From 7bc73b7ef9402f81a6bb496b03ba84197f76e642 Mon Sep 17 00:00:00 2001
From: Maxime Coste <frrrwww@gmail.com>
Date: Tue, 13 May 2014 18:59:22 +0100
Subject: [PATCH] negative coordinates are invalid

---
 src/buffer.inl.hh | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/src/buffer.inl.hh b/src/buffer.inl.hh
index 9cfa2d0f..5375d993 100644
--- a/src/buffer.inl.hh
+++ b/src/buffer.inl.hh
@@ -52,6 +52,9 @@ inline ByteCount Buffer::offset(ByteCoord c) const
 
 inline bool Buffer::is_valid(ByteCoord c) const
 {
+    if (c.line < 0 or c.column < 0)
+        return false;
+
     return (c.line < line_count() and c.column < m_lines[c.line].length()) or
            (c.line == line_count() - 1 and c.column == m_lines.back().length()) or
            (c.line == line_count() and c.column == 0);