Bug#17926: mysql.exe crashes when ctrl-c is pressed in windows

SIGINT is handled in funny ways on windows, which could lead to problems when
Control-C was pressed in the client during a long-running query.  Now Control-C
during a query aborts that query (by sending KILL to the server on a second
connexion), while Control-C outside of a running query terminates the client.

client/mysql.cc

@@ -136,7 +136,8 @@ static my_bool info_flag=0,ignore_errors=0,wait_flag=0,quick=0,
 	       tty_password= 0, opt_nobeep=0, opt_reconnect=1,
 	       default_charset_used= 0, opt_secure_auth= 0,
                default_pager_set= 0, opt_sigint_ignore= 0,
-         show_warnings = 0;
+               show_warnings= 0;
+static volatile int executing_query= 0, interrupted_query= 0;
 static ulong opt_max_allowed_packet, opt_net_buffer_length;
 static uint verbose=0,opt_silent=0,opt_mysql_port=0, opt_local_infile=0;
 static my_string opt_mysql_unix_port=0;
@@ -338,6 +339,7 @@ static void end_timer(ulong start_time,char *buff);
 static void mysql_end_timer(ulong start_time,char *buff);
 static void nice_time(double sec,char *buff,bool part_second);
 static sig_handler mysql_end(int sig);
+static sig_handler mysql_sigint(int sig);
 
 
 int main(int argc,char *argv[])
@@ -420,7 +422,7 @@ int main(int argc,char *argv[])
   if (opt_sigint_ignore)
     signal(SIGINT, SIG_IGN);
   else
-    signal(SIGINT, mysql_end);			// Catch SIGINT to clean up
+    signal(SIGINT, mysql_sigint);		// Catch SIGINT to clean up
   signal(SIGQUIT, mysql_end);			// Catch SIGQUIT to clean up
 
   /*
@@ -488,6 +490,28 @@ int main(int argc,char *argv[])
 #endif
 }
 
+sig_handler mysql_sigint(int sig)
+{
+  char kill_buffer[40];
+  MYSQL *kill_mysql= NULL;
+
+  signal(SIGINT, mysql_sigint);
+
+  /* terminate if no query being executed, or we already tried interrupting */
+  if (!executing_query || interrupted_query++)
+    mysql_end(sig);
+
+  kill_mysql= mysql_init(kill_mysql);
+  if (!mysql_real_connect(kill_mysql,current_host, current_user, opt_password,
+                          "", opt_mysql_port, opt_mysql_unix_port,0))
+    mysql_end(sig);
+  /* kill_buffer is always big enough because max length of %lu is 15 */
+  sprintf(kill_buffer, "KILL /*!50000 QUERY */ %lu", mysql_thread_id(&mysql));
+  mysql_real_query(kill_mysql, kill_buffer, strlen(kill_buffer));
+  mysql_close(kill_mysql);
+  tee_fprintf(stdout, "Query aborted by Ctrl+C\n");
+}
+
 sig_handler mysql_end(int sig)
 {
   mysql_close(&mysql);
@@ -1008,6 +1032,8 @@ static int read_and_execute(bool interactive)
       if (opt_outfile && glob_buffer.is_empty())
 	fflush(OUTFILE);
 
+      interrupted_query= 0;
+
 #if defined( __WIN__) || defined(OS2) || defined(__NETWARE__)
       tee_fputs(prompt, stdout);
 #if defined(__NETWARE__)
@@ -1998,6 +2024,8 @@ com_go(String *buffer,char *line __attribute__((unused)))
 
   timer=start_timer();
 
+  executing_query= 1;
+
   error= mysql_real_query_for_lazy(buffer->ptr(),buffer->length());
 
 #ifdef HAVE_READLINE
@@ -2012,6 +2040,7 @@ com_go(String *buffer,char *line __attribute__((unused)))
   if (error)
   {
     buffer->length(0); // Remove query on error
+    executing_query= 0;
     return error;
   }
   error=0;
@@ -2022,14 +2051,20 @@ com_go(String *buffer,char *line __attribute__((unused)))
     if (quick)
     {
       if (!(result=mysql_use_result(&mysql)) && mysql_field_count(&mysql))
+      {
+        executing_query= 0;
 	return put_error(&mysql);
       }
+    }
     else
     {
       error= mysql_store_result_for_lazy(&result);
       if (error)
+      {
+        executing_query= 0;
 	return error;
       }
+    }
 
     if (verbose >= 3 || !opt_silent)
       mysql_end_timer(timer,time_buff);
@@ -2089,6 +2124,9 @@ com_go(String *buffer,char *line __attribute__((unused)))
       fflush(stdout);
     mysql_free_result(result);
   } while (!(err= mysql_next_result(&mysql)));
+
+  executing_query= 0;
+
   if (err >= 1)
     error= put_error(&mysql);