test: fix chmod mask testing on windows

Currently this uncovers a regression in `fs.fchmodSync(fd, mode_sync);`
No solution yet...

Also as issue on macOS in test-fs-chmod:94 fail to access file1

Fixes:#12803

test/known_issues/test-fs-fchmod-12835.js

@@ -0,0 +1,37 @@
+'use strict';
+const common = require('../common');
+
+// Windows only: Test fchmod on files with `attrib -a -h -i -r -s`
+// setting RO then can't set RW back
+
+const {strictEqual, ok} = require('assert');
+const {execSync} = require('child_process');
+const fs = require('fs');
+
+ok(common.isWindows, 'reset of test only for windows');
+
+process.on('exit', function() {
+  console.log('Trying to cleanup');
+  try {
+    execSync(`del /q /f ${tmpFile}`);
+  } catch (e) {
+    console.log(e);
+  }
+});
+
+const RO = 0o100444; // 33060 0b1000000100100100
+const RW = 0o100666; // 33206 0b1000000110110110
+
+const tmpFile = `${common.tmpDir}\\${Date.now()}gigi.js`;
+
+const fd = fs.openSync(tmpFile, 'a');
+execSync(`attrib -a -h -i -r -s ${tmpFile}`);
+fs.fchmodSync(fd, RO);
+const actual2 = fs.fstatSync(fd).mode;
+console.log(`${tmpFile} mode: ${actual2}`);
+strictEqual(actual2, RO);
+
+fs.fchmodSync(fd, RW); // This does not work.
+const actual3 = fs.fstatSync(fd).mode;
+console.log(`${tmpFile} mode: ${actual3}`);
+strictEqual(actual3, RW); // BANG!

test/parallel/parallel.status

@@ -7,10 +7,14 @@ prefix parallel
 [true] # This section applies to all platforms
 
 [$system==win32]
+# https://github.com/nodejs/node/issues/12803
+test-fs-chmod                 : PASS,FLAKY
 
 [$system==linux]
 
 [$system==macos]
+# https://github.com/nodejs/node/issues/12803
+test-fs-chmod                 : PASS,FLAKY
 
 [$arch==arm || $arch==arm64]
 

test/parallel/test-fs-chmod.js

@@ -24,9 +24,11 @@ const common = require('../common');
 const assert = require('assert');
 const path = require('path');
 const fs = require('fs');
+const {execSync} = require('child_process');
 
 let mode_async;
 let mode_sync;
+const windows_writable_mask = 0o222;
 
 // Need to hijack fs.open/close to make sure that things
 // get closed once they're opened.
@@ -64,15 +66,27 @@ function closeSync() {
 
 // On Windows chmod is only able to manipulate read-only bit
 if (common.isWindows) {
-  mode_async = 0o400;   // read-only
-  mode_sync = 0o600;    // read-write
+  mode_async = 0o444;   // read-only
+  mode_sync = 0o666;    // read-write
 } else {
   mode_async = 0o777;
   mode_sync = 0o644;
 }
 
-const file1 = path.join(common.fixturesDir, 'a.js');
-const file2 = path.join(common.fixturesDir, 'a1.js');
+const file1 = path.join(common.tmpDir, Date.now() + 'duck.js');
+const file2 = path.join(common.tmpDir, Date.now() + 'goose.js');
+fs.writeFileSync(file1, 'ga ga');
+fs.writeFileSync(file2, 'waq waq');
+// to flush some buffers
+console.log('written');
+console.log('written some more');
+if (common.isWindows) {
+  execSync(`attrib -a -h -i -r -s ${file1}`);
+  execSync(`attrib -a -h -i -r -s ${file2}`);
+} else {
+  execSync(`touch ${file1}`);
+  execSync(`touch ${file2}`);
+}
 
 fs.chmod(file1, mode_async.toString(8), common.mustCall((err) => {
   assert.ifError(err);
@@ -87,7 +101,7 @@ fs.chmod(file1, mode_async.toString(8), common.mustCall((err) => {
 
   fs.chmodSync(file1, mode_sync);
   if (common.isWindows) {
-    assert.ok((fs.statSync(file1).mode & 0o777) & mode_sync);
+    assert.ok((fs.statSync(file1).mode & 0o777) & windows_writable_mask);
   } else {
     assert.strictEqual(mode_sync, fs.statSync(file1).mode & 0o777);
   }
@@ -109,7 +123,7 @@ fs.open(file2, 'a', common.mustCall((err, fd) => {
 
     fs.fchmodSync(fd, mode_sync);
     if (common.isWindows) {
-      assert.ok((fs.fstatSync(fd).mode & 0o777) & mode_sync);
+      assert.ok((fs.fstatSync(fd).mode & 0o777) & windows_writable_mask);
     } else {
       assert.strictEqual(mode_sync, fs.fstatSync(fd).mode & 0o777);
     }
@@ -139,5 +153,7 @@ if (fs.lchmod) {
 
 
 process.on('exit', function() {
+  fs.chmodSync(file1, mode_sync);
+  fs.chmodSync(file2, mode_sync);
   assert.strictEqual(0, openCount);
 });