From 3d5a3f03fa160edd0423ab6e8e93ba43c56b97a8 Mon Sep 17 00:00:00 2001
From: ridiculousfish <corydoras@ridiculousfish.com>
Date: Mon, 8 Oct 2012 23:47:32 -0700
Subject: [PATCH] Fix to prevent buff_pos from underflowing in reader_kill

---
 reader.cpp | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/reader.cpp b/reader.cpp
index 4ea0c3967..289a3fa9b 100644
--- a/reader.cpp
+++ b/reader.cpp
@@ -494,7 +494,9 @@ static void reader_kill( size_t begin_idx, size_t length, int mode, int newv )
 	}
 
 	if( data->buff_pos > begin_idx ) {
-		data->buff_pos = maxi( begin_idx, data->buff_pos-length );
+        /* Move the buff position back by the number of characters we deleted, but don't go past buff_pos */
+        size_t backtrack = mini(data->buff_pos - begin_idx, length);
+        data->buff_pos -= backtrack;
 	}
 	
     data->command_line.erase(begin_idx, length);