test: add known_issues test for fs.copyFile()

test/known_issues/known_issues.status

@@ -7,18 +7,24 @@ prefix known_issues
 [true] # This section applies to all platforms
 
 [$system==win32]
+test-fs-copyfile-respect-permissions: SKIP
 
 [$system==linux]
 test-vm-timeout-escape-promise: PASS,FLAKY
+test-fs-copyfile-respect-permissions: SKIP
 
 [$system==macos]
 
 [$system==solaris]
+test-fs-copyfile-respect-permissions: SKIP
 
 [$system==freebsd]
+test-fs-copyfile-respect-permissions: SKIP
 
 [$system==aix]
+test-fs-copyfile-respect-permissions: SKIP
 
 [$arch==arm]
 # https://github.com/nodejs/node/issues/24120
 test-vm-timeout-escape-nexttick: PASS,FLAKY
+test-fs-copyfile-respect-permissions: SKIP

test/known_issues/test-fs-copyfile-respect-permissions.js

@@ -0,0 +1,50 @@
+'use strict';
+
+// Test that fs.copyFile() respects file permissions.
+// Ref: https://github.com/nodejs/node/issues/26936
+
+const common = require('../common');
+
+const tmpdir = require('../common/tmpdir');
+tmpdir.refresh();
+
+const assert = require('assert');
+const fs = require('fs');
+const path = require('path');
+
+let n = 0;
+
+function beforeEach() {
+  n++;
+  const source = path.join(tmpdir.path, `source${n}`);
+  const dest = path.join(tmpdir.path, `dest${n}`);
+  fs.writeFileSync(source, 'source');
+  fs.writeFileSync(dest, 'dest');
+  fs.chmodSync(dest, '444');
+
+  const check = (err) => {
+    assert.strictEqual(err.code, 'EACCESS');
+    assert.strictEqual(fs.readFileSync(dest, 'utf8'), 'dest');
+  };
+
+  return { source, dest, check };
+}
+
+// Test synchronous API.
+{
+  const { source, dest, check } = beforeEach();
+  assert.throws(() => { fs.copyFileSync(source, dest); }, check);
+}
+
+// Test promises API.
+{
+  const { source, dest, check } = beforeEach();
+  assert.throws(async () => { await fs.promises.copyFile(source, dest); },
+                check);
+}
+
+// Test callback API.
+{
+  const { source, dest, check } = beforeEach();
+  fs.copyFile(source, dest, common.mustCall(check));
+}