From a8e6427210ea07eb1ed67f23152bb4713377832a Mon Sep 17 00:00:00 2001
From: MikeCAT <mikecat@users.noreply.github.com>
Date: Wed, 3 Aug 2022 22:35:43 +0000
Subject: [PATCH] terminal: improve how to deal with special characters

* invalidate first_arg if it is beyond redir_char or pipe_char
  * improve behavior of "cat> z.txt", for example
* improve behavior when both of redir_char and pipe_char is used
  * don't open output file (redirect) if the output is pipe
  * throw error if pipe is after redirect
---
 kernel/terminal.cpp | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/kernel/terminal.cpp b/kernel/terminal.cpp
index 600d4a1f2..dfddd015f 100644
--- a/kernel/terminal.cpp
+++ b/kernel/terminal.cpp
@@ -366,6 +366,18 @@ void Terminal::ExecuteLine() {
   char* first_arg = strchr(&linebuf_[0], ' ');
   char* redir_char = strchr(&linebuf_[0], '>');
   char* pipe_char = strchr(&linebuf_[0], '|');
+  if (first_arg) {
+    if (redir_char && redir_char < first_arg) first_arg = 0;
+    else if (pipe_char && pipe_char < first_arg) first_arg = 0;
+  }
+  if (redir_char && pipe_char) {
+    if (pipe_char < redir_char) {
+      redir_char = 0;
+    } else {
+      PrintToFD(*files_[2], "pipe after redirect is not supported\n");
+      return;
+    }
+  }
   if (first_arg) {
     *first_arg = 0;
     do {