From 3c3f5b2da0d06dc4a91af381febde67e758cff90 Mon Sep 17 00:00:00 2001 From: Stephane Chazelas Date: Tue, 3 Feb 2015 21:22:06 +0000 Subject: tail: fix -f to follow changes after a rename * src/tail.c (tail_forever_inotify): Only monitor write()s and truncate()s to files in --follow=descriptor mode, thus avoiding the bug where we removed the watch on renamed files. Also adjust the inotify event processing code that is now significant only in --follow=name mode. * tests/tail-2/F-vs-rename.sh: Improve this existing test by running in both polling and inotify modes. * tests/tail-2/f-vs-rename.sh: A new test based on the existing one. * tests/local.mk: Reference the new test. * NEWS: Mention the bug. Fixes http://bugs.gnu.org/19760 (cherry picked from commit d313a0b24234d3366ec263111469f219f5b4634f) Conflicts: NEWS tests/tail-2/F-vs-rename.sh --- src/tail.c | 31 +++++++-------- tests/local.mk | 1 + tests/tail-2/F-vs-rename.sh | 94 +++++++++++++++++++++++---------------------- tests/tail-2/f-vs-rename.sh | 51 ++++++++++++++++++++++++ 4 files changed, 114 insertions(+), 63 deletions(-) create mode 100755 tests/tail-2/f-vs-rename.sh diff --git a/src/tail.c b/src/tail.c index 37b94df..3f42406 100644 --- a/src/tail.c +++ b/src/tail.c @@ -158,13 +158,6 @@ struct File_spec uintmax_t n_unchanged_stats; }; -#if HAVE_INOTIFY -/* The events mask used with inotify on files. This mask is not used on - directories. */ -static const uint32_t inotify_wd_mask = (IN_MODIFY | IN_ATTRIB - | IN_DELETE_SELF | IN_MOVE_SELF); -#endif - /* Keep trying to open a file even if it is inaccessible when tail starts or if it becomes inaccessible later -- useful only with -f. */ static bool reopen_inaccessible_files; @@ -1389,6 +1382,13 @@ tail_forever_inotify (int wd, struct File_spec *f, size_t n_files, if (! wd_to_name) xalloc_die (); + /* The events mask used with inotify on files (not directories). */ + uint32_t inotify_wd_mask = IN_MODIFY; + /* TODO: Perhaps monitor these events in Follow_descriptor mode also, + to tag reported file names with "deleted", "moved" etc. */ + if (follow_mode == Follow_name) + inotify_wd_mask |= (IN_ATTRIB | IN_DELETE_SELF | IN_MOVE_SELF); + /* Add an inotify watch for each watched file. If -F is specified then watch its parent directory too, in this way when they re-appear we can add them again to the watch list. */ @@ -1640,20 +1640,17 @@ tail_forever_inotify (int wd, struct File_spec *f, size_t n_files, if (ev->mask & (IN_ATTRIB | IN_DELETE_SELF | IN_MOVE_SELF)) { - /* For IN_DELETE_SELF, we always want to remove the watch. - However, for IN_MOVE_SELF (the file we're watching has - been clobbered via a rename), when tailing by NAME, we - must continue to watch the file. It's only when following - by file descriptor that we must remove the watch. */ - if ((ev->mask & IN_DELETE_SELF) - || ((ev->mask & IN_MOVE_SELF) - && follow_mode == Follow_descriptor)) + /* Note for IN_MOVE_SELF (the file we're watching has + been clobbered via a rename) we leave the watch + in place since it may still be part of the set + of watched names. */ + if (ev->mask & IN_DELETE_SELF) { inotify_rm_watch (wd, fspec->wd); hash_delete (wd_to_name, fspec); } - if (follow_mode == Follow_name) - recheck (fspec, false); + + recheck (fspec, false); continue; } diff --git a/tests/tail-2/F-vs-rename.sh b/tests/tail-2/F-vs-rename.sh index 3e31ec8..f530d4c 100755 --- a/tests/tail-2/F-vs-rename.sh +++ b/tests/tail-2/F-vs-rename.sh @@ -1,7 +1,7 @@ #!/bin/sh -# demonstrate that tail -F works when renaming the tailed files -# Before coreutils-8.3, tail -F a b would stop tracking additions to b -# after "mv a b". +# Demonstrate that tail -F works when renaming the tailed files. +# Between coreutils 7.5 and 8.2 inclusive, 'tail -F a b' would +# stop tracking additions to b after 'mv a b'. # Copyright (C) 2009-2014 Free Software Foundation, Inc. @@ -21,55 +21,57 @@ . "${srcdir=.}/tests/init.sh"; path_prepend_ ./src print_ver_ tail -touch a b || framework_failure_ - -debug='---disable-inotify' -debug= -tail $debug -F -s.1 a b > out 2>&1 & pid=$! - check_tail_output() { local delay="$1" - grep "$tail_re" out > /dev/null || + grep "$tail_re" out || { sleep $delay; return 1; } } -# Wait up to 6.3s for tail to start -echo x > a -tail_re='^x$' retry_delay_ check_tail_output .1 7 || fail=1 - -mv a b || fail=1 - -# Wait 6.3s for this diagnostic: -# tail: 'a' has become inaccessible: No such file or directory -tail_re='inaccessible' retry_delay_ check_tail_output .1 7 || fail=1 - -echo x > a -# Wait up to 6.3s for this to appear in the output: -# "tail: '...' has appeared; following end of new file" -tail_re='has appeared' retry_delay_ check_tail_output .1 7 || - { echo "$0: a: unexpected delay?"; cat out; fail=1; } - -echo y >> b -# Wait up to 6.3s for "y" to appear in the output: -tail_f_vs_rename_2() { - local delay="$1" - tr '\n' @ < out | grep '@@==> b <==@y@$' > /dev/null || - { sleep $delay; return 1; } -} -retry_delay_ tail_f_vs_rename_2 .1 7 || - { echo "$0: b: unexpected delay?"; cat out; fail=1; } - -echo z >> a -# Wait up to 6.3s for "z" to appear in the output: -tail_f_vs_rename_3() { - local delay="$1" - tr '\n' @ < out | grep '@@==> a <==@z@$' > /dev/null || - { sleep $delay; return 1; } -} -retry_delay_ tail_f_vs_rename_3 .1 7 || - { echo "$0: a: unexpected delay?"; cat out; fail=1; } +touch a b || framework_failure_ -kill -HUP $pid +for mode in '' '---disable-inotify'; do + tail $mode -F -s.1 a b > out 2>&1 & pid=$! + + # Wait up to 12.7s for tail to start. + echo x > a + tail_re='^x$' retry_delay_ check_tail_output .1 7 || fail=1 + + mv a b || fail=1 + + # Wait 12.7s for this diagnostic: + # tail: 'a' has become inaccessible: No such file or directory + tail_re='inaccessible' retry_delay_ check_tail_output .1 7 || fail=1 + + echo x > a + # Wait up to 12.7s for this to appear in the output: + # "tail: '...' has appeared; following end of new file" + tail_re='has appeared' retry_delay_ check_tail_output .1 7 || + { echo "$0: a: unexpected delay?"; cat out; fail=1; } + + echo y >> b + # Wait up to 12.7s for "y" to appear in the output: + tail_f_vs_rename_2() { + local delay="$1" + tr '\n' @ < out | grep '@@==> b <==@y@$' > /dev/null || + { sleep $delay; return 1; } + } + retry_delay_ tail_f_vs_rename_2 .1 7 || + { echo "$0: b: unexpected delay?"; cat out; fail=1; } + + echo z >> a + # Wait up to 12.7s for "z" to appear in the output: + tail_f_vs_rename_3() { + local delay="$1" + tr '\n' @ < out | grep '@@==> a <==@z@$' > /dev/null || + { sleep $delay; return 1; } + } + retry_delay_ tail_f_vs_rename_3 .1 7 || + { echo "$0: a: unexpected delay?"; cat out; fail=1; } + + kill $pid + + wait $pid +done Exit $fail diff --git a/tests/tail-2/f-vs-rename.sh b/tests/tail-2/f-vs-rename.sh new file mode 100755 index 0000000..4bff41c --- /dev/null +++ b/tests/tail-2/f-vs-rename.sh @@ -0,0 +1,51 @@ +#!/bin/sh +# Demonstrate that tail -f works when renaming the tailed files. +# Between coreutils 7.5 and 8.23 inclusive, 'tail -f a' would +# stop tracking additions to b after 'mv a b'. + +# Copyright (C) 2015 Free Software Foundation, Inc. + +# This program is free software: you can redistribute it and/or modify +# it under the terms of the GNU General Public License as published by +# the Free Software Foundation, either version 3 of the License, or +# (at your option) any later version. + +# This program is distributed in the hope that it will be useful, +# but WITHOUT ANY WARRANTY; without even the implied warranty of +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +# GNU General Public License for more details. + +# You should have received a copy of the GNU General Public License +# along with this program. If not, see . + +. "${srcdir=.}/tests/init.sh"; path_prepend_ ./src +print_ver_ tail + +check_tail_output() +{ + local delay="$1" + grep "$tail_re" out || + { sleep $delay; return 1; } +} + +touch a || framework_failure_ + +for mode in '' '---disable-inotify'; do + tail $mode -f -s.1 a > out 2>&1 & pid=$! + + # Wait up to 12.7s for tail to start. + echo x > a + tail_re='^x$' retry_delay_ check_tail_output .1 7 || fail=1 + + mv a b || fail=1 + + echo y >> b + # Wait up to 12.7s for "y" to appear in the output: + tail_re='^y$' retry_delay_ check_tail_output .1 7 || fail=1 + + kill $pid + + wait $pid +done + +Exit $fail -- 1.7.12.1