install: follow unit file symlinks in /usr, but not /etc when looking for [Install] data

Some distributions use alias unit files via symlinks in /usr to cover
for legacy service names. With this change we'll allow "systemctl
enable" on such aliases.

Previously, our rule was that symlinks are user configuration that
"systemctl enable" + "systemctl disable" creates and removes, while unit
files is where the instructions to do so are store. As a result of the
rule we'd never read install information through symlinks, since that
would mix enablement state with installation instructions.

Now, the new rule is that only symlinks inside of /etc are
configuration. Unit files, and symlinks in /usr are now valid for
installation instructions.

This patch is quite a rework of the whole install logic, and makes the
following addional changes:

- Adds a complete test "test-instal-root" that tests the install logic
  pretty comprehensively.

- Never uses canonicalize_file_name(), because that's incompatible with
  operation relative to a specific root directory.

- unit_file_get_state() is reworked to return a proper error, and
  returns the state in a call-by-ref parameter. This cleans up confusion
  between the enum type and errno-like errors.

- The new logic puts a limit on how long to follow unit file symlinks:
  it will do so only for 64 steps at max.

- The InstallContext object's fields are renamed to will_process and
  has_processed (will_install and has_installed) since they are also
  used for deinstallation and all kinds of other operations.

- The root directory is always verified before use.

- install.c is reordered to place the exported functions together.

- Stricter rules are followed when traversing symlinks: the unit suffix
  must say identical, and it's not allowed to link between regular units
  and templated units.

- Various modernizations

- The "invalid" unit file state has been renamed to "bad", in order to
  avoid confusion between UNIT_FILE_INVALID and
  _UNIT_FILE_STATE_INVALID. Given that the state should normally not be
  seen and is not documented this should not be a problematic change.
  The new name is now documented however.

Fixes #1375, #1718, #1706

1 files changed, 665 insertions, 0 deletions

diff --git a/src/test/test-install-root.c b/src/test/test-install-root.c
new file mode 100644
index 0000000000..08fde94f7f
--- /dev/null
+++ b/src/test/test-install-root.c
@@ -0,0 +1,665 @@
+/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
+
+/***
+  This file is part of systemd.
+
+  Copyright 2011 Lennart Poettering
+
+  systemd is free software; you can redistribute it and/or modify it
+  under the terms of the GNU Lesser General Public License as published by
+  the Free Software Foundation; either version 2.1 of the License, or
+  (at your option) any later version.
+
+  systemd 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
+  Lesser General Public License for more details.
+
+  You should have received a copy of the GNU Lesser General Public License
+  along with systemd; If not, see <http://www.gnu.org/licenses/>.
+***/
+
+#include "alloc-util.h"
+#include "fileio.h"
+#include "install.h"
+#include "mkdir.h"
+#include "rm-rf.h"
+#include "string-util.h"
+
+static void test_basic_mask_and_enable(const char *root) {
+        const char *p;
+        UnitFileState state;
+        UnitFileChange *changes = NULL;
+        unsigned n_changes = 0;
+
+        assert_se(unit_file_get_state(UNIT_FILE_SYSTEM, root, "a.service", NULL) == -ENOENT);
+        assert_se(unit_file_get_state(UNIT_FILE_SYSTEM, root, "b.service", NULL) == -ENOENT);
+        assert_se(unit_file_get_state(UNIT_FILE_SYSTEM, root, "c.service", NULL) == -ENOENT);
+        assert_se(unit_file_get_state(UNIT_FILE_SYSTEM, root, "d.service", NULL) == -ENOENT);
+
+        p = strjoina(root, "/usr/lib/systemd/system/a.service");
+        assert_se(write_string_file(p,
+                                    "[Install]\n"
+                                    "WantedBy=multi-user.target\n", WRITE_STRING_FILE_CREATE) >= 0);
+
+        assert_se(unit_file_get_state(UNIT_FILE_SYSTEM, root, "a.service", NULL) >= 0);
+        assert_se(unit_file_get_state(UNIT_FILE_SYSTEM, root, "a.service", &state) >= 0 && state == UNIT_FILE_DISABLED);
+
+        p = strjoina(root, "/usr/lib/systemd/system/b.service");
+        assert_se(symlink("a.service", p) >= 0);
+
+        assert_se(unit_file_get_state(UNIT_FILE_SYSTEM, root, "b.service", NULL) >= 0);
+        assert_se(unit_file_get_state(UNIT_FILE_SYSTEM, root, "b.service", &state) >= 0 && state == UNIT_FILE_DISABLED);
+
+        p = strjoina(root, "/usr/lib/systemd/system/c.service");
+        assert_se(symlink("/usr/lib/systemd/system/a.service", p) >= 0);
+
+        assert_se(unit_file_get_state(UNIT_FILE_SYSTEM, root, "c.service", NULL) >= 0);
+        assert_se(unit_file_get_state(UNIT_FILE_SYSTEM, root, "c.service", &state) >= 0 && state == UNIT_FILE_DISABLED);
+
+        p = strjoina(root, "/usr/lib/systemd/system/d.service");
+        assert_se(symlink("c.service", p) >= 0);
+
+        /* This one is interesting, as d follows a relative, then an absolute symlink */
+        assert_se(unit_file_get_state(UNIT_FILE_SYSTEM, root, "d.service", NULL) >= 0);
+        assert_se(unit_file_get_state(UNIT_FILE_SYSTEM, root, "d.service", &state) >= 0 && state == UNIT_FILE_DISABLED);
+
+        assert_se(unit_file_mask(UNIT_FILE_SYSTEM, false, root, STRV_MAKE("a.service"), false, &changes, &n_changes) >= 0);
+        assert_se(n_changes == 1);
+        assert_se(changes[0].type == UNIT_FILE_SYMLINK);
+        assert_se(streq(changes[0].source, "/dev/null"));
+        p = strjoina(root, SYSTEM_CONFIG_UNIT_PATH"/a.service");
+        assert_se(streq(changes[0].path, p));
+
+        unit_file_changes_free(changes, n_changes);
+        changes = NULL; n_changes = 0;
+
+        assert_se(unit_file_get_state(UNIT_FILE_SYSTEM, root, "a.service", &state) >= 0 && state == UNIT_FILE_MASKED);
+        assert_se(unit_file_get_state(UNIT_FILE_SYSTEM, root, "b.service", &state) >= 0 && state == UNIT_FILE_MASKED);
+        assert_se(unit_file_get_state(UNIT_FILE_SYSTEM, root, "c.service", &state) >= 0 && state == UNIT_FILE_MASKED);
+        assert_se(unit_file_get_state(UNIT_FILE_SYSTEM, root, "d.service", &state) >= 0 && state == UNIT_FILE_MASKED);
+
+        /* Enabling a masked unit should fail! */
+        assert_se(unit_file_enable(UNIT_FILE_SYSTEM, false, root, STRV_MAKE("a.service"), false, &changes, &n_changes) == -ESHUTDOWN);
+        unit_file_changes_free(changes, n_changes);
+        changes = NULL; n_changes = 0;
+
+        assert_se(unit_file_unmask(UNIT_FILE_SYSTEM, false, root, STRV_MAKE("a.service"), &changes, &n_changes) >= 0);
+        assert_se(n_changes == 1);
+        assert_se(changes[0].type == UNIT_FILE_UNLINK);
+        p = strjoina(root, SYSTEM_CONFIG_UNIT_PATH"/a.service");
+        assert_se(streq(changes[0].path, p));
+        unit_file_changes_free(changes, n_changes);
+        changes = NULL; n_changes = 0;
+
+        assert_se(unit_file_enable(UNIT_FILE_SYSTEM, false, root, STRV_MAKE("a.service"), false, &changes, &n_changes) == 1);
+        assert_se(n_changes == 1);
+        assert_se(changes[0].type == UNIT_FILE_SYMLINK);
+        assert_se(streq(changes[0].source, "/usr/lib/systemd/system/a.service"));
+        p = strjoina(root, SYSTEM_CONFIG_UNIT_PATH"/multi-user.target.wants/a.service");
+        assert_se(streq(changes[0].path, p));
+        unit_file_changes_free(changes, n_changes);
+        changes = NULL; n_changes = 0;
+
+        assert_se(unit_file_get_state(UNIT_FILE_SYSTEM, root, "a.service", &state) >= 0 && state == UNIT_FILE_ENABLED);
+        assert_se(unit_file_get_state(UNIT_FILE_SYSTEM, root, "b.service", &state) >= 0 && state == UNIT_FILE_ENABLED);
+        assert_se(unit_file_get_state(UNIT_FILE_SYSTEM, root, "c.service", &state) >= 0 && state == UNIT_FILE_ENABLED);
+        assert_se(unit_file_get_state(UNIT_FILE_SYSTEM, root, "d.service", &state) >= 0 && state == UNIT_FILE_ENABLED);
+
+        /* Enabling it again should succeed but be a NOP */
+        assert_se(unit_file_enable(UNIT_FILE_SYSTEM, false, root, STRV_MAKE("a.service"), false, &changes, &n_changes) == 1);
+        assert_se(n_changes == 0);
+        unit_file_changes_free(changes, n_changes);
+        changes = NULL; n_changes = 0;
+
+        assert_se(unit_file_disable(UNIT_FILE_SYSTEM, false, root, STRV_MAKE("a.service"), &changes, &n_changes) >= 0);
+        assert_se(n_changes == 1);
+        assert_se(changes[0].type == UNIT_FILE_UNLINK);
+        p = strjoina(root, SYSTEM_CONFIG_UNIT_PATH"/multi-user.target.wants/a.service");
+        assert_se(streq(changes[0].path, p));
+        unit_file_changes_free(changes, n_changes);
+        changes = NULL; n_changes = 0;
+
+        assert_se(unit_file_get_state(UNIT_FILE_SYSTEM, root, "a.service", &state) >= 0 && state == UNIT_FILE_DISABLED);
+        assert_se(unit_file_get_state(UNIT_FILE_SYSTEM, root, "b.service", &state) >= 0 && state == UNIT_FILE_DISABLED);
+        assert_se(unit_file_get_state(UNIT_FILE_SYSTEM, root, "c.service", &state) >= 0 && state == UNIT_FILE_DISABLED);
+        assert_se(unit_file_get_state(UNIT_FILE_SYSTEM, root, "d.service", &state) >= 0 && state == UNIT_FILE_DISABLED);
+
+        /* Disabling a disabled unit must suceed but be a NOP */
+        assert_se(unit_file_disable(UNIT_FILE_SYSTEM, false, root, STRV_MAKE("a.service"), &changes, &n_changes) >= 0);
+        assert_se(n_changes == 0);
+        unit_file_changes_free(changes, n_changes);
+        changes = NULL; n_changes = 0;
+
+        /* Let's enable this indirectly via a symlink */
+        assert_se(unit_file_enable(UNIT_FILE_SYSTEM, false, root, STRV_MAKE("d.service"), false, &changes, &n_changes) >= 0);
+        assert_se(n_changes == 1);
+        assert_se(changes[0].type == UNIT_FILE_SYMLINK);
+        assert_se(streq(changes[0].source, "/usr/lib/systemd/system/a.service"));
+        p = strjoina(root, SYSTEM_CONFIG_UNIT_PATH"/multi-user.target.wants/a.service");
+        assert_se(streq(changes[0].path, p));
+        unit_file_changes_free(changes, n_changes);
+        changes = NULL; n_changes = 0;
+
+        assert_se(unit_file_get_state(UNIT_FILE_SYSTEM, root, "a.service", &state) >= 0 && state == UNIT_FILE_ENABLED);
+        assert_se(unit_file_get_state(UNIT_FILE_SYSTEM, root, "b.service", &state) >= 0 && state == UNIT_FILE_ENABLED);
+        assert_se(unit_file_get_state(UNIT_FILE_SYSTEM, root, "c.service", &state) >= 0 && state == UNIT_FILE_ENABLED);
+        assert_se(unit_file_get_state(UNIT_FILE_SYSTEM, root, "d.service", &state) >= 0 && state == UNIT_FILE_ENABLED);
+
+        /* Let's try to reenable */
+
+        assert_se(unit_file_reenable(UNIT_FILE_SYSTEM, false, root, STRV_MAKE("b.service"), false, &changes, &n_changes) >= 0);
+        assert_se(n_changes == 2);
+        assert_se(changes[0].type == UNIT_FILE_UNLINK);
+        p = strjoina(root, SYSTEM_CONFIG_UNIT_PATH"/multi-user.target.wants/a.service");
+        assert_se(streq(changes[0].path, p));
+        assert_se(changes[1].type == UNIT_FILE_SYMLINK);
+        assert_se(streq(changes[1].source, "/usr/lib/systemd/system/a.service"));
+        assert_se(streq(changes[1].path, p));
+        unit_file_changes_free(changes, n_changes);
+        changes = NULL; n_changes = 0;
+
+        assert_se(unit_file_get_state(UNIT_FILE_SYSTEM, root, "a.service", &state) >= 0 && state == UNIT_FILE_ENABLED);
+        assert_se(unit_file_get_state(UNIT_FILE_SYSTEM, root, "b.service", &state) >= 0 && state == UNIT_FILE_ENABLED);
+        assert_se(unit_file_get_state(UNIT_FILE_SYSTEM, root, "c.service", &state) >= 0 && state == UNIT_FILE_ENABLED);
+        assert_se(unit_file_get_state(UNIT_FILE_SYSTEM, root, "d.service", &state) >= 0 && state == UNIT_FILE_ENABLED);
+}
+
+static void test_linked_units(const char *root) {
+        const char *p, *q;
+        UnitFileState state;
+        UnitFileChange *changes = NULL;
+        unsigned n_changes = 0, i;
+
+        /*
+         * We'll test three cases here:
+         *
+         * a) a unit file in /opt, that we use "systemctl link" and
+         * "systemctl enable" on to make it available to the system
+         *
+         * b) a unit file in /opt, that is statically linked into
+         * /usr/lib/systemd/system, that "enable" should work on
+         * correctly.
+         *
+         * c) a unit file in /opt, that is linked into
+         * /etc/systemd/system, and where "enable" should result in
+         * -ELOOP, since using information from /etc to generate
+         * information in /etc should not be allowed.
+         */
+
+        p = strjoina(root, "/opt/linked.service");
+        assert_se(write_string_file(p,
+                                    "[Install]\n"
+                                    "WantedBy=multi-user.target\n", WRITE_STRING_FILE_CREATE) >= 0);
+
+        p = strjoina(root, "/opt/linked2.service");
+        assert_se(write_string_file(p,
+                                    "[Install]\n"
+                                    "WantedBy=multi-user.target\n", WRITE_STRING_FILE_CREATE) >= 0);
+
+        p = strjoina(root, "/opt/linked3.service");
+        assert_se(write_string_file(p,
+                                    "[Install]\n"
+                                    "WantedBy=multi-user.target\n", WRITE_STRING_FILE_CREATE) >= 0);
+
+        assert_se(unit_file_get_state(UNIT_FILE_SYSTEM, root, "linked.service", NULL) == -ENOENT);
+        assert_se(unit_file_get_state(UNIT_FILE_SYSTEM, root, "linked2.service", NULL) == -ENOENT);
+        assert_se(unit_file_get_state(UNIT_FILE_SYSTEM, root, "linked3.service", NULL) == -ENOENT);
+
+        p = strjoina(root, "/usr/lib/systemd/system/linked2.service");
+        assert_se(symlink("/opt/linked2.service", p) >= 0);
+
+        p = strjoina(root, SYSTEM_CONFIG_UNIT_PATH"/linked3.service");
+        assert_se(symlink("/opt/linked3.service", p) >= 0);
+
+        assert_se(unit_file_get_state(UNIT_FILE_SYSTEM, root, "linked.service", &state) == -ENOENT);
+        assert_se(unit_file_get_state(UNIT_FILE_SYSTEM, root, "linked2.service", &state) >= 0 && state == UNIT_FILE_DISABLED);
+        assert_se(unit_file_get_state(UNIT_FILE_SYSTEM, root, "linked3.service", &state) >= 0 && state == UNIT_FILE_LINKED);
+
+        /* First, let's link the unit into the search path */
+        assert_se(unit_file_link(UNIT_FILE_SYSTEM, false, root, STRV_MAKE("/opt/linked.service"), false, &changes, &n_changes) >= 0);
+        assert_se(n_changes == 1);
+        assert_se(changes[0].type == UNIT_FILE_SYMLINK);
+        assert_se(streq(changes[0].source, "/opt/linked.service"));
+        p = strjoina(root, SYSTEM_CONFIG_UNIT_PATH"/linked.service");
+        assert_se(streq(changes[0].path, p));
+        unit_file_changes_free(changes, n_changes);
+        changes = NULL; n_changes = 0;
+
+        assert_se(unit_file_get_state(UNIT_FILE_SYSTEM, root, "linked.service", &state) >= 0 && state == UNIT_FILE_LINKED);
+
+        /* Let's unlink it from the search path again */
+        assert_se(unit_file_disable(UNIT_FILE_SYSTEM, false, root, STRV_MAKE("linked.service"), &changes, &n_changes) >= 0);
+        assert_se(n_changes == 1);
+        assert_se(changes[0].type == UNIT_FILE_UNLINK);
+        p = strjoina(root, SYSTEM_CONFIG_UNIT_PATH"/linked.service");
+        assert_se(streq(changes[0].path, p));
+        unit_file_changes_free(changes, n_changes);
+        changes = NULL; n_changes = 0;
+
+        assert_se(unit_file_get_state(UNIT_FILE_SYSTEM, root, "linked.service", NULL) == -ENOENT);
+
+        /* Now, let's not just link it, but also enable it */
+        assert_se(unit_file_enable(UNIT_FILE_SYSTEM, false, root, STRV_MAKE("/opt/linked.service"), false, &changes, &n_changes) >= 0);
+        assert_se(n_changes == 2);
+        p = strjoina(root, SYSTEM_CONFIG_UNIT_PATH"/multi-user.target.wants/linked.service");
+        q = strjoina(root, SYSTEM_CONFIG_UNIT_PATH"/linked.service");
+        for (i = 0 ; i < n_changes; i++) {
+                assert_se(changes[i].type == UNIT_FILE_SYMLINK);
+                assert_se(streq(changes[i].source, "/opt/linked.service"));
+
+                if (p && streq(changes[i].path, p))
+                        p = NULL;
+                else if (q && streq(changes[i].path, q))
+                        q = NULL;
+                else
+                        assert_not_reached("wut?");
+        }
+        assert(!p && !q);
+        unit_file_changes_free(changes, n_changes);
+        changes = NULL; n_changes = 0;
+
+        assert_se(unit_file_get_state(UNIT_FILE_SYSTEM, root, "linked.service", &state) >= 0 && state == UNIT_FILE_ENABLED);
+
+        /* And let's unlink it again */
+        assert_se(unit_file_disable(UNIT_FILE_SYSTEM, false, root, STRV_MAKE("linked.service"), &changes, &n_changes) >= 0);
+        assert_se(n_changes == 2);
+        p = strjoina(root, SYSTEM_CONFIG_UNIT_PATH"/multi-user.target.wants/linked.service");
+        q = strjoina(root, SYSTEM_CONFIG_UNIT_PATH"/linked.service");
+        for (i = 0; i < n_changes; i++) {
+                assert_se(changes[i].type == UNIT_FILE_UNLINK);
+
+                if (p && streq(changes[i].path, p))
+                        p = NULL;
+                else if (q && streq(changes[i].path, q))
+                        q = NULL;
+                else
+                        assert_not_reached("wut?");
+        }
+        assert(!p && !q);
+        unit_file_changes_free(changes, n_changes);
+        changes = NULL; n_changes = 0;
+
+        assert_se(unit_file_get_state(UNIT_FILE_SYSTEM, root, "linked.service", NULL) == -ENOENT);
+
+        assert_se(unit_file_enable(UNIT_FILE_SYSTEM, false, root, STRV_MAKE("linked2.service"), false, &changes, &n_changes) >= 0);
+        assert_se(n_changes == 2);
+        p = strjoina(root, SYSTEM_CONFIG_UNIT_PATH"/multi-user.target.wants/linked2.service");
+        q = strjoina(root, SYSTEM_CONFIG_UNIT_PATH"/linked2.service");
+        for (i = 0 ; i < n_changes; i++) {
+                assert_se(changes[i].type == UNIT_FILE_SYMLINK);
+                assert_se(streq(changes[i].source, "/opt/linked2.service"));
+
+                if (p && streq(changes[i].path, p))
+                        p = NULL;
+                else if (q && streq(changes[i].path, q))
+                        q = NULL;
+                else
+                        assert_not_reached("wut?");
+        }
+        assert(!p && !q);
+        unit_file_changes_free(changes, n_changes);
+        changes = NULL; n_changes = 0;
+
+        assert_se(unit_file_enable(UNIT_FILE_SYSTEM, false, root, STRV_MAKE("linked3.service"), false, &changes, &n_changes) == -ELOOP);
+        unit_file_changes_free(changes, n_changes);
+        changes = NULL; n_changes = 0;
+}
+
+static void test_default(const char *root) {
+        _cleanup_free_ char *def = NULL;
+        UnitFileChange *changes = NULL;
+        unsigned n_changes = 0;
+        const char *p;
+
+        p = strjoina(root, "/usr/lib/systemd/system/test-default-real.target");
+        assert_se(write_string_file(p, "# pretty much empty", WRITE_STRING_FILE_CREATE) >= 0);
+
+        p = strjoina(root, "/usr/lib/systemd/system/test-default.target");
+        assert_se(symlink("test-default-real.target", p) >= 0);
+
+        assert_se(unit_file_get_default(UNIT_FILE_SYSTEM, root, &def) == -ENOENT);
+
+        assert_se(unit_file_set_default(UNIT_FILE_SYSTEM, root, "idontexist.target", false, &changes, &n_changes) == -ENOENT);
+        assert_se(n_changes == 0);
+        unit_file_changes_free(changes, n_changes);
+        changes = NULL; n_changes = 0;
+
+        assert_se(unit_file_get_default(UNIT_FILE_SYSTEM, root, &def) == -ENOENT);
+
+        assert_se(unit_file_set_default(UNIT_FILE_SYSTEM, root, "test-default.target", false, &changes, &n_changes) >= 0);
+        assert_se(n_changes == 1);
+        assert_se(changes[0].type == UNIT_FILE_SYMLINK);
+        assert_se(streq(changes[0].source, "/usr/lib/systemd/system/test-default-real.target"));
+        p = strjoina(root, SYSTEM_CONFIG_UNIT_PATH"/default.target");
+        assert_se(streq(changes[0].path, p));
+        unit_file_changes_free(changes, n_changes);
+        changes = NULL; n_changes = 0;
+
+        assert_se(unit_file_get_default(UNIT_FILE_SYSTEM, root, &def) >= 0);
+        assert_se(streq_ptr(def, "test-default-real.target"));
+}
+
+static void test_add_dependency(const char *root) {
+        UnitFileChange *changes = NULL;
+        unsigned n_changes = 0;
+        const char *p;
+
+        p = strjoina(root, "/usr/lib/systemd/system/real-add-dependency-test-target.target");
+        assert_se(write_string_file(p, "# pretty much empty", WRITE_STRING_FILE_CREATE) >= 0);
+
+        p = strjoina(root, "/usr/lib/systemd/system/add-dependency-test-target.target");
+        assert_se(symlink("real-add-dependency-test-target.target", p) >= 0);
+
+        p = strjoina(root, "/usr/lib/systemd/system/real-add-dependency-test-service.service");
+        assert_se(write_string_file(p, "# pretty much empty", WRITE_STRING_FILE_CREATE) >= 0);
+
+        p = strjoina(root, "/usr/lib/systemd/system/add-dependency-test-service.service");
+        assert_se(symlink("real-add-dependency-test-service.service", p) >= 0);
+
+        assert_se(unit_file_add_dependency(UNIT_FILE_SYSTEM, false, root, STRV_MAKE("add-dependency-test-service.service"), "add-dependency-test-target.target", UNIT_WANTS, false, &changes, &n_changes) >= 0);
+        assert_se(n_changes == 1);
+        assert_se(changes[0].type == UNIT_FILE_SYMLINK);
+        assert_se(streq(changes[0].source, "/usr/lib/systemd/system/real-add-dependency-test-service.service"));
+        p = strjoina(root, SYSTEM_CONFIG_UNIT_PATH"/real-add-dependency-test-target.target.wants/real-add-dependency-test-service.service");
+        assert_se(streq(changes[0].path, p));
+        unit_file_changes_free(changes, n_changes);
+        changes = NULL; n_changes = 0;
+}
+
+static void test_template_enable(const char *root) {
+        UnitFileChange *changes = NULL;
+        unsigned n_changes = 0;
+        UnitFileState state;
+        const char *p;
+
+        assert_se(unit_file_get_state(UNIT_FILE_SYSTEM, root, "template@.service", &state) == -ENOENT);
+        assert_se(unit_file_get_state(UNIT_FILE_SYSTEM, root, "template@def.service", &state) == -ENOENT);
+        assert_se(unit_file_get_state(UNIT_FILE_SYSTEM, root, "template@foo.service", &state) == -ENOENT);
+        assert_se(unit_file_get_state(UNIT_FILE_SYSTEM, root, "template-symlink@foo.service", &state) == -ENOENT);
+
+        p = strjoina(root, "/usr/lib/systemd/system/template@.service");
+        assert_se(write_string_file(p,
+                                    "[Install]\n"
+                                    "DefaultInstance=def\n"
+                                    "WantedBy=multi-user.target\n", WRITE_STRING_FILE_CREATE) >= 0);
+
+        p = strjoina(root, "/usr/lib/systemd/system/template-symlink@.service");
+        assert_se(symlink("template@.service", p) >= 0);
+
+        assert_se(unit_file_get_state(UNIT_FILE_SYSTEM, root, "template@.service", &state) >= 0 && state == UNIT_FILE_DISABLED);
+        assert_se(unit_file_get_state(UNIT_FILE_SYSTEM, root, "template@def.service", &state) >= 0 && state == UNIT_FILE_DISABLED);
+        assert_se(unit_file_get_state(UNIT_FILE_SYSTEM, root, "template@foo.service", &state) >= 0 && state == UNIT_FILE_DISABLED);
+        assert_se(unit_file_get_state(UNIT_FILE_SYSTEM, root, "template-symlink@.service", &state) >= 0 && state == UNIT_FILE_DISABLED);
+        assert_se(unit_file_get_state(UNIT_FILE_SYSTEM, root, "template-symlink@def.service", &state) >= 0 && state == UNIT_FILE_DISABLED);
+        assert_se(unit_file_get_state(UNIT_FILE_SYSTEM, root, "template-symlink@foo.service", &state) >= 0 && state == UNIT_FILE_DISABLED);
+
+        assert_se(unit_file_enable(UNIT_FILE_SYSTEM, false, root, STRV_MAKE("template@.service"), false, &changes, &n_changes) >= 0);
+        assert_se(n_changes == 1);
+        assert_se(changes[0].type == UNIT_FILE_SYMLINK);
+        assert_se(streq(changes[0].source, "/usr/lib/systemd/system/template@.service"));
+        p = strjoina(root, SYSTEM_CONFIG_UNIT_PATH"/multi-user.target.wants/template@def.service");
+        assert_se(streq(changes[0].path, p));
+        unit_file_changes_free(changes, n_changes);
+        changes = NULL; n_changes = 0;
+
+        assert_se(unit_file_get_state(UNIT_FILE_SYSTEM, root, "template@.service", &state) >= 0 && state == UNIT_FILE_ENABLED);
+        assert_se(unit_file_get_state(UNIT_FILE_SYSTEM, root, "template@def.service", &state) >= 0 && state == UNIT_FILE_ENABLED);
+        assert_se(unit_file_get_state(UNIT_FILE_SYSTEM, root, "template@foo.service", &state) >= 0 && state == UNIT_FILE_DISABLED);
+        assert_se(unit_file_get_state(UNIT_FILE_SYSTEM, root, "template-symlink@.service", &state) >= 0 && state == UNIT_FILE_ENABLED);
+        assert_se(unit_file_get_state(UNIT_FILE_SYSTEM, root, "template-symlink@def.service", &state) >= 0 && state == UNIT_FILE_ENABLED);
+        assert_se(unit_file_get_state(UNIT_FILE_SYSTEM, root, "template-symlink@foo.service", &state) >= 0 && state == UNIT_FILE_DISABLED);
+
+        assert_se(unit_file_disable(UNIT_FILE_SYSTEM, false, root, STRV_MAKE("template@.service"), &changes, &n_changes) >= 0);
+        assert_se(n_changes == 1);
+        assert_se(changes[0].type == UNIT_FILE_UNLINK);
+        assert_se(streq(changes[0].path, p));
+        unit_file_changes_free(changes, n_changes);
+        changes = NULL; n_changes = 0;
+
+        assert_se(unit_file_get_state(UNIT_FILE_SYSTEM, root, "template@.service", &state) >= 0 && state == UNIT_FILE_DISABLED);
+        assert_se(unit_file_get_state(UNIT_FILE_SYSTEM, root, "template@def.service", &state) >= 0 && state == UNIT_FILE_DISABLED);
+        assert_se(unit_file_get_state(UNIT_FILE_SYSTEM, root, "template@foo.service", &state) >= 0 && state == UNIT_FILE_DISABLED);
+        assert_se(unit_file_get_state(UNIT_FILE_SYSTEM, root, "template-symlink@.service", &state) >= 0 && state == UNIT_FILE_DISABLED);
+        assert_se(unit_file_get_state(UNIT_FILE_SYSTEM, root, "template-symlink@def.service", &state) >= 0 && state == UNIT_FILE_DISABLED);
+        assert_se(unit_file_get_state(UNIT_FILE_SYSTEM, root, "template-symlink@foo.service", &state) >= 0 && state == UNIT_FILE_DISABLED);
+
+        assert_se(unit_file_enable(UNIT_FILE_SYSTEM, false, root, STRV_MAKE("template@foo.service"), false, &changes, &n_changes) >= 0);
+        assert_se(changes[0].type == UNIT_FILE_SYMLINK);
+        assert_se(streq(changes[0].source, "/usr/lib/systemd/system/template@.service"));
+        p = strjoina(root, SYSTEM_CONFIG_UNIT_PATH"/multi-user.target.wants/template@foo.service");
+        assert_se(streq(changes[0].path, p));
+        unit_file_changes_free(changes, n_changes);
+        changes = NULL; n_changes = 0;
+
+        assert_se(unit_file_get_state(UNIT_FILE_SYSTEM, root, "template@.service", &state) >= 0 && state == UNIT_FILE_ENABLED);
+        assert_se(unit_file_get_state(UNIT_FILE_SYSTEM, root, "template@def.service", &state) >= 0 && state == UNIT_FILE_DISABLED);
+        assert_se(unit_file_get_state(UNIT_FILE_SYSTEM, root, "template@foo.service", &state) >= 0 && state == UNIT_FILE_ENABLED);
+        assert_se(unit_file_get_state(UNIT_FILE_SYSTEM, root, "template-symlink@foo.service", &state) >= 0 && state == UNIT_FILE_ENABLED);
+        assert_se(unit_file_get_state(UNIT_FILE_SYSTEM, root, "template-symlink@def.service", &state) >= 0 && state == UNIT_FILE_DISABLED);
+        assert_se(unit_file_get_state(UNIT_FILE_SYSTEM, root, "template-symlink@foo.service", &state) >= 0 && state == UNIT_FILE_ENABLED);
+
+        assert_se(unit_file_disable(UNIT_FILE_SYSTEM, false, root, STRV_MAKE("template@foo.service"), &changes, &n_changes) >= 0);
+        assert_se(n_changes == 1);
+        assert_se(changes[0].type == UNIT_FILE_UNLINK);
+        assert_se(streq(changes[0].path, p));
+        unit_file_changes_free(changes, n_changes);
+        changes = NULL; n_changes = 0;
+
+        assert_se(unit_file_get_state(UNIT_FILE_SYSTEM, root, "template@.service", &state) >= 0 && state == UNIT_FILE_DISABLED);
+        assert_se(unit_file_get_state(UNIT_FILE_SYSTEM, root, "template@def.service", &state) >= 0 && state == UNIT_FILE_DISABLED);
+        assert_se(unit_file_get_state(UNIT_FILE_SYSTEM, root, "template@foo.service", &state) >= 0 && state == UNIT_FILE_DISABLED);
+        assert_se(unit_file_get_state(UNIT_FILE_SYSTEM, root, "template@quux.service", &state) >= 0 && state == UNIT_FILE_DISABLED);
+        assert_se(unit_file_get_state(UNIT_FILE_SYSTEM, root, "template-symlink@.service", &state) >= 0 && state == UNIT_FILE_DISABLED);
+        assert_se(unit_file_get_state(UNIT_FILE_SYSTEM, root, "template-symlink@def.service", &state) >= 0 && state == UNIT_FILE_DISABLED);
+        assert_se(unit_file_get_state(UNIT_FILE_SYSTEM, root, "template-symlink@foo.service", &state) >= 0 && state == UNIT_FILE_DISABLED);
+        assert_se(unit_file_get_state(UNIT_FILE_SYSTEM, root, "template-symlink@quux.service", &state) >= 0 && state == UNIT_FILE_DISABLED);
+
+        assert_se(unit_file_enable(UNIT_FILE_SYSTEM, false, root, STRV_MAKE("template-symlink@quux.service"), false, &changes, &n_changes) >= 0);
+        assert_se(changes[0].type == UNIT_FILE_SYMLINK);
+        assert_se(streq(changes[0].source, "/usr/lib/systemd/system/template@.service"));
+        p = strjoina(root, SYSTEM_CONFIG_UNIT_PATH"/multi-user.target.wants/template@quux.service");
+        assert_se(streq(changes[0].path, p));
+        unit_file_changes_free(changes, n_changes);
+        changes = NULL; n_changes = 0;
+
+        assert_se(unit_file_get_state(UNIT_FILE_SYSTEM, root, "template@.service", &state) >= 0 && state == UNIT_FILE_ENABLED);
+        assert_se(unit_file_get_state(UNIT_FILE_SYSTEM, root, "template@def.service", &state) >= 0 && state == UNIT_FILE_DISABLED);
+        assert_se(unit_file_get_state(UNIT_FILE_SYSTEM, root, "template@foo.service", &state) >= 0 && state == UNIT_FILE_DISABLED);
+        assert_se(unit_file_get_state(UNIT_FILE_SYSTEM, root, "template@quux.service", &state) >= 0 && state == UNIT_FILE_ENABLED);
+        assert_se(unit_file_get_state(UNIT_FILE_SYSTEM, root, "template-symlink@.service", &state) >= 0 && state == UNIT_FILE_ENABLED);
+        assert_se(unit_file_get_state(UNIT_FILE_SYSTEM, root, "template-symlink@def.service", &state) >= 0 && state == UNIT_FILE_DISABLED);
+        assert_se(unit_file_get_state(UNIT_FILE_SYSTEM, root, "template-symlink@foo.service", &state) >= 0 && state == UNIT_FILE_DISABLED);
+        assert_se(unit_file_get_state(UNIT_FILE_SYSTEM, root, "template-symlink@quux.service", &state) >= 0 && state == UNIT_FILE_ENABLED);
+}
+
+static void test_indirect(const char *root) {
+        UnitFileChange *changes = NULL;
+        unsigned n_changes = 0;
+        UnitFileState state;
+        const char *p;
+
+        assert_se(unit_file_get_state(UNIT_FILE_SYSTEM, root, "indirecta.service", &state) == -ENOENT);
+        assert_se(unit_file_get_state(UNIT_FILE_SYSTEM, root, "indirectb.service", &state) == -ENOENT);
+        assert_se(unit_file_get_state(UNIT_FILE_SYSTEM, root, "indirectc.service", &state) == -ENOENT);
+
+        p = strjoina(root, "/usr/lib/systemd/system/indirecta.service");
+        assert_se(write_string_file(p,
+                                    "[Install]\n"
+                                    "Also=indirectb.service\n", WRITE_STRING_FILE_CREATE) >= 0);
+
+        p = strjoina(root, "/usr/lib/systemd/system/indirectb.service");
+        assert_se(write_string_file(p,
+                                    "[Install]\n"
+                                    "WantedBy=multi-user.target\n", WRITE_STRING_FILE_CREATE) >= 0);
+
+        p = strjoina(root, "/usr/lib/systemd/system/indirectc.service");
+        assert_se(symlink("indirecta.service", p) >= 0);
+
+        assert_se(unit_file_get_state(UNIT_FILE_SYSTEM, root, "indirecta.service", &state) >= 0 && state == UNIT_FILE_INDIRECT);
+        assert_se(unit_file_get_state(UNIT_FILE_SYSTEM, root, "indirectb.service", &state) >= 0 && state == UNIT_FILE_DISABLED);
+        assert_se(unit_file_get_state(UNIT_FILE_SYSTEM, root, "indirectc.service", &state) >= 0 && state == UNIT_FILE_INDIRECT);
+
+        assert_se(unit_file_enable(UNIT_FILE_SYSTEM, false, root, STRV_MAKE("indirectc.service"), false, &changes, &n_changes) >= 0);
+        assert_se(n_changes == 1);
+        assert_se(changes[0].type == UNIT_FILE_SYMLINK);
+        assert_se(streq(changes[0].source, "/usr/lib/systemd/system/indirectb.service"));
+        p = strjoina(root, SYSTEM_CONFIG_UNIT_PATH"/multi-user.target.wants/indirectb.service");
+        assert_se(streq(changes[0].path, p));
+        unit_file_changes_free(changes, n_changes);
+        changes = NULL; n_changes = 0;
+
+        assert_se(unit_file_get_state(UNIT_FILE_SYSTEM, root, "indirecta.service", &state) >= 0 && state == UNIT_FILE_INDIRECT);
+        assert_se(unit_file_get_state(UNIT_FILE_SYSTEM, root, "indirectb.service", &state) >= 0 && state == UNIT_FILE_ENABLED);
+        assert_se(unit_file_get_state(UNIT_FILE_SYSTEM, root, "indirectc.service", &state) >= 0 && state == UNIT_FILE_INDIRECT);
+
+        assert_se(unit_file_disable(UNIT_FILE_SYSTEM, false, root, STRV_MAKE("indirectc.service"), &changes, &n_changes) >= 0);
+        assert_se(n_changes == 1);
+        assert_se(changes[0].type == UNIT_FILE_UNLINK);
+        p = strjoina(root, SYSTEM_CONFIG_UNIT_PATH"/multi-user.target.wants/indirectb.service");
+        assert_se(streq(changes[0].path, p));
+        unit_file_changes_free(changes, n_changes);
+        changes = NULL; n_changes = 0;
+}
+
+static void test_preset_and_list(const char *root) {
+        UnitFileChange *changes = NULL;
+        unsigned n_changes = 0, i;
+        const char *p, *q;
+        UnitFileState state;
+        bool got_yes = false, got_no = false;
+        Iterator j;
+        UnitFileList *fl;
+        Hashmap *h;
+
+        assert_se(unit_file_get_state(UNIT_FILE_SYSTEM, root, "preset-yes.service", &state) == -ENOENT);
+        assert_se(unit_file_get_state(UNIT_FILE_SYSTEM, root, "preset-no.service", &state) == -ENOENT);
+
+        p = strjoina(root, "/usr/lib/systemd/system/preset-yes.service");
+        assert_se(write_string_file(p,
+                                    "[Install]\n"
+                                    "WantedBy=multi-user.target\n", WRITE_STRING_FILE_CREATE) >= 0);
+
+        p = strjoina(root, "/usr/lib/systemd/system/preset-no.service");
+        assert_se(write_string_file(p,
+                                    "[Install]\n"
+                                    "WantedBy=multi-user.target\n", WRITE_STRING_FILE_CREATE) >= 0);
+
+        p = strjoina(root, "/usr/lib/systemd/system-preset/test.preset");
+        assert_se(write_string_file(p,
+                                    "enable *-yes.*\n"
+                                    "disable *\n", WRITE_STRING_FILE_CREATE) >= 0);
+
+        assert_se(unit_file_get_state(UNIT_FILE_SYSTEM, root, "preset-yes.service", &state) >= 0 && state == UNIT_FILE_DISABLED);
+        assert_se(unit_file_get_state(UNIT_FILE_SYSTEM, root, "preset-no.service", &state) >= 0 && state == UNIT_FILE_DISABLED);
+
+        assert_se(unit_file_preset(UNIT_FILE_SYSTEM, false, root, STRV_MAKE("preset-yes.service"), UNIT_FILE_PRESET_FULL, false, &changes, &n_changes) >= 0);
+        assert_se(n_changes == 1);
+        assert_se(changes[0].type == UNIT_FILE_SYMLINK);
+        assert_se(streq(changes[0].source, "/usr/lib/systemd/system/preset-yes.service"));
+        p = strjoina(root, SYSTEM_CONFIG_UNIT_PATH"/multi-user.target.wants/preset-yes.service");
+        assert_se(streq(changes[0].path, p));
+        unit_file_changes_free(changes, n_changes);
+        changes = NULL; n_changes = 0;
+
+        assert_se(unit_file_get_state(UNIT_FILE_SYSTEM, root, "preset-yes.service", &state) >= 0 && state == UNIT_FILE_ENABLED);
+        assert_se(unit_file_get_state(UNIT_FILE_SYSTEM, root, "preset-no.service", &state) >= 0 && state == UNIT_FILE_DISABLED);
+
+        assert_se(unit_file_disable(UNIT_FILE_SYSTEM, false, root, STRV_MAKE("preset-yes.service"), &changes, &n_changes) >= 0);
+        assert_se(n_changes == 1);
+        assert_se(changes[0].type == UNIT_FILE_UNLINK);
+        p = strjoina(root, SYSTEM_CONFIG_UNIT_PATH"/multi-user.target.wants/preset-yes.service");
+        assert_se(streq(changes[0].path, p));
+        unit_file_changes_free(changes, n_changes);
+        changes = NULL; n_changes = 0;
+
+        assert_se(unit_file_get_state(UNIT_FILE_SYSTEM, root, "preset-yes.service", &state) >= 0 && state == UNIT_FILE_DISABLED);
+        assert_se(unit_file_get_state(UNIT_FILE_SYSTEM, root, "preset-no.service", &state) >= 0 && state == UNIT_FILE_DISABLED);
+
+        assert_se(unit_file_preset(UNIT_FILE_SYSTEM, false, root, STRV_MAKE("preset-no.service"), UNIT_FILE_PRESET_FULL, false, &changes, &n_changes) >= 0);
+        assert_se(n_changes == 0);
+        unit_file_changes_free(changes, n_changes);
+        changes = NULL; n_changes = 0;
+
+        assert_se(unit_file_get_state(UNIT_FILE_SYSTEM, root, "preset-yes.service", &state) >= 0 && state == UNIT_FILE_DISABLED);
+        assert_se(unit_file_get_state(UNIT_FILE_SYSTEM, root, "preset-no.service", &state) >= 0 && state == UNIT_FILE_DISABLED);
+
+        assert_se(unit_file_preset_all(UNIT_FILE_SYSTEM, false, root, UNIT_FILE_PRESET_FULL, false, &changes, &n_changes) >= 0);
+
+        assert_se(n_changes > 0);
+
+        p = strjoina(root, SYSTEM_CONFIG_UNIT_PATH"/multi-user.target.wants/preset-yes.service");
+
+        for (i = 0; i < n_changes; i++) {
+
+                if (changes[i].type == UNIT_FILE_SYMLINK) {
+                        assert_se(streq(changes[i].source, "/usr/lib/systemd/system/preset-yes.service"));
+                        assert_se(streq(changes[i].path, p));
+                } else
+                        assert_se(changes[i].type == UNIT_FILE_UNLINK);
+        }
+
+        unit_file_changes_free(changes, n_changes);
+        changes = NULL; n_changes = 0;
+
+        assert_se(unit_file_get_state(UNIT_FILE_SYSTEM, root, "preset-yes.service", &state) >= 0 && state == UNIT_FILE_ENABLED);
+        assert_se(unit_file_get_state(UNIT_FILE_SYSTEM, root, "preset-no.service", &state) >= 0 && state == UNIT_FILE_DISABLED);
+
+        assert_se(h = hashmap_new(&string_hash_ops));
+        assert_se(unit_file_get_list(UNIT_FILE_SYSTEM, root, h) >= 0);
+
+        p = strjoina(root, "/usr/lib/systemd/system/preset-yes.service");
+        q = strjoina(root, "/usr/lib/systemd/system/preset-no.service");
+
+        HASHMAP_FOREACH(fl, h, j) {
+                assert_se(unit_file_get_state(UNIT_FILE_SYSTEM, root, basename(fl->path), &state) >= 0);
+                assert_se(fl->state == state);
+
+                if (streq(fl->path, p)) {
+                        got_yes = true;
+                        assert_se(fl->state == UNIT_FILE_ENABLED);
+                } else if (streq(fl->path, q)) {
+                        got_no = true;
+                        assert_se(fl->state == UNIT_FILE_DISABLED);
+                } else
+                        assert_se(IN_SET(fl->state, UNIT_FILE_DISABLED, UNIT_FILE_STATIC, UNIT_FILE_INDIRECT));
+        }
+
+        unit_file_list_free(h);
+
+        assert_se(got_yes && got_no);
+}
+
+int main(int argc, char *argv[]) {
+        char root[] = "/tmp/rootXXXXXX";
+        const char *p;
+
+        assert_se(mkdtemp(root));
+
+        p = strjoina(root, "/usr/lib/systemd/system/");
+        assert_se(mkdir_p(p, 0755) >= 0);
+
+        p = strjoina(root, SYSTEM_CONFIG_UNIT_PATH"/");
+        assert_se(mkdir_p(p, 0755) >= 0);
+
+        p = strjoina(root, "/run/systemd/system/");
+        assert_se(mkdir_p(p, 0755) >= 0);
+
+        p = strjoina(root, "/opt/");
+        assert_se(mkdir_p(p, 0755) >= 0);
+
+        p = strjoina(root, "/usr/lib/systemd/system-preset/");
+        assert_se(mkdir_p(p, 0755) >= 0);
+
+        test_basic_mask_and_enable(root);
+        test_linked_units(root);
+        test_default(root);
+        test_add_dependency(root);
+        test_template_enable(root);
+        test_indirect(root);
+        test_preset_and_list(root);
+
+        assert_se(rm_rf(root, REMOVE_ROOT|REMOVE_PHYSICAL) >= 0);
+
+        return 0;
+}