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authorGiuseppe Scrivano <gscrivano@gnu.org>2009-10-20 10:49:17 +0200
committerJim Meyering <meyering@redhat.com>2009-10-22 10:25:58 +0200
commit029b6b14c5c4eba3071cac835efd5b277ff2337a (patch)
tree1cdb8cfb290473c4226dd181f03e2f7e90ca0203 /tests/tail-2/inotify-race
parentcd0f3036f606276654f2293a4d90df5efd21bd99 (diff)
downloadcoreutils-029b6b14c5c4eba3071cac835efd5b277ff2337a.tar.xz
tests: add a test for the `tail -f' race condition bug
If new data becomes available between the initial read and when tail registers the inotify watch descriptors, ensure that it is read before a new event happens on the file. * tests/Makefile.am (TESTS): Add tail-2/inotify-race. * tests/tail-2/inotify-race: New file.
Diffstat (limited to 'tests/tail-2/inotify-race')
-rwxr-xr-xtests/tail-2/inotify-race66
1 files changed, 66 insertions, 0 deletions
diff --git a/tests/tail-2/inotify-race b/tests/tail-2/inotify-race
new file mode 100755
index 000000000..025272c02
--- /dev/null
+++ b/tests/tail-2/inotify-race
@@ -0,0 +1,66 @@
+#!/bin/sh
+# Ensure that tail does not ignore data that is appended to a tailed-forever
+# file between tail's initial read-to-EOF, and when the inotify watches
+# are established in tail_forever_inotify. That data could be ignored
+# indefinitely if no *other* data is appended, but it would be printed as
+# soon as any additional appended data is detected.
+
+# Copyright (C) 2009 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 <http://www.gnu.org/licenses/>.
+
+if test "$VERBOSE" = yes; then
+ set -x
+ tail --version
+fi
+
+. $srcdir/test-lib.sh
+
+fail=0
+
+touch file || framework_failure
+touch tail.out || framework_failure
+
+( gdb --version ) > gdb.out 2>&1
+case $(cat gdb.out) in
+ *'GNU gdb'*) ;;
+ *) skip_test_ "can't run gdb";;
+esac
+
+# See if gdb works:
+gdb -nx --batch-silent \
+ --eval-command='break tail_forever_inotify' \
+ --eval-command='run -f file' \
+ --eval-command='quit' \
+ tail < /dev/null > gdb.out 2>&1
+
+test -s gdb.out && skip_test_ "can't set breakpoints in tail"
+
+# Run "tail -f file", stopping to append a line just before
+# inotify initialization, and then continue. Before the fix,
+# that just-appended line would never be output.
+timeout 10s gdb -nx --batch-silent \
+ --eval-command='break tail_forever_inotify' \
+ --eval-command='run -f file >> tail.out' \
+ --eval-command="shell echo never-seen-with-tail-7.5 >> file" \
+ --eval-command='continue' \
+ --eval-command='quit' \
+ tail < /dev/null &
+pid=$!
+
+tail --pid=$pid -f tail.out | (read; kill $pid)
+
+test -s tail.out || fail=1
+
+Exit $fail