From c2c324c49755a8e4932d01fba931d1d517b22d71 Mon Sep 17 00:00:00 2001
From: Boris Faure <billiob@gmail.com>
Date: Sun, 24 May 2020 00:19:33 +0200
Subject: [PATCH] sb: fix error: applying zero offset to null pointer

Found by UndefinedBehaviorSanitizer
---
 src/bin/sb.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/src/bin/sb.c b/src/bin/sb.c
index defe4b01..66d11df5 100644
--- a/src/bin/sb.c
+++ b/src/bin/sb.c
@@ -146,7 +146,8 @@ ty_sb_lskip(struct ty_sb *sb, size_t len)
    else
      {
         /* buffer is empty, get rid of gap */
-        sb->buf -= sb->gap;
+        if (sb->buf)
+          sb->buf -= sb->gap;
         sb->gap = 0;
      }
 }