1 files changed, 62 insertions, 0 deletions
diff --git a/tests/tail-2/tail-n0f.sh b/tests/tail-2/tail-n0f.sh
new file mode 100755
index 0000000..d7efcf3
--- /dev/null
+++ b/tests/tail-2/tail-n0f.sh
@@ -0,0 +1,62 @@
+#!/bin/sh
+# Make sure that 'tail -n0 -f' and 'tail -c0 -f' sleep
+# rather than doing what amounted to a busy-wait.
+
+# Copyright (C) 2003-2018 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/>.
+
+# This bug was fixed for 5.0.91
+# It skips the test if your system lacks a /proc/$pid/status
+# file, or if its contents don't look right.
+
+. "${srcdir=.}/tests/init.sh"; path_prepend_ ./src
+print_ver_ tail
+
+require_proc_pid_status_
+
+touch empty || framework_failure_
+echo anything > nonempty || framework_failure_
+
+# First verify that -[nc]0 without -f, exit without reading
+touch unreadable || framework_failure_
+chmod 0 unreadable || framework_failure_
+tail -c0 unreadable || fail=1
+tail -n0 unreadable || fail=1
+
+# Terminate any background tail process
+cleanup_() { kill $pid 2>/dev/null && wait $pid; }
+
+for mode in '' '---disable-inotify'; do
+  for file in empty nonempty; do
+    for c_or_n in c n; do
+      tail --sleep=4 -${c_or_n} 0 -f $mode $file & pid=$!
+      tail_sleeping()
+      {
+        local delay="$1"; sleep $delay
+        state=$(get_process_status_ $pid)
+        case $state in
+          S*) ;;
+          *) return 1;;
+        esac
+      }
+      # Wait up to 1.5s for tail to sleep
+      retry_delay_ tail_sleeping .1 4 ||
+        { echo $0: process in unexpected state: $state >&2; fail=1; }
+      cleanup_
+    done
+  done
+done
+
+Exit $fail