Fix Out-of-bound read (#57)

* add check for out-of-bound read

* remove unused count variable

Author: mcpcpc

kirc.c

@@ -536,10 +536,12 @@ static int handleServerMessage(void) {
 }
 
 static void handleUserInput(char *usrin) {
+    if (usrin == NULL) return;
+
     char *tok;
     size_t msg_len = strlen(usrin);
 
-    if (usrin[msg_len - 1] == '\n') {
+    if (msg_len > 0 && usrin[msg_len - 1] == '\n') {
         usrin[msg_len - 1] = '\0';
     }
 
@@ -616,7 +618,7 @@ int main(int argc, char **argv) {
     fds[1].events = POLLIN;
 
     char usrin[MSG_MAX];
-    int  count, byteswaiting = 1;
+    int  byteswaiting = 1;
 
     for (;;) {
         int poll_res = poll(fds, 2, -1);