From 88d3aee71cb9f2138f5a683699507be29286012f Mon Sep 17 00:00:00 2001
From: Jan Scheer <jhscheer@users.noreply.github.com>
Date: Wed, 31 Aug 2022 15:47:01 +0200
Subject: [PATCH] tail: fix offset for stdin redirect if multiple input files

---
 src/uu/tail/src/tail.rs    |  7 +++++--
 tests/by-util/test_tail.rs | 33 ++++++++++++++++++++++++++++++++-
 2 files changed, 37 insertions(+), 3 deletions(-)

diff --git a/src/uu/tail/src/tail.rs b/src/uu/tail/src/tail.rs
index 717eac6d8..28a65093d 100644
--- a/src/uu/tail/src/tail.rs
+++ b/src/uu/tail/src/tail.rs
@@ -503,8 +503,11 @@ fn uu_tail(mut settings: Settings) -> UResult<()> {
                     }
 
                     let mut reader;
-                    if file.is_seekable(settings.stdin_offset)
-                        && metadata.as_ref().unwrap().get_block_size() > 0
+                    if file.is_seekable(if display_name.is_stdin() {
+                        settings.stdin_offset
+                    } else {
+                        0
+                    }) && metadata.as_ref().unwrap().get_block_size() > 0
                     {
                         bounded_tail(&mut file, &settings);
                         reader = BufReader::new(file);
diff --git a/tests/by-util/test_tail.rs b/tests/by-util/test_tail.rs
index 16bdf77ee..1a48cebfe 100644
--- a/tests/by-util/test_tail.rs
+++ b/tests/by-util/test_tail.rs
@@ -107,7 +107,38 @@ fn test_stdin_redirect_offset() {
     let mut fh = std::fs::File::open(at.plus("k")).unwrap();
     fh.seek(SeekFrom::Start(2)).unwrap();
 
-    ts.ucmd().set_stdin(fh).run().stdout_is("2\n").succeeded();
+    ts.ucmd()
+        .set_stdin(fh)
+        .run()
+        .no_stderr()
+        .stdout_is("2\n")
+        .succeeded();
+}
+
+#[test]
+#[cfg(all(unix, not(any(target_os = "android", target_vendor = "apple"))))] // FIXME: make this work not just on Linux
+fn test_stdin_redirect_offset2() {
+    // like test_stdin_redirect_offset but with multiple files
+    use std::io::{Seek, SeekFrom};
+
+    let ts = TestScenario::new(util_name!());
+    let at = &ts.fixtures;
+
+    at.write("k", "1\n2\n");
+    at.write("l", "3\n4\n");
+    at.write("m", "5\n6\n");
+    let mut fh = std::fs::File::open(at.plus("k")).unwrap();
+    fh.seek(SeekFrom::Start(2)).unwrap();
+
+    ts.ucmd()
+        .set_stdin(fh)
+        .args(&["k", "-", "l", "m"])
+        .run()
+        .no_stderr()
+        .stdout_is(
+            "==> k <==\n1\n2\n\n==> standard input <==\n2\n\n==> l <==\n3\n4\n\n==> m <==\n5\n6\n",
+        )
+        .succeeded();
 }
 
 #[test]