Use Node's path helpers under NODERAWFS (#17849)

Ensures that absolute paths are handled correctly on Windows as well. Using these helpers
should be safe, since binaries linked with -sNODERAWFS can only be used on Node.js, see:

emscripten/src/library_noderawfs.js

Line 28 in e98554f
       throw new Error("NODERAWFS is currently only supported on Node.js environment.") 

Context: #16296
Resolves: #17360.
Resolves: #17819.
Supersedes: #17821.

Author: kleisauke

src/library_async.js

@@ -456,7 +456,7 @@ mergeInto(LibraryManager.library, {
     return Asyncify.handleSleep((wakeUp) => {
       var _url = UTF8ToString(url);
       var _file = UTF8ToString(file);
-      _file = PATH_FS.resolve(FS.cwd(), _file);
+      _file = PATH_FS.resolve(_file);
       var destinationDirectory = PATH.dirname(_file);
       FS.createPreloadedFile(
         destinationDirectory,

src/library_fs.js

@@ -119,7 +119,7 @@ FS.staticInit();` +
     // paths
     //
     lookupPath: (path, opts = {}) => {
-      path = PATH_FS.resolve(FS.cwd(), path);
+      path = PATH_FS.resolve(path);
 
       if (!path) return { path: '', node: null };
 
@@ -133,8 +133,8 @@ FS.staticInit();` +
         throw new FS.ErrnoError({{{ cDefine('ELOOP') }}});
       }
 
-      // split the path
-      var parts = PATH.normalizeArray(path.split('/').filter((p) => !!p), false);
+      // split the absolute path
+      var parts = path.split('/').filter((p) => !!p);
 
       // start at the root
       var current = FS.root;

src/library_nodepath.js

@@ -0,0 +1,37 @@
+/**
+ * @license
+ * Copyright 2022 The Emscripten Authors
+ * SPDX-License-Identifier: MIT
+ */
+
+// This implementation ensures that Windows-style paths are being
+// used when running on a Windows operating system - see:
+// https://nodejs.org/api/path.html#path_windows_vs_posix
+// It's only used/needed when linking with `-sNODERAWFS`, as that
+// will replace all normal filesystem access with direct Node.js
+// operations. Hence, using `nodePath` should be safe here.
+
+mergeInto(LibraryManager.library, {
+  $PATH: {
+    isAbs: (path) => nodePath['isAbsolute'](path),
+    normalize: (path) => nodePath['normalize'](path),
+    dirname: (path) => nodePath['dirname'](path),
+    basename: (path) => nodePath['basename'](path),
+    join: function () {
+      return nodePath['join'].apply(null, arguments);
+    },
+    join2: (l, r) => nodePath['join'](l, r),
+  },
+  // The FS-using parts are split out into a separate object, so simple path
+  // usage does not require the FS.
+  $PATH_FS__deps: ['$FS'],
+  $PATH_FS__docs: '/** @type{{resolve: function(...*)}} */',
+  $PATH_FS: {
+    resolve: function () {
+      var paths = Array.prototype.slice.call(arguments, 0);
+      paths.unshift(FS.cwd());
+      return nodePath['posix']['resolve'].apply(null, paths);
+    },
+    relative: (from, to) => nodePath['posix']['relative'](from || FS.cwd(), to || FS.cwd()),
+  }
+});

src/modules.js

@@ -91,6 +91,8 @@ global.LibraryManager = {
           libraries.push('library_nodefs.js');
         }
         libraries.push('library_noderawfs.js');
+        // NODERAWFS overwrites library_path.js
+        libraries.push('library_nodepath.js');
       }
     } else if (WASMFS) {
       libraries.push('library_wasmfs.js');

src/settings.js

@@ -944,8 +944,7 @@ var FORCE_FILESYSTEM = false;
 // Node.js to access the real local filesystem on your OS, the code will not
 // necessarily be portable between OSes - it will be as portable as a Node.js
 // program would be, which means that differences in how the underlying OS
-// handles permissions and errors and so forth may be noticeable.  This has
-// mostly been tested on Linux so far.
+// handles permissions and errors and so forth may be noticeable.
 // [link]
 var NODERAWFS = false;
 

test/test_other.py

@@ -8488,6 +8488,17 @@ def test_noderawfs_disables_embedding(self):
     err = self.expect_fail(base + ['--embed-file', 'somefile'])
     self.assertContained(expected, err)
 
+  def test_noderawfs_access_abspath(self):
+    create_file('foo', 'bar')
+    create_file('access.c', r'''
+      #include <unistd.h>
+      int main(int argc, char** argv) {
+        return access(argv[1], F_OK);
+      }
+    ''')
+    self.run_process([EMCC, 'access.c', '-sNODERAWFS'])
+    self.run_js('a.out.js', args=[os.path.abspath('foo')])
+
   @disabled('https://github.com/nodejs/node/issues/18265')
   def test_node_code_caching(self):
     self.run_process([EMCC, test_file('hello_world.c'),