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8825dc321a
PR-URL: https://github.com/nodejs/node/pull/53611 Reviewed-By: Anna Henningsen <anna@addaleax.net> Reviewed-By: Chengzhong Wu <legendecas@gmail.com>
169 lines
7.2 KiB
C++
169 lines
7.2 KiB
C++
#ifndef SRC_NODE_CONTEXT_DATA_H_
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#define SRC_NODE_CONTEXT_DATA_H_
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#if defined(NODE_WANT_INTERNALS) && NODE_WANT_INTERNALS
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#include "util.h"
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#include "v8.h"
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namespace node {
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// Pick an index that's hopefully out of the way when we're embedded inside
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// another application. Performance-wise or memory-wise it doesn't matter:
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// Context::SetAlignedPointerInEmbedderData() is backed by a FixedArray,
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// worst case we pay a one-time penalty for resizing the array.
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#ifndef NODE_CONTEXT_EMBEDDER_DATA_INDEX
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#define NODE_CONTEXT_EMBEDDER_DATA_INDEX 32
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#endif
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#ifndef NODE_CONTEXT_SANDBOX_OBJECT_INDEX
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#define NODE_CONTEXT_SANDBOX_OBJECT_INDEX 33
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#endif
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#ifndef NODE_CONTEXT_ALLOW_WASM_CODE_GENERATION_INDEX
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#define NODE_CONTEXT_ALLOW_WASM_CODE_GENERATION_INDEX 34
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#endif
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#ifndef NODE_BINDING_DATA_STORE_INDEX
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#define NODE_BINDING_DATA_STORE_INDEX 35
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#endif
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#ifndef NODE_CONTEXT_ALLOW_CODE_GENERATION_FROM_STRINGS_INDEX
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#define NODE_CONTEXT_ALLOW_CODE_GENERATION_FROM_STRINGS_INDEX 36
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#endif
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#ifndef NODE_CONTEXT_CONTEXTIFY_CONTEXT_INDEX
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#define NODE_CONTEXT_CONTEXTIFY_CONTEXT_INDEX 37
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#endif
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#ifndef NODE_CONTEXT_REALM_INDEX
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#define NODE_CONTEXT_REALM_INDEX 38
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#endif
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// NODE_CONTEXT_TAG must be greater than any embedder indexes so that a single
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// check on the number of embedder data fields can assure the presence of all
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// embedder indexes.
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#ifndef NODE_CONTEXT_TAG
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#define NODE_CONTEXT_TAG 39
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#endif
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/**
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* These are indexes used to set Node.js-specific data in the V8 contexts
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* via v8::Context::SetAlignedPointerInEmbedderData() (for pointers) and
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* v8::Context::SetEmbedderData() (for v8::Values).
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*
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* There are five types of contexts in Node.js:
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* 1. Default V8 context, with nothing Node.js-specific. This is normally only
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* created by the embedders that uses v8::Context APIs directly and is not
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* available through the Node.js JS APIs. Its context snapshot in the
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* built-in v8 startup snapshot is stored using
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* v8::SnapshotCreator::SetDefaultContext() - effectively at index 0.
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* 2. Default Node.js main context. When Node.js is launched typically there is
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* a main thread on which a main node::Environment is created. The
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* Environment is associated with its own v8::Isolate (env->isolate()) and a
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* main v8::Context (env->context()). The corresponding data structure is
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* node::NodeMainInstance and the Environment is created in
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* node::NodeMainInstance::Run(). Its context snapshot in the built-in V8
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* startup snapshot is stored at node::SnapshotData::kNodeMainContextIndex.
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* 3. Node.js worker context. When a Worker instance is created via
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* new worker_threads.Worker(), it gets its own OS thread, its
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* own node::Environment, its own v8::Isolate and its own v8::Context.
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* The corresponding data structure is node::Worker and the Environment
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* is created in node::Worker::Run().
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* Its context snapshot in the built-in V8 startup snapshot is stored at
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* node::SnapshotData::kNodeBaseContextIndex.
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* 4. Contextified vm context: When a contextified context is created via
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* vm.createContext() or other related vm APIs, the vm.Context instance
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* gets its own v8::Context. It shares the thread, the v8::Isolate and
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* the node::Environment with the context where the vm APIs are called.
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* The corresponding data structure is node::ContextifyContext and
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* the initialization code is in node::ContextifyContext::New().
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* Its context snapshot in the built-in V8 startup snapshot is stored at
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* node::SnapshotData::kNodeVMContextIndex.
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* 5. ShadowRealm context: When a JS ShadowRealm is created via new ShadowRealm,
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* it gets its own v8::Context. It also shares the thread, the v8::Isolate
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* and the node::Environment with the context where the ShadowRealm
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* constructor is called. The corresponding data structure is
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* node::ShadowRealm and the initialization code is in
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* node::ShadowRealm::New().
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*/
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enum ContextEmbedderIndex {
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// Pointer to the node::Environment associated with the context. Only set for
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// context type 2-5. Used by Environment::GetCurrent(context) to retrieve
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// the node::Environment associated with any Node.js context in the
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// V8 callbacks.
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kEnvironment = NODE_CONTEXT_EMBEDDER_DATA_INDEX,
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// A v8::Value which is the sandbox object used to create the contextified vm
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// context. For example the first argument of vm.createContext().
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// Only set for context type 4 and used in ContextifyContext methods.
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kSandboxObject = NODE_CONTEXT_SANDBOX_OBJECT_INDEX,
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// A v8::Value indicating whether the context allows WebAssembly code
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// generation.
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// Only set for context type 2-5, and for them the default is v8::True.
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// For context type 4 it's configurable via options.codeGeneration.wasm in the
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// vm APIs. Used in the default v8::AllowWasmCodeGenerationCallback.
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kAllowWasmCodeGeneration = NODE_CONTEXT_ALLOW_WASM_CODE_GENERATION_INDEX,
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// A v8::Value indicating whether the context allows code generation via
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// eval() or new Function().
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// Only set for context type 2-5, and for them the default is v8::True.
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// For context type 4 it's configurable via options.codeGeneration.strings in
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// the
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// vm APIs. Used in the default v8::AllowCodeGenerationFromStringsCallback.
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kAllowCodeGenerationFromStrings =
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NODE_CONTEXT_ALLOW_CODE_GENERATION_FROM_STRINGS_INDEX,
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// Pointer to the node::ContextifyContext associated with vm.Contexts.
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// Only set for context type 4. Used by ContextifyContext::Get() to get
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// to the ContextifyContext from the property interceptors.
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kContextifyContext = NODE_CONTEXT_CONTEXTIFY_CONTEXT_INDEX,
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// Pointer to the node::Realm associated with the context.
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// Only set for context type 2-3 and 5. For context type 2-3, it points to a
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// node::PrincipalRealm. For context type 5 it points to a node::ShadowRealm.
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// Used by Realm::GetCurrent(context) to retrieve the associated node::Realm
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// with any Node.js context in the V8 callbacks.
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kRealm = NODE_CONTEXT_REALM_INDEX,
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// Pointer to a constant address which is
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// node::ContextEmbedderTag::kNodeContextTagPtr.
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// Only set for context type 2-5. Used by ContextEmbedderTag::IsNodeContext()
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// to check whether a context is a Node.js context.
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kContextTag = NODE_CONTEXT_TAG,
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};
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class ContextEmbedderTag {
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public:
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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
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// context.
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context->SetAlignedPointerInEmbedderData(
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ContextEmbedderIndex::kContextTag,
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ContextEmbedderTag::kNodeContextTagPtr);
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}
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static inline bool IsNodeContext(v8::Local<v8::Context> context) {
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if (UNLIKELY(context.IsEmpty())) {
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return false;
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}
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if (UNLIKELY(context->GetNumberOfEmbedderDataFields() <=
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ContextEmbedderIndex::kContextTag)) {
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return false;
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}
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if (UNLIKELY(context->GetAlignedPointerFromEmbedderData(
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ContextEmbedderIndex::kContextTag) !=
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ContextEmbedderTag::kNodeContextTagPtr)) {
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return false;
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}
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return true;
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}
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private:
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static void* const kNodeContextTagPtr;
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static int const kNodeContextTag;
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ContextEmbedderTag() = delete;
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};
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} // namespace node
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#endif // defined(NODE_WANT_INTERNALS) && NODE_WANT_INTERNALS
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#endif // SRC_NODE_CONTEXT_DATA_H_
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