1 files changed, 98 insertions, 0 deletions
diff --git a/tests/tail-2/inotify-race.sh b/tests/tail-2/inotify-race.sh
new file mode 100755
index 0000000..53a78bc
--- /dev/null
+++ b/tests/tail-2/inotify-race.sh
@@ -0,0 +1,98 @@
+#!/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) 2009-2022 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 <https://www.gnu.org/licenses/>.
+
+. "${srcdir=.}/tests/init.sh"; path_prepend_ ./src
+print_ver_ tail sleep
+
+# Terminate any background gdb/tail process
+cleanup_() {
+  kill $pid 2>/dev/null && wait $pid
+  kill $sleep 2>/dev/null && wait $sleep
+}
+
+touch file || framework_failure_
+touch tail.out || framework_failure_
+
+( timeout 10s gdb --version ) > gdb.out 2>&1
+case $(cat gdb.out) in
+    *'GNU gdb'*) ;;
+    *) skip_ "can't run gdb";;
+esac
+
+# Break on a line rather than a symbol, to cater for inline functions
+break_src="$abs_top_srcdir/src/tail.c"
+break_line=$(grep -n ^tail_forever_inotify "$break_src") || framework_failure_
+break_line=$(echo "$break_line" | cut -d: -f1) || framework_failure_
+
+
+# Note we get tail to monitor a background sleep process
+# rather than using timeout(1), as timeout sends SIGCONT
+# signals to its monitored process, and gdb (7.9 at least)
+# has _intermittent_ issues with this.
+# Sending SIGCONT resulted in either delayed child termination,
+# or no child termination resulting in a hung test.
+# See https://sourceware.org/bugzilla/show_bug.cgi?id=18364
+
+env sleep 10 & sleep=$!
+
+# See if gdb works and
+# tail_forever_inotify is compiled and run
+gdb -nx --batch-silent \
+    --eval-command="break $break_line"             \
+    --eval-command="run --pid=$sleep -f file"      \
+    --eval-command='quit'                          \
+    tail < /dev/null > gdb.out 2>&1
+
+kill $sleep || skip_ 'breakpoint not hit'
+wait $sleep
+
+# FIXME: The above is seen to _intermittently_ fail with:
+# warning: .dynamic section for "/lib/libc.so.6" is not at the expected address
+# warning: difference appears to be caused by prelink, adjusting expectations
+compare /dev/null gdb.out || skip_ "can't set breakpoints in tail"
+
+env sleep 10 & sleep=$!
+
+# 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.
+gdb -nx --batch-silent \
+    --eval-command="break $break_line"             \
+    --eval-command="run --pid=$sleep -f file >> tail.out"       \
+    --eval-command='shell echo never-seen-with-tail-7.5 >> file' \
+    --eval-command='continue'                      \
+    --eval-command='quit'                          \
+    tail < /dev/null > /dev/null 2>&1 & pid=$!
+
+tail --pid=$pid -f tail.out | (read REPLY; kill $pid)
+
+# gdb has a bug in Debian's gdb-6.8-3 at least that causes it to not
+# cleanup and exit correctly when it receives a SIGTERM, but
+# killing sleep, should cause the tail process and thus gdb to exit.
+kill $sleep
+wait $sleep
+
+wait $pid
+
+compare /dev/null tail.out && fail=1
+
+Exit $fail