fs: translate error code properly in cpSync

UV error code needs to be negative integer so it can be mapped
correctly. The filesystem error are positive integer, so we need to
handle it before throwing.

Co-authored-by: Jake Yuesong Li <jake.yuesong@gmail.com>

src/node_file.cc

@@ -3147,7 +3147,11 @@ static void CpSyncCheckPaths(const FunctionCallbackInfo<Value>& args) {
                         ? std::filesystem::symlink_status(src_path, error_code)
                         : std::filesystem::status(src_path, error_code);
   if (error_code) {
-    return env->ThrowUVException(EEXIST, "lstat", nullptr, src.out());
+    return env->ThrowUVException(
+        error_code.value() > 0 ? -error_code.value() : error_code.value(),
+        dereference ? "stat" : "lstat",
+        nullptr,
+        src.out());
   }
   auto dest_status =
       dereference ? std::filesystem::symlink_status(dest_path, error_code)

test/parallel/test-fs-cp.mjs

@@ -419,6 +419,26 @@ if (!isWindows) {
   );
 }
 
+// It throws error if attempt is made to copy a file with name too long.
+{
+  const src = 'a'.repeat(5000);
+  const dest = nextdir();
+  assert.throws(
+    () => cpSync(src, dest, mustNotMutateObjectDeep()),
+    { code: 'ENAMETOOLONG' }
+  );
+}
+
+// It throws error if attempt is made to copy a dir not exist.
+{
+  const src = nextdir();
+  const dest = nextdir();
+  assert.throws(
+    () => cpSync(src, dest, mustNotMutateObjectDeep({ recursive: true })),
+    { code: 'ENOENT' }
+  );
+}
+
 // It makes file writeable when updating timestamp, if not writeable.
 {
   const src = nextdir();