[nodefs] Fix execute permission bit on Windows when retrieving mode attribute (#21902)

Author: fluiddot

src/library_nodefs.js

@@ -123,14 +123,19 @@ addToLibrary({
         var path = NODEFS.realPath(node);
         var stat;
         NODEFS.tryFSOperation(() => stat = fs.lstatSync(path));
-        // node.js v0.10.20 doesn't report blksize and blocks on Windows. Fake
-        // them with default blksize of 4096.
-        // See http://support.microsoft.com/kb/140365
-        if (NODEFS.isWindows && !stat.blksize) {
-          stat.blksize = 4096;
-        }
-        if (NODEFS.isWindows && !stat.blocks) {
-          stat.blocks = (stat.size+stat.blksize-1)/stat.blksize|0;
+        if (NODEFS.isWindows) {
+          // node.js v0.10.20 doesn't report blksize and blocks on Windows. Fake
+          // them with default blksize of 4096.
+          // See http://support.microsoft.com/kb/140365
+          if (!stat.blksize) {
+            stat.blksize = 4096;
+          }
+          if (!stat.blocks) {
+            stat.blocks = (stat.size+stat.blksize-1)/stat.blksize|0;
+          }
+          // Node.js on Windows never represents permission bit 'x', so
+          // propagate read bits to execute bits.
+          stat.mode |= (stat.mode & {{{ cDefs.S_IRUSR | cDefs.S_IRGRP | cDefs.S_IROTH }}}) >> 2;
         }
         return {
           dev: stat.dev,

test/test_other.py

@@ -14286,6 +14286,51 @@ def test_windows_batch_file_dp0_expansion_bug(self):
     create_file('build_with_quotes.bat',  f'@"emcc" {test_file("hello_world.c")}')
     self.run_process(['build_with_quotes.bat'])
 
+  @only_windows('Check that directory permissions are properly retrieved on Windows')
+  @requires_node
+  def test_windows_nodefs_execution_permission(self):
+    src = r'''
+    #include <assert.h>
+    #include <emscripten.h>
+    #include <sys/stat.h>
+    #include <string.h>
+    #include <stdio.h>
+
+    void setup() {
+      EM_ASM(
+        FS.mkdir('/working');
+        FS.mount(NODEFS, { root: '.' }, '/working');
+        FS.mkdir('/working/new-dir');
+        FS.writeFile('/working/new-dir/test.txt', 'test');
+      );
+    }
+
+    void test() {
+      int err;
+      struct stat s;
+      memset(&s, 0, sizeof(s));
+      err = stat("/working/new-dir", &s);
+      assert(S_ISDIR(s.st_mode));
+      assert(s.st_mode & S_IXUSR);
+      assert(s.st_mode & S_IXGRP);
+      assert(s.st_mode & S_IXOTH);
+
+      err = stat("/working/new-dir/test.txt", &s);
+      assert(s.st_mode & S_IXUSR);
+      assert(s.st_mode & S_IXGRP);
+      assert(s.st_mode & S_IXOTH);
+
+      puts("success");
+    }
+
+    int main(int argc, char * argv[]) {
+      setup();
+      test();
+      return EXIT_SUCCESS;
+    }
+    '''
+    self.do_run(src, emcc_args=['-lnodefs.js'])
+
   @parameterized({
     'wasm2js': (True,),
     '': (False,)