make the read builtin respect ctrl-C

builtin.cpp

@@ -2399,6 +2399,7 @@ static int builtin_read(parser_t &parser, wchar_t **argv)
         }
         /* No autosuggestions in builtin_read */
         reader_set_allow_autosuggesting(false);
+        reader_set_interruptible(true);
 
         reader_set_buffer(commandline, wcslen(commandline));
         proc_push_interactive(1);

reader.cpp

@@ -580,10 +580,23 @@ static void reader_kill(size_t begin_idx, size_t length, int mode, int newv)
 
 }
 
+
+/* 
+   Called from a signal handler, so make sure to check \c data exists.
+   This is in fact racey as there is no guarantee that \c *data's members are
+   written to memory before \c data is. But signal handling is currently racey 
+   anyway, so this should be fixed together with the rest of the signal 
+   handling infrastructure. 
+*/
+static bool get_interruptible()
+{
+    return data ? data->interruptible : false;
+}
+
 /* This is called from a signal handler! */
 void reader_handle_int(int sig)
 {
-    if (!is_interactive_read)
+    if (!is_interactive_read || get_interruptible())
     {
         parser_t::skip_all_blocks();
     }