tests/tail/inotify-race.sh

   1 #!/bin/sh
   2 # Ensure that tail does not ignore data that is appended to a tailed-forever
   3 # file between tail's initial read-to-EOF, and when the inotify watches
   4 # are established in tail_forever_inotify.  That data could be ignored
   5 # indefinitely if no *other* data is appended, but it would be printed as
   6 # soon as any additional appended data is detected.
   7
   8 # Copyright (C) 2009-2024 Free Software Foundation, Inc.
   9
  10 # This program is free software: you can redistribute it and/or modify
  11 # it under the terms of the GNU General Public License as published by
  12 # the Free Software Foundation, either version 3 of the License, or
  13 # (at your option) any later version.
  14
  15 # This program is distributed in the hope that it will be useful,
  16 # but WITHOUT ANY WARRANTY; without even the implied warranty of
  17 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  18 # GNU General Public License for more details.
  19
  20 # You should have received a copy of the GNU General Public License
  21 # along with this program.  If not, see <https://www.gnu.org/licenses/>.
  22
  23 . "${srcdir=.}/tests/init.sh"; path_prepend_ ./src
  24 print_ver_ tail sleep
  25
  26 grep '^#define HAVE_INOTIFY 1' "$CONFIG_HEADER" >/dev/null && is_local_dir_ . \
  27   || skip_ 'inotify is not supported'
  28
  29 # Terminate any background gdb/tail process
  30 cleanup_() {
  31   kill $pid 2>/dev/null && wait $pid
  32   kill $sleep 2>/dev/null && wait $sleep
  33 }
  34
  35 touch file || framework_failure_
  36 touch tail.out || framework_failure_
  37
  38 ( timeout 10s gdb --version ) > gdb.out 2>&1
  39 case $(cat gdb.out) in
  40     *'GNU gdb'*) ;;
  41     *) skip_ "can't run gdb";;
  42 esac
  43
  44 # Break on a line rather than a symbol, to cater for inline functions
  45 break_src="$abs_top_srcdir/src/tail.c"
  46 break_line=$(grep -n ^tail_forever_inotify "$break_src") || framework_failure_
  47 break_line=$(echo "$break_line" | cut -d: -f1) || framework_failure_
  48
  49
  50 # Note we get tail to monitor a background sleep process
  51 # rather than using timeout(1), as timeout sends SIGCONT
  52 # signals to its monitored process, and gdb (7.9 at least)
  53 # has _intermittent_ issues with this.
  54 # Sending SIGCONT resulted in either delayed child termination,
  55 # or no child termination resulting in a hung test.
  56 # See https://sourceware.org/bugzilla/show_bug.cgi?id=18364
  57
  58 env sleep 10 & sleep=$!
  59
  60 # See if gdb works and
  61 # tail_forever_inotify is compiled and run
  62 gdb -nx --batch-silent \
  63     --eval-command="break $break_line"             \
  64     --eval-command="run --pid=$sleep -f file"      \
  65     --eval-command='quit'                          \
  66     tail < /dev/null > gdb.out 2>&1
  67
  68 kill $sleep || skip_ 'breakpoint not hit'
  69 wait $sleep
  70
  71 # FIXME: The above is seen to _intermittently_ fail with:
  72 # warning: .dynamic section for "/lib/libc.so.6" is not at the expected address
  73 # warning: difference appears to be caused by prelink, adjusting expectations
  74 compare /dev/null gdb.out || skip_ "can't set breakpoints in tail"
  75
  76 env sleep 10 & sleep=$!
  77
  78 # Run "tail -f file", stopping to append a line just before
  79 # inotify initialization, and then continue.  Before the fix,
  80 # that just-appended line would never be output.
  81 gdb -nx --batch-silent \
  82     --eval-command="break $break_line"             \
  83     --eval-command="run --pid=$sleep -f file >> tail.out"       \
  84     --eval-command='shell echo never-seen-with-tail-7.5 >> file' \
  85     --eval-command='continue'                      \
  86     --eval-command='quit'                          \
  87     tail < /dev/null > /dev/null 2>&1 & pid=$!
  88
  89 tail --pid=$pid -f tail.out | (read REPLY; kill $pid)
  90
  91 # gdb has a bug in Debian's gdb-6.8-3 at least that causes it to not
  92 # cleanup and exit correctly when it receives a SIGTERM, but
  93 # killing sleep, should cause the tail process and thus gdb to exit.
  94 kill $sleep
  95 wait $sleep
  96
  97 wait $pid
  98
  99 compare /dev/null tail.out && fail=1
 100
 101 Exit $fail