vm/IndirectRefTable.cpp - platform/dalvik - Git at Google

 /*
  * Copyright (C) 2009 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.
  */

 /*
  * Indirect reference table management.
  */
 #include "Dalvik.h"

 static void abortMaybe() {
     // If CheckJNI is on, it'll give a more detailed error before aborting.
     // Otherwise, we want to abort rather than hand back a bad reference.
     if (!gDvmJni.useCheckJni) {
         dvmAbort();
     }
 }

 bool IndirectRefTable::init(size_t initialCount,
         size_t maxCount, IndirectRefKind desiredKind)
 {
     assert(initialCount > 0);
     assert(initialCount <= maxCount);
     assert(kind != kIndirectKindInvalid);

     table = (Object**) malloc(initialCount * sizeof(Object*));
     if (table == NULL) {
         return false;
     }
 #ifndef NDEBUG
     memset(table, 0xd1, initialCount * sizeof(Object*));
 #endif

     slotData =
         (IndirectRefSlot*) calloc(maxCount, sizeof(IndirectRefSlot));
     if (slotData == NULL) {
         return false;
     }

     segmentState.all = IRT_FIRST_SEGMENT;
     allocEntries = initialCount;
     maxEntries = maxCount;
     kind = desiredKind;

     return true;
 }

 /*
  * Clears out the contents of a IndirectRefTable, freeing allocated storage.
  */
 void IndirectRefTable::destroy()
 {
     free(table);
     free(slotData);
     table = NULL;
     allocEntries = maxEntries = -1;
 }

 /*
  * Make sure that the entry at "idx" is correctly paired with "iref".
  */
 bool IndirectRefTable::checkEntry(const char* what, IndirectRef iref, int idx) const
 {
     Object* obj = table[idx];
     IndirectRef checkRef = toIndirectRef(obj, idx);
     if (checkRef != iref) {
         if (indirectRefKind(iref) != kIndirectKindWeakGlobal) {
             LOGE("JNI ERROR (app bug): attempt to %s stale %s reference (req=%p vs cur=%p; table=%p)",
                     what, indirectRefKindToString(kind), iref, checkRef, this);
             abortMaybe();
         }
         return false;
     }
     return true;
 }

 IndirectRef IndirectRefTable::add(u4 cookie, Object* obj)
 {
     IRTSegmentState prevState;
     prevState.all = cookie;
     size_t topIndex = segmentState.parts.topIndex;

     assert(obj != NULL);
     assert(dvmIsValidObject(obj));
     assert(table != NULL);
     assert(allocEntries <= maxEntries);
     assert(segmentState.parts.numHoles >= prevState.parts.numHoles);

     if (topIndex == allocEntries) {
         /* reached end of allocated space; did we hit buffer max? */
         if (topIndex == maxEntries) {
             LOGE("JNI ERROR (app bug): %s reference table overflow (max=%d)",
                     indirectRefKindToString(kind), maxEntries);
             dump(indirectRefKindToString(kind));
             dvmAbort();
         }

         size_t newSize = allocEntries * 2;
         if (newSize > maxEntries) {
             newSize = maxEntries;
         }
         assert(newSize > allocEntries);

         Object** newTable = (Object**) realloc(table, newSize * sizeof(Object*));
         if (newTable == NULL) {
             LOGE("JNI ERROR (app bug): unable to expand %s reference table (from %d to %d, max=%d)",
                     indirectRefKindToString(kind),
                     allocEntries, newSize, maxEntries);
             dump(indirectRefKindToString(kind));
             dvmAbort();
         }

         /* update entries; adjust "nextEntry" in case memory moved */
         table = newTable;
         allocEntries = newSize;
     }

     IndirectRef result;

     /*
      * We know there's enough room in the table.  Now we just need to find
      * the right spot.  If there's a hole, find it and fill it; otherwise,
      * add to the end of the list.
      */
     int numHoles = segmentState.parts.numHoles - prevState.parts.numHoles;
     if (numHoles > 0) {
         assert(topIndex > 1);
         /* find the first hole; likely to be near the end of the list */
         Object** pScan = &table[topIndex - 1];
         assert(*pScan != NULL);
         while (*--pScan != NULL) {
             assert(pScan >= table + prevState.parts.topIndex);
         }
         updateSlotAdd(obj, pScan - table);
         result = toIndirectRef(obj, pScan - table);
         *pScan = obj;
         segmentState.parts.numHoles--;
     } else {
         /* add to the end */
         updateSlotAdd(obj, topIndex);
         result = toIndirectRef(obj, topIndex);
         table[topIndex++] = obj;
         segmentState.parts.topIndex = topIndex;
     }

     assert(result != NULL);
     return result;
 }

 /*
  * Verify that the indirect table lookup is valid.
  *
  * Returns "false" if something looks bad.
  */
 bool IndirectRefTable::getChecked(IndirectRef iref) const
 {
     if (iref == NULL) {
         LOGW("Attempt to look up NULL %s reference",
                 indirectRefKindToString(kind));
         return false;
     }
     if (indirectRefKind(iref) == kIndirectKindInvalid) {
         LOGE("JNI ERROR (app bug): invalid %s reference (%p)",
                 indirectRefKindToString(kind), iref);
         abortMaybe();
         return false;
     }

     int topIndex = segmentState.parts.topIndex;
     int idx = extractIndex(iref);
     if (idx >= topIndex) {
         /* bad -- stale reference? */
         LOGE("JNI ERROR (app bug): accessed stale %s reference at index %d (top=%d)",
                 indirectRefKindToString(kind), idx, topIndex);
         abortMaybe();
         return false;
     }

     if (!checkEntry("use", iref, idx)) {
         return false;
     }

     return true;
 }

 static int linearScan(IndirectRef iref, int bottomIndex, int topIndex, Object** table) {
     for (int i = bottomIndex; i < topIndex; ++i) {
         if (table[i] == reinterpret_cast<Object*>(iref)) {
             return i;
         }
     }
     return -1;
 }

 bool IndirectRefTable::contains(IndirectRef iref) const {
     return linearScan(iref, 0, segmentState.parts.topIndex, table) != -1;
 }

 /*
  * Remove "obj" from "pRef".  We extract the table offset bits from "iref"
  * and zap the corresponding entry, leaving a hole if it's not at the top.
  *
  * If the entry is not between the current top index and the bottom index
  * specified by the cookie, we don't remove anything.  This is the behavior
  * required by JNI's DeleteLocalRef function.
  *
  * Note this is NOT called when a local frame is popped.  This is only used
  * for explicit single removals.
  *
  * Returns "false" if nothing was removed.
  */
 bool IndirectRefTable::remove(u4 cookie, IndirectRef iref)
 {
     IRTSegmentState prevState;
     prevState.all = cookie;
     int topIndex = segmentState.parts.topIndex;
     int bottomIndex = prevState.parts.topIndex;

     assert(table != NULL);
     assert(allocEntries <= maxEntries);
     assert(segmentState.parts.numHoles >= prevState.parts.numHoles);

     int idx = extractIndex(iref);
     bool fakeDirectReferenceHack = false;

     if (indirectRefKind(iref) == kIndirectKindInvalid && gDvmJni.workAroundAppJniBugs) {
         idx = linearScan(iref, bottomIndex, topIndex, table);
         fakeDirectReferenceHack = true;
         if (idx == -1) {
             LOGW("trying to work around app JNI bugs, but didn't find %p in table!", iref);
             return false;
         }
     }

     if (idx < bottomIndex) {
         /* wrong segment */
         LOGV("Attempt to remove index outside index area (%d vs %d-%d)",
             idx, bottomIndex, topIndex);
         return false;
     }
     if (idx >= topIndex) {
         /* bad -- stale reference? */
         LOGD("Attempt to remove invalid index %d (bottom=%d top=%d)",
             idx, bottomIndex, topIndex);
         return false;
     }

     if (idx == topIndex-1) {
         /*
          * Top-most entry.  Scan up and consume holes.  No need to NULL
          * out the entry, since the test vs. topIndex will catch it.
          */
         if (fakeDirectReferenceHack == false && !checkEntry("remove", iref, idx)) {
             return false;
         }

 #ifndef NDEBUG
         table[idx] = (Object*)0xd3d3d3d3;
 #endif

         int numHoles =
             segmentState.parts.numHoles - prevState.parts.numHoles;
         if (numHoles != 0) {
             while (--topIndex > bottomIndex && numHoles != 0) {
                 LOGV("+++ checking for hole at %d (cookie=0x%08x) val=%p",
                     topIndex-1, cookie, table[topIndex-1]);
                 if (table[topIndex-1] != NULL)
                     break;
                 LOGV("+++ ate hole at %d", topIndex-1);
                 numHoles--;
             }
             segmentState.parts.numHoles =
                 numHoles + prevState.parts.numHoles;
             segmentState.parts.topIndex = topIndex;
         } else {
             segmentState.parts.topIndex = topIndex-1;
             LOGV("+++ ate last entry %d", topIndex-1);
         }
     } else {
         /*
          * Not the top-most entry.  This creates a hole.  We NULL out the
          * entry to prevent somebody from deleting it twice and screwing up
          * the hole count.
          */
         if (table[idx] == NULL) {
             LOGV("--- WEIRD: removing null entry %d", idx);
             return false;
         }
         if (fakeDirectReferenceHack == false && !checkEntry("remove", iref, idx)) {
             return false;
         }

         table[idx] = NULL;
         segmentState.parts.numHoles++;
         LOGV("+++ left hole at %d, holes=%d",
             idx, segmentState.parts.numHoles);
     }

     return true;
 }

 const char* indirectRefKindToString(IndirectRefKind kind)
 {
     switch (kind) {
     case kIndirectKindInvalid:      return "invalid";
     case kIndirectKindLocal:        return "local";
     case kIndirectKindGlobal:       return "global";
     case kIndirectKindWeakGlobal:   return "weak global";
     default:                        return "UNKNOWN";
     }
 }

 void IndirectRefTable::dump(const char* descr) const
 {
     dvmDumpReferenceTableContents(table, capacity(), descr);
 }
	/*
	* Copyright (C) 2009 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.
	*/

	/*
	* Indirect reference table management.
	*/
	#include "Dalvik.h"

	static void abortMaybe() {
	// If CheckJNI is on, it'll give a more detailed error before aborting.
	// Otherwise, we want to abort rather than hand back a bad reference.
	if (!gDvmJni.useCheckJni) {
	dvmAbort();
	}
	}

	bool IndirectRefTable::init(size_t initialCount,
	size_t maxCount, IndirectRefKind desiredKind)
	{
	assert(initialCount > 0);
	assert(initialCount <= maxCount);
	assert(kind != kIndirectKindInvalid);

	table = (Object*) malloc(initialCount sizeof(Object*));
	if (table == NULL) {
	return false;
	}
	#ifndef NDEBUG
	memset(table, 0xd1, initialCount * sizeof(Object*));
	#endif

	slotData =
	(IndirectRefSlot*) calloc(maxCount, sizeof(IndirectRefSlot));
	if (slotData == NULL) {
	return false;
	}

	segmentState.all = IRT_FIRST_SEGMENT;
	allocEntries = initialCount;
	maxEntries = maxCount;
	kind = desiredKind;

	return true;
	}

	/*
	* Clears out the contents of a IndirectRefTable, freeing allocated storage.
	*/
	void IndirectRefTable::destroy()
	{
	free(table);
	free(slotData);
	table = NULL;
	allocEntries = maxEntries = -1;
	}

	/*
	* Make sure that the entry at "idx" is correctly paired with "iref".
	*/
	bool IndirectRefTable::checkEntry(const char* what, IndirectRef iref, int idx) const
	{
	Object* obj = table[idx];
	IndirectRef checkRef = toIndirectRef(obj, idx);
	if (checkRef != iref) {
	if (indirectRefKind(iref) != kIndirectKindWeakGlobal) {
	LOGE("JNI ERROR (app bug): attempt to %s stale %s reference (req=%p vs cur=%p; table=%p)",
	what, indirectRefKindToString(kind), iref, checkRef, this);
	abortMaybe();
	}
	return false;
	}
	return true;
	}

	IndirectRef IndirectRefTable::add(u4 cookie, Object* obj)
	{
	IRTSegmentState prevState;
	prevState.all = cookie;
	size_t topIndex = segmentState.parts.topIndex;

	assert(obj != NULL);
	assert(dvmIsValidObject(obj));
	assert(table != NULL);
	assert(allocEntries <= maxEntries);
	assert(segmentState.parts.numHoles >= prevState.parts.numHoles);

	if (topIndex == allocEntries) {
	/* reached end of allocated space; did we hit buffer max? */
	if (topIndex == maxEntries) {
	LOGE("JNI ERROR (app bug): %s reference table overflow (max=%d)",
	indirectRefKindToString(kind), maxEntries);
	dump(indirectRefKindToString(kind));
	dvmAbort();
	}

	size_t newSize = allocEntries * 2;
	if (newSize > maxEntries) {
	newSize = maxEntries;
	}
	assert(newSize > allocEntries);

	Object newTable = (Object) realloc(table, newSize * sizeof(Object*));
	if (newTable == NULL) {
	LOGE("JNI ERROR (app bug): unable to expand %s reference table (from %d to %d, max=%d)",
	indirectRefKindToString(kind),
	allocEntries, newSize, maxEntries);
	dump(indirectRefKindToString(kind));
	dvmAbort();
	}

	/* update entries; adjust "nextEntry" in case memory moved */
	table = newTable;
	allocEntries = newSize;
	}

	IndirectRef result;

	/*
	* We know there's enough room in the table. Now we just need to find
	* the right spot. If there's a hole, find it and fill it; otherwise,
	* add to the end of the list.
	*/
	int numHoles = segmentState.parts.numHoles - prevState.parts.numHoles;
	if (numHoles > 0) {
	assert(topIndex > 1);
	/* find the first hole; likely to be near the end of the list */
	Object** pScan = &table[topIndex - 1];
	assert(*pScan != NULL);
	while (*--pScan != NULL) {
	assert(pScan >= table + prevState.parts.topIndex);
	}
	updateSlotAdd(obj, pScan - table);
	result = toIndirectRef(obj, pScan - table);
	*pScan = obj;
	segmentState.parts.numHoles--;
	} else {
	/* add to the end */
	updateSlotAdd(obj, topIndex);
	result = toIndirectRef(obj, topIndex);
	table[topIndex++] = obj;
	segmentState.parts.topIndex = topIndex;
	}

	assert(result != NULL);
	return result;
	}

	/*
	* Verify that the indirect table lookup is valid.
	*
	* Returns "false" if something looks bad.
	*/
	bool IndirectRefTable::getChecked(IndirectRef iref) const
	{
	if (iref == NULL) {
	LOGW("Attempt to look up NULL %s reference",
	indirectRefKindToString(kind));
	return false;
	}
	if (indirectRefKind(iref) == kIndirectKindInvalid) {
	LOGE("JNI ERROR (app bug): invalid %s reference (%p)",
	indirectRefKindToString(kind), iref);
	abortMaybe();
	return false;
	}

	int topIndex = segmentState.parts.topIndex;
	int idx = extractIndex(iref);
	if (idx >= topIndex) {
	/* bad -- stale reference? */
	LOGE("JNI ERROR (app bug): accessed stale %s reference at index %d (top=%d)",
	indirectRefKindToString(kind), idx, topIndex);
	abortMaybe();
	return false;
	}

	if (!checkEntry("use", iref, idx)) {
	return false;
	}

	return true;
	}

	static int linearScan(IndirectRef iref, int bottomIndex, int topIndex, Object** table) {
	for (int i = bottomIndex; i < topIndex; ++i) {
	if (table[i] == reinterpret_cast<Object*>(iref)) {
	return i;
	}
	}
	return -1;
	}

	bool IndirectRefTable::contains(IndirectRef iref) const {
	return linearScan(iref, 0, segmentState.parts.topIndex, table) != -1;
	}

	/*
	* Remove "obj" from "pRef". We extract the table offset bits from "iref"
	* and zap the corresponding entry, leaving a hole if it's not at the top.
	*
	* If the entry is not between the current top index and the bottom index
	* specified by the cookie, we don't remove anything. This is the behavior
	* required by JNI's DeleteLocalRef function.
	*
	* Note this is NOT called when a local frame is popped. This is only used
	* for explicit single removals.
	*
	* Returns "false" if nothing was removed.
	*/
	bool IndirectRefTable::remove(u4 cookie, IndirectRef iref)
	{
	IRTSegmentState prevState;
	prevState.all = cookie;
	int topIndex = segmentState.parts.topIndex;
	int bottomIndex = prevState.parts.topIndex;

	assert(table != NULL);
	assert(allocEntries <= maxEntries);
	assert(segmentState.parts.numHoles >= prevState.parts.numHoles);

	int idx = extractIndex(iref);
	bool fakeDirectReferenceHack = false;

	if (indirectRefKind(iref) == kIndirectKindInvalid && gDvmJni.workAroundAppJniBugs) {
	idx = linearScan(iref, bottomIndex, topIndex, table);
	fakeDirectReferenceHack = true;
	if (idx == -1) {
	LOGW("trying to work around app JNI bugs, but didn't find %p in table!", iref);
	return false;
	}
	}

	if (idx < bottomIndex) {
	/* wrong segment */
	LOGV("Attempt to remove index outside index area (%d vs %d-%d)",
	idx, bottomIndex, topIndex);
	return false;
	}
	if (idx >= topIndex) {
	/* bad -- stale reference? */
	LOGD("Attempt to remove invalid index %d (bottom=%d top=%d)",
	idx, bottomIndex, topIndex);
	return false;
	}

	if (idx == topIndex-1) {
	/*
	* Top-most entry. Scan up and consume holes. No need to NULL
	* out the entry, since the test vs. topIndex will catch it.
	*/
	if (fakeDirectReferenceHack == false && !checkEntry("remove", iref, idx)) {
	return false;
	}

	#ifndef NDEBUG
	table[idx] = (Object*)0xd3d3d3d3;
	#endif

	int numHoles =
	segmentState.parts.numHoles - prevState.parts.numHoles;
	if (numHoles != 0) {
	while (--topIndex > bottomIndex && numHoles != 0) {
	LOGV("+++ checking for hole at %d (cookie=0x%08x) val=%p",
	topIndex-1, cookie, table[topIndex-1]);
	if (table[topIndex-1] != NULL)
	break;
	LOGV("+++ ate hole at %d", topIndex-1);
	numHoles--;
	}
	segmentState.parts.numHoles =
	numHoles + prevState.parts.numHoles;
	segmentState.parts.topIndex = topIndex;
	} else {
	segmentState.parts.topIndex = topIndex-1;
	LOGV("+++ ate last entry %d", topIndex-1);
	}
	} else {
	/*
	* Not the top-most entry. This creates a hole. We NULL out the
	* entry to prevent somebody from deleting it twice and screwing up
	* the hole count.
	*/
	if (table[idx] == NULL) {
	LOGV("--- WEIRD: removing null entry %d", idx);
	return false;
	}
	if (fakeDirectReferenceHack == false && !checkEntry("remove", iref, idx)) {
	return false;
	}

	table[idx] = NULL;
	segmentState.parts.numHoles++;
	LOGV("+++ left hole at %d, holes=%d",
	idx, segmentState.parts.numHoles);
	}

	return true;
	}

	const char* indirectRefKindToString(IndirectRefKind kind)
	{
	switch (kind) {
	case kIndirectKindInvalid: return "invalid";
	case kIndirectKindLocal: return "local";
	case kIndirectKindGlobal: return "global";
	case kIndirectKindWeakGlobal: return "weak global";
	default: return "UNKNOWN";
	}
	}

	void IndirectRefTable::dump(const char* descr) const
	{
	dvmDumpReferenceTableContents(table, capacity(), descr);
	}