add File#flock.

README.md

@@ -176,7 +176,7 @@ DEALINGS IN THE SOFTWARE.
 | File#chmod                  |          |      |
 | File#chown                  |          |      |
 | File#ctime                  |          |      |
-| File#flock                  |          |      |
+| File#flock                  |   o      |      |
 | File#lstat                  |          |      |
 | File#mtime                  |          |      |
 | File#path, File#to_path     |   o      |      |

src/file.c

@@ -36,6 +36,9 @@
 
 #define STAT(p, s)        stat(p, s)
 
+extern mrb_value mrb_io_fileno(mrb_state *mrb, mrb_value io);
+
+
 mrb_value
 mrb_file_s_umask(mrb_state *mrb, mrb_value klass)
 {
@@ -262,6 +265,36 @@ mrb_file__gethome(mrb_state *mrb, mrb_value klass)
   return mrb_str_new_cstr(mrb, home);
 }
 
+mrb_value
+mrb_file_flock(mrb_state *mrb, mrb_value self)
+{
+  mrb_int operation;
+  int fd;
+
+  mrb_get_args(mrb, "i", &operation);
+  fd = mrb_fixnum(mrb_io_fileno(mrb, self));
+
+  while (flock(fd, operation) == -1) {
+    switch (errno) {
+      case EINTR:
+        /* retry */
+        break;
+      case EAGAIN:      /* NetBSD */
+#if defined(EWOULDBLOCK) && EWOULDBLOCK != EAGAIN
+      case EWOULDBLOCK: /* FreeBSD OpenBSD Linux */
+#endif
+        if (operation & LOCK_NB) {
+          return mrb_false_value();
+        }
+        /* FALLTHRU - should not happen */
+      default:
+        mrb_sys_fail(mrb, "flock failed");
+        break;
+    }
+  }
+  return mrb_fixnum_value(0);
+}
+
 void
 mrb_init_file(mrb_state *mrb)
 {
@@ -282,6 +315,8 @@ mrb_init_file(mrb_state *mrb)
   mrb_define_class_method(mrb, file, "_getwd",    mrb_file__getwd,     MRB_ARGS_NONE());
   mrb_define_class_method(mrb, file, "_gethome",  mrb_file__gethome,   MRB_ARGS_OPT(1));
 
+  mrb_define_method(mrb, file, "flock", mrb_file_flock, MRB_ARGS_REQ(1));
+
   cnst = mrb_define_module_under(mrb, file, "Constants");
   mrb_define_const(mrb, cnst, "LOCK_SH", mrb_fixnum_value(LOCK_SH));
   mrb_define_const(mrb, cnst, "LOCK_EX", mrb_fixnum_value(LOCK_EX));

test/file.rb

@@ -49,6 +49,17 @@ assert('File.extname') do
   assert_equal '', File.extname('.foo')
 end
 
+assert('IO#flock') do
+  f = File.open $mrbtest_io_rfname
+  assert_equal(f.flock(File::LOCK_SH), 0)
+  assert_equal(f.flock(File::LOCK_UN), 0)
+  assert_equal(f.flock(File::LOCK_EX | File::LOCK_UN), 0)
+  assert_equal(f.flock(File::LOCK_UN), 0)
+  f.close
+  true
+end
+
+
 assert('File.size') do
   File.size($mrbtest_io_rfname) == $mrbtest_io_msg.size + 1  and
   File.size($mrbtest_io_wfname) == 0