test: tail: test that --follow works on a symbolic link

* tests/tail/follow-symlink.sh: New file.
* tests/local.mk (all_tests): Add the test.

diff --git a/tests/local.mk b/tests/local.mk
index 6d572e679b1b5a35faaf6e9311b514be85fd0120..04f6cb1e36cf727cb7117afd488599aa1c018eec 100644 (file)
--- a/tests/local.mk
+++ b/tests/local.mk
@@ -193,6 +193,7 @@ all_tests =                                 \
   tests/tail/F-vs-rename.sh                    \
   tests/tail/F-headers.sh                      \
   tests/tail/descriptor-vs-rename.sh           \
+  tests/tail/follow-symlink.sh                 \
   tests/tail/inotify-rotate.sh                 \
   tests/tail/inotify-rotate-resources.sh       \
   tests/tail/inotify-dir-recreate.sh           \

diff --git a/tests/tail/follow-symlink.sh b/tests/tail/follow-symlink.sh
new file mode 100755 (executable)
index 0000000..4cf62eb
--- /dev/null
+++ b/tests/tail/follow-symlink.sh
@@ -0,0 +1,50 @@
+#!/bin/sh
+# Test that --follow works on a symbolic link.
+
+# Copyright (C) 2026 Free Software Foundation, Inc.
+
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+. "${srcdir=.}/tests/init.sh"; path_prepend_ ./src
+print_ver_ tail
+
+check_tail_output()
+{
+  local delay="$1"
+  grep "$tail_re" out ||
+    { sleep $delay; return 1; }
+}
+
+# Terminate any background tail process
+cleanup_() { kill $pid 2>/dev/null && wait $pid; }
+
+# Speedup the non inotify case
+fastpoll='-s.1 --max-unchanged-stats=1'
+
+for mode in '' '---disable-inotify'; do
+  rm -f file link out || framework_failure_
+  touch file || framework_failure_
+  ln -s file link || framework_failure_
+  tail $mode $fastpoll -f link >out 2>err & pid=$!
+  for c in a b c; do
+    # Wait up to 12.7s for tail to start.
+    echo "$c" >> file
+    tail_re="^$c$" retry_delay_ check_tail_output .1 7 || { cat out; fail=1; }
+  done
+  compare file out || fail=1
+  compare /dev/null err || fail=1
+  cleanup_
+done
+
+Exit $fail