Implemented #2877 in another way

dbms/programs/client/Client.cpp

@@ -90,6 +90,7 @@ namespace ErrorCodes
     extern const int UNEXPECTED_PACKET_FROM_SERVER;
     extern const int CLIENT_OUTPUT_FORMAT_SPECIFIED;
     extern const int LOGICAL_ERROR;
+    extern const int CANNOT_SET_SIGNAL_HANDLER;
 }
 
 
@@ -1516,6 +1517,29 @@ public:
             }
         }
 
+#if USE_READLINE
+        auto clear_prompt_or_exit = [](int)
+        {
+            /// This is signal safe. Error code is not checked.
+            (void) write(STDOUT_FILENO, "\n", 1);
+
+            if (rl_line_buffer[0])
+            {
+                rl_replace_line("", 0);
+                rl_forced_update_display();
+            }
+            else
+            {
+                /// A little dirty, but we struggle to find better way to correctly
+                /// force readline to exit after returning from the signal handler.
+                exit(0);
+            }
+        };
+
+        if (signal(SIGINT, clear_prompt_or_exit) == SIG_ERR)
+            throwFromErrno("Cannot set signal handler.", ErrorCodes::CANNOT_SET_SIGNAL_HANDLER);
+#endif
+
         ioctl(0, TIOCGWINSZ, &terminal_size);
 
         namespace po = boost::program_options;

dbms/src/Common/ErrorCodes.cpp

@@ -387,6 +387,7 @@ namespace ErrorCodes
     extern const int EXTERNAL_SERVER_IS_NOT_RESPONDING = 410;
     extern const int PTHREAD_ERROR = 411;
     extern const int NETLINK_ERROR = 412;
+    extern const int CANNOT_SET_SIGNAL_HANDLER = 413;
 
     extern const int KEEPER_EXCEPTION = 999;
     extern const int POCO_EXCEPTION = 1000;