add IO.close_on_exec?

src/io.c

@@ -724,6 +724,47 @@ mrb_io_fileno(mrb_state *mrb, mrb_value io)
   return mrb_fixnum_value(fptr->fd);
 }
 
+void
+mrb_notimplement(mrb_state *mrb)
+{
+  mrb_raise(mrb, E_SCRIPT_ERROR, "unimplemented on this machine");
+  
+  return -1;
+}
+
+#if defined(F_GETFD) && defined(F_SETFD) && defined(FD_CLOEXEC)
+mrb_value
+mrb_io_close_on_exec_p(mrb_state *mrb, mrb_value io)
+{
+  struct mrb_io *fptr;
+  mrb_value write_io;
+  int fd, ret;
+  
+  fptr = (struct mrb_io *)mrb_get_datatype(mrb, io, &mrb_io_type);
+  if(fptr->fd2 >= 0){
+    if ((ret = fcntl(fptr->fd2, F_GETFD)) == -1) mrb_sys_fail(mrb, "F_GETFD failed");
+    if (!(ret & FD_CLOEXEC)) return mrb_bool_value(0);
+  }
+
+  if(fptr->fd < 0){
+    mrb_raise(mrb, E_IO_ERROR, "closed stream");
+  } else {
+    if ((ret = fcntl(fptr->fd, F_GETFD)) == -1) mrb_sys_fail(mrb, "F_GETFD failed");
+    if (!(ret & FD_CLOEXEC)) return mrb_bool_value(0);
+  }
+
+  return mrb_bool_value(1);
+}
+#else
+#define mrb_io_close_on_exec_p mrb_f_notimplement
+mrb_f_notimplement(mrb_state *mrb, mrb_value io)
+{   
+	mrb_notimplement();
+
+  return -1;
+}
+#endif
+
 void
 mrb_init_io(mrb_state *mrb)
 {
@@ -749,5 +790,8 @@ mrb_init_io(mrb_state *mrb)
   mrb_define_method(mrb, io, "pid",        mrb_io_pid,        MRB_ARGS_NONE());   /* 15.2.20.5.2 */
   mrb_define_method(mrb, io, "fileno",     mrb_io_fileno,     MRB_ARGS_NONE());
 
+  mrb_define_method(mrb, io, "close_on_exec?",    mrb_io_close_on_exec_p,      MRB_ARGS_NONE());
+/*  mrb_define_method(mrb, io, "close_on_exec=",    mrb_io_set_close_on_exec,    MRB_ARGS_REQ(1));*/
+
   mrb_gv_set(mrb, mrb_intern_cstr(mrb, "$/"), mrb_str_new_cstr(mrb, "\n"));
 }