test: don't rely on "nobody" user for TEST-43

The name is not as universal as we want, still, hence let's use our own
user we create with sysusers.d/. That should yield same behaviour
everywhere (and also test sysusers a bit as side effect).

test/TEST-43-PRIVATEUSER-UNPRIV/test.sh

@@ -15,20 +15,23 @@ test_setup() {
 
         mask_supporting_services
 
-        usermod --root $initdir -d /home/nobody -s /bin/bash nobody
-        mkdir $initdir/home $initdir/home/nobody
-        # Ubuntu's equivalent is nogroup
-        chown nobody:nobody $initdir/home/nobody || chown nobody:nogroup $initdir/home/nobody
+        # Allocate user for running test case under
+        mkdir -p $initdir/etc/sysusers.d
+        cat >$initdir/etc/sysusers.d/testuser.conf <<EOF
+u testuser    4711     "Test User" /home/testuser
+EOF
 
-        enable_user_manager nobody
+        mkdir -p $initdir/home/testuser -m 0700
+        chown 4711:4711 $initdir/home/testuser
 
-        nobody_uid=$(id -u nobody)
+        enable_user_manager testuser
 
         # setup the testsuite service
         cat >$initdir/etc/systemd/system/testsuite.service <<EOF
 [Unit]
 Description=Testsuite service
-After=systemd-logind.service user@$nobody_uid.service
+After=systemd-logind.service user@4711.service
+Wants=user@4711.service
 
 [Service]
 ExecStart=/testsuite.sh

test/TEST-43-PRIVATEUSER-UNPRIV/testsuite.sh

@@ -10,12 +10,12 @@ runas() {
     su "$userid" -s /bin/sh -c 'XDG_RUNTIME_DIR=/run/user/$UID exec "$@"' -- sh "$@"
 }
 
-runas nobody systemctl --user --wait is-system-running
+runas testuser systemctl --user --wait is-system-running
 
-runas nobody systemd-run --user --unit=test-private-users \
+runas testuser systemd-run --user --unit=test-private-users \
     -p PrivateUsers=yes -P echo hello
 
-runas nobody systemd-run --user --unit=test-private-tmp-innerfile \
+runas testuser systemd-run --user --unit=test-private-tmp-innerfile \
     -p PrivateUsers=yes -p PrivateTmp=yes \
     -P touch /tmp/innerfile.txt
 # File should not exist outside the job's tmp directory.
@@ -23,31 +23,31 @@ test ! -e /tmp/innerfile.txt
 
 touch /tmp/outerfile.txt
 # File should not appear in unit's private tmp.
-runas nobody systemd-run --user --unit=test-private-tmp-outerfile \
+runas testuser systemd-run --user --unit=test-private-tmp-outerfile \
     -p PrivateUsers=yes -p PrivateTmp=yes \
     -P test ! -e /tmp/outerfile.txt
 
 # Confirm that creating a file in home works
-runas nobody systemd-run --user --unit=test-unprotected-home \
-    -P touch /home/nobody/works.txt
-test -e /home/nobody/works.txt
+runas testuser systemd-run --user --unit=test-unprotected-home \
+    -P touch /home/testuser/works.txt
+test -e /home/testuser/works.txt
 
 # Confirm that creating a file in home is blocked under read-only
-runas nobody systemd-run --user --unit=test-protect-home-read-only \
+runas testuser systemd-run --user --unit=test-protect-home-read-only \
     -p PrivateUsers=yes -p ProtectHome=read-only \
     -P bash -c '
-        test -e /home/nobody/works.txt
-        ! touch /home/nobody/blocked.txt
+        test -e /home/testuser/works.txt
+        ! touch /home/testuser/blocked.txt
     '
-test ! -e /home/nobody/blocked.txt
+test ! -e /home/testuser/blocked.txt
 
 # Check that tmpfs hides the whole directory
-runas nobody systemd-run --user --unit=test-protect-home-tmpfs \
+runas testuser systemd-run --user --unit=test-protect-home-tmpfs \
     -p PrivateUsers=yes -p ProtectHome=tmpfs \
-    -P test ! -e /home/nobody
+    -P test ! -e /home/testuser
 
 # Confirm that home, /root, and /run/user are inaccessible under "yes"
-runas nobody systemd-run --user --unit=test-protect-home-yes \
+runas testuser systemd-run --user --unit=test-protect-home-yes \
     -p PrivateUsers=yes -p ProtectHome=yes \
     -P bash -c '
         test "$(stat -c %a /home)" = "0"
@@ -59,7 +59,7 @@ runas nobody systemd-run --user --unit=test-protect-home-yes \
 # namespace (no CAP_SETGID in the parent namespace to write the additional
 # mapping of the user supplied group and thus cannot change groups to an
 # unmapped group ID)
-! runas nobody systemd-run --user --unit=test-group-fail \
+! runas testuser systemd-run --user --unit=test-group-fail \
     -p PrivateUsers=yes -p Group=daemon \
     -P true