src: add support for externally shared js builtins

BUILDING.md

@@ -1052,6 +1052,44 @@ To make `./myModule.js` available via `require('myModule')` and
 > .\vcbuild link-module './myModule.js' link-module './myModule2.js'
 ```
 
+## Building to use shared dependencies at runtime
+
+By default Node.js is built so that all dependencies are bundled into
+the Node.js binary itself. This provides a single binary that includes
+the correct versions of all dependencies on which it depends.
+
+Some Node.js distributions, however, prefer to manage dependencies.
+A number of `configure` options are provided to support this use case.
+
+* For dependencies with native code, the first set of options allow
+  Node.js to be built so that it uses a shared library
+  at runtime instead of building and including the dependency
+  in the Node.js binary itself. These options are in the
+  `Shared libraries` section of the `configure` help
+  (run `./configure --help` to get the complete list).
+  They provide the ability to enable the use of a shared library,
+  to set the name of the shared library, and to set the paths that
+  contain the include and shared library files.
+
+* For dependencies with JavaScript code (including WASM), the second
+  set of options allow the Node.js binary to be built so that it loads
+  the JavaScript for dependencies at runtime instead of being built into
+  the Node.js binary itself. These options are in the `Shared builtins`
+  section of the `configure` help
+  (run `./configure --help` to get the complete list). They
+  provide the ability to set the path to an external JavaScript file
+  for the dependency to be used at runtime.
+
+It is the responsibility of any distribution
+shipping with these options to:
+
+* ensure that the shared dependencies available at runtime
+  match what is expected by the Node.js binary. A
+  mismatch may result in crashes or unexpected behavior.
+* fully test that Node.js operates as expected with the
+  external dependencies. There may be little or no test coverage
+  within the Node.js project CI for these non-default options.
+
 ## Note for downstream distributors of Node.js
 
 The Node.js ecosystem is reliant on ABI compatibility within a major release.

configure.py

@@ -57,6 +57,11 @@
 with open ('tools/icu/icu_versions.json') as f:
   icu_versions = json.load(f)
 
+shareable_builtins = {'cjs_module_lexer/lexer': 'deps/cjs-module-lexer/lexer.js',
+                     'cjs_module_lexer/dist/lexer': 'deps/cjs-module-lexer/dist/lexer.js',
+                     'undici/undici': 'deps/undici/undici.js'
+}
+
 # create option groups
 shared_optgroup = parser.add_argument_group("Shared libraries",
     "Flags that allows you to control whether you want to build against "
@@ -70,6 +75,9 @@
     "library you want to build against.")
 http2_optgroup = parser.add_argument_group("HTTP2",
     "Flags that allows you to control HTTP2 features in Node.js")
+shared_builtin_optgroup = parser.add_argument_group("Shared builtins",
+    "Flags that allows you to control whether you want to build against "
+    "internal builtins or shared files.")
 
 # Options should be in alphabetical order but keep --prefix at the top,
 # that's arguably the one people will be looking for most.
@@ -422,6 +430,16 @@
 
 parser.add_argument_group(shared_optgroup)
 
+for builtin in shareable_builtins:
+  builtin_id = 'shared_builtin_' + builtin + '_path'
+  shared_builtin_optgroup.add_argument('--shared-builtin-' + builtin + '-path',
+    action='store',
+    dest='node_shared_builtin_' + builtin.replace('/', '_') + '_path',
+    help='Path to shared file for ' + builtin + ' builtin. '
+         'Will be used instead of bundled version at runtime')
+
+parser.add_argument_group(shared_builtin_optgroup)
+
 static_optgroup.add_argument('--static-zoslib-gyp',
     action='store',
     dest='static_zoslib_gyp',
@@ -1951,6 +1969,19 @@ def make_bin_override():
 configure_inspector(output)
 configure_section_file(output)
 
+# configure shareable builtins
+output['variables']['node_builtin_shareable_builtins'] = []
+for builtin in shareable_builtins:
+  builtin_id = 'node_shared_builtin_' + builtin.replace('/', '_') + '_path'
+  if getattr(options, builtin_id):
+    if options.with_intl == 'none':
+      option_name = '--shared-builtin-' + builtin + '-path'
+      error(option_name + ' is incompatible with --with-intl=none' )
+    else:
+      output['defines'] += [builtin_id.upper() + '=' + getattr(options, builtin_id)]
+  else:
+    output['variables']['node_builtin_shareable_builtins'] += [shareable_builtins[builtin]]
+
 # Forward OSS-Fuzz settings
 output['variables']['ossfuzz'] = b(options.ossfuzz)
 

doc/contributing/maintaining-dependencies.md

@@ -0,0 +1,106 @@
+# Maintaining Dependencies
+
+Node.js depends on additional components beyond the Node.js code
+itself. These dependencies provide both native and JavaScript code
+and are built together with the code under the `src` and `lib`
+directories to create the Node.js binaries.
+
+All dependencies are located within the `deps` directory.
+
+Any code which meets one or more of these conditions should
+be managed as a dependency:
+
+* originates in an upstream project and is maintained
+  in that upstream project.
+* is not built from the `preferred form of the work for
+  making modifications to it` (see
+  [GNU GPL v2, section 3.](https://www.gnu.org/licenses/old-licenses/gpl-2.0.en.html)
+  when `make node` is run. A good example is
+  WASM code generated from C (the preferred form).
+  Typically generation is only supported on a subset of platforms, needs
+  additional tools, and is pre-built outside of the `make node`
+  step and then committed as a WASM binary in the directory
+  for the dependency under the `deps` directory.
+
+By default all dependencies are bundled into the Node.js
+binary, however, `configure` options should be available to
+use an externalized version at runtime when:
+
+* the dependency provides native code and is available as
+  a shared library in one or more of the common Node.js
+  distributions.
+* the dependency provides JavaScript and is not built
+  from the `preferred form of the work for making modifications
+  to it` when `make node` is run.
+
+Many distributions use externalized dependencies for one or
+more of these reasons:
+
+1. They have a requirement to build everything that they ship
+   from the `preferred form of the work for making
+   modifications to it`. This means that they need to
+   replace any pre-built components (for example WASM
+   binaries) with an equivalent that they have built.
+2. They manage the dependency separately as it is used by
+   more applications than just Node.js. Linking against
+   a shared library allows them to manage updates and
+   CVE fixes against the library instead of having to
+   patch all of the individual applications.
+3. They have a system wide configuration for the
+   dependency that all applications should respect.
+
+## Supporting externalized dependencies with native code.
+
+Support for externalized dependencies with native code for which a
+shared library is available can added by:
+
+* adding options to `configure.py`. These are added to the
+  shared\_optgroup and include an options to:
+  * enable use of a shared library
+  * set the name of the shared library
+  * set the path to the directory with the includes for the
+    shared library
+  * set the path to where to find the shared library at
+    runtime
+* add a call to configure\_library() to `configure.py` for the
+  library at the end of list of existing configure\_library() calls.
+  If there are additional libraries that are required it is
+  possible to list more than one with the `pkgname` option.
+* in `node.gypi` guard the build for the dependency
+  with `node_shared_depname` so that is is only built if
+  the dependency is being bundled into Node.js itself. For example:
+
+```text
+    [ 'node_shared_brotli=="false"', {
+      'dependencies': [ 'deps/brotli/brotli.gyp:brotli' ],
+    }],
+```
+
+## Supporting externalizable dependencies with JavaScript codeIZA
+
+Support for an externalizable dependency with JavaScript code
+can be added by:
+
+* adding an entry to the `sharable_builtins` map in
+  `configure.py`. The path should correspond to the file
+  within the deps directory that is normally bundled into
+  Node.js. For example `deps/cjs-module-lexer/lexer.js`.
+  This will add a new option for building with that dependency
+  externalized. After adding the entry you can see
+  the new option by running `./configure --help`.
+
+* adding a call to `AddExternalizedBuiltin` to the constructor
+  for BuildinLoader in `src/node_builtins.cc` for the
+  dependency using the `NODE_SHARED_BUILTLIN` #define generated for
+  the dependency. After running `./configure` with the new
+  option you can find the #define in `config.gypi`. You can cut and
+  paste one of the existing entries and then update to match the
+  inport name for the dependency and the #define generated.
+
+## Supporting non-externalized dependencies with JavaScript code
+
+If the dependency consists of JavaScript in the
+`preferred form of the work for making modifications to it`, it
+can be added as a non-externalizable dependency. In this case
+simply add the path to the JavaScript file in the `deps_files`
+list in the `node.gyp` file.

node.gyp

@@ -48,9 +48,7 @@
       'deps/v8/tools/tickprocessor-driver.mjs',
       'deps/acorn/acorn/dist/acorn.js',
       'deps/acorn/acorn-walk/dist/walk.js',
-      'deps/cjs-module-lexer/lexer.js',
-      'deps/cjs-module-lexer/dist/lexer.js',
-      'deps/undici/undici.js',
+      '<@(node_builtin_shareable_builtins)',
     ],
     'node_mksnapshot_exec': '<(PRODUCT_DIR)/<(EXECUTABLE_PREFIX)node_mksnapshot<(EXECUTABLE_SUFFIX)',
     'conditions': [

src/node_builtins.cc

@@ -32,6 +32,24 @@ BuiltinLoader BuiltinLoader::instance_;
 
 BuiltinLoader::BuiltinLoader() : config_(GetConfig()), has_code_cache_(false) {
   LoadJavaScriptSource();
+#if defined(NODE_HAVE_I18N_SUPPORT)
+#ifdef NODE_SHARED_BUILTIN_CJS_MODULE_LEXER_LEXER_PATH
+  AddExternalizedBuiltin(
+      "internal/deps/cjs-module-lexer/lexer",
+      STRINGIFY(NODE_SHARED_BUILTIN_CJS_MODULE_LEXER_LEXER_PATH));
+#endif  // NODE_SHARED_BUILTIN_CJS_MODULE_LEXER_LEXER_PATH
+
+#ifdef NODE_SHARED_BUILTIN_CJS_MODULE_LEXER_DIST_LEXER_PATH
+  AddExternalizedBuiltin(
+      "internal/deps/cjs-module-lexer/dist/lexer",
+      STRINGIFY(NODE_SHARED_BUILTIN_CJS_MODULE_LEXER_DIST_LEXER_PATH));
+#endif  // NODE_SHARED_BUILTIN_CJS_MODULE_LEXER_DIST_LEXER_PATH
+
+#ifdef NODE_SHARED_BUILTIN_UNDICI_UNDICI_PATH
+  AddExternalizedBuiltin("internal/deps/undici/undici",
+                         STRINGIFY(NODE_SHARED_BUILTIN_UNDICI_UNDICI_PATH));
+#endif  // NODE_SHARED_BUILTIN_UNDICI_UNDICI_PATH
+#endif  // NODE_HAVE_I18N_SUPPORT
 }
 
 BuiltinLoader* BuiltinLoader::GetInstance() {
@@ -219,6 +237,29 @@ MaybeLocal<String> BuiltinLoader::LoadBuiltinSource(Isolate* isolate,
 #endif  // NODE_BUILTIN_MODULES_PATH
 }
 
+#if defined(NODE_HAVE_I18N_SUPPORT)
+void BuiltinLoader::AddExternalizedBuiltin(const char* id,
+                                           const char* filename) {
+  std::string source;
+  int r = ReadFileSync(&source, filename);
+  if (r != 0) {
+    fprintf(
+        stderr, "Cannot load externalized builtin: \"%s:%s\".\n", id, filename);
+    ABORT();
+    return;
+  }
+
+  icu::UnicodeString utf16 = icu::UnicodeString::fromUTF8(
+      icu::StringPiece(source.data(), source.length()));
+  auto source_utf16 = std::make_unique<icu::UnicodeString>(utf16);
+  Add(id,
+      UnionBytes(reinterpret_cast<const uint16_t*>((*source_utf16).getBuffer()),
+                 utf16.length()));
+  // keep source bytes for builtin alive while BuiltinLoader exists
+  GetInstance()->externalized_source_bytes_.push_back(std::move(source_utf16));
+}
+#endif  // NODE_HAVE_I18N_SUPPORT
+
 // Returns Local<Function> of the compiled module if return_code_cache
 // is false (we are only compiling the function).
 // Otherwise return a Local<Object> containing the cache.

src/node_builtins.h

@@ -3,10 +3,14 @@
 
 #if defined(NODE_WANT_INTERNALS) && NODE_WANT_INTERNALS
 
+#include <list>
 #include <map>
 #include <memory>
 #include <set>
 #include <string>
+#if defined(NODE_HAVE_I18N_SUPPORT)
+#include <unicode/unistr.h>
+#endif  // NODE_HAVE_I18N_SUPPORT
 #include <vector>
 #include "node_mutex.h"
 #include "node_union_bytes.h"
@@ -120,11 +124,18 @@ class NODE_EXTERN_PRIVATE BuiltinLoader {
   static void HasCachedBuiltins(
       const v8::FunctionCallbackInfo<v8::Value>& args);
 
+#if defined(NODE_HAVE_I18N_SUPPORT)
+  static void AddExternalizedBuiltin(const char* id, const char* filename);
+#endif  // NODE_HAVE_I18N_SUPPORT
+
   static BuiltinLoader instance_;
   BuiltinCategories builtin_categories_;
   BuiltinSourceMap source_;
   BuiltinCodeCacheMap code_cache_;
   UnionBytes config_;
+#if defined(NODE_HAVE_I18N_SUPPORT)
+  std::list<std::unique_ptr<icu::UnicodeString>> externalized_source_bytes_;
+#endif  // NODE_HAVE_I18N_SUPPORT
 
   // Used to synchronize access to the code cache map
   Mutex code_cache_mutex_;