test: integration test for PassFileDescriptorsToExec= option

Check if socket file descriptors are passed to ExecXYZ= commands from the
socket unit depending on whether PassFileDescriptorsToExec= option is set.

test/testsuite-07.units/pass-fds-to-exec-no.socket

@@ -0,0 +1,35 @@
+# SPDX-License-Identifier: LGPL-2.1-or-later
+[Unit]
+Description=Test if ExecXYZ= commands don't inherit listen FDs when PassFileDescriptorsToExec= is unset
+
+[Socket]
+# With Accept= set we don't need a corresponding service unit
+Accept=yes
+FileDescriptorName=foo
+ListenStream=127.0.0.1:1234
+ListenStream=[::1]:1234
+PassFileDescriptorsToExec=no
+ExecStartPre=\
+        test ExecStartPre -a \
+             -z ${LISTEN_FDS} -a \
+             -z ${LISTEN_FDNAMES} -a \
+             ! -e /dev/fd/3 -a \
+             ! -e /dev/fd/4
+ExecStartPost=\
+        test ExecStartPost -a \
+             -z ${LISTEN_FDS} -a \
+             -z ${LISTEN_FDNAMES} -a \
+             ! -e /dev/fd/3 -a \
+             ! -e /dev/fd/4
+ExecStopPre=\
+        test ExecStopPre -a \
+             -z ${LISTEN_FDS} -a \
+             -z ${LISTEN_FDNAMES} -a \
+             ! -e /dev/fd/3 -a \
+             ! -e /dev/fd/4
+ExecStopPost=\
+        test ExecStopPost -a \
+             -z ${LISTEN_FDS} -a \
+             -z ${LISTEN_FDNAMES} -a \
+             ! -e /dev/fd/3 -a \
+             ! -e /dev/fd/4

test/testsuite-07.units/pass-fds-to-exec-yes.socket

@@ -0,0 +1,36 @@
+# SPDX-License-Identifier: LGPL-2.1-or-later
+[Unit]
+Description=Test if ExecXYZ= commands inherit listen FDs when PassFileDescriptorsToExec= is set
+
+[Socket]
+# With Accept= set we don't need a corresponding service unit
+Accept=yes
+FileDescriptorName=foo
+ListenStream=127.0.0.1:1234
+ListenStream=[::1]:1234
+PassFileDescriptorsToExec=yes
+# ExecStartPre runs before we create sockets. Nothing to pass.
+ExecStartPre=\
+        test ExecStartPre -a \
+             -z ${LISTEN_FDS} -a \
+             -z ${LISTEN_FDNAMES} -a \
+             ! -e /dev/fd/3 -a \
+             ! -e /dev/fd/4
+ExecStartPost=\
+        test ExecStartPost -a \
+             ${LISTEN_FDS} = 2 -a \
+             ${LISTEN_FDNAMES} = foo:foo -a \
+             -S /dev/fd/3 -a \
+             -S /dev/fd/4
+ExecStopPre=\
+        test "ExecStopPre" -a \
+             ${LISTEN_FDS} = 2 -a \
+             ${LISTEN_FDNAMES} = foo:foo -a \
+             -S /dev/fd/3 -a \
+             -S /dev/fd/4
+ExecStopPost=\
+        test "ExecStopPost" -a \
+             ${LISTEN_FDS} = 2 -a \
+             ${LISTEN_FDNAMES} = foo:foo -a \
+             -S /dev/fd/3 -a \
+             -S /dev/fd/4

test/units/testsuite-07.socket-pass-fds.sh

@@ -0,0 +1,11 @@
+#!/usr/bin/env bash
+# SPDX-License-Identifier: LGPL-2.1-or-later
+set -eux
+set -o pipefail
+
+# Test PassFileDescriptorsToExec= option in socket units
+
+for u in pass-fds-to-exec-{no,yes}.socket; do
+    systemctl start "$u"
+    systemctl stop "$u"
+done