tests/tail-2/inotify-rotate-resources.sh

   1 #!/bin/sh
   2 # ensure that tail -F doesn't leak inotify resources
   3
   4 # Copyright (C) 2015-2017 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 <http://www.gnu.org/licenses/>.
  18
  19 . "${srcdir=.}/tests/init.sh"; path_prepend_ ./src
  20 print_ver_ tail
  21
  22 # Inotify not used on remote file systems
  23 require_local_dir_
  24
  25 grep '^#define HAVE_INOTIFY 1' "$CONFIG_HEADER" >/dev/null \
  26   || skip_ 'inotify required'
  27
  28 require_strace_ 'inotify_add_watch,inotify_rm_watch'
  29
  30 check_tail_output()
  31 {
  32   local delay="$1"
  33   grep "$tail_re" out > /dev/null ||
  34     { sleep $delay; return 1; }
  35 }
  36
  37 # Wait up to 25.5 seconds for grep REGEXP 'out' to succeed.
  38 grep_timeout() { tail_re="$1" retry_delay_ check_tail_output .1 8; }
  39
  40 check_strace()
  41 {
  42   local delay="$1"
  43   grep "$strace_re" strace.out > /dev/null ||
  44     { sleep $delay; return 1; }
  45 }
  46
  47 cleanup_fail()
  48 {
  49   cat out
  50   warn_ $1
  51   fail=1
  52 }
  53
  54 # Terminate any background tail process
  55 cleanup_() { kill $pid 2>/dev/null && wait $pid; }
  56
  57 fastpoll='-s.1 --max-unchanged-stats=1'
  58
  59 touch k || framework_failure_
  60
  61 # Note the timeout guard isn't strictly necessary here,
  62 # however without it strace will ignore SIGTERM.
  63 # strace does always honor SIGTERM with the -I2 option,
  64 # though that's not available on RHEL6 for example.
  65 timeout 180 strace -e inotify_add_watch,inotify_rm_watch -o strace.out \
  66   tail -F $fastpoll k >> out 2>&1 & pid=$!
  67
  68 reverted_to_polling_=0
  69 for i in $(seq 2); do
  70     echo $i
  71
  72     echo 'tailed' > k;
  73
  74     # Wait for watch on (new) file
  75     strace_re='inotify_add_watch.*MODIFY' retry_delay_ check_strace .1 8 ||
  76       no_watch_=1
  77
  78     # Assume this is not because we're leaking
  79     # (resources may already be depleted)
  80     # The explicit check for inotify_rm_watch should confirm that.
  81     grep -F 'reverting to polling' out >/dev/null && skip_ 'inotify unused'
  82
  83     # Otherwise failure is unknown
  84     test "$no_watch_" && { cat out; framework_failure_ 'no inotify_add_watch'; }
  85
  86     mv k k.tmp
  87     # wait for tail to detect the rename
  88     grep_timeout 'inaccessible' ||
  89       { cleanup_fail 'failed to detect rename'; break; }
  90
  91     # Note we strace here rather than consuming all available watches
  92     # to be more efficient, but more importantly avoid depleting resources.
  93     # Note also available resources can currently be tuned with:
  94     #  sudo sysctl -w fs.inotify.max_user_watches=$smallish_number
  95     # However that impacts all processes for the current user, and also
  96     # may not be supported in future, instead being auto scaled to RAM
  97     # like the Linux epoll resources were.
  98     if test "$i" -gt 1; then
  99       strace_re='inotify_rm_watch' retry_delay_ check_strace .1 8 ||
 100         { cleanup_fail 'failed to find inotify_rm_watch syscall'; break; }
 101     fi
 102
 103     >out && >strace.out || framework_failure_ 'failed to reset output files'
 104 done
 105
 106 cleanup_
 107
 108 Exit $fail