From 2b2c2b64c26487387b4f536f7ed78babc30add23 Mon Sep 17 00:00:00 2001
From: Nick Fitzgerald <fitzgen@gmail.com>
Date: Sun, 27 Mar 2016 14:29:47 -0700
Subject: [PATCH] tail: When tailing a file in bytes mode, seek directly to the
 specified byte

When tailing a file, as opposed to stdin, and we are tailing bytes rather than
lines, we can seek the requested number of bytes from the end of the file. This
side steps the whole `backwards_thru_file` file loop and blocks of reads.

Fixes #833.
---
 src/tail/tail.rs | 7 ++-----
 1 file changed, 2 insertions(+), 5 deletions(-)

diff --git a/src/tail/tail.rs b/src/tail/tail.rs
index 996740e81..865f4f40c 100755
--- a/src/tail/tail.rs
+++ b/src/tail/tail.rs
@@ -336,11 +336,8 @@ fn bounded_tail(mut file: File, settings: &Settings) {
                 }
             });
         },
-        FilterMode::Bytes(mut count) => {
-            backwards_thru_file(&mut file, size, &mut buf, &mut |_| {
-                count -= 1;
-                count == 0
-            });
+        FilterMode::Bytes(count) => {
+            file.seek(SeekFrom::End(-(count as i64))).unwrap();
         },
     }