108 lines
3.3 KiB
Bash
Executable file
108 lines
3.3 KiB
Bash
Executable file
#!/bin/sh
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# ensure that tail -F doesn't leak inotify resources
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# Copyright (C) 2015-2025 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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. "${srcdir=.}/tests/init.sh"; path_prepend_ ./src
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print_ver_ tail
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# Inotify not used on remote file systems
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require_local_dir_
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grep '^#define HAVE_INOTIFY 1' "$CONFIG_HEADER" >/dev/null \
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|| skip_ 'inotify required'
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require_strace_ 'inotify_add_watch,inotify_rm_watch'
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check_tail_output()
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{
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local delay="$1"
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grep "$tail_re" out > /dev/null ||
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{ sleep $delay; return 1; }
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}
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# Wait up to 25.5 seconds for grep REGEXP 'out' to succeed.
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grep_timeout() { tail_re="$1" retry_delay_ check_tail_output .1 8; }
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check_strace()
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{
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local delay="$1"
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grep "$strace_re" strace.out > /dev/null ||
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{ sleep $delay; return 1; }
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}
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cleanup_fail()
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{
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cat out
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warn_ $1
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fail=1
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}
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# Terminate any background tail process
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cleanup_() { kill $pid 2>/dev/null && wait $pid; }
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fastpoll='-s.1 --max-unchanged-stats=1'
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touch k || framework_failure_
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# Note the timeout guard isn't strictly necessary here,
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# however without it strace will ignore SIGTERM.
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# strace does always honor SIGTERM with the -I2 option,
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# though that's not available on RHEL6 for example.
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timeout 180 strace -e inotify_add_watch,inotify_rm_watch -o strace.out \
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tail -F $fastpoll k >> out 2>&1 & pid=$!
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reverted_to_polling_=0
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for i in $(seq 2); do
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echo $i
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echo 'tailed' > k;
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# Wait for watch on (new) file
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strace_re='inotify_add_watch.*MODIFY' retry_delay_ check_strace .1 8 ||
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no_watch_=1
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# Assume this is not because we're leaking
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# (resources may already be depleted)
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# The explicit check for inotify_rm_watch should confirm that.
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grep -F 'reverting to polling' out >/dev/null && skip_ 'inotify unused'
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# Otherwise failure is unknown
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test "$no_watch_" && { cat out; framework_failure_ 'no inotify_add_watch'; }
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mv k k.tmp
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# wait for tail to detect the rename
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grep_timeout 'inaccessible' ||
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{ cleanup_fail 'failed to detect rename'; break; }
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# Note we strace here rather than consuming all available watches
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# to be more efficient, but more importantly avoid depleting resources.
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# Note also available resources can currently be tuned with:
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# sudo sysctl -w fs.inotify.max_user_watches=$smallish_number
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# However that impacts all processes for the current user, and also
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# may not be supported in future, instead being auto scaled to RAM
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# like the Linux epoll resources were.
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if test "$i" -gt 1; then
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strace_re='inotify_rm_watch' retry_delay_ check_strace .1 8 ||
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{ cleanup_fail 'failed to find inotify_rm_watch syscall'; break; }
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fi
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>out && >strace.out || framework_failure_ 'failed to reset output files'
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done
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cleanup_
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Exit $fail
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