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#!/bin/sh
# inotify-based tail would output redundant headers for
# overlapping inotify events while it was suspended
# Copyright (C) 2017-2022 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 sleep
# Function to count number of lines from tail
# while ignoring transient errors due to resource limits
countlines_ ()
{
grep -Ev 'inotify (resources exhausted|cannot be used)' out | wc -l
}
# Function to check the expected line count in 'out'.
# Called via retry_delay_(). Sleep some time - see retry_delay_() - if the
# line count is still smaller than expected.
wait4lines_ ()
{
local delay=$1
local elc=$2 # Expected line count.
[ "$(countlines_)" -ge "$elc" ] || { sleep $delay; return 1; }
}
# Speedup the non inotify case
fastpoll='---dis -s.1 --max-unchanged-stats=1'
# Terminate any background tail process
cleanup_() {
kill $pid 2>/dev/null && wait $pid;
kill $sleep 2>/dev/null && wait $sleep
}
echo start > file1 || framework_failure_
echo start > file2 || framework_failure_
# Use this as a way to gracefully terminate tail
env sleep 20 & sleep=$!
tail $fastpoll --pid=$sleep -f file1 file2 > out & pid=$!
kill -0 $pid || fail=1
# Wait for 5 initial lines
retry_delay_ wait4lines_ .1 6 5 || fail=1
# Suspend tail so single read() caters for multiple inotify events
kill -STOP $pid || fail=1
# Interleave writes to files to generate overlapping inotify events
echo line >> file1 || framework_failure_
echo line >> file2 || framework_failure_
echo line >> file1 || framework_failure_
echo line >> file2 || framework_failure_
# Resume tail processing
kill -CONT $pid || fail=1
# Wait for 8 more lines
retry_delay_ wait4lines_ .1 6 13 || fail=1
kill $sleep && wait || framework_failure_
test "$(countlines_)" = 13 || fail=1
Exit $fail
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