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/*
* 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.
*/
#include "indirect_reference_table.h"
#include "jni_internal.h"
#include "reference_table.h"
#include "runtime.h"
#include "utils.h"
#include <cstdlib>
namespace art {
static void AbortMaybe() {
// If -Xcheck:jni is on, it'll give a more detailed error before aborting.
if (!Runtime::Current()->GetJavaVM()->check_jni) {
// Otherwise, we want to abort rather than hand back a bad reference.
LOG(FATAL) << "JNI ERROR (app bug): see above.";
}
}
IndirectReferenceTable::IndirectReferenceTable(size_t initialCount,
size_t maxCount, IndirectRefKind desiredKind)
{
CHECK_GT(initialCount, 0U);
CHECK_LE(initialCount, maxCount);
CHECK_NE(desiredKind, kSirtOrInvalid);
table_ = reinterpret_cast<const Object**>(malloc(initialCount * sizeof(const Object*)));
CHECK(table_ != NULL);
#ifndef NDEBUG
memset(table_, 0xd1, initialCount * sizeof(const Object*));
#endif
slot_data_ = reinterpret_cast<IndirectRefSlot*>(calloc(initialCount, sizeof(IndirectRefSlot)));
CHECK(slot_data_ != NULL);
segmentState.all = IRT_FIRST_SEGMENT;
alloc_entries_ = initialCount;
max_entries_ = maxCount;
kind_ = desiredKind;
}
IndirectReferenceTable::~IndirectReferenceTable() {
free(table_);
free(slot_data_);
table_ = NULL;
slot_data_ = NULL;
alloc_entries_ = max_entries_ = -1;
}
/*
* Make sure that the entry at "idx" is correctly paired with "iref".
*/
bool IndirectReferenceTable::CheckEntry(const char* what, IndirectRef iref, int idx) const {
const Object* obj = table_[idx];
IndirectRef checkRef = ToIndirectRef(obj, idx);
if (checkRef != iref) {
LOG(ERROR) << "JNI ERROR (app bug): attempt to " << what
<< " stale " << kind_ << " " << iref
<< " (should be " << checkRef << ")";
AbortMaybe();
return false;
}
return true;
}
IndirectRef IndirectReferenceTable::Add(uint32_t cookie, const Object* obj) {
IRTSegmentState prevState;
prevState.all = cookie;
size_t topIndex = segmentState.parts.topIndex;
DCHECK(obj != NULL);
// TODO: stronger sanity check on the object (such as in heap)
DCHECK(IsAligned(reinterpret_cast<intptr_t>(obj), 8));
DCHECK(table_ != NULL);
DCHECK_LE(alloc_entries_, max_entries_);
DCHECK_GE(segmentState.parts.numHoles, prevState.parts.numHoles);
if (topIndex == alloc_entries_) {
/* reached end of allocated space; did we hit buffer max? */
if (topIndex == max_entries_) {
LOG(ERROR) << "JNI ERROR (app bug): " << kind_ << " table overflow "
<< "(max=" << max_entries_ << ")";
Dump();
LOG(FATAL); // TODO: operator<< for IndirectReferenceTable
}
size_t newSize = alloc_entries_ * 2;
if (newSize > max_entries_) {
newSize = max_entries_;
}
DCHECK_GT(newSize, alloc_entries_);
table_ = (const Object**) realloc(table_, newSize * sizeof(const Object*));
slot_data_ = (IndirectRefSlot*) realloc(slot_data_, newSize * sizeof(IndirectRefSlot));
if (table_ == NULL || slot_data_ == NULL) {
LOG(ERROR) << "JNI ERROR (app bug): unable to expand "
<< kind_ << " table (from "
<< alloc_entries_ << " to " << newSize
<< ", max=" << max_entries_ << ")";
Dump();
LOG(FATAL); // TODO: operator<< for IndirectReferenceTable
}
// Clear the newly-allocated slot_data_ elements.
memset(slot_data_ + alloc_entries_, 0, (newSize - alloc_entries_) * sizeof(IndirectRefSlot));
alloc_entries_ = newSize;
}
/*
* 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.
*/
IndirectRef result;
int numHoles = segmentState.parts.numHoles - prevState.parts.numHoles;
if (numHoles > 0) {
DCHECK_GT(topIndex, 1U);
/* find the first hole; likely to be near the end of the list */
const Object** pScan = &table_[topIndex - 1];
DCHECK(*pScan != NULL);
while (*--pScan != NULL) {
DCHECK_GE(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;
}
DCHECK(result != NULL);
return result;
}
/*
* Verify that the indirect table lookup is valid.
*
* Returns "false" if something looks bad.
*/
bool IndirectReferenceTable::GetChecked(IndirectRef iref) const {
if (iref == NULL) {
LOG(WARNING) << "Attempt to look up NULL " << kind_;
return false;
}
if (GetIndirectRefKind(iref) == kSirtOrInvalid) {
LOG(ERROR) << "JNI ERROR (app bug): invalid " << kind_ << " " << iref;
AbortMaybe();
return false;
}
int topIndex = segmentState.parts.topIndex;
int idx = ExtractIndex(iref);
if (idx >= topIndex) {
/* bad -- stale reference? */
LOG(ERROR) << "JNI ERROR (app bug): accessed stale " << kind_ << " " << iref << " (index " << idx << " in a table of size " << topIndex << ")";
AbortMaybe();
return false;
}
if (table_[idx] == NULL) {
LOG(ERROR) << "JNI ERROR (app bug): accessed deleted " << kind_ << " " << iref;
AbortMaybe();
return false;
}
if (!CheckEntry("use", iref, idx)) {
return false;
}
return true;
}
static int LinearScan(IndirectRef iref, int bottomIndex, int topIndex, const Object** table) {
for (int i = bottomIndex; i < topIndex; ++i) {
if (table[i] == reinterpret_cast<const Object*>(iref)) {
return i;
}
}
return -1;
}
bool IndirectReferenceTable::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 IndirectReferenceTable::Remove(uint32_t cookie, IndirectRef iref) {
IRTSegmentState prevState;
prevState.all = cookie;
int topIndex = segmentState.parts.topIndex;
int bottomIndex = prevState.parts.topIndex;
DCHECK(table_ != NULL);
DCHECK_LE(alloc_entries_, max_entries_);
DCHECK_GE(segmentState.parts.numHoles, prevState.parts.numHoles);
int idx = ExtractIndex(iref);
JavaVMExt* vm = Runtime::Current()->GetJavaVM();
if (GetIndirectRefKind(iref) == kSirtOrInvalid || vm->work_around_app_jni_bugs) {
idx = LinearScan(iref, bottomIndex, topIndex, table_);
if (idx == -1) {
LOG(WARNING) << "trying to work around app JNI bugs, but didn't find " << iref << " in table!";
return false;
}
}
if (idx < bottomIndex) {
/* wrong segment */
LOG(INFO) << "Attempt to remove index outside index area (" << idx << " vs " << bottomIndex << "-" << topIndex << ")";
return false;
}
if (idx >= topIndex) {
/* bad -- stale reference? */
LOG(INFO) << "Attempt to remove invalid index " << idx << " (bottom=" << bottomIndex << " top=" << topIndex << ")";
return false;
}
if (idx == topIndex-1) {
// Top-most entry. Scan up and consume holes.
if (!vm->work_around_app_jni_bugs && !CheckEntry("remove", iref, idx)) {
return false;
}
table_[idx] = NULL;
int numHoles = segmentState.parts.numHoles - prevState.parts.numHoles;
if (numHoles != 0) {
while (--topIndex > bottomIndex && numHoles != 0) {
//LOG(INFO) << "+++ checking for hole at " << topIndex-1 << " (cookie=" << cookie << ") val=" << table_[topIndex-1];
if (table_[topIndex-1] != NULL) {
break;
}
//LOG(INFO) << "+++ ate hole at " << (topIndex-1);
numHoles--;
}
segmentState.parts.numHoles = numHoles + prevState.parts.numHoles;
segmentState.parts.topIndex = topIndex;
} else {
segmentState.parts.topIndex = topIndex-1;
//LOG(INFO) << "+++ ate last entry " << 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) {
LOG(INFO) << "--- WEIRD: removing null entry " << idx;
return false;
}
if (!vm->work_around_app_jni_bugs && !CheckEntry("remove", iref, idx)) {
return false;
}
table_[idx] = NULL;
segmentState.parts.numHoles++;
//LOG(INFO) << "+++ left hole at " << idx << ", holes=" << segmentState.parts.numHoles;
}
return true;
}
void IndirectReferenceTable::VisitRoots(Heap::RootVisitor* visitor, void* arg) {
typedef IndirectReferenceTable::iterator It; // TODO: C++0x auto
for (It it = begin(), end = this->end(); it != end; ++it) {
visitor(**it, arg);
}
}
std::ostream& operator<<(std::ostream& os, IndirectRefKind rhs) {
switch (rhs) {
case kSirtOrInvalid:
os << "stack indirect reference table or invalid reference";
break;
case kLocal:
os << "local reference";
break;
case kGlobal:
os << "global reference";
break;
case kWeakGlobal:
os << "weak global reference";
break;
default:
os << "IndirectRefKind[" << static_cast<int>(rhs) << "]";
break;
}
return os;
}
void IndirectReferenceTable::Dump() const {
LOG(WARNING) << kind_ << " table dump:";
std::vector<const Object*> entries(table_, table_ + Capacity());
ReferenceTable::Dump(entries);
}
} // namespace art