I get TypeError: Cannot read properties of undefined (reading 'has') when checking permission

I am experimenting with the Node.js permission model in Node.js v20. One of the features it provides is the ability to check for permissions during runtime. So here is my simplified code:

// app.js
console.log(process.permission.has("fs.read"));

When I run the program using node app.js, I receive an error that looks like so:

console.log(process.permission.has("fs.read"));
                               ^

TypeError: Cannot read properties of undefined (reading 'has')
    at file:///home/stanley/example-app/app.js:1:32
    at ModuleJob.run (node:internal/modules/esm/module_job:192:25)
    at async DefaultModuleLoader.import (node:internal/modules/esm/loader:246:24)
    at async loadESM (node:internal/process/esm_loader:40:7)
    at async handleMainPromise (node:internal/modules/run_main:66:12)

Node.js v20.3.0

When I run the program with the `--experimental-permission flag, I receive this error:

node:internal/modules/cjs/loader:179
  const result = internalModuleStat(filename);
                 ^

Error: Access to this API has been restricted
    at stat (node:internal/modules/cjs/loader:179:18)
    at Module._findPath (node:internal/modules/cjs/loader:651:16)
    at resolveMainPath (node:internal/modules/run_main:15:25)
    at Function.executeUserEntryPoint [as runMain] (node:internal/modules/run_main:76:24)
    at node:internal/main/run_main_module:23:47 {
  code: 'ERR_ACCESS_DENIED',
  permission: 'FileSystemRead',
  resource: '/home/stanley/example_app/app.js'
}

Node.js v20.3.0

I expect the program to print false in the console, but instead, I receive this error.

From the Process-based permissions doc:

> The Node.js Permission Model is a mechanism for restricting access to specific resources during execution. The API exists behind a flag --experimental-permission which when enabled, will restrict access to all available permissions.

To allow Node access to the file system. We can use the --allow-fs-read and --allow-fs-write flags.

--allow-fs-read=* - It will allow all FileSystemRead operations.

index.js:

const fs = require('fs');
const path = require('path');

console.log('Has fs.read permission?', process.permission.has("fs.read"));
console.log('Has fs.write permission?', process.permission.has("fs.write"));

console.log('JSON: ', fs.readFileSync(path.resolve(__dirname, './a.json'), 'utf-8'))

fs.writeFileSync(path.resolve(__dirname, './b.json'), JSON.stringify({status: 'ok'}))

a.json:

{
  "name": "lin"
}

$ node --experimental-permission --allow-fs-read=* index.js

OR, use specific files(must be absolute paths, relative paths are not supported)

node --experimental-permission --allow-fs-read=/home/lindu/workspace/nodejs-examples/v20/a.json,/home/lindu/workspace/nodejs-examples/v20/index.js index.js

Node process can only read a.json and index.js files.

Output:

Has fs.read permission? true
Has fs.write permission? false
JSON:  {
  "name": "lin"
}

node:fs:589
  const result = binding.open(pathModule.toNamespacedPath(path),
                         ^

Error: Access to this API has been restricted
    at Object.openSync (node:fs:589:26)
    at Object.writeFileSync (node:fs:2323:35)
    at Object.<anonymous> (/home/lindu/workspace/nodejs-examples/v20/app.js:9:4)
    at Module._compile (node:internal/modules/cjs/loader:1255:14)
    at Module._extensions..js (node:internal/modules/cjs/loader:1309:10)
    at Module.load (node:internal/modules/cjs/loader:1113:32)
    at Module._load (node:internal/modules/cjs/loader:960:12)
    at Function.executeUserEntryPoint [as runMain] (node:internal/modules/run_main:83:12)
    at node:internal/main/run_main_module:23:47 {
  code: 'ERR_ACCESS_DENIED',
  permission: 'FileSystemWrite',
  resource: '/home/lindu/workspace/nodejs-examples/v20/b.json'
}

Node.js v20.3.0

Above code allow all FileSystemRead operations, but not allow all FileSystemWrite operations.

So the fs.writeFileSync operation fails.