tests/tail/assert.sh
#!/bin/sh
# Test for assertion failure in "test".

# Copyright (C) 1999-2025 Free Software Foundation, Inc.

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# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
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# This test fails with tail from textutils-2.0.
# It would get something like this:
#   tail: tail.c:718: recheck: Assertion 'valid_file_spec (f)' failed.
#   Aborted
# due to a race condition in which a dev/inode pair is reused.

. "${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 a foo out
  touch a foo || framework_failure_

  tail $mode --follow=name $fastpoll a foo > out 2>&1 & pid=$!

  # Wait up to 12.7s for tail to start.
  echo x > a || framework_failure_
  tail_re='^x$' retry_delay_ check_tail_output .1 7 ||
    { cat out; fail=1; break; }

  # Wait 12.7s for this diagnostic:
  # tail: foo: No such file or directory
  rm foo || framework_failure_
  tail_re='No such file' retry_delay_ check_tail_output .1 7 ||
    { cat out; fail=1; break; }

  # Wait up to 12.7s for tail to notice new foo file
  ok='ok ok ok'
  echo "$ok" > foo || framework_failure_
  tail_re="^$ok$" retry_delay_ check_tail_output .1 7 ||
    { echo "$0: foo: unexpected delay?"; cat out; fail=1; break; }

  cleanup_
done

Exit $fail
