[js] Implement nqp::lockfh/nqp::unlockfh

Author: pmurias

src/vm/js/Operations.nqp

@@ -488,6 +488,9 @@ class QAST::OperationsJS {
     add_simple_op('rename', $T_VOID, [$T_STR, $T_STR], :side_effects);
     add_simple_op('filenofh', $T_INT, [$T_OBJ]);
 
+    add_simple_op('lockfh', $T_OBJ, [$T_OBJ, $T_INT], :side_effects);
+    add_simple_op('unlockfh', $T_OBJ, [$T_OBJ], :side_effects);
+
     add_simple_op('bootarray', $T_OBJ, []);
 
     add_simple_op('getpid', $T_INT, []);

src/vm/js/nqp-runtime/io.js

@@ -607,3 +607,13 @@ op.copy = function(source, target) {
 op.rename = function(oldPath, newPath) {
   fs.renameSync(oldPath, newPath);
 };
+
+op.lockfh = function(fh, flags) {
+  fs.flockSync(fh.fd, (flags & 0x01 ? 'sh' : 'ex') + (flags & 0x10 ? 'nb' : ''));
+  return fh;
+};
+
+op.unlockfh = function(fh, flags) {
+  fs.flockSync(fh.fd, 'un');
+  return fh;
+};