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src: extract common context embedder tag checks #44258

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src: extract common context embedder tag checks #44258

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11 changes: 1 addition & 10 deletions src/env-inl.h
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Expand Up @@ -177,16 +177,7 @@ inline Environment* Environment::GetCurrent(v8::Isolate* isolate) {
}

inline Environment* Environment::GetCurrent(v8::Local<v8::Context> context) {
if (UNLIKELY(context.IsEmpty())) {
return nullptr;
}
if (UNLIKELY(context->GetNumberOfEmbedderDataFields() <=
ContextEmbedderIndex::kContextTag)) {
return nullptr;
}
if (UNLIKELY(context->GetAlignedPointerFromEmbedderData(
ContextEmbedderIndex::kContextTag) !=
Environment::kNodeContextTagPtr)) {
if (UNLIKELY(!ContextEmbedderTag::IsNodeContext(context))) {
return nullptr;
}
return static_cast<Environment*>(
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10 changes: 4 additions & 6 deletions src/env.cc
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Expand Up @@ -61,9 +61,9 @@ using v8::WeakCallbackInfo;
using v8::WeakCallbackType;
using worker::Worker;

int const Environment::kNodeContextTag = 0x6e6f64;
void* const Environment::kNodeContextTagPtr = const_cast<void*>(
static_cast<const void*>(&Environment::kNodeContextTag));
int const ContextEmbedderTag::kNodeContextTag = 0x6e6f64;
void* const ContextEmbedderTag::kNodeContextTagPtr = const_cast<void*>(
static_cast<const void*>(&ContextEmbedderTag::kNodeContextTag));

void AsyncHooks::SetJSPromiseHooks(Local<Function> init,
Local<Function> before,
Expand Down Expand Up @@ -512,11 +512,9 @@ void TrackingTraceStateObserver::UpdateTraceCategoryState() {

void Environment::AssignToContext(Local<v8::Context> context,
const ContextInfo& info) {
ContextEmbedderTag::TagNodeContext(context);
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Technically this should be done at the end of this method and the tagging should not be done before other fields are initialized, in case the ContextCreated call below invokes anything that attempts to access context fields, though it wouldn't be a problem until #44252 which makes it possible to fire ContextCreated() on contexts that have a global object with interceptors that attempt to access context fields, and the problem predates this PR anyway , so I am good with leaving it for that PR instead.

context->SetAlignedPointerInEmbedderData(ContextEmbedderIndex::kEnvironment,
this);
// Used by Environment::GetCurrent to know that we are on a node context.
context->SetAlignedPointerInEmbedderData(ContextEmbedderIndex::kContextTag,
Environment::kNodeContextTagPtr);
// Used to retrieve bindings
context->SetAlignedPointerInEmbedderData(
ContextEmbedderIndex::kBindingListIndex, &(this->bindings_));
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3 changes: 0 additions & 3 deletions src/env.h
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Expand Up @@ -1573,9 +1573,6 @@ class Environment : public MemoryRetainer {
uint64_t thread_id_;
std::unordered_set<worker::Worker*> sub_worker_contexts_;

static void* const kNodeContextTagPtr;
static int const kNodeContextTag;

#if HAVE_INSPECTOR
std::unique_ptr<inspector::Agent> inspector_agent_;
bool is_in_inspector_console_call_ = false;
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55 changes: 47 additions & 8 deletions src/node_context_data.h
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Expand Up @@ -3,6 +3,9 @@

#if defined(NODE_WANT_INTERNALS) && NODE_WANT_INTERNALS

#include "util.h"
#include "v8.h"

namespace node {

// Pick an index that's hopefully out of the way when we're embedded inside
Expand All @@ -21,26 +24,62 @@ namespace node {
#define NODE_CONTEXT_ALLOW_WASM_CODE_GENERATION_INDEX 34
#endif

#ifndef NODE_CONTEXT_TAG
#define NODE_CONTEXT_TAG 35
#endif

#ifndef NODE_BINDING_LIST
#define NODE_BINDING_LIST_INDEX 36
#define NODE_BINDING_LIST_INDEX 35
#endif

#ifndef NODE_CONTEXT_ALLOW_CODE_GENERATION_FROM_STRINGS_INDEX
#define NODE_CONTEXT_ALLOW_CODE_GENERATION_FROM_STRINGS_INDEX 37
#define NODE_CONTEXT_ALLOW_CODE_GENERATION_FROM_STRINGS_INDEX 36
#endif

// NODE_CONTEXT_TAG must be greater than any embedder indexes so that a single
// check on the number of embedder data fields can assure the presence of all
// embedder indexes.
#ifndef NODE_CONTEXT_TAG
#define NODE_CONTEXT_TAG 37
#endif

enum ContextEmbedderIndex {
kEnvironment = NODE_CONTEXT_EMBEDDER_DATA_INDEX,
kSandboxObject = NODE_CONTEXT_SANDBOX_OBJECT_INDEX,
kAllowWasmCodeGeneration = NODE_CONTEXT_ALLOW_WASM_CODE_GENERATION_INDEX,
kContextTag = NODE_CONTEXT_TAG,
kBindingListIndex = NODE_BINDING_LIST_INDEX,
kAllowCodeGenerationFromStrings =
NODE_CONTEXT_ALLOW_CODE_GENERATION_FROM_STRINGS_INDEX
NODE_CONTEXT_ALLOW_CODE_GENERATION_FROM_STRINGS_INDEX,
kContextTag = NODE_CONTEXT_TAG,
};

class ContextEmbedderTag {
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public:
static inline void TagNodeContext(v8::Local<v8::Context> context) {
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// Used by ContextEmbedderTag::IsNodeContext to know that we are on a node
// context.
context->SetAlignedPointerInEmbedderData(
ContextEmbedderIndex::kContextTag,
ContextEmbedderTag::kNodeContextTagPtr);
}

static inline bool IsNodeContext(v8::Local<v8::Context> context) {
if (UNLIKELY(context.IsEmpty())) {
return false;
}
if (UNLIKELY(context->GetNumberOfEmbedderDataFields() <=
ContextEmbedderIndex::kContextTag)) {
return false;
}
if (UNLIKELY(context->GetAlignedPointerFromEmbedderData(
ContextEmbedderIndex::kContextTag) !=
ContextEmbedderTag::kNodeContextTagPtr)) {
return false;
}
return true;
}

private:
static void* const kNodeContextTagPtr;
static int const kNodeContextTag;

ContextEmbedderTag() = delete;
};

} // namespace node
Expand Down