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deps: backport 1f8555 from v8's upstream
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Original commit message:

    api: introduce SealHandleScope

    When debugging Handle leaks in io.js we found it very convenient to be
    able to Seal some specific (root in our case) scope to prevent Handle
    allocations in it, and easily find leakage.

    R=yangguo
    BUG=

    Review URL: https://codereview.chromium.org/1079713002

    Cr-Commit-Position: refs/heads/master@{#27766}

Should help us identify and fix Handle leaks in core and user-space code.

PR-URL: #3945
Reviewed-By: Fedor Indutny <fedor@indutny.com>
Reviewed-By: James Snell <jasnell@gmail.com>
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trevnorris authored and rvagg committed Dec 4, 2015
1 parent cf98211 commit fbc8cd9
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Showing 5 changed files with 76 additions and 4 deletions.
21 changes: 21 additions & 0 deletions deps/v8/include/v8.h
Original file line number Diff line number Diff line change
Expand Up @@ -944,6 +944,27 @@ class ScriptOrigin {
};


class V8_EXPORT SealHandleScope {
public:
SealHandleScope(Isolate* isolate);
~SealHandleScope();

private:
// Make it hard to create heap-allocated or illegal handle scopes by
// disallowing certain operations.
SealHandleScope(const SealHandleScope&);
void operator=(const SealHandleScope&);
void* operator new(size_t size);
void operator delete(void*, size_t);

internal::Isolate* isolate_;
int prev_level_;
internal::Object** prev_limit_;
};




/**
* A compiled JavaScript script, not yet tied to a Context.
*/
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21 changes: 21 additions & 0 deletions deps/v8/src/api.cc
Original file line number Diff line number Diff line change
Expand Up @@ -637,6 +637,27 @@ i::Object** EscapableHandleScope::Escape(i::Object** escape_value) {
}


SealHandleScope::SealHandleScope(Isolate* isolate) {
i::Isolate* internal_isolate = reinterpret_cast<i::Isolate*>(isolate);

isolate_ = internal_isolate;
i::HandleScopeData* current = internal_isolate->handle_scope_data();
prev_limit_ = current->limit;
current->limit = current->next;
prev_level_ = current->level;
current->level = 0;
}


SealHandleScope::~SealHandleScope() {
i::HandleScopeData* current = isolate_->handle_scope_data();
DCHECK_EQ(0, current->level);
current->level = prev_level_;
DCHECK_EQ(current->next, current->limit);
current->limit = prev_limit_;
}


void Context::Enter() {
i::Handle<i::Context> env = Utils::OpenHandle(this);
i::Isolate* isolate = env->GetIsolate();
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5 changes: 1 addition & 4 deletions deps/v8/src/api.h
Original file line number Diff line number Diff line change
Expand Up @@ -642,17 +642,14 @@ void HandleScopeImplementer::DeleteExtensions(internal::Object** prev_limit) {
while (!blocks_.is_empty()) {
internal::Object** block_start = blocks_.last();
internal::Object** block_limit = block_start + kHandleBlockSize;
#ifdef DEBUG

// SealHandleScope may make the prev_limit to point inside the block.
if (block_start <= prev_limit && prev_limit <= block_limit) {
#ifdef ENABLE_HANDLE_ZAPPING
internal::HandleScope::ZapRange(prev_limit, block_limit);
#endif
break;
}
#else
if (prev_limit == block_limit) break;
#endif

blocks_.RemoveLast();
#ifdef ENABLE_HANDLE_ZAPPING
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1 change: 1 addition & 0 deletions deps/v8/test/cctest/cctest.status
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Expand Up @@ -43,6 +43,7 @@
# they don't fail then test.py has failed.
'test-serialize/TestThatAlwaysFails': [FAIL],
'test-serialize/DependentTestThatAlwaysFails': [FAIL],
'test-api/SealHandleScope': [FAIL],

# This test always fails. It tests that LiveEdit causes abort when turned off.
'test-debug/LiveEditDisabled': [FAIL],
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32 changes: 32 additions & 0 deletions deps/v8/test/cctest/test-api.cc
Original file line number Diff line number Diff line change
Expand Up @@ -20625,6 +20625,38 @@ void CallCompletedCallbackException() {
}


TEST(SealHandleScope) {
v8::Isolate* isolate = CcTest::isolate();
v8::HandleScope handle_scope(isolate);
LocalContext env;

v8::SealHandleScope seal(isolate);

// Should fail
v8::Local<v8::Object> obj = v8::Object::New(isolate);

USE(obj);
}


TEST(SealHandleScopeNested) {
v8::Isolate* isolate = CcTest::isolate();
v8::HandleScope handle_scope(isolate);
LocalContext env;

v8::SealHandleScope seal(isolate);

{
v8::HandleScope handle_scope(isolate);

// Should work
v8::Local<v8::Object> obj = v8::Object::New(isolate);

USE(obj);
}
}


TEST(CallCompletedCallbackOneException) {
LocalContext env;
v8::HandleScope scope(env->GetIsolate());
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