lib: generate allowedNodeEnvironmentFlags lazily

PR-URL: #22638
Reviewed-By: James M Snell <[email protected]>
Reviewed-By: Ruben Bridgewater <[email protected]>

Author: addaleax

lib/internal/bootstrap/node.js

@@ -670,117 +670,132 @@
     const has = Function.call.bind(Set.prototype.has);
     const test = Function.call.bind(RegExp.prototype.test);
 
-    const {
-      getOptions,
-      types: { kV8Option },
-      envSettings: { kAllowedInEnvironment }
-    } = internalBinding('options');
-    const { options, aliases } = getOptions();
-
-    const allowedV8EnvironmentFlags = [];
-    const allowedNodeEnvironmentFlags = [];
-    for (const [name, info] of options) {
-      if (info.envVarSettings === kAllowedInEnvironment) {
-        if (info.type === kV8Option) {
-          allowedV8EnvironmentFlags.push(name);
-        } else {
-          allowedNodeEnvironmentFlags.push(name);
+    const get = () => {
+      const {
+        getOptions,
+        types: { kV8Option },
+        envSettings: { kAllowedInEnvironment }
+      } = internalBinding('options');
+      const { options, aliases } = getOptions();
+
+      const allowedV8EnvironmentFlags = [];
+      const allowedNodeEnvironmentFlags = [];
+      for (const [name, info] of options) {
+        if (info.envVarSettings === kAllowedInEnvironment) {
+          if (info.type === kV8Option) {
+            allowedV8EnvironmentFlags.push(name);
+          } else {
+            allowedNodeEnvironmentFlags.push(name);
+          }
         }
       }
-    }
 
-    for (const [ from, expansion ] of aliases) {
-      let isAccepted = true;
-      for (const to of expansion) {
-        if (!to.startsWith('-')) continue;
-        const recursiveExpansion = aliases.get(to);
-        if (recursiveExpansion) {
-          expansion.push(...recursiveExpansion);
-          continue;
+      for (const [ from, expansion ] of aliases) {
+        let isAccepted = true;
+        for (const to of expansion) {
+          if (!to.startsWith('-')) continue;
+          const recursiveExpansion = aliases.get(to);
+          if (recursiveExpansion) {
+            expansion.push(...recursiveExpansion);
+            continue;
+          }
+          isAccepted = options.get(to).envVarSettings === kAllowedInEnvironment;
+          if (!isAccepted) break;
+        }
+        if (isAccepted) {
+          let canonical = from;
+          if (canonical.endsWith('='))
+            canonical = canonical.substr(0, canonical.length - 1);
+          if (canonical.endsWith(' <arg>'))
+            canonical = canonical.substr(0, canonical.length - 4);
+          allowedNodeEnvironmentFlags.push(canonical);
         }
-        isAccepted = options.get(to).envVarSettings === kAllowedInEnvironment;
-        if (!isAccepted) break;
-      }
-      if (isAccepted) {
-        let canonical = from;
-        if (canonical.endsWith('='))
-          canonical = canonical.substr(0, canonical.length - 1);
-        if (canonical.endsWith(' <arg>'))
-          canonical = canonical.substr(0, canonical.length - 4);
-        allowedNodeEnvironmentFlags.push(canonical);
       }
-    }
 
-    const trimLeadingDashes = (flag) => replace(flag, leadingDashesRegex, '');
-
-    // Save these for comparison against flags provided to
-    // process.allowedNodeEnvironmentFlags.has() which lack leading dashes.
-    // Avoid interference w/ user code by flattening `Set.prototype` into
-    // each object.
-    const [nodeFlags, v8Flags] = [
-      allowedNodeEnvironmentFlags, allowedV8EnvironmentFlags
-    ].map((flags) => Object.defineProperties(
-      new Set(flags.map(trimLeadingDashes)),
-      Object.getOwnPropertyDescriptors(Set.prototype))
-    );
-
-    class NodeEnvironmentFlagsSet extends Set {
-      constructor(...args) {
-        super(...args);
-
-        // the super constructor consumes `add`, but
-        // disallow any future adds.
-        this.add = () => this;
-      }
+      const trimLeadingDashes = (flag) => replace(flag, leadingDashesRegex, '');
+
+      // Save these for comparison against flags provided to
+      // process.allowedNodeEnvironmentFlags.has() which lack leading dashes.
+      // Avoid interference w/ user code by flattening `Set.prototype` into
+      // each object.
+      const [nodeFlags, v8Flags] = [
+        allowedNodeEnvironmentFlags, allowedV8EnvironmentFlags
+      ].map((flags) => Object.defineProperties(
+        new Set(flags.map(trimLeadingDashes)),
+        Object.getOwnPropertyDescriptors(Set.prototype))
+      );
 
-      delete() {
-        // noop, `Set` API compatible
-        return false;
-      }
+      class NodeEnvironmentFlagsSet extends Set {
+        constructor(...args) {
+          super(...args);
 
-      clear() {
-        // noop
-      }
+          // the super constructor consumes `add`, but
+          // disallow any future adds.
+          this.add = () => this;
+        }
 
-      has(key) {
-        // This will return `true` based on various possible
-        // permutations of a flag, including present/missing leading
-        // dash(es) and/or underscores-for-dashes in the case of V8-specific
-        // flags.  Strips any values after `=`, inclusive.
-        // TODO(addaleax): It might be more flexible to run the option parser
-        // on a dummy option set and see whether it rejects the argument or
-        // not.
-        if (typeof key === 'string') {
-          key = replace(key, trailingValuesRegex, '');
-          if (test(leadingDashesRegex, key)) {
-            return has(this, key) ||
-                  has(v8Flags,
-                      replace(
+        delete() {
+          // noop, `Set` API compatible
+          return false;
+        }
+
+        clear() {
+          // noop
+        }
+
+        has(key) {
+          // This will return `true` based on various possible
+          // permutations of a flag, including present/missing leading
+          // dash(es) and/or underscores-for-dashes in the case of V8-specific
+          // flags.  Strips any values after `=`, inclusive.
+          // TODO(addaleax): It might be more flexible to run the option parser
+          // on a dummy option set and see whether it rejects the argument or
+          // not.
+          if (typeof key === 'string') {
+            key = replace(key, trailingValuesRegex, '');
+            if (test(leadingDashesRegex, key)) {
+              return has(this, key) ||
+                    has(v8Flags,
                         replace(
-                          key,
-                          leadingDashesRegex,
-                          ''
-                        ),
-                        replaceDashesRegex,
-                        '_'
-                      )
-                  );
+                          replace(
+                            key,
+                            leadingDashesRegex,
+                            ''
+                          ),
+                          replaceDashesRegex,
+                          '_'
+                        )
+                    );
+            }
+            return has(nodeFlags, key) ||
+                  has(v8Flags, replace(key, replaceDashesRegex, '_'));
           }
-          return has(nodeFlags, key) ||
-                has(v8Flags, replace(key, replaceDashesRegex, '_'));
+          return false;
         }
-        return false;
       }
-    }
 
-    Object.freeze(NodeEnvironmentFlagsSet.prototype.constructor);
-    Object.freeze(NodeEnvironmentFlagsSet.prototype);
+      Object.freeze(NodeEnvironmentFlagsSet.prototype.constructor);
+      Object.freeze(NodeEnvironmentFlagsSet.prototype);
+
+      return process.allowedNodeEnvironmentFlags = Object.freeze(
+        new NodeEnvironmentFlagsSet(
+          allowedNodeEnvironmentFlags.concat(allowedV8EnvironmentFlags)
+        ));
+    };
 
-    process.allowedNodeEnvironmentFlags = Object.freeze(
-      new NodeEnvironmentFlagsSet(
-        allowedNodeEnvironmentFlags.concat(allowedV8EnvironmentFlags)
-      )
-    );
+    Object.defineProperty(process, 'allowedNodeEnvironmentFlags', {
+      get,
+      set(value) {
+        Object.defineProperty(this, 'allowedNodeEnvironmentFlags', {
+          value,
+          configurable: true,
+          enumerable: true,
+          writable: true
+        });
+      },
+      enumerable: true,
+      configurable: true
+    });
   }
 
   startup();