1#!/bin/sh
2# ensure that tail -F handles rotation
3
4# Copyright (C) 2009-2023 Free Software Foundation, Inc.
5
6# This program is free software: you can redistribute it and/or modify
7# it under the terms of the GNU General Public License as published by
8# the Free Software Foundation, either version 3 of the License, or
9# (at your option) any later version.
10
11# This program is distributed in the hope that it will be useful,
12# but WITHOUT ANY WARRANTY; without even the implied warranty of
13# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
14# GNU General Public License for more details.
15
16# You should have received a copy of the GNU General Public License
17# along with this program.  If not, see <https://www.gnu.org/licenses/>.
18
19. "${srcdir=.}/tests/init.sh"; path_prepend_ ./src
20print_ver_ tail
21
22grep '^#define HAVE_INOTIFY 1' "$CONFIG_HEADER" >/dev/null \
23  || expensive_
24
25check_tail_output()
26{
27  local delay="$1"
28  grep "$tail_re" out > /dev/null ||
29    { sleep $delay; return 1; }
30}
31
32# Wait up to 25.5 seconds for grep REGEXP 'out' to succeed.
33grep_timeout() { tail_re="$1" retry_delay_ check_tail_output .1 8; }
34
35# Terminate any background tail process
36cleanup_() { kill $pid 2>/dev/null && wait $pid; }
37
38cleanup_fail()
39{
40  cat out
41  warn_ $1
42  cleanup_
43  fail=1
44}
45
46# Speedup the non inotify case
47fastpoll='-s.1 --max-unchanged-stats=1'
48
49# Perform at least this many iterations, because on multi-core systems
50# the offending sequence of events can be surprisingly uncommon.
51# See: https://lists.gnu.org/r/bug-coreutils/2009-11/msg00213.html
52for i in $(seq 50); do
53    echo $i
54    rm -f k x out
55
56    # Normally less than a second is required here, but with heavy load
57    # and a lot of file system activity, even 20 seconds is insufficient, which
58    # leads to this timeout killing tail before the "ok" is written below.
59    >k && >x || framework_failure_ failed to initialize files
60    timeout 60 tail $fastpoll -F k > out 2>&1 & pid=$!
61
62    echo 'tailed' > k;
63    # wait for 'tailed' to appear in out
64    grep_timeout 'tailed' || { cleanup_fail 'failed to find "tailed"'; break; }
65
66    mv x k
67    # wait for tail to detect the rename
68    grep_timeout 'tail:' || { cleanup_fail 'failed to detect rename'; break; }
69
70    echo ok >> k
71    # wait for "ok" to appear in 'out'
72    grep_timeout 'ok' || { cleanup_fail 'failed to detect echoed ok'; break; }
73
74    cleanup_
75done
76
77Exit $fail
78