81 lines
2.4 KiB
Bash
Executable file
81 lines
2.4 KiB
Bash
Executable file
#!/bin/sh
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# inotify-based tail would output redundant headers for
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# overlapping inotify events while it was suspended
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# Copyright (C) 2017-2025 Free Software Foundation, Inc.
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# This program is free software: you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation, either version 3 of the License, or
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# (at your option) any later version.
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# This program is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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# You should have received a copy of the GNU General Public License
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# along with this program. If not, see <https://www.gnu.org/licenses/>.
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. "${srcdir=.}/tests/init.sh"; path_prepend_ ./src
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print_ver_ tail sleep
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# Function to count number of lines from tail
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# while ignoring transient errors due to resource limits
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countlines_ ()
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{
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grep -Ev 'inotify (resources exhausted|cannot be used)' out | wc -l
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}
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# Function to check the expected line count in 'out'.
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# Called via retry_delay_(). Sleep some time - see retry_delay_() - if the
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# line count is still smaller than expected.
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wait4lines_ ()
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{
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local delay=$1
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local elc=$2 # Expected line count.
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[ "$(countlines_)" -ge "$elc" ] || { sleep $delay; return 1; }
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}
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# Speedup the non inotify case
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fastpoll='---dis -s.1 --max-unchanged-stats=1'
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# Terminate any background tail process
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cleanup_() {
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kill $pid 2>/dev/null && wait $pid;
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kill $sleep 2>/dev/null && wait $sleep
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}
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echo start > file1 || framework_failure_
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echo start > file2 || framework_failure_
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# Use this as a way to gracefully terminate tail
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env sleep 20 & sleep=$!
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tail $fastpoll --pid=$sleep -f file1 file2 > out & pid=$!
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kill -0 $pid || fail=1
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# Wait for 5 initial lines
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retry_delay_ wait4lines_ .1 6 5 || fail=1
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# Suspend tail so single read() caters for multiple inotify events
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kill -STOP $pid || fail=1
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# Interleave writes to files to generate overlapping inotify events
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echo line >> file1 || framework_failure_
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echo line >> file2 || framework_failure_
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echo line >> file1 || framework_failure_
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echo line >> file2 || framework_failure_
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# Resume tail processing
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kill -CONT $pid || fail=1
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# Wait for 8 more lines
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retry_delay_ wait4lines_ .1 6 13 || fail=1
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kill $sleep && wait || framework_failure_
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test "$(countlines_)" = 13 || fail=1
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Exit $fail
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