node-fallbacks: bind free process and Buffer in the browser polyfills, fix util, process and timers, make require() of assert and events callable

bunfig.toml

@@ -40,6 +40,6 @@ ignorePatterns = [
 ]
 
 [lint]
-# `bun lint` lints src/js.
+# `bun lint` lints src/js and the browser polyfills in src/node-fallbacks.
 config = "oxlint.json"
-ignorePatterns = ["/*", "!/src", "/src/*", "!/src/js"]
+ignorePatterns = ["/*", "!/src", "/src/*", "!/src/js", "!/src/node-fallbacks"]

oxlint.json

@@ -118,6 +118,23 @@
       "rules": {
         "bun/no-unused-expressions": "off"
       }
+    },
+    {
+      // Browser polyfills that `bun build --target=browser` inlines into the
+      // user's bundle. They are plain JS, not JSC builtins: a `$intrinsic`,
+      // a node global such as `process` or `Buffer`, or any other undeclared
+      // name is a ReferenceError in the browser. Read `globalThis.process`.
+      "files": ["src/node-fallbacks/*.js"],
+      "env": { "browser": true, "es2024": true },
+      "rules": {
+        "no-undef": "error",
+        "no-unused-vars": "off",
+        "no-useless-rename": "off"
+      }
+    },
+    {
+      "files": ["src/node-fallbacks/assert.js", "src/node-fallbacks/events.js", "src/node-fallbacks/stream.js"],
+      "env": { "commonjs": true }
     }
   ]
 }

src/node-fallbacks/assert.js

@@ -1,25 +1,2 @@
-import * as assert from "./node_modules/assert";
-
-export const {
-  AssertionError,
-  CallTracker,
-  deepEqual,
-  deepStrictEqual,
-  doesNotMatch,
-  doesNotReject,
-  doesNotThrow,
-  equal,
-  fail,
-  ifError,
-  match,
-  notDeepEqual,
-  notDeepStrictEqual,
-  notEqual,
-  notStrictEqual,
-  ok,
-  rejects,
-  strict,
-  strictEqual,
-  throws,
-} = assert;
-export default assert;
+// CommonJS so that `require("assert")` returns the callable function.
+module.exports = require("./node_modules/assert");

src/node-fallbacks/build-fallbacks.ts

@@ -17,39 +17,59 @@ for (const name of allFiles) {
 
 for (let fileIndex = 0; fileIndex < allFiles.length; fileIndex++) {
   const name = allFiles[fileIndex];
-  const mod = basename(name, extname(name)).replaceAll(".", "/");
-  const file = allFiles.find(f => f.startsWith(mod));
-  const externals = [...builtins];
-  const i = externals.indexOf(name);
-  if (i !== -1) {
-    externals.splice(i, 1);
-  }
 
   // Build all files at once with specific options
   const externalModules = builtins
     .concat(moduleFiles.filter(f => f !== name))
     .flatMap(b => [`--external:node:${b}`, `--external:${b}`])
     .join(" ");
 
+  // A source that sets `module.exports` stays CommonJS, so `require()` of the polyfill returns that value.
+  const format = /^module\.exports\s*=/m.test(fs.readFileSync(name, "utf8")) ? "cjs" : "esm";
+
+  // Free `process` / `Buffer` in the npm packages: rename, then import from the sibling polyfill.
+  const injectedGlobals = [
+    {
+      defines: ["process", "global.process"],
+      id: "__bun_process",
+      skip: ["process.js"],
+      esm: 'import __bun_process from "process";',
+      cjs: 'var __bun_process = require("process").default;',
+    },
+    {
+      defines: ["Buffer", "global.Buffer"],
+      id: "__bun_Buffer",
+      // assert.js: only npm util's never-called isBuffer() names Buffer; the import would cost 31 KB.
+      skip: ["buffer.js", "assert.js"],
+      esm: 'import { Buffer as __bun_Buffer } from "buffer";',
+      cjs: 'var __bun_Buffer = require("buffer").Buffer;',
+    },
+  ].filter(g => !g.skip.includes(name));
+  const defineGlobals = injectedGlobals.flatMap(g => g.defines.map(d => `--define=${d}:${g.id}`)).join(" ");
+
   // Create the build command with all the specified options
   const buildCommand =
-    Bun.$`bun build --define=process.env.NODE_DEBUG:"false" --define=process.env.READABLE_STREAM="'enable'" --define=global:globalThis --outdir=${outdir} ${name} --minify-syntax --minify-whitespace --format=${name.includes("stream") ? "cjs" : "esm"} --target=node ${{ raw: externalModules }}`.text();
+    Bun.$`bun build --define=process.env.NODE_DEBUG:"false" --define=process.env.READABLE_STREAM="'enable'" --define=global:globalThis ${{ raw: defineGlobals }} --outdir=${outdir} ${name} --minify-syntax --minify-whitespace --format=${format} --target=node ${{ raw: externalModules }}`.text();
 
   commands.push(
-    buildCommand.then(async text => {
+    buildCommand.then(async () => {
       // This is very brittle. But that should be okay for our usecase
       let outfile = fs
         .readFileSync(`${outdir}/${name}`, "utf8")
         .replaceAll("__require(", "require(")
         .replaceAll("import.meta.url", "''")
         .replaceAll("createRequire", "")
-        .replaceAll("global.process", "require('process')")
         .trim();
 
       while (outfile.startsWith("import{")) {
         outfile = outfile.slice(outfile.indexOf(";") + 1);
       }
 
+      for (const { id, esm, cjs } of injectedGlobals) {
+        if (!outfile.includes(id)) continue;
+        outfile = (format === "cjs" ? cjs : esm) + outfile;
+      }
+
       if (outfile.includes('"node:module"')) {
         console.log(outfile);
         throw new Error("Unexpected import in " + name);

src/node-fallbacks/console.js

@@ -1 +1,24 @@
+// Hardcoded module "node:console"
+export const {
+  assert,
+  clear,
+  count,
+  countReset,
+  debug,
+  dir,
+  dirxml,
+  error,
+  group,
+  groupCollapsed,
+  groupEnd,
+  info,
+  log,
+  table,
+  time,
+  timeEnd,
+  timeLog,
+  timeStamp,
+  trace,
+  warn,
+} = console;
 export default console;

src/node-fallbacks/constants.js

@@ -206,3 +206,213 @@ export const R_OK = 4;
 export const W_OK = 2;
 export const X_OK = 1;
 export const UV_UDP_REUSEADDR = 4;
+
+export default {
+  O_RDONLY,
+  O_WRONLY,
+  O_RDWR,
+  S_IFMT,
+  S_IFREG,
+  S_IFDIR,
+  S_IFCHR,
+  S_IFBLK,
+  S_IFIFO,
+  S_IFLNK,
+  S_IFSOCK,
+  O_CREAT,
+  O_EXCL,
+  O_NOCTTY,
+  O_TRUNC,
+  O_APPEND,
+  O_DIRECTORY,
+  O_NOFOLLOW,
+  O_SYNC,
+  O_SYMLINK,
+  O_NONBLOCK,
+  S_IRWXU,
+  S_IRUSR,
+  S_IWUSR,
+  S_IXUSR,
+  S_IRWXG,
+  S_IRGRP,
+  S_IWGRP,
+  S_IXGRP,
+  S_IRWXO,
+  S_IROTH,
+  S_IWOTH,
+  S_IXOTH,
+  E2BIG,
+  EACCES,
+  EADDRINUSE,
+  EADDRNOTAVAIL,
+  EAFNOSUPPORT,
+  EAGAIN,
+  EALREADY,
+  EBADF,
+  EBADMSG,
+  EBUSY,
+  ECANCELED,
+  ECHILD,
+  ECONNABORTED,
+  ECONNREFUSED,
+  ECONNRESET,
+  EDEADLK,
+  EDESTADDRREQ,
+  EDOM,
+  EDQUOT,
+  EEXIST,
+  EFAULT,
+  EFBIG,
+  EHOSTUNREACH,
+  EIDRM,
+  EILSEQ,
+  EINPROGRESS,
+  EINTR,
+  EINVAL,
+  EIO,
+  EISCONN,
+  EISDIR,
+  ELOOP,
+  EMFILE,
+  EMLINK,
+  EMSGSIZE,
+  EMULTIHOP,
+  ENAMETOOLONG,
+  ENETDOWN,
+  ENETRESET,
+  ENETUNREACH,
+  ENFILE,
+  ENOBUFS,
+  ENODATA,
+  ENODEV,
+  ENOENT,
+  ENOEXEC,
+  ENOLCK,
+  ENOLINK,
+  ENOMEM,
+  ENOMSG,
+  ENOPROTOOPT,
+  ENOSPC,
+  ENOSR,
+  ENOSTR,
+  ENOSYS,
+  ENOTCONN,
+  ENOTDIR,
+  ENOTEMPTY,
+  ENOTSOCK,
+  ENOTSUP,
+  ENOTTY,
+  ENXIO,
+  EOPNOTSUPP,
+  EOVERFLOW,
+  EPERM,
+  EPIPE,
+  EPROTO,
+  EPROTONOSUPPORT,
+  EPROTOTYPE,
+  ERANGE,
+  EROFS,
+  ESPIPE,
+  ESRCH,
+  ESTALE,
+  ETIME,
+  ETIMEDOUT,
+  ETXTBSY,
+  EWOULDBLOCK,
+  EXDEV,
+  SIGHUP,
+  SIGINT,
+  SIGQUIT,
+  SIGILL,
+  SIGTRAP,
+  SIGABRT,
+  SIGIOT,
+  SIGBUS,
+  SIGFPE,
+  SIGKILL,
+  SIGUSR1,
+  SIGSEGV,
+  SIGUSR2,
+  SIGPIPE,
+  SIGALRM,
+  SIGTERM,
+  SIGCHLD,
+  SIGCONT,
+  SIGSTOP,
+  SIGTSTP,
+  SIGTTIN,
+  SIGTTOU,
+  SIGURG,
+  SIGXCPU,
+  SIGXFSZ,
+  SIGVTALRM,
+  SIGPROF,
+  SIGWINCH,
+  SIGIO,
+  SIGSYS,
+  SSL_OP_ALL,
+  SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION,
+  SSL_OP_CIPHER_SERVER_PREFERENCE,
+  SSL_OP_CISCO_ANYCONNECT,
+  SSL_OP_COOKIE_EXCHANGE,
+  SSL_OP_CRYPTOPRO_TLSEXT_BUG,
+  SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS,
+  SSL_OP_EPHEMERAL_RSA,
+  SSL_OP_LEGACY_SERVER_CONNECT,
+  SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER,
+  SSL_OP_MICROSOFT_SESS_ID_BUG,
+  SSL_OP_MSIE_SSLV2_RSA_PADDING,
+  SSL_OP_NETSCAPE_CA_DN_BUG,
+  SSL_OP_NETSCAPE_CHALLENGE_BUG,
+  SSL_OP_NETSCAPE_DEMO_CIPHER_CHANGE_BUG,
+  SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG,
+  SSL_OP_NO_COMPRESSION,
+  SSL_OP_NO_QUERY_MTU,
+  SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION,
+  SSL_OP_NO_SSLv2,
+  SSL_OP_NO_SSLv3,
+  SSL_OP_NO_TICKET,
+  SSL_OP_NO_TLSv1,
+  SSL_OP_NO_TLSv1_1,
+  SSL_OP_NO_TLSv1_2,
+  SSL_OP_PKCS1_CHECK_1,
+  SSL_OP_PKCS1_CHECK_2,
+  SSL_OP_SINGLE_DH_USE,
+  SSL_OP_SINGLE_ECDH_USE,
+  SSL_OP_SSLEAY_080_CLIENT_DH_BUG,
+  SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG,
+  SSL_OP_TLS_BLOCK_PADDING_BUG,
+  SSL_OP_TLS_D5_BUG,
+  SSL_OP_TLS_ROLLBACK_BUG,
+  ENGINE_METHOD_DSA,
+  ENGINE_METHOD_DH,
+  ENGINE_METHOD_RAND,
+  ENGINE_METHOD_ECDH,
+  ENGINE_METHOD_ECDSA,
+  ENGINE_METHOD_CIPHERS,
+  ENGINE_METHOD_DIGESTS,
+  ENGINE_METHOD_STORE,
+  ENGINE_METHOD_PKEY_METHS,
+  ENGINE_METHOD_PKEY_ASN1_METHS,
+  ENGINE_METHOD_ALL,
+  ENGINE_METHOD_NONE,
+  DH_CHECK_P_NOT_SAFE_PRIME,
+  DH_CHECK_P_NOT_PRIME,
+  DH_UNABLE_TO_CHECK_GENERATOR,
+  DH_NOT_SUITABLE_GENERATOR,
+  NPN_ENABLED,
+  RSA_PKCS1_PADDING,
+  RSA_SSLV23_PADDING,
+  RSA_NO_PADDING,
+  RSA_PKCS1_OAEP_PADDING,
+  RSA_X931_PADDING,
+  RSA_PKCS1_PSS_PADDING,
+  POINT_CONVERSION_COMPRESSED,
+  POINT_CONVERSION_UNCOMPRESSED,
+  POINT_CONVERSION_HYBRID,
+  F_OK,
+  R_OK,
+  W_OK,
+  X_OK,
+  UV_UDP_REUSEADDR,
+};

src/node-fallbacks/domain.js

@@ -1,2 +1,3 @@
 import domain from "domain-browser";
 export var { create, createDomain } = domain;
+export default domain;

src/node-fallbacks/events.js

@@ -530,15 +530,5 @@ Object.assign(EventEmitter, {
   listenerCount,
 });
 
-export default EventEmitter;
-export {
-  EventEmitter,
-  addAbortListener,
-  captureRejectionSymbol,
-  getEventListeners,
-  getMaxListeners,
-  EventEmitter as init,
-  listenerCount,
-  once,
-  setMaxListeners,
-};
+// CommonJS so that `require("events")` returns the constructor.
+module.exports = EventEmitter;