From: Paul Eggert <eggert@cs.ucla.edu>
Date: Tue, 29 Jul 2025 16:37:44 +0000 (-0700)
Subject: tail: optimize tail -n +2**63
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=10aa908ebd8d487f0dbbc77abb317a94d33f460d;p=thirdparty%2Fcoreutils.git

tail: optimize tail -n +2**63

* src/tail.c (tail_lines): Also optimize ‘tail -n +N’
on a seekable file, where OFF_T_MAX <= N < UINTMAX_MAX.
Of course this is very unlikely.
---

diff --git a/src/tail.c b/src/tail.c
index 4715bd1d85..db6aea4a04 100644
--- a/src/tail.c
+++ b/src/tail.c
@@ -1955,7 +1955,7 @@ tail_lines (char const *pretty_filename, int fd, struct stat const *st,
     {
       /* If skipping all input use lseek if possible, for speed.  */
       off_t pos;
-      if (n_lines == UINTMAX_MAX && 0 <= (pos = lseek (fd, 0, SEEK_END)))
+      if (OFF_T_MAX <= n_lines && 0 <= (pos = lseek (fd, 0, SEEK_END)))
         *read_pos = pos;
       else
         {