exitInternal(), which can call JNI exit hook
#ifdef WITH_PROFILER
    LOGI("GC lifetime allocation: %d bytes\n", gDvm.allocProf.allocCount);
    if (CALC_CACHE_STATS) {
        dvmDumpAtomicCacheStats(gDvm.instanceofCache);
        dvmDumpBootClassPath();
    }
#endif
#ifdef PROFILE_FIELD_ACCESS
    dvmDumpFieldAccessCounts();
#endif

    exit(status);
}


/*
 * ===========================================================================
 *      Class, Object, Array
 * ===========================================================================
 */

/*
 * Get the class's type descriptor from a reference type ID.
 */
const char* dvmDbgGetClassDescriptor(RefTypeId id)
{
    ClassObject* clazz;

    clazz = refTypeIdToClassObject(id);
    return clazz->descriptor;
}

/*
 * Convert a RefTypeId to an ObjectId.
 */
ObjectId dvmDbgGetClassObject(RefTypeId id)
{
    ClassObject* clazz = refTypeIdToClassObject(id);
    return objectToObjectId((Object*) clazz);
}

/*
 * Return the superclass of a class (will be NULL for java/lang/Object).
 */
RefTypeId dvmDbgGetSuperclass(RefTypeId id)
{
    ClassObject* clazz = refTypeIdToClassObject(id);
    return classObjectToRefTypeId(clazz->super);
}

/*
 * Return a class's defining class loader.
 */
RefTypeId dvmDbgGetClassLoader(RefTypeId id)
{
    ClassObject* clazz = refTypeIdToClassObject(id);
    return objectToObjectId(clazz->classLoader);
}

/*
 * Return a class's access flags.
 */
u4 dvmDbgGetAccessFlags(RefTypeId id)
{
    ClassObject* clazz = refTypeIdToClassObject(id);
    return clazz->accessFlags & JAVA_FLAGS_MASK;
}

/*
 * Is this class an interface?
 */
bool dvmDbgIsInterface(RefTypeId id)
{
    ClassObject* clazz = refTypeIdToClassObject(id);
    return dvmIsInterfaceClass(clazz);
}

/*
 * dvmHashForeach callback
 */
static int copyRefType(void* vclazz, void* varg)
{
    RefTypeId** pRefType = (RefTypeId**)varg;
    **pRefType = classObjectToRefTypeId((ClassObject*) vclazz);
    (*pRefType)++;
    return 0;
}

/*
 * Get the complete list of reference classes (i.e. all classes except
 * the primitive types).
 *
 * Returns a newly-allocated buffer full of RefTypeId values.
 */
void dvmDbgGetClassList(u4* pNumClasses, RefTypeId** pClassRefBuf)
{
    RefTypeId* pRefType;

    dvmHashTableLock(gDvm.loadedClasses);
    *pNumClasses = dvmHashTableNumEntries(gDvm.loadedClasses);
    pRefType = *pClassRefBuf = malloc(sizeof(RefTypeId) * *pNumClasses);

    if (dvmHashForeach(gDvm.loadedClasses, copyRefType, &pRefType) != 0) {
        LOGW("Warning: problem getting class list\n");
        /* not really expecting this to happen */
    } else {
        assert(pRefType - *pClassRefBuf == (int) *pNumClasses);
    }

    dvmHashTableUnlock(gDvm.loadedClasses);
}

/*
 * Get the list of reference classes "visible" to the specified class
 * loader.  A class is visible to a class loader if the ClassLoader object
 * is the defining loader or is listed as an initiating loader.
 *
 * Returns a newly-allocated buffer full of RefTypeId values.
 */
void dvmDbgGetVisibleClassList(ObjectId classLoaderId, u4* pNumClasses,
    RefTypeId** pClassRefBuf)
{
    Object* classLoader;
    int numClasses = 0, maxClasses;

    classLoader = objectIdToObject(classLoaderId);
    // I don't think classLoader can be NULL, but the spec doesn't say

    LOGVV("GetVisibleList: comparing to %p\n", classLoader);

    dvmHashTableLock(gDvm.loadedClasses);

    /* over-allocate the return buffer */
    maxClasses = dvmHashTableNumEntries(gDvm.loadedClasses);
    *pClassRefBuf = malloc(sizeof(RefTypeId) * maxClasses);

    /*
     * Run through the list, looking for matches.
     */
    HashIter iter;
    for (dvmHashIterBegin(gDvm.loadedClasses, &iter); !dvmHashIterDone(&iter);
        dvmHashIterNext(&iter))
    {
        ClassObject* clazz = (ClassObject*) dvmHashIterData(&iter);

        if (clazz->classLoader == classLoader ||
            dvmLoaderInInitiatingList(clazz, classLoader))
        {
            LOGVV("  match '%s'\n", clazz->descriptor);
            (*pClassRefBuf)[numClasses++] = classObjectToRefTypeId(clazz);
        }
    }
    *pNumClasses = numClasses;

    dvmHashTableUnlock(gDvm.loadedClasses);
}

/*
 * Generate the "JNI signature" for a class, e.g. "Ljava/lang/String;".
 *
 * Our class descriptors are in the correct format, so we just copy that.
 * TODO: figure out if we can avoid the copy now that we're using
 * descriptors instead of unadorned class names.
 *
 * Returns a newly-allocated string.
 */
static char* generateJNISignature(ClassObject* clazz)
{
    return strdup(clazz->descriptor);
}

/*
 * Get information about a class.
 *
 * If "pSignature" is not NULL, *pSignature gets the "JNI signature" of
 * the class.
 */
void dvmDbgGetClassInfo(RefTypeId classId, u1* pTypeTag, u4* pStatus,
    char** pSignature)
{
    ClassObject* clazz = refTypeIdToClassObject(classId);

    if (clazz->descriptor[0] == '[') {
        /* generated array class */
        *pStatus = CS_VERIFIED | CS_PREPARED;
        *pTypeTag = TT_ARRAY;
    } else {
        if (clazz->status == CLASS_ERROR)
            *pStatus = CS_ERROR;
        else
            *pStatus = CS_VERIFIED | CS_PREPARED | CS_INITIALIZED;
        if (dvmIsInterfaceClass(clazz))
            *pTypeTag = TT_INTERFACE;
        else
            *pTypeTag = TT_CLASS;
    }
    if (pSignature != NULL)
        *pSignature = generateJNISignature(clazz);
}

/*
 * Search the list of loaded classes for a match.
 */
bool dvmDbgFindLoadedClassBySignature(const char* classDescriptor,
        RefTypeId* pRefTypeId)
{
    ClassObject* clazz;

    clazz = dvmFindLoadedClass(classDescriptor);
    if (clazz != NULL) {
        *pRefTypeId = classObjectToRefTypeId(clazz);
        return true;
    } else
        return false;
}


/*
 * Get an object's class and "type tag".
 */
void dvmDbgGetObjectType(ObjectId objectId, u1* pRefTypeTag,
    RefTypeId* pRefTypeId)
{
    Object* obj = objectIdToObject(objectId);

    if (dvmIsArrayClass(obj->clazz))
        *pRefTypeTag = TT_ARRAY;
    else if (dvmIsInterfaceClass(obj->clazz))
        *pRefTypeTag = TT_INTERFACE;
    else
        *pRefTypeTag = TT_CLASS;
    *pRefTypeId = classObjectToRefTypeId(obj->clazz);
}

/*
 * Get a class object's "type tag".
 */
u1 dvmDbgGetClassObjectType(RefTypeId refTypeId)
{
    ClassObject* clazz = refTypeIdToClassObject(refTypeId);

    if (dvmIsArrayClass(clazz))
        return TT_ARRAY;
    else if (dvmIsInterfaceClass(clazz))
        return TT_INTERFACE;
    else
        return TT_CLASS;
}

/*
 * Get a class' signature.
 *
 * Returns a newly-allocated string.
 */
char* dvmDbgGetSignature(RefTypeId refTypeId)
{
    ClassObject* clazz;

    clazz = refTypeIdToClassObject(refTypeId);
    assert(clazz != NULL);

    return generateJNISignature(clazz);
}

/*
 * Get class' source file.
 *
 * Returns a newly-allocated string.
 */
const char* dvmDbgGetSourceFile(RefTypeId refTypeId)
{
    ClassObject* clazz;

    clazz = refTypeIdToClassObject(refTypeId);
    assert(clazz != NULL);

    return clazz->sourceFile;
}

/*
 * Get an object's type name.  Converted to a "JNI signature".
 *
 * Returns a newly-allocated string.
 */
char* dvmDbgGetObjectTypeName(ObjectId objectId)
{
    Object* obj = objectIdToObject(objectId);

    assert(obj != NULL);

    return generateJNISignature(obj->clazz);
}

/*
 * Given a type signature (e.g. "Ljava/lang/String;"), return the JDWP
 * "type tag".
 *
 * In many cases this is necessary but not sufficient.  For example, if
 * we have a NULL String object, we want to return JT_STRING.  If we have
 * a java/lang/Object that holds a String reference, we also want to
 * return JT_STRING.  See dvmDbgGetObjectTag().
 */
int dvmDbgGetSignatureTag(const char* type)
{
    /*
     * We're not checking the class loader here (to guarantee that JT_STRING
     * is truly the one and only String), but it probably doesn't matter
     * for our purposes.
     */
    if (strcmp(type, "Ljava/lang/String;") == 0)
        return JT_STRING;
    else if (strcmp(type, "Ljava/lang/Class;") == 0)
        return JT_CLASS_OBJECT; 
    else if (strcmp(type, "Ljava/lang/Thread;") == 0)
        return JT_THREAD;
    else if (strcmp(type, "Ljava/lang/ThreadGroup;") == 0)
        return JT_THREAD_GROUP;
    else if (strcmp(type, "Ljava/lang/ClassLoader;") == 0)
        return JT_CLASS_LOADER;

    switch (type[0]) {
    case '[':       return JT_ARRAY;
    case 'B':       return JT_BYTE;
    case 'C':       return JT_CHAR;
    case 'L':       return JT_OBJECT;
    case 'F':       return JT_FLOAT;
    case 'D':       return JT_DOUBLE;
    case 'I':       return JT_INT;
    case 'J':       return JT_LONG;
    case 'S':       return JT_SHORT;
    case 'V':       return JT_VOID;
    case 'Z':       return JT_BOOLEAN;
    default:
        LOGE("ERROR: unhandled type '%s'\n", type);
        assert(false);
        return -1;
    }
}

/*
 * Methods declared to return Object might actually be returning one
 * of the "refined types".  We need to check the object explicitly.
 */
static u1 resultTagFromObject(Object* obj)
{
    ClassObject* clazz;

    if (obj == NULL)
        return JT_OBJECT;

    clazz = obj->clazz;

    /*
     * Comparing against the known classes is faster than string
     * comparisons.  It ensures that we only find the classes in the
     * bootstrap class loader, which may or may not be what we want.
     */
    if (clazz == gDvm.classJavaLangString)
        return JT_STRING;
    else if (clazz == gDvm.classJavaLangClass)
        return JT_CLASS_OBJECT;
    else if (clazz == gDvm.classJavaLangThread)
        return JT_THREAD;
    else if (clazz == gDvm.classJavaLangThreadGroup)
        return JT_THREAD_GROUP;
    else if (strcmp(clazz->descriptor, "Ljava/lang/ClassLoader;") == 0)
        return JT_CLASS_LOADER;
    else if (clazz->descriptor[0] == '[')
        return JT_ARRAY;
    else
        return JT_OBJECT;
}

/*
 * Determine the tag for an object with a known type.
 */
int dvmDbgGetObjectTag(ObjectId objectId, const char* type)
{
    u1 tag;

    tag = dvmDbgGetSignatureTag(type);
    if (tag == JT_OBJECT && objectId != 0)
        tag = resultTagFromObject(objectIdToObject(objectId));

    return tag;
}

/*
 * Get the widths of the specified JDWP.Tag value.
 */
int dvmDbgGetTagWidth(int tag)
{
    switch (tag) {
    case JT_VOID:
        return 0;
    case JT_BYTE:
    case JT_BOOLEAN:
        return 1;
    case JT_CHAR:
    case JT_SHORT:
        return 2;
    case JT_FLOAT:
    case JT_INT:
        return 4;
    case JT_ARRAY:
    case JT_OBJECT:
    case JT_STRING:
    case JT_THREAD:
    case JT_THREAD_GROUP:
    case JT_CLASS_LOADER:
    case JT_CLASS_OBJECT:
        return sizeof(ObjectId);
    case JT_DOUBLE:
    case JT_LONG:
        return 8;
    default:
        LOGE("ERROR: unhandled tag '%c'\n", tag);
        assert(false);
        return -1;
    }
}

/*
 * Determine whether or not a tag represents a primitive type.
 */
static bool isTagPrimitive(u1 tag)
{
    switch (tag) {
    case JT_BYTE:
    case JT_CHAR:
    case JT_FLOAT:
    case JT_DOUBLE:
    case JT_INT:
    case JT_LONG:
    case JT_SHORT:
    case JT_VOID:
    case JT_BOOLEAN:
        return true;
    case JT_ARRAY:
    case JT_OBJECT:
    case JT_STRING:
    case JT_CLASS_OBJECT:
    case JT_THREAD:
    case JT_THREAD_GROUP:
    case JT_CLASS_LOADER:
        return false;
    default:
        LOGE("ERROR: unhandled tag '%c'\n", tag);
        assert(false);
        return false;
    }
}


/*
 * Return the length of the specified array.
 */
int dvmDbgGetArrayLength(ObjectId arrayId)
{
    ArrayObject* arrayObj = (ArrayObject*) objectIdToObject(arrayId);
    assert(dvmIsArray(arrayObj));
    return arrayObj->length;
}

/*
 * Return a tag indicating the general type of elements in the array.
 */
int dvmDbgGetArrayElementTag(ObjectId arrayId)
{
    ArrayObject* arrayObj = (ArrayObject*) objectIdToObject(arrayId);

    assert(dvmIsArray(arrayObj));

    return dvmDbgGetSignatureTag(arrayObj->obj.clazz->descriptor + 1);
}

/*
 * Copy a series of values with the specified width, changing the byte
 * ordering to big-endian.
 */
static void copyValuesToBE(u1* out, const u1* in, int count, int width)
{
    int i;

    switch (width) {
    case 1:
        memcpy(out, in, count);
        break;
    case 2:
        for (i = 0; i < count; i++)
            *(((u2*) out)+i) = get2BE(in + i*2);
        break;
    case 4:
        for (i = 0; i < count; i++)
            *(((u4*) out)+i) = get4BE(in + i*4);
        break;
    case 8:
        for (i = 0; i < count; i++)
            *(((u8*) out)+i) = get8BE(in + i*8);
        break;
    default:
        assert(false);
    }
}

/*
 * Copy a series of values with the specified with, changing the
 * byte order from big-endian.
 */
static void copyValuesFromBE(u1* out, const u1* in, int count, int width)
{
    int i;

    switch (width) {
    case 1:
        memcpy(out, in, count);
        break;
    case 2:
        for (i = 0; i < count; i++)
            set2BE(out + i*2, *((u2*)in + i));
        break;
    case 4:
        for (i = 0; i < count; i++)
            set4BE(out + i*4, *((u4*)in + i));
        break;
    case 8:
        for (i = 0; i < count; i++)
            set8BE(out + i*8, *((u8*)in + i));
        break;
    default:
        assert(false);
    }
}

/*
 * Output a piece of an array to the reply buffer.
 *
 * Returns "false" if something looks fishy.
 */
bool dvmDbgOutputArray(ObjectId arrayId, int firstIndex, int count,
    ExpandBuf* pReply)
{
    ArrayObject* arrayObj = (ArrayObject*) objectIdToObject(arrayId);
    const u1* data = (const u1*)arrayObj->contents;
    u1 tag;

    assert(dvmIsArray(arrayObj));

    if (firstIndex + count > (int)arrayObj->length) {
        LOGW("Request for index=%d + count=%d excceds length=%d\n",
            firstIndex, count, arrayObj->length);
        return false;
    }

    tag = dvmDbgGetSignatureTag(arrayObj->obj.clazz->descriptor + 1);

    if (isTagPrimitive(tag)) {
        int width = dvmDbgGetTagWidth(tag);
        u1* outBuf;

        outBuf = expandBufAddSpace(pReply, count * width);

        copyValuesToBE(outBuf, data + firstIndex*width, count, width);
    } else {
        Object** pObjects;
        int i;

        pObjects = (Object**) data;
        pObjects += firstIndex;

        LOGV("    --> copying %d object IDs\n", count);
        //assert(tag == JT_OBJECT);     // could be object or "refined" type

        for (i = 0; i < count; i++, pObjects++) {
            u1 thisTag;
            if (*pObjects != NULL)
                thisTag = resultTagFromObject(*pObjects);
            else
                thisTag = tag;
            expandBufAdd1(pReply, thisTag);
            expandBufAddObjectId(pReply, objectToObjectId(*pObjects));
        }
    }

    return true;
}

/*
 * Set a range of elements in an array from the data in "buf".
 */
bool dvmDbgSetArrayElements(ObjectId arrayId, int firstIndex, int count,
    const u1* buf)
{
    ArrayObject* arrayObj = (ArrayObject*) objectIdToObject(arrayId);
    u1* data = (u1*)arrayObj->contents;
    u1 tag;

    assert(dvmIsArray(arrayObj));

    if (firstIndex + count > (int)arrayObj->length) {
        LOGW("Attempt to set index=%d + count=%d excceds length=%d\n",
            firstIndex, count, arrayObj->length);
        return false;
    }

    tag = dvmDbgGetSignatureTag(arrayObj->obj.clazz->descriptor + 1);

    if (isTagPrimitive(tag)) {
        int width = dvmDbgGetTagWidth(tag);

        LOGV("    --> setting %d '%c' width=%d\n", count, tag, width);

        copyValuesFromBE(data + firstIndex*width, buf, count, width);
    } else {
        Object** pObjects;
        int i;

        pObjects = (Object**) data;
        pObjects += firstIndex;

        LOGV("    --> setting %d objects", count);

        /* should do array type check here */
        for (i = 0; i < count; i++) {
            ObjectId id = dvmReadObjectId(&buf);
            *pObjects++ = objectIdToObject(id);
        }
    }

    return true;
}

/*
 * Create a new string.
 *
 * The only place the reference will be held in the VM is in our registry.
 */
ObjectId dvmDbgCreateString(const char* str)
{
    StringObject* strObj;

    strObj = dvmCreateStringFromCstr(str, ALLOC_DEFAULT);
    dvmReleaseTrackedAlloc((Object*) strObj, NULL);
    return objectToObjectId((Object*) strObj);
}

/*
 * Allocate a new object of the specified type.
 *
 * Add it to the registry to prevent it from being GCed.
 */
ObjectId dvmDbgCreateObject(RefTypeId classId)
{
    ClassObject* clazz = refTypeIdToClassObject(classId);
    Object* newObj = dvmAllocObject(clazz, ALLOC_DEFAULT);
    dvmReleaseTrackedAlloc(newObj, NULL);
    return objectToObjectId(newObj);
}

/*
 * Determine if "instClassId" is an instance of "classId".
 */
bool dvmDbgMatchType(RefTypeId instClassId, RefTypeId classId)
{
    ClassObject* instClazz = refTypeIdToClassObject(instClassId);
    ClassObject* clazz = refTypeIdToClassObject(classId);

    return dvmInstanceof(instClazz, clazz);
}


/*
 * ===========================================================================
 *      Method and Field
 * ===========================================================================
 */

/*
 * Get the method name from a MethodId.
 */
const char* dvmDbgGetMethodName(RefTypeId refTypeId, MethodId id)
{
    Method* meth;

    meth = methodIdToMethod(refTypeId, id);
    return meth->name;
}

/*
 * For ReferenceType.Fields and ReferenceType.FieldsWithGeneric:
 * output all fields declared by the class.  Inerhited fields are
 * not included.
 */
void dvmDbgOutputAllFields(RefTypeId refTypeId, bool withGeneric,
    ExpandBuf* pReply)
{
    static const u1 genericSignature[1] = "";
    ClassObject* clazz;
    Field* field;
    u4 declared;
    int i;

    clazz = refTypeIdToClassObject(refTypeId);
    assert(clazz != NULL);

    declared = clazz->sfieldCount + clazz->ifieldCount;
    expandBufAdd4BE(pReply, declared);

    for (i = 0; i < clazz->sfieldCount; i++) {
        field = (Field*) &clazz->sfields[i];

        expandBufAddFieldId(pReply, fieldToFieldId(field));
        expandBufAddUtf8String(pReply, (const u1*) field->name);
        expandBufAddUtf8String(pReply, (const u1*) field->signature);
        if (withGeneric)
            expandBufAddUtf8String(pReply, genericSignature);
        expandBufAdd4BE(pReply, field->accessFlags);
    }
    for (i = 0; i < clazz->ifieldCount; i++) {
        field = (Field*) &clazz->ifields[i];

        expandBufAddFieldId(pReply, fieldToFieldId(field));
        expandBufAddUtf8String(pReply, (const u1*) field->name);
        expandBufAddUtf8String(pReply, (const u1*) field->signature);
        if (withGeneric)
            expandBufAddUtf8String(pReply, genericSignature);
        expandBufAdd4BE(pReply, field->accessFlags);
    }
}

/*
 * For ReferenceType.Methods and ReferenceType.MethodsWithGeneric:
 * output all methods declared by the class.  Inherited methods are
 * not included.
 */
void dvmDbgOutputAllMethods(RefTypeId refTypeId, bool withGeneric,
    ExpandBuf* pReply)
{
    DexStringCache stringCache;
    static const u1 genericSignature[1] = "";
    ClassObject* clazz;
    Method* meth;
    u4 declared;
    int i;

    dexStringCacheInit(&stringCache);
    
    clazz = refTypeIdToClassObject(refTypeId);
    assert(clazz != NULL);

    declared = clazz->directMethodCount + clazz->virtualMethodCount;
    expandBufAdd4BE(pReply, declared);

    for (i = 0; i < clazz->directMethodCount; i++) {
        meth = &clazz->directMethods[i];

        expandBufAddMethodId(pReply, methodToMethodId(meth));
        expandBufAddUtf8String(pReply, (const u1*) meth->name);

        expandBufAddUtf8String(pReply,
            (const u1*) dexProtoGetMethodDescriptor(&meth->prototype,
                    &stringCache));

        if (withGeneric)
            expandBufAddUtf8String(pReply, genericSignature);
        expandBufAdd4BE(pReply, meth->accessFlags);
    }
    for (i = 0; i < clazz->virtualMethodCount; i++) {
        meth = &clazz->virtualMethods[i];

        expandBufAddMethodId(pReply, methodToMethodId(meth));
        expandBufAddUtf8String(pReply, (const u1*) meth->name);

        expandBufAddUtf8String(pReply,
            (const u1*) dexProtoGetMethodDescriptor(&meth->prototype,
                    &stringCache));

        if (withGeneric)
            expandBufAddUtf8String(pReply, genericSignature);
        expandBufAdd4BE(pReply, meth->accessFlags);
    }

    dexStringCacheRelease(&stringCache);
}

/*
 * Output all interfaces directly implemented by the class.
 */
void dvmDbgOutputAllInterfaces(RefTypeId refTypeId, ExpandBuf* pReply)
{
    ClassObject* clazz;
    int i, start, count;

    clazz = refTypeIdToClassObject(refTypeId);
    assert(clazz != NULL);

    if (clazz->super == NULL)
        start = 0;
    else
        start = clazz->super->iftableCount;

    count = clazz->iftableCount - start;
    expandBufAdd4BE(pReply, count);
    for (i = start; i < clazz->iftableCount; i++) {
        ClassObject* iface = clazz->iftable[i].clazz;
        expandBufAddRefTypeId(pReply, classObjectToRefTypeId(iface));
    }
}

typedef struct DebugCallbackContext {
    int numItems;
    ExpandBuf* pReply;
    // used by locals table
    bool withGeneric;
} DebugCallbackContext;

static int lineTablePositionsCb(void *cnxt, u4 address, u4 lineNum) 
{
    DebugCallbackContext *pContext = (DebugCallbackContext *)cnxt;

    expandBufAdd8BE(pContext->pReply, address);
    expandBufAdd4BE(pContext->pReply, lineNum);
    pContext->numItems++;

    return 0;
}

/*
 * For Method.LineTable: output the line table.
 *
 * Note we operate in Dalvik's 16-bit units rather than bytes.
 */
void dvmDbgOutputLineTable(RefTypeId refTypeId, MethodId methodId,
    ExpandBuf* pReply)
{
    Method* method;
    u8 start, end;
    int i;
    DebugCallbackContext context;

    memset (&context, 0, sizeof(DebugCallbackContext));

    method = methodIdToMethod(refTypeId, methodId);
    if (dvmIsNativeMethod(method)) {
        start = (u8) -1;
        end = (u8) -1;
    } else {
        start = 0;
        end = dvmGetMethodInsnsSize(method);
    }

    expandBufAdd8BE(pReply, start);
    expandBufAdd8BE(pReply, end);

    // Add numLines later
    size_t numLinesOffset = expandBufGetLength(pReply);
    expandBufAdd4BE(pReply, 0);

    context.pReply = pReply;

    dexDecodeDebugInfo(method->clazz->pDvmDex->pDexFile,
        dvmGetMethodCode(method),
        method->clazz->descriptor,
        method->prototype.protoIdx,
        method->accessFlags,
        lineTablePositionsCb, NULL, &context);

    set4BE(expandBufGetBuffer(pReply) + numLinesOffset, context.numItems);
}

/*
 * Eclipse appears to expect that the "this" reference is in slot zero.
 * If it's not, the "variables" display will show two copies of "this",
 * possibly because it gets "this" from SF.ThisObject and then displays
 * all locals with nonzero slot numbers.
 *
 * So, we remap the item in slot 0 to 1000, and remap "this" to zero.  On
 * SF.GetValues / SF.SetValues we map them back.
 */
static int tweakSlot(int slot, const char* name)
{
    int newSlot = slot;

    if (strcmp(name, "this") == 0)      // only remap "this" ptr
        newSlot = 0;
    else if (slot == 0)                 // always remap slot 0
        newSlot = kSlot0Sub;

    LOGV("untweak: %d to %d\n", slot, newSlot);
    return newSlot;
}

/*
 * Reverse Eclipse hack.
 */
static int untweakSlot(int slot, const void* framePtr)
{
    int newSlot = slot;

    if (slot == kSlot0Sub) {
        newSlot = 0;
    } else if (slot == 0) {
        const StackSaveArea* saveArea = SAVEAREA_FROM_FP(framePtr);
        const Method* method = saveArea->method;
        newSlot = method->registersSize - method->insSize;
    }

    LOGV("untweak: %d to %d\n", slot, newSlot);
    return newSlot;
}

static void variableTableCb (void *cnxt, u2 reg, u4 startAddress,
        u4 endAddress, const char *name, const char *descriptor,
        const char *signature)
{
    DebugCallbackContext *pContext = (DebugCallbackContext *)cnxt;

    reg = (u2) tweakSlot(reg, name);

    LOGV("    %2d: %d(%d) '%s' '%s' slot=%d\n",
        pContext->numItems, startAddress, endAddress - startAddress,
        name, descriptor, reg);

    expandBufAdd8BE(pContext->pReply, startAddress);
    expandBufAddUtf8String(pContext->pReply, (const u1*)name);
    expandBufAddUtf8String(pContext->pReply, (const u1*)descriptor);
    if (pContext->withGeneric) {
        expandBufAddUtf8String(pContext->pReply, (const u1*) signature);
    }
    expandBufAdd4BE(pContext->pReply, endAddress - startAddress);
    expandBufAdd4BE(pContext->pReply, reg);

    pContext->numItems++;
}

/*
 * For Method.VariableTable[WithGeneric]: output information about local
 * variables for the specified method.
 */
void dvmDbgOutputVariableTable(RefTypeId refTypeId, MethodId methodId,
    bool withGeneric, ExpandBuf* pReply)
{
    Method* method;
    DebugCallbackContext context;

    memset (&context, 0, sizeof(DebugCallbackContext));
    
    method = methodIdToMethod(refTypeId, methodId);

    expandBufAdd4BE(pReply, method->insSize);

    // Add numLocals later
    size_t numLocalsOffset = expandBufGetLength(pReply);
    expandBufAdd4BE(pReply, 0);

    context.pReply = pReply;
    context.withGeneric = withGeneric;
    dexDecodeDebugInfo(method->clazz->pDvmDex->pDexFile,
        dvmGetMethodCode(method),
        method->clazz->descriptor,
        method->prototype.protoIdx,
        method->accessFlags,
        NULL, variableTableCb, &context);

    set4BE(expandBufGetBuffer(pReply) + numLocalsOffset, context.numItems);
}

/*
 * Get the type tag for the field's type.
 */
int dvmDbgGetFieldTag(ObjectId objId, FieldId fieldId)
{
    Object* obj = objectIdToObject(objId);
    RefTypeId classId = classObjectToRefTypeId(obj->clazz);
    Field* field = fieldIdToField(classId, fieldId);

    return dvmDbgGetSignatureTag(field->signature);
}

/*
 * Get the type tag for the static field's type.
 */
int dvmDbgGetStaticFieldTag(RefTypeId refTypeId, FieldId fieldId)
{
    Field* field = fieldIdToField(refTypeId, fieldId);
    return dvmDbgGetSignatureTag(field->signature);
}

/*
 * Copy the value of a field into the specified buffer.
 */
void dvmDbgGetFieldValue(ObjectId objectId, FieldId fieldId, u1* buf,
    int expectedLen)
{
    Object* obj = objectIdToObject(objectId);
    RefTypeId classId = classObjectToRefTypeId(obj->clazz);
    InstField* field = (InstField*) fieldIdToField(classId, fieldId);
    Object* objVal;
    u4 intVal;
    u8 longVal;

    switch (field->field.signature[0]) {
    case JT_BOOLEAN:
        assert(expectedLen == 1);
        intVal = dvmGetFieldBoolean(obj, field->byteOffset);
        set1(buf, intVal != 0);
        break;
    case JT_BYTE:
        assert(expectedLen == 1);
        intVal = dvmGetFieldInt(obj, field->byteOffset);
        set1(buf, intVal);
        break;
    case JT_SHORT:
    case JT_CHAR:
        assert(expectedLen == 2);
        intVal = dvmGetFieldInt(obj, field->byteOffset);
        set2BE(buf, intVal);
        break;
    case JT_INT:
    case JT_FLOAT:
        assert(expectedLen == 4);
        intVal = dvmGetFieldInt(obj, field->byteOffset);
        set4BE(buf, intVal);
        break;
    case JT_ARRAY:
    case JT_OBJECT:
        assert(expectedLen == sizeof(ObjectId));
        objVal = dvmGetFieldObject(obj, field->byteOffset);
        dvmSetObjectId(buf, objectToObjectId(objVal));
        break;
    case JT_DOUBLE:
    case JT_LONG:
        assert(expectedLen == 8);
        longVal = dvmGetFieldLong(obj, field->byteOffset);
        set8BE(buf, longVal);
        break;
    default:
        LOGE("ERROR: unhandled class type '%s'\n", field->field.signature);
        assert(false);
        break;
    }
}

/*
 * Set the value of the specified field.
 */
void dvmDbgSetFieldValue(ObjectId objectId, FieldId fieldId, u8 value,
    int width)
{
    Object* obj = objectIdToObject(objectId);
    RefTypeId classId = classObjectToRefTypeId(obj->clazz);
    InstField* field = (InstField*) fieldIdToField(classId, fieldId);

    switch (field->field.signature[0]) {
    case JT_BOOLEAN:
        assert(width == 1);
        dvmSetFieldBoolean(obj, field->byteOffset, value != 0);
        break;
    case JT_BYTE:
        assert(width == 1);
        dvmSetFieldInt(obj, field->byteOffset, value);
        break;
    case JT_SHORT:
    case JT_CHAR:
        assert(width == 2);
        dvmSetFieldInt(obj, field->byteOffset, value);
        break;
    case JT_INT:
    case JT_FLOAT:
        assert(width == 4);
        dvmSetFieldInt(obj, field->byteOffset, value);
        break;
    case JT_ARRAY:
    case JT_OBJECT:
        assert(width == sizeof(ObjectId));
        dvmSetFieldObject(obj, field->byteOffset, objectIdToObject(value));
        break;
    case JT_DOUBLE:
    case JT_LONG:
        assert(width == 8);
        dvmSetFieldLong(obj, field->byteOffset, value);
        break;
    default:
        LOGE("ERROR: unhandled class type '%s'\n", field->field.signature);
        assert(false);
        break;
    }
}

/*
 * Copy the value of a static field into the specified buffer.
 */
void dvmDbgGetStaticFieldValue(RefTypeId refTypeId, FieldId fieldId, u1* buf,
    int expectedLen)
{
    StaticField* sfield = (StaticField*) fieldIdToField(refTypeId, fieldId);
    Object* objVal;
    JValue value;

    switch (sfield->field.signature[0]) {
    case JT_BOOLEAN:
        assert(expectedLen == 1);
        set1(buf, dvmGetStaticFieldBoolean(sfield));
        break;
    case JT_BYTE:
        assert(expectedLen == 1);
        set1(buf, dvmGetStaticFieldByte(sfield));
        break;
    case JT_SHORT:
        assert(expectedLen == 2);
        set2BE(buf, dvmGetStaticFieldShort(sfield));
        break;
    case JT_CHAR:
        assert(expectedLen == 2);
        set2BE(buf, dvmGetStaticFieldChar(sfield));
        break;
    case JT_INT:
        assert(expectedLen == 4);
        set4BE(buf, dvmGetStaticFieldInt(sfield));
        break;
    case JT_FLOAT:
        assert(expectedLen == 4);
        value.f = dvmGetStaticFieldFloat(sfield);
        set4BE(buf, value.i);
        break;
    case JT_ARRAY:
    case JT_OBJECT:
        assert(expectedLen == sizeof(ObjectId));
        objVal = dvmGetStaticFieldObject(sfield);
        dvmSetObjectId(buf, objectToObjectId(objVal));
        break;
    case JT_LONG:
        assert(expectedLen == 8);
        set8BE(buf, dvmGetStaticFieldLong(sfield));
        break;
    case JT_DOUBLE:
        assert(expectedLen == 8);
        value.d = dvmGetStaticFieldDouble(sfield);
        set8BE(buf, value.j);
        break;
    default:
        LOGE("ERROR: unhandled class type '%s'\n", sfield->field.signature);
        assert(false);
        break;
    }
}

/*
 * Set the value of a static field.
 */
void dvmDbgSetStaticFieldValue(RefTypeId refTypeId, FieldId fieldId,
    u8 rawValue, int width)
{
    StaticField* sfield = (StaticField*) fieldIdToField(refTypeId, fieldId);
    Object* objVal;
    JValue value;
    
    value.j = rawValue;

    switch (sfield->field.signature[0]) {
    case JT_BOOLEAN:
        assert(width == 1);
        dvmSetStaticFieldBoolean(sfield, value.z);
        break;
    case JT_BYTE:
        assert(width == 1);
        dvmSetStaticFieldByte(sfield, value.b);
        break;
    case JT_SHORT:
        assert(width == 2);
        dvmSetStaticFieldShort(sfield, value.s);
        break;
    case JT_CHAR:
        assert(width == 2);
        dvmSetStaticFieldChar(sfield, value.c);
        break;
    case JT_INT:
        assert(width == 4);
        dvmSetStaticFieldInt(sfield, value.i);
        break;
    case JT_FLOAT:
        assert(width == 4);
        dvmSetStaticFieldFloat(sfield, value.f);
        break;
    case JT_ARRAY:
    case JT_OBJECT:
        assert(width == sizeof(ObjectId));
        objVal = objectIdToObject(rawValue);
        dvmSetStaticFieldObject(sfield, objVal);
        break;
    case JT_LONG:
        assert(width == 8);
        dvmSetStaticFieldLong(sfield, value.j);
        break;
    case JT_DOUBLE:
        assert(width == 8);
        dvmSetStaticFieldDouble(sfield, value.d);
        break;
    default:
        LOGE("ERROR: unhandled class type '%s'\n", sfield->field.signature);
        assert(false);
        break;
    }
}

/*
 * Convert a string object to a UTF-8 string.
 *
 * Returns a newly-allocated string.
 */
char* dvmDbgStringToUtf8(ObjectId strId)
{
    StringObject* strObj = (StringObject*) objectIdToObject(strId);

    return dvmCreateCstrFromString(strObj);
}


/*
 * ===========================================================================
 *      Thread and ThreadGroup
 * ===========================================================================
 */

/*
 * Convert a thread object to a Thread ptr.
 *
 * This currently requires running through the list of threads and finding
 * a match.
 *
 * IMPORTANT: grab gDvm.threadListLock before calling here.
 */
static Thread* threadObjToThread(Object* threadObj)
{
    Thread* thread;

    for (thread = gDvm.threadList; thread != NULL; thread = thread->next) {
        if (thread->threadObj == threadObj)
            break;
    }

    return thread;
}

/*
 * Get the status and suspend state of a thread.
 */
bool dvmDbgGetThreadStatus(ObjectId threadId, u4* pThreadStatus,
    u4* pSuspendStatus)
{
    Object* threadObj;
    Thread* thread;
    bool result = false;
    
    threadObj = objectIdToObject(threadId);
    assert(threadObj != NULL);

    /* lock the thread list, so the thread doesn't vanish while we work */
    dvmLockThreadList(NULL);

    thread = threadObjToThread(threadObj);
    if (thread == NULL)
        goto bail;

    switch (thread->status) {
    case THREAD_ZOMBIE:         *pThreadStatus = TS_ZOMBIE;     break;
    case THREAD_RUNNING:        *pThreadStatus = TS_RUNNING;    break;
    case THREAD_TIMED_WAIT:     *pThreadStatus = TS_SLEEPING;   break;
    case THREAD_MONITOR:        *pThreadStatus = TS_MONITOR;    break;
    case THREAD_WAIT:           *pThreadStatus = TS_WAIT;       break;
    case THREAD_INITIALIZING:   *pThreadStatus = TS_ZOMBIE;     break;
    case THREAD_STARTING:       *pThreadStatus = TS_ZOMBIE;     break;
    case THREAD_NATIVE:         *pThreadStatus = TS_RUNNING;    break;
    case THREAD_VMWAIT:         *pThreadStatus = TS_WAIT;       break;
    default:
        assert(false);
        *pThreadStatus = THREAD_ZOMBIE;
        break;
    }

    if (dvmIsSuspended(thread))
        *pSuspendStatus = SUSPEND_STATUS_SUSPENDED;
    else
        *pSuspendStatus = 0;

    result = true;

bail:
    dvmUnlockThreadList();
    return result;
}

/*
 * Get the thread's suspend count.
 */
u4 dvmDbgGetThreadSuspendCount(ObjectId threadId)
{
    Object* threadObj;
    Thread* thread;
    u4 result = 0;
    
    threadObj = objectIdToObject(threadId);
    assert(threadObj != NULL);

    /* lock the thread list, so the thread doesn't vanish while we work */
    dvmLockThreadList(NULL);

    thread = threadObjToThread(threadObj);
    if (thread == NULL)
        goto bail;

    result = thread->suspendCount;

bail:
    dvmUnlockThreadList();
    return result;
}

/*
 * Determine whether or not a thread exists in the VM's thread list.
 *
 * Returns "true" if the thread exists.
 */
bool dvmDbgThreadExists(ObjectId threadId)
{
    Object* threadObj;
    Thread* thread;
    bool result;
    
    threadObj = objectIdToObject(threadId);
    assert(threadObj != NULL);

    /* lock the thread list, so the thread doesn't vanish while we work */
    dvmLockThreadList(NULL);

    thread = threadObjToThread(threadObj);
    if (thread == NULL)
        result = false;
    else
        result = true;

    dvmUnlockThreadList();
    return result;
}

/*
 * Determine whether or not a thread is suspended.
 *
 * Returns "false" if the thread is running or doesn't exist.
 */
bool dvmDbgIsSuspended(ObjectId threadId)
{
    Object* threadObj;
    Thread* thread;
    bool result = false;
    
    threadObj = objectIdToObject(threadId);
    assert(threadObj != NULL);

    /* lock the thread list, so the thread doesn't vanish while we work */
    dvmLockThreadList(NULL);

    thread = threadObjToThread(threadObj);
    if (thread == NULL)
        goto bail;

    result = dvmIsSuspended(thread);

bail:
    dvmUnlockThreadList();
    return result;
}

#if 0
/*
 * Wait until a thread suspends.
 *
 * We stray from the usual pattern here, and release the thread list lock
 * before we use the Thread.  This is necessary and should be safe in this
 * circumstance; see comments in dvmWaitForSuspend().
 */
void dvmDbgWaitForSuspend(ObjectId threadId)
{
    Object* threadObj;
    Thread* thread;
    
    threadObj = objectIdToObject(threadId);
    assert(threadObj != NULL);

    dvmLockThreadList(NULL);
    thread = threadObjToThread(threadObj);
    dvmUnlockThreadList();

    if (thread != NULL)
        dvmWaitForSuspend(thread);
}
#endif


/*
 * Return the ObjectId for the "system" thread group.
 */
ObjectId dvmDbgGetSystemThreadGroupId(void)
{
    Object* groupObj = dvmGetSystemThreadGroup();
    return objectToObjectId(groupObj);
}

/*
 * Return the ObjectId for the "system" thread group.
 */
ObjectId dvmDbgGetMainThreadGroupId(void)
{
    Object* groupObj = dvmGetMainThreadGroup();
    return objectToObjectId(groupObj);
}

/*
 * Get the name of a thread.
 *
 * Returns a newly-allocated string.
 */
char* dvmDbgGetThreadName(ObjectId threadId)
{
    Object* threadObj;
    StringObject* nameStr;
    char* str;
    char* result;

    threadObj = objectIdToObject(threadId);
    assert(threadObj != NULL);

    nameStr = (StringObject*) dvmGetFieldObject(threadObj,
                                                gDvm.offJavaLangThread_name);
    str = dvmCreateCstrFromString(nameStr);
    result = (char*) malloc(strlen(str) + 20);

    /* lock the thread list, so the thread doesn't vanish while we work */
    dvmLockThreadList(NULL);
    Thread* thread = threadObjToThread(threadObj);
    if (thread != NULL)
        sprintf(result, "<%d> %s", thread->threadId, str);
    else
        sprintf(result, "%s", str);
    dvmUnlockThreadList();

    free(str);
    return result;
}

/*
 * Get a thread's group.
 */
ObjectId dvmDbgGetThreadGroup(ObjectId threadId)
{
    Object* threadObj;
    Object* group;

    threadObj = objectIdToObject(threadId);
    assert(threadObj != NULL);

    group = dvmGetFieldObject(threadObj, gDvm.offJavaLangThread_group);
    return objectToObjectId(group);
}


/*
 * Get the name of a thread group.
 *
 * Returns a newly-allocated string.
 */
char* dvmDbgGetThreadGroupName(ObjectId threadGroupId)
{
    Object* threadGroup;
    InstField* nameField;
    StringObject* nameStr;

    threadGroup = objectIdToObject(threadGroupId);
    assert(threadGroup != NULL);

    nameField = dvmFindInstanceField(gDvm.classJavaLangThreadGroup,
                    "name", "Ljava/lang/String;");
    if (nameField == NULL) {
        LOGE("unable to find name field in ThreadGroup\n");
        return NULL;
    }

    nameStr = (StringObject*) dvmGetFieldObject(threadGroup,
                                                nameField->byteOffset);
    return dvmCreateCstrFromString(nameStr);
}

/*
 * Get the parent of a thread group.
 *
 * Returns a newly-allocated string.
 */
ObjectId dvmDbgGetThreadGroupParent(ObjectId threadGroupId)
{
    Object* threadGroup;
    InstField* parentField;
    Object* parent;

    threadGroup = objectIdToObject(threadGroupId);
    assert(threadGroup != NULL);

    parentField = dvmFindInstanceField(gDvm.classJavaLangThreadGroup,
                    "parent", "Ljava/lang/ThreadGroup;");
    if (parentField == NULL) {
        LOGE("unable to find parent field in ThreadGroup\n");
        parent = NULL;
    } else {
        parent = dvmGetFieldObject(threadGroup, parentField->byteOffset);
    }
    return objectToObjectId(parent);
}

/*
 * Get the list of threads in the thread group.
 *
 * We do this by running through the full list of threads and returning
 * the ones that have the ThreadGroup object as their owner.
 *
 * If threadGroupId is set to "kAllThreads", we ignore the group field and
 * return all threads.
 *
 * The caller must free "*ppThreadIds".
 */
void dvmDbgGetThreadGroupThreads(ObjectId threadGroupId,
    ObjectId** ppThreadIds, u4* pThreadCount)
{
    Object* targetThreadGroup = NULL;
    InstField* groupField = NULL;
    Thread* thread;
    int count;

    if (threadGroupId != THREAD_GROUP_ALL) {
        targetThreadGroup = objectIdToObject(threadGroupId);
        assert(targetThreadGroup != NULL);
    }

    groupField = dvmFindInstanceField(gDvm.classJavaLangThread,
        "group", "Ljava/lang/ThreadGroup;");

    dvmLockThreadList(NULL);

    thread = gDvm.threadList;
    count = 0;
    for (thread = gDvm.threadList; thread != NULL; thread = thread->next) {
        Object* group;

        /* Skip over the JDWP support thread.  Some debuggers
         * get bent out of shape when they can't suspend and
         * query all threads, so it's easier if we just don't
         * tell them about us.
         */
        if (thread->handle == dvmJdwpGetDebugThread(gDvm.jdwpState))
            continue;

        /* This thread is currently being created, and isn't ready
         * to be seen by the debugger yet.
         */
        if (thread->threadObj == NULL)
            continue;

        group = dvmGetFieldObject(thread->threadObj, groupField->byteOffset);
        if (threadGroupId == THREAD_GROUP_ALL || group == targetThreadGroup)
            count++;
    }

    *pThreadCount = count;

    if (count == 0) {
        *ppThreadIds = NULL;
    } else {
        ObjectId* ptr;
        ptr = *ppThreadIds = (ObjectId*) malloc(sizeof(ObjectId) * count);

        for (thread = gDvm.threadList; thread != NULL; thread = thread->next) {
            Object* group;

            /* Skip over the JDWP support thread.  Some debuggers
             * get bent out of shape when they can't suspend and
             * query all threads, so it's easier if we just don't
             * tell them about us.
             */
            if (thread->handle == dvmJdwpGetDebugThread(gDvm.jdwpState))
                continue;

            /* This thread is currently being created, and isn't ready
             * to be seen by the debugger yet.
             */
            if (thread->threadObj == NULL)
                continue;

            group = dvmGetFieldObject(thread->threadObj,groupField->byteOffset);
            if (threadGroupId == THREAD_GROUP_ALL || group == targetThreadGroup)
            {
                *ptr++ = objectToObjectId(thread->threadObj);
                count--;
            }
        }

        assert(count == 0);
    }

    dvmUnlockThreadList();
}

/*
 * Get all threads.
 *
 * The caller must free "*ppThreadIds".
 */
void dvmDbgGetAllThreads(ObjectId** ppThreadIds, u4* pThreadCount)
{
    dvmDbgGetThreadGroupThreads(THREAD_GROUP_ALL, ppThreadIds, pThreadCount);
}


/*
 * Count up the #of frames on the thread's stack.
 *
 * Returns -1 on failure;
 */
int dvmDbgGetThreadFrameCount(ObjectId threadId)
{
    Object* threadObj;
    Thread* thread;
    void* framePtr;
    u4 count = 0;

    threadObj = objectIdToObject(threadId);

    dvmLockThreadList(NULL);

    thread = threadObjToThread(threadObj);
    if (thread == NULL)
        goto bail;

    framePtr = thread->curFrame;
    while (framePtr != NULL) {
        if (!dvmIsBreakFrame(framePtr))
            count++;

        framePtr = SAVEAREA_FROM_FP(framePtr)->prevFrame;
    }

bail:
    dvmUnlockThreadList();
    return count;
}

/*
 * Get info for frame N from the specified thread's stack.
 */
bool dvmDbgGetThreadFrame(ObjectId threadId, int num, FrameId* pFrameId,
    JdwpLocation* pLoc)
{
    Object* threadObj;
    Thread* thread;
    void* framePtr;
    int count;

    threadObj = objectIdToObject(threadId);

    dvmLockThreadList(NULL);

    thread = threadObjToThread(threadObj);
    if (thread == NULL)
        goto bail;

    framePtr = thread->curFrame;
    count = 0;
    while (framePtr != NULL) {
        const StackSaveArea* saveArea = SAVEAREA_FROM_FP(framePtr);
        const Method* method = saveArea->method;

        if (!dvmIsBreakFrame(framePtr)) {
            if (count == num) {
                *pFrameId = frameToFrameId(framePtr);
                if (dvmIsInterfaceClass(method->clazz))
                    pLoc->typeTag = TT_INTERFACE;
                else
                    pLoc->typeTag = TT_CLASS;
                pLoc->classId = classObjectToRefTypeId(method->clazz);
                pLoc->methodId = methodToMethodId(method);
                if (dvmIsNativeMethod(method))
                    pLoc->idx = (u8)-1;
                else
                    pLoc->idx = saveArea->xtra.currentPc - method->insns;
                dvmUnlockThreadList();
                return true;
            }

            count++;
        }

        framePtr = saveArea->prevFrame;
    }

bail:
    dvmUnlockThreadList();
    return false;
}

/*
 * Get the ThreadId for the current thread.
 */
ObjectId dvmDbgGetThreadSelfId(void)
{
    Thread* self = dvmThreadSelf();
    return objectToObjectId(self->threadObj);
}

/*
 * Suspend the VM.
 */
void dvmDbgSuspendVM(bool isEvent)
{
    dvmSuspendAllThreads(isEvent ? SUSPEND_FOR_DEBUG_EVENT : SUSPEND_FOR_DEBUG);
}

/*
 * Resume the VM.
 */
void dvmDbgResumeVM()
{
    dvmResumeAllThreads(SUSPEND_FOR_DEBUG);
}

/*
 * Suspend one thread (not ourselves).
 */
void dvmDbgSuspendThread(ObjectId threadId)
{
    Object* threadObj = objectIdToObject(threadId);
    Thread* thread;

    dvmLockThreadList(NULL);

    thread = threadObjToThread(threadObj);
    if (thread == NULL) {
        /* can happen if our ThreadDeath notify crosses in the mail */
        LOGW("WARNING: threadid=%llx obj=%p no match\n", threadId, threadObj);
    } else {
        dvmSuspendThread(thread);
    }

    dvmUnlockThreadList();
}

/*
 * Resume one thread (not ourselves).
 */
void dvmDbgResumeThread(ObjectId threadId)
{
    Object* threadObj = objectIdToObject(threadId);
    Thread* thread;

    dvmLockThreadList(NULL);

    thread = threadObjToThread(threadObj);
    if (thread == NULL) {
        LOGW("WARNING: threadid=%llx obj=%p no match\n", threadId, threadObj);
    } else {
        dvmResumeThread(thread);
    }

    dvmUnlockThreadList();
}

/*
 * Suspend ourselves after sending an event to the debugger.
 */
void dvmDbgSuspendSelf(void)
{
    dvmSuspendSelf(true);
}

/*
 * Get the "this" object for the specified frame.
 */
static Object* getThisObject(const u4* framePtr)
{
    const StackSaveArea* saveArea = SAVEAREA_FROM_FP(framePtr);
    const Method* method = saveArea->method;
    int argOffset = method->registersSize - method->insSize;
    Object* thisObj;

    if (method == NULL) {
        /* this is a "break" frame? */
        assert(false);
        return NULL;
    }

    LOGVV("  Pulling this object for frame at %p\n", framePtr);
    LOGVV("    Method='%s' native=%d static=%d this=%p\n",
        method->name, dvmIsNativeMethod(method),
        dvmIsStaticMethod(method), (Object*) framePtr[argOffset]);

    /*
     * No "this" pointer for statics.  No args on the interp stack for
     * native methods invoked directly from the VM.
     */
    if (dvmIsNativeMethod(method) || dvmIsStaticMethod(method))
        thisObj = NULL;
    else
        thisObj = (Object*) framePtr[argOffset];

    if (thisObj != NULL && !dvmIsValidObject(thisObj)) {
        LOGW("Debugger: invalid 'this' pointer %p in %s.%s; returning NULL\n",
            framePtr, method->clazz->descriptor, method->name);
        thisObj = NULL;
    }

    return thisObj;
}

/*
 * Return the "this" object for the specified frame.  The thread must be
 * suspended.
 */
bool dvmDbgGetThisObject(ObjectId threadId, FrameId frameId, ObjectId* pThisId)
{
    const u4* framePtr = frameIdToFrame(frameId);
    Object* thisObj;

    UNUSED_PARAMETER(threadId);

    thisObj = getThisObject(framePtr);

    *pThisId = objectToObjectId(thisObj);
    return true;
}

/*
 * Copy the value of a method argument or local variable into the
 * specified buffer.  The value will be preceeded with the tag.
 */
void dvmDbgGetLocalValue(ObjectId threadId, FrameId frameId, int slot,
    u1 tag, u1* buf, int expectedLen)
{
    const u4* framePtr = frameIdToFrame(frameId);
    Object* objVal;
    u4 intVal;
    u8 longVal;

    UNUSED_PARAMETER(threadId);

    slot = untweakSlot(slot, framePtr);     // Eclipse workaround

    switch (tag) {
    case JT_BOOLEAN:
        assert(expectedLen == 1);
        intVal = framePtr[slot];
        set1(buf+1, intVal != 0);
        break;
    case JT_BYTE:
        assert(expectedLen == 1);
        intVal = framePtr[slot];
        set1(buf+1, intVal);
        break;
    case JT_SHORT:
    case JT_CHAR:
        assert(expectedLen == 2);
        intVal = framePtr[slot];
        set2BE(buf+1, intVal);
        break;
    case JT_INT:
    case JT_FLOAT:
        assert(expectedLen == 4);
        intVal = framePtr[slot];
        set4BE(buf+1, intVal);
        break;
    case JT_ARRAY:
        assert(expectedLen == 8);
        {
            /* convert to "ObjectId" */
            objVal = (Object*)framePtr[slot];
            if (objVal != NULL && !dvmIsValidObject(objVal)) {
                LOGW("JDWP: slot %d expected to hold array, %p invalid\n",
                    slot, objVal);
                dvmAbort();         // DEBUG: make it obvious
                objVal = NULL;
                tag = JT_OBJECT;    // JT_ARRAY not expected for NULL ref
            }
            dvmSetObjectId(buf+1, objectToObjectId(objVal));
        }
        break;
    case JT_OBJECT:
        assert(expectedLen == 8);
        {
            /* convert to "ObjectId" */
            objVal = (Object*)framePtr[slot];
            //char* name;

            if (objVal != NULL) {
                if (!dvmIsValidObject(objVal)) {
                    LOGW("JDWP: slot %d expected to hold object, %p invalid\n",
                        slot, objVal);
                    dvmAbort();         // DEBUG: make it obvious
                    objVal = NULL;
                }
                //name = generateJNISignature(objVal->clazz);
                tag = resultTagFromObject(objVal);
                //free(name);
            } else {
                tag = JT_OBJECT;
            }
            dvmSetObjectId(buf+1, objectToObjectId(objVal));
        }
        break;
    case JT_DOUBLE:
    case JT_LONG:
        assert(expectedLen == 8);
        longVal = *(u8*)(&framePtr[slot]);
        set8BE(buf+1, longVal);
        break;
    default:
        LOGE("ERROR: unhandled tag '%c'\n", tag);
        assert(false);
        break;
    }

    set1(buf, tag);
}

/*
 * Copy a new value into an argument or local variable.
 */
void dvmDbgSetLocalValue(ObjectId threadId, FrameId frameId, int slot, u1 tag,
    u8 value, int width)
{
    u4* framePtr = frameIdToFrame(frameId);

    UNUSED_PARAMETER(threadId);

    slot = untweakSlot(slot, framePtr);     // Eclipse workaround

    switch (tag) {
    case JT_BOOLEAN:
        assert(width == 1);
        framePtr[slot] = (u4)value;
        break;
    case JT_BYTE:
        assert(width == 1);
        framePtr[slot] = (u4)value;
        break;
    case JT_SHORT:
    case JT_CHAR:
        assert(width == 2);
        framePtr[slot] = (u4)value;
        break;
    case JT_INT:
    case JT_FLOAT:
        assert(width == 4);
        framePtr[slot] = (u4)value;
        break;
    case JT_STRING:
        /* The debugger calls VirtualMachine.CreateString to create a new
         * string, then uses this to set the object reference, when you
         * edit a String object */
    case JT_ARRAY:
    case JT_OBJECT:
        assert(width == sizeof(ObjectId));
        framePtr[slot] = (u4) objectIdToObject(value);
        break;
    case JT_DOUBLE:
    case JT_LONG:
        assert(width == 8);
        *(u8*)(&framePtr[slot]) = value;
        break;
    case JT_VOID:
    case JT_CLASS_OBJECT:
    case JT_THREAD:
    case JT_THREAD_GROUP:
    case JT_CLASS_LOADER:
    default:
        LOGE("ERROR: unhandled tag '%c'\n", tag);
        assert(false);
        break;
    }
}


/*
 * ===========================================================================
 *      Debugger notification
 * ===========================================================================
 */

/*
 * Tell JDWP that a breakpoint address has been reached.
 *
 * "pcOffset" will be -1 for native methods.
 * "thisPtr" will be NULL for static methods.
 */
void dvmDbgPostLocationEvent(const Method* method, int pcOffset,
    Object* thisPtr, int eventFlags)
{
    JdwpLocation loc;

    if (dvmIsInterfaceClass(method->clazz))
        loc.typeTag = TT_INTERFACE;
    else
        loc.typeTag = TT_CLASS;
    loc.classId = classObjectToRefTypeId(method->clazz);
    loc.methodId = methodToMethodId(method);
    loc.idx = pcOffset;

    /*
     * Note we use "NoReg" so we don't keep track of references that are
     * never actually sent to the debugger.  The "thisPtr" is only used to
     * compare against registered events.
     */

    if (dvmJdwpPostLocationEvent(gDvm.jdwpState, &loc,
            objectToObjectIdNoReg(thisPtr), eventFlags))
    {
        classObjectToRefTypeId(method->clazz);
        objectToObjectId(thisPtr);
    }
}

/*
 * Tell JDWP that an exception has occurred.
 */
void dvmDbgPostException(void* throwFp, int throwRelPc, void* catchFp,
    int catchRelPc, Object* exception)
{
    JdwpLocation throwLoc, catchLoc;
    const Method* throwMeth;
    const Method* catchMeth;

    throwMeth = SAVEAREA_FROM_FP(throwFp)->method;
    if (dvmIsInterfaceClass(throwMeth->clazz))
        throwLoc.typeTag = TT_INTERFACE;
    else
        throwLoc.typeTag = TT_CLASS;
    throwLoc.classId = classObjectToRefTypeId(throwMeth->clazz);
    throwLoc.methodId = methodToMethodId(throwMeth);
    throwLoc.idx = throwRelPc;

    if (catchRelPc < 0) {
        memset(&catchLoc, 0, sizeof(catchLoc));
    } else {
        catchMeth = SAVEAREA_FROM_FP(catchFp)->method;
        if (dvmIsInterfaceClass(catchMeth->clazz))
            catchLoc.typeTag = TT_INTERFACE;
        else
            catchLoc.typeTag = TT_CLASS;
        catchLoc.classId = classObjectToRefTypeId(catchMeth->clazz);
        catchLoc.methodId = methodToMethodId(catchMeth);
        catchLoc.idx = catchRelPc;
    }

    /* need this for InstanceOnly filters */
    Object* thisObj = getThisObject(throwFp);

    /*
     * Hand the event to the JDWP exception handler.  Note we're using the
     * "NoReg" objectID on the exception, which is not strictly correct --
     * the exception object WILL be passed up to the debugger if the
     * debugger is interested in the event.  We do this because the current
     * implementation of the debugger object registry never throws anything
     * away, and some people were experiencing a fatal build up of exception
     * objects when dealing with certain libraries.
     */
    dvmJdwpPostException(gDvm.jdwpState, &throwLoc,
        objectToObjectIdNoReg(exception),
        classObjectToRefTypeId(exception->clazz), &catchLoc,
        objectToObjectId(thisObj));
}

/*
 * Tell JDWP and/or DDMS that a thread has started.
 */
void dvmDbgPostThreadStart(Thread* thread)
{
    if (gDvm.debuggerActive) {
        dvmJdwpPostThreadChange(gDvm.jdwpState,
            objectToObjectId(thread->threadObj), true);
    }
    if (gDvm.ddmThreadNotification)
        dvmDdmSendThreadNotification(thread, true);
}

/*
 * Tell JDWP and/or DDMS that a thread has gone away.
 */
void dvmDbgPostThreadDeath(Thread* thread)
{
    if (gDvm.debuggerActive) {
        dvmJdwpPostThreadChange(gDvm.jdwpState,
            objectToObjectId(thread->threadObj), false);
    }
    if (gDvm.ddmThreadNotification)
        dvmDdmSendThreadNotification(thread, false);
}

/*
 * Tell JDWP that a new class has been prepared.
 */
void dvmDbgPostClassPrepare(ClassObject* clazz)
{
    int tag;
    char* signature;

    if (dvmIsInterfaceClass(clazz))
        tag = TT_INTERFACE;
    else
        tag = TT_CLASS;

    // TODO - we currently always send both "verified" and "prepared" since
    // debuggers seem to like that.  There might be some advantage to honesty,
    // since the class may not yet be verified.
    signature = generateJNISignature(clazz);
    dvmJdwpPostClassPrepare(gDvm.jdwpState, tag, classObjectToRefTypeId(clazz),
        signature, CS_VERIFIED | CS_PREPARED);
    free(signature);
}

/*
 * The JDWP event mechanism has registered an event with a LocationOnly
 * mod.  Tell the interpreter to call us if we hit the specified
 * address.
 */
bool dvmDbgWatchLocation(const JdwpLocation* pLoc)
{
    Method* method = methodIdToMethod(pLoc->classId, pLoc->methodId);
    assert(!dvmIsNativeMethod(method));
    dvmAddBreakAddr(method, pLoc->idx);
    return true;        /* assume success */
}

/*
 * An event with a LocationOnly mod has been removed.
 */
void dvmDbgUnwatchLocation(const JdwpLocation* pLoc)
{
    Method* method = methodIdToMethod(pLoc->classId, pLoc->methodId);
    assert(!dvmIsNativeMethod(method));
    dvmClearBreakAddr(method, pLoc->idx);
}

/*
 * The JDWP event mechanism has registered a single-step event.  Tell
 * the interpreter about it.
 */
bool dvmDbgConfigureStep(ObjectId threadId, enum JdwpStepSize size,
    enum JdwpStepDepth depth)
{
    Object* threadObj;
    Thread* thread;
    bool result = false;

    threadObj = objectIdToObject(threadId);
    assert(threadObj != NULL);

    /*
     * Get a pointer to the Thread struct for this ID.  The pointer will
     * be used strictly for comparisons against the current thread pointer
     * after the setup is complete, so we can safely release the lock.
     */
    dvmLockThreadList(NULL);
    thread = threadObjToThread(threadObj);

    if (thread == NULL) {
        LOGE("Thread for single-step not found\n");
        goto bail;
    }
    if (!dvmIsSuspended(thread)) {
        LOGE("Thread for single-step not suspended\n");
        assert(!"non-susp step");      // I want to know if this can happen
        goto bail;
    }

    assert(dvmIsSuspended(thread));
    if (!dvmAddSingleStep(thread, size, depth))
        goto bail;

    result = true;

bail:
    dvmUnlockThreadList();
    return result;
}

/*
 * A single-step event has been removed.
 */
void dvmDbgUnconfigureStep(ObjectId threadId)
{
    UNUSED_PARAMETER(threadId);

    /* right now it's global, so don't need to find Thread */
    dvmClearSingleStep(NULL);
}

/*
 * Invoke a method in a thread that has been stopped on a breakpoint or
 * other debugger event.  (This function is called from the JDWP thread.)
 *
 * Note that access control is not enforced, per spec.
 */
JdwpError dvmDbgInvokeMethod(ObjectId threadId, ObjectId objectId,
    RefTypeId classId, MethodId methodId, u4 numArgs, ObjectId* argArray,
    u4 options, u1* pResultTag, u8* pResultValue, ObjectId* pExceptObj)
{
    Object* threadObj = objectIdToObject(threadId);
    Thread* targetThread;
    JdwpError err = ERR_NONE;

    dvmLockThreadList(NULL);

    targetThread = threadObjToThread(threadObj);
    if (targetThread == NULL) {
        err = ERR_INVALID_THREAD;       /* thread does not exist */
        dvmUnlockThreadList();
        goto bail;
    }
    if (!targetThread->invokeReq.ready) {
        err = ERR_INVALID_THREAD;       /* thread not stopped by event */
        dvmUnlockThreadList();
        goto bail;
    }

    /*
     * We currently have a bug where we don't successfully resume the
     * target thread if the suspend count is too deep.  We're expected to
     * require one "resume" for each "suspend", but when asked to execute
     * a method we have to resume fully and then re-suspend it back to the
     * same level.  (The easiest way to cause this is to type "suspend"
     * multiple times in jdb.)
     *
     * It's unclear what this means when the event specifies "resume all"
     * and some threads are suspended more deeply than others.  This is
     * a rare problem, so for now we just prevent it from hanging forever
     * by rejecting the method invocation request.  Without this, we will
     * be stuck waiting on a suspended thread.
     */
    if (targetThread->suspendCount > 1) {
        LOGW("threadid=%d: suspend count on threadid=%d is %d, too deep "
             "for method exec\n",
            dvmThreadSelf()->threadId, targetThread->threadId,
            targetThread->suspendCount);
        err = ERR_THREAD_SUSPENDED;     /* probably not expected here */
        dvmUnlockThreadList();
        goto bail;
    }

    /*
     * TODO: ought to screen the various IDs, and verify that the argument
     * list is valid.
     */

    targetThread->invokeReq.obj = objectIdToObject(objectId);
    targetThread->invokeReq.thread = threadObj;
    targetThread->invokeReq.clazz = refTypeIdToClassObject(classId);
    targetThread->invokeReq.method = methodIdToMethod(classId, methodId);
    targetThread->invokeReq.numArgs = numArgs;
    targetThread->invokeReq.argArray = argArray;
    targetThread->invokeReq.options = options;
    targetThread->invokeReq.invokeNeeded = true;

    /*
     * This is a bit risky -- if the thread goes away we're sitting high
     * and dry -- but we must release this before the dvmResumeAllThreads
     * call, and it's unwise to hold it during dvmWaitForSuspend.
     */
    dvmUnlockThreadList();

    /*
     * We change our (JDWP thread) status, which should be THREAD_RUNNING,
     * so the VM can suspend for a GC if the invoke request causes us to
     * run out of memory.  It's also a good idea to change it before locking
     * the invokeReq mutex, although that should never be held for long.
     */
    Thread* self = dvmThreadSelf();
    int oldStatus = dvmChangeStatus(self, THREAD_VMWAIT);

    LOGV("    Transferring control to event thread\n");
    dvmLockMutex(&targetThread->invokeReq.lock);

    if ((options & INVOKE_SINGLE_THREADED) == 0) {
        LOGV("      Resuming all threads\n");
        dvmResumeAllThreads(SUSPEND_FOR_DEBUG_EVENT);
    } else {
        LOGV("      Resuming event thread only\n");
        dvmResumeThread(targetThread);
    }

    /*
     * Wait for the request to finish executing.
     */
    while (targetThread->invokeReq.invokeNeeded) {
        pthread_cond_wait(&targetThread->invokeReq.cv,
                          &targetThread->invokeReq.lock);
    }
    dvmUnlockMutex(&targetThread->invokeReq.lock);
    LOGV("    Control has returned from event thread\n");

    /* wait for thread to re-suspend itself */
    dvmWaitForSuspend(targetThread);

    /*
     * Done waiting, switch back to RUNNING.
     */
    dvmChangeStatus(self, oldStatus);

    /*
     * Suspend the threads.  We waited for the target thread to suspend
     * itself, so all we need to do is suspend the others.
     *
     * The suspendAllThreads() call will double-suspend the event thread,
     * so we want to resume the target thread once to keep the books straight.
     */
    if ((options & INVOKE_SINGLE_THREADED) == 0) {
        LOGV("      Suspending all threads\n");
        dvmSuspendAllThreads(SUSPEND_FOR_DEBUG_EVENT);
        LOGV("      Resuming event thread to balance the count\n");
        dvmResumeThread(targetThread);
    }

    /*
     * Set up the result.
     */
    *pResultTag = targetThread->invokeReq.resultTag;
    if (isTagPrimitive(targetThread->invokeReq.resultTag))
        *pResultValue = targetThread->invokeReq.resultValue.j;
    else
        *pResultValue = objectToObjectId(targetThread->invokeReq.resultValue.l);
    *pExceptObj = targetThread->invokeReq.exceptObj;
    err = targetThread->invokeReq.err;

bail:
    return err;
}

/*
 * Determine the tag type for the return value for this method.
 */
static u1 resultTagFromSignature(const Method* method)
{
    const char* descriptor = dexProtoGetReturnType(&method->prototype);
    return dvmDbgGetSignatureTag(descriptor);
}

/*
 * Execute the method described by "*pReq".
 *
 * We're currently in VMWAIT, because we're stopped on a breakpoint.  We
 * want to switch to RUNNING while we execute.
 */
void dvmDbgExecuteMethod(DebugInvokeReq* pReq)
{
    Thread* self = dvmThreadSelf();
    const Method* meth;
    Object* oldExcept;
    int oldStatus;

    /*
     * We can be called while an exception is pending in the VM.  We need
     * to preserve that across the method invocation.
     */
    oldExcept = dvmGetException(self);
    dvmClearException(self);

    oldStatus = dvmChangeStatus(self, THREAD_RUNNING);

    /*
     * Translate the method through the vtable, unless we're calling a
     * direct method or the debugger wants to suppress it.
     */
    if ((pReq->options & INVOKE_NONVIRTUAL) != 0 || pReq->obj == NULL ||
        dvmIsDirectMethod(pReq->method))
    {
        meth = pReq->method;
    } else {
        meth = dvmGetVirtualizedMethod(pReq->clazz, pReq->method);
    }
    assert(meth != NULL);

    assert(sizeof(jvalue) == sizeof(u8));

    IF_LOGV() {
        char* desc = dexProtoCopyMethodDescriptor(&meth->prototype);
        LOGV("JDWP invoking method %p/%p %s.%s:%s\n",
            pReq->method, meth, meth->clazz->descriptor, meth->name, desc);
        free(desc);
    }

    dvmCallMethodA(self, meth, pReq->obj, false, &pReq->resultValue,
        (jvalue*)pReq->argArray);
    pReq->exceptObj = objectToObjectId(dvmGetException(self));
    pReq->resultTag = resultTagFromSignature(meth);
    if (pReq->exceptObj != 0) {
        Object* exc = dvmGetException(self);
        LOGD("  JDWP invocation returning with exceptObj=%p (%s)\n",
            exc, exc->clazz->descriptor);
        //dvmLogExceptionStackTrace();
        dvmClearException(self);
        /*
         * Nothing should try to use this, but it looks like something is.
         * Make it null to be safe.
         */
        pReq->resultValue.j = 0; /*0xadadadad;*/
    } else if (pReq->resultTag == JT_OBJECT) {
        /* if no exception thrown, examine object result more closely */
        u1 newTag = resultTagFromObject(pReq->resultValue.l);
        if (newTag != pReq->resultTag) {
            LOGVV("  JDWP promoted result from %d to %d\n",
                pReq->resultTag, newTag);
            pReq->resultTag = newTag;
        }
    }

    if (oldExcept != NULL)
        dvmSetException(self, oldExcept);
    dvmChangeStatus(self, oldStatus);
}

// for dvmAddressSetForLine
typedef struct AddressSetContext {
    bool lastAddressValid;
    u4 lastAddress;
    u4 lineNum;
    AddressSet *pSet;
} AddressSetContext;

// for dvmAddressSetForLine
static int addressSetCb (void *cnxt, u4 address, u4 lineNum)
{
    AddressSetContext *pContext = (AddressSetContext *)cnxt;

    if (lineNum == pContext->lineNum) {
        if (!pContext->lastAddressValid) {
            // Everything from this address until the next line change is ours
            pContext->lastAddress = address;
            pContext->lastAddressValid = true;
        }
        // else, If we're already in a valid range for this lineNum,
        // just keep going (shouldn't really happen)
    } else if (pContext->lastAddressValid) { // and the line number is new
        u4 i;
        // Add everything from the last entry up until here to the set
        for (i = pContext->lastAddress; i < address; i++) {
            dvmAddressSetSet(pContext->pSet, i);
        }

        pContext->lastAddressValid = false;
    }

    // there may be multiple entries for a line
    return 0;
}
/*
 * Build up a set of bytecode addresses associated with a line number
 */
const AddressSet *dvmAddressSetForLine(const Method* method, int line)
{
    AddressSet *result;
    const DexFile *pDexFile = method->clazz->pDvmDex->pDexFile;
    u4 insnsSize = dvmGetMethodInsnsSize(method);
    AddressSetContext context;

    result = calloc(1, sizeof(AddressSet) + (insnsSize/8) + 1);
    result->setSize = insnsSize;

    memset(&context, 0, sizeof(context));
    context.pSet = result;
    context.lineNum = line;
    context.lastAddressValid = false;

    dexDecodeDebugInfo(pDexFile, dvmGetMethodCode(method),
        method->clazz->descriptor,
        method->prototype.protoIdx,
        method->accessFlags,
        addressSetCb, NULL, &context);

    // If the line number was the last in the position table...
    if (context.lastAddressValid) {
        u4 i;
        for (i = context.lastAddress; i < insnsSize; i++) {
            dvmAddressSetSet(result, i);
        }
    }

    return result;
}


/*
 * ===========================================================================
 *      Dalvik Debug Monitor support
 * ===========================================================================
 */

/*
 * We have received a DDM packet over JDWP.  Hand it off to the VM.
 */
bool dvmDbgDdmHandlePacket(const u1* buf, int dataLen, u1** pReplyBuf,
    int* pReplyLen)
{
    return dvmDdmHandlePacket(buf, dataLen, pReplyBuf, pReplyLen);
}

/*
 * First DDM packet has arrived over JDWP.  Notify the press.
 */
void dvmDbgDdmConnected(void)
{
    dvmDdmConnected();
}

/*
 * JDWP connection has dropped.
 */
void dvmDbgDdmDisconnected(void)
{
    dvmDdmDisconnected();
}

/*
 * Send up a JDWP event packet with a DDM chunk in it.
 */
void dvmDbgDdmSendChunk(int type, size_t len, const u1* buf)
{
    assert(buf != NULL);
    struct iovec vec[1] = { {(void*)buf, len} };
    dvmDbgDdmSendChunkV(type, vec, 1);
}

/*
 * Send up a JDWP event packet with a DDM chunk in it.  The chunk is
 * concatenated from multiple source buffers.
 */
void dvmDbgDdmSendChunkV(int type, const struct iovec* iov, int iovcnt)
{
    if (gDvm.jdwpState == NULL) {
        LOGV("Debugger thread not active, ignoring DDM send (t=0x%08x l=%d)\n",
            type, len);
        return;
    }

    dvmJdwpDdmSendChunkV(gDvm.jdwpState, type, iov, iovcnt);
}