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[9.x] backport 19112, 19177 (bootstrapper & loaders reafactor) #19374

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1 change: 0 additions & 1 deletion .eslintrc.yaml
Original file line number Diff line number Diff line change
Expand Up @@ -214,4 +214,3 @@ globals:
LTTNG_HTTP_SERVER_RESPONSE: false
LTTNG_NET_SERVER_CONNECTION: false
LTTNG_NET_STREAM_END: false
internalBinding: false
1 change: 1 addition & 0 deletions lib/domain.js
Original file line number Diff line number Diff line change
Expand Up @@ -30,6 +30,7 @@ const util = require('util');
const EventEmitter = require('events');
const errors = require('internal/errors');
const { createHook } = require('async_hooks');
const { internalBinding } = require('internal/bootstrap/loaders');

// overwrite process.domain with a getter/setter that will allow for more
// effective optimizations
Expand Down
217 changes: 217 additions & 0 deletions lib/internal/bootstrap/loaders.js
Original file line number Diff line number Diff line change
@@ -0,0 +1,217 @@
// This file creates the internal module & binding loaders used by built-in
// modules. In contrast, user land modules are loaded using
// lib/internal/modules/cjs/loader.js (CommonJS Modules) or
// lib/internal/modules/esm/* (ES Modules).
//
// This file is compiled and run by node.cc before bootstrap/node.js
// was called, therefore the loaders are bootstraped before we start to
// actually bootstrap Node.js. It creates the following objects:
//
// C++ binding loaders:
// - process.binding(): the legacy C++ binding loader, accessible from user land
// because it is an object attached to the global process object.
// These C++ bindings are created using NODE_BUILTIN_MODULE_CONTEXT_AWARE()
// and have their nm_flags set to NM_F_BUILTIN. We do not make any guarantees
// about the stability of these bindings, but still have to take care of
// compatibility issues caused by them from time to time.
// - process._linkedBinding(): intended to be used by embedders to add
// additional C++ bindings in their applications. These C++ bindings
// can be created using NODE_MODULE_CONTEXT_AWARE_CPP() with the flag
// NM_F_LINKED.
// - internalBinding(): the private internal C++ binding loader, inaccessible
// from user land because they are only available from NativeModule.require()
// These C++ bindings are created using NODE_MODULE_CONTEXT_AWARE_INTERNAL()
// and have their nm_flags set to NM_F_INTERNAL.
//
// Internal JavaScript module loader:
// - NativeModule: a minimal module system used to load the JavaScript core
// modules found in lib/**/*.js and deps/**/*.js. All core modules are
// compiled into the node binary via node_javascript.cc generated by js2c.py,
// so they can be loaded faster without the cost of I/O. This class makes the
// lib/internal/*, deps/internal/* modules and internalBinding() available by
// default to core modules, and lets the core modules require itself via
// require('internal/bootstrap/loaders') even when this file is not written in
// CommonJS style.
//
// Other objects:
// - process.moduleLoadList: an array recording the bindings and the modules
// loaded in the process and the order in which they are loaded.

'use strict';

(function bootstrapInternalLoaders(process, getBinding, getLinkedBinding,
getInternalBinding) {

// Set up process.moduleLoadList
const moduleLoadList = [];
Object.defineProperty(process, 'moduleLoadList', {
value: moduleLoadList,
configurable: true,
enumerable: true,
writable: false
});

// Set up process.binding() and process._linkedBinding()
{
const bindingObj = Object.create(null);

process.binding = function binding(module) {
module = String(module);
let mod = bindingObj[module];
if (typeof mod !== 'object') {
mod = bindingObj[module] = getBinding(module);
moduleLoadList.push(`Binding ${module}`);
}
return mod;
};

process._linkedBinding = function _linkedBinding(module) {
module = String(module);
let mod = bindingObj[module];
if (typeof mod !== 'object')
mod = bindingObj[module] = getLinkedBinding(module);
return mod;
};
}

// Set up internalBinding() in the closure
let internalBinding;
{
const bindingObj = Object.create(null);
internalBinding = function internalBinding(module) {
let mod = bindingObj[module];
if (typeof mod !== 'object') {
mod = bindingObj[module] = getInternalBinding(module);
moduleLoadList.push(`Internal Binding ${module}`);
}
return mod;
};
}

// Minimal sandbox helper
const ContextifyScript = process.binding('contextify').ContextifyScript;
function runInThisContext(code, options) {
const script = new ContextifyScript(code, options);
return script.runInThisContext();
}

// Set up NativeModule
function NativeModule(id) {
this.filename = `${id}.js`;
this.id = id;
this.exports = {};
this.loaded = false;
this.loading = false;
}

NativeModule._source = getBinding('natives');
NativeModule._cache = {};

const config = getBinding('config');

// Think of this as module.exports in this file even though it is not
// written in CommonJS style.
const loaderExports = { internalBinding, NativeModule };
const loaderId = 'internal/bootstrap/loaders';
NativeModule.require = function(id) {
if (id === loaderId) {
return loaderExports;
}

const cached = NativeModule.getCached(id);
if (cached && (cached.loaded || cached.loading)) {
return cached.exports;
}

if (!NativeModule.exists(id)) {
// Model the error off the internal/errors.js model, but
// do not use that module given that it could actually be
// the one causing the error if there's a bug in Node.js
const err = new Error(`No such built-in module: ${id}`);
err.code = 'ERR_UNKNOWN_BUILTIN_MODULE';
err.name = 'Error [ERR_UNKNOWN_BUILTIN_MODULE]';
throw err;
}

moduleLoadList.push(`NativeModule ${id}`);

const nativeModule = new NativeModule(id);

nativeModule.cache();
nativeModule.compile();

return nativeModule.exports;
};

NativeModule.getCached = function(id) {
return NativeModule._cache[id];
};

NativeModule.exists = function(id) {
return NativeModule._source.hasOwnProperty(id);
};

if (config.exposeInternals) {
NativeModule.nonInternalExists = function(id) {
// Do not expose this to user land even with --expose-internals
if (id === loaderId) {
return false;
}
return NativeModule.exists(id);
};

NativeModule.isInternal = function(id) {
// Do not expose this to user land even with --expose-internals
return id === loaderId;
};
} else {
NativeModule.nonInternalExists = function(id) {
return NativeModule.exists(id) && !NativeModule.isInternal(id);
};

NativeModule.isInternal = function(id) {
return id.startsWith('internal/');
};
}

NativeModule.getSource = function(id) {
return NativeModule._source[id];
};

NativeModule.wrap = function(script) {
return NativeModule.wrapper[0] + script + NativeModule.wrapper[1];
};

NativeModule.wrapper = [
'(function (exports, require, module, process) {',
'\n});'
];

NativeModule.prototype.compile = function() {
let source = NativeModule.getSource(this.id);
source = NativeModule.wrap(source);

this.loading = true;

try {
const fn = runInThisContext(source, {
filename: this.filename,
lineOffset: 0,
displayErrors: true
});
fn(this.exports, NativeModule.require, this, process);

this.loaded = true;
} finally {
this.loading = false;
}
};

NativeModule.prototype.cache = function() {
NativeModule._cache[this.id] = this;
};

// This will be passed to the bootstrapNodeJSCore function in
// bootstrap/node.js.
return loaderExports;
});
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