>From d461bfd2743547360793acd2118d4c08ad7b84a8 Mon Sep 17 00:00:00 2001 From: Bernhard Voelker
Date: Sat, 20 Apr 2013 16:33:06 +0200 Subject: [PATCH 1/2] tail: let -f --retry wait for inaccessible files The --retry option is indeed useful for both following modes by name and by file descriptor. The difference is that in the latter case, it is effective only during the initial open. As a regression of the implementation of the inotify support, tail -f --retry would immediately exit if the given file is inaccessible. * src/tail.c (usage): Change the description of the --retry option: remove the note that this option would mainly be useful when following by name. (main): Change diagnosing dubios uses of --retry option: when the --retry option is used without following, then issue a warning that this option is ignored; when it is used together with --follow=descriptor, then issue a warning that it is only effective for the initial open. Disable inotify also in the case when the initial open in tail_file() failed (which is the actual bug fix). * init.cfg (retry_delay_): Pass excess arguments to the test function. * tests/tail-2/retry.sh: Add new tests. * tests/local.mk (all_tests): Mention it. * doc/coreutils.texi (tail invocation): Enhance the documentation of the --retry option. Clarify the difference in tail's behavior regarding the --retry option when combined with the following modes name versus descriptor. * NEWS (Bug fixes): Mention the fix. Reported by Noel Morrison in: http://lists.gnu.org/archive/html/coreutils/2013-04/msg00003.html --- NEWS | 5 +++ doc/coreutils.texi | 14 ++++++-- init.cfg | 4 ++- src/tail.c | 21 ++++++++---- tests/local.mk | 1 + tests/tail-2/retry.sh | 94 +++++++++++++++++++++++++++++++++++++++++++++++++++ 6 files changed, 129 insertions(+), 10 deletions(-) create mode 100644 tests/tail-2/retry.sh diff --git a/NEWS b/NEWS index 0db53d7..fc05b8a 100644 --- a/NEWS +++ b/NEWS @@ -13,6 +13,11 @@ GNU coreutils NEWS -*- outline -*- the relative link on the dereferenced path of an existing link. [This bug was introduced when --relative was added in coreutils-8.16.] + tail --retry -f now waits for the files specified to appear. Before, tail + would immediately exit when such a file is inaccessible during the initial + open. + [This bug was introduced when inotify support was added in coreutils-7.5] + ** New features join accepts a new option: --zero-terminated (-z). As with the sort,uniq diff --git a/doc/coreutils.texi b/doc/coreutils.texi index 92917f1..f6f2eb4 100644 --- a/doc/coreutils.texi +++ b/doc/coreutils.texi @@ -3155,9 +3155,17 @@ will keep trying until it becomes accessible again. @item --retry @opindex --retry -This option is useful mainly when following by name (i.e., with -@option{--follow=name}). -Without this option, when tail encounters a file that doesn't +Indefinitely try to open the specified file. +This option is useful mainly when following (and otherwise issues a warning). + +When following by file descriptor (i.e., with @option{--follow=descriptor}), +this option only affects the initial open of the file, as after a successful +open, @command{tail} will start following the file descriptor. + +When following by name (i.e., with @option{--follow=name}), @command{tail} +infinitely retries to re-open the given files until killed. + +Without this option, when @command{tail} encounters a file that doesn't exist or is otherwise inaccessible, it reports that fact and never checks it again. diff --git a/init.cfg b/init.cfg index 7976b61..33122cc 100644 --- a/init.cfg +++ b/init.cfg @@ -556,11 +556,13 @@ working_umask_or_skip_() # Note ensure you do _not_ quote the parameter to GNU sleep in # your function, as it may contain separate values that sleep # needs to accumulate. +# Further function arguments will be forwarded to the test function. retry_delay_() { local test_func=$1 local init_delay=$2 local max_n_tries=$3 + shift 3 || return 1 local attempt=1 local num_sleeps=$attempt @@ -568,7 +570,7 @@ retry_delay_() while test $attempt -le $max_n_tries; do local delay=$($AWK -v n=$num_sleeps -v s="$init_delay" \ 'BEGIN { print s * n }') - "$test_func" "$delay" && { time_fail=0; break; } || time_fail=1 + "$test_func" "$delay" "$@" && { time_fail=0; break; } || time_fail=1 attempt=$(expr $attempt + 1) num_sleeps=$(expr $num_sleeps '*' 2) done diff --git a/src/tail.c b/src/tail.c index cdaecdd..3735757 100644 --- a/src/tail.c +++ b/src/tail.c @@ -294,9 +294,7 @@ With no FILE, or when FILE is -, read standard input.\n\ fputs (_("\ --pid=PID with -f, terminate after process ID, PID dies\n\ -q, --quiet, --silent never output headers giving file names\n\ - --retry keep trying to open a file even when it is or\n\ - becomes inaccessible; useful when following by\n\ - name, i.e., with --follow=name\n\ + --retry keep trying to open a file if it is inaccessible\n\ "), stdout); fputs (_("\ -s, --sleep-interval=N with -f, sleep for approximately N seconds\n\ @@ -2030,8 +2028,14 @@ parse_options (int argc, char **argv, } } - if (reopen_inaccessible_files && follow_mode != Follow_name) - error (0, 0, _("warning: --retry is useful mainly when following by name")); + if (reopen_inaccessible_files) + { + if (!forever) + error (0, 0, _("warning: --retry ignored; --retry is useful" + " only when following")); + else if (follow_mode == Follow_descriptor) + error (0, 0, _("warning: --retry only effective for the initial open")); + } if (pid && !forever) error (0, 0, @@ -2182,6 +2186,10 @@ main (int argc, char **argv) in this case because it would miss any updates to the file that were not initiated from the local system. + ok is false when one of the files specified could not be opened for + reading. In this case and when following by descriptor, + tail_forever_inotify() cannot be used (in its current implementation). + FIXME: inotify doesn't give any notification when a new (remote) file or directory is mounted on top a watched file. When follow_mode == Follow_name we would ideally like to detect that. @@ -2193,7 +2201,8 @@ main (int argc, char **argv) is recreated, then we don't recheck any new file when follow_mode == Follow_name */ if (!disable_inotify && (tailable_stdin (F, n_files) - || any_remote_file (F, n_files))) + || any_remote_file (F, n_files) + || (!ok && follow_mode == Follow_descriptor))) disable_inotify = true; if (!disable_inotify) diff --git a/tests/local.mk b/tests/local.mk index 0b019d9..f47da8d 100644 --- a/tests/local.mk +++ b/tests/local.mk @@ -390,6 +390,7 @@ all_tests = \ tests/misc/uniq-perf.sh \ tests/misc/xattr.sh \ tests/tail-2/wait.sh \ + tests/tail-2/retry.sh \ tests/chmod/c-option.sh \ tests/chmod/equal-x.sh \ tests/chmod/equals.sh \ diff --git a/tests/tail-2/retry.sh b/tests/tail-2/retry.sh new file mode 100644 index 0000000..71d1015 --- /dev/null +++ b/tests/tail-2/retry.sh @@ -0,0 +1,94 @@ +#!/bin/sh +# Exercise tail's behavior regarding missing files with/without --retry. + +# Copyright (C) 2013 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