tests/tail/tail-n0f.sh

   1 #!/bin/sh
   2 # Make sure that 'tail -n0 -f' and 'tail -c0 -f' sleep
   3 # rather than doing what amounted to a busy-wait.
   4
   5 # Copyright (C) 2003-2024 Free Software Foundation, Inc.
   6
   7 # This program is free software: you can redistribute it and/or modify
   8 # it under the terms of the GNU General Public License as published by
   9 # the Free Software Foundation, either version 3 of the License, or
  10 # (at your option) any later version.
  11
  12 # This program is distributed in the hope that it will be useful,
  13 # but WITHOUT ANY WARRANTY; without even the implied warranty of
  14 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15 # GNU General Public License for more details.
  16
  17 # You should have received a copy of the GNU General Public License
  18 # along with this program.  If not, see <https://www.gnu.org/licenses/>.
  19
  20 # This bug was fixed for 5.0.91
  21 # It skips the test if your system lacks a /proc/$pid/status
  22 # file, or if its contents don't look right.
  23
  24 . "${srcdir=.}/tests/init.sh"; path_prepend_ ./src
  25 print_ver_ tail
  26
  27 require_proc_pid_status_
  28
  29 touch empty || framework_failure_
  30 echo anything > nonempty || framework_failure_
  31
  32 # First verify that -[nc]0 without -f, exit without reading
  33 touch unreadable || framework_failure_
  34 chmod 0 unreadable || framework_failure_
  35 tail -c0 unreadable || fail=1
  36 tail -n0 unreadable || fail=1
  37
  38 # Terminate any background tail process
  39 cleanup_() { kill $pid 2>/dev/null && wait $pid; }
  40
  41 for mode in '' '---disable-inotify'; do
  42   for file in empty nonempty; do
  43     for c_or_n in c n; do
  44       tail --sleep=4 -${c_or_n} 0 -f $mode $file & pid=$!
  45       tail_sleeping()
  46       {
  47         local delay="$1"; sleep $delay
  48         state=$(get_process_status_ $pid)
  49         case $state in
  50           S*) ;;
  51           *) return 1;;
  52         esac
  53       }
  54       # Wait up to 1.5s for tail to sleep
  55       retry_delay_ tail_sleeping .1 4 ||
  56         { echo $0: process in unexpected state: $state >&2; fail=1; }
  57       cleanup_
  58     done
  59   done
  60 done
  61
  62 Exit $fail