Removed a SIGWINCH race.

[nelhage@nelhage.com: Use sig_atomic_t, and document the remaining race better]

reptyr.c

@@ -108,7 +108,7 @@ int writeall(int fd, const void *buf, ssize_t count) {
     return 0;
 }
 
-int winch_happened = 0;
+volatile sig_atomic_t winch_happened = 0;
 
 void do_winch(int signal) {
     winch_happened = 1;
@@ -120,9 +120,13 @@ void do_proxy(int pty) {
     fd_set set;
     while (1) {
         if (winch_happened) {
-            resize_pty(pty);
-            /* FIXME: racy against a second resize */
             winch_happened = 0;
+            /*
+             * FIXME: If a signal comes in after this point but before
+             * select(), the resize will be delayed until we get more
+             * input. signalfd() is probably the cleanest solution.
+             */
+            resize_pty(pty);
         }
         FD_ZERO(&set);
         FD_SET(0, &set);
@@ -244,11 +248,11 @@ int main(int argc, char **argv) {
     }
 
     setup_raw(&saved_termios);
-    resize_pty(pty);
     memset(&act, 0, sizeof act);
     act.sa_handler = do_winch;
     act.sa_flags   = 0;
     sigaction(SIGWINCH, &act, NULL);
+    resize_pty(pty);
     do_proxy(pty);
     tcsetattr(0, TCSANOW, &saved_termios);