diff --git a/src/shared/offline-passwd.c b/src/shared/offline-passwd.c
new file mode 100644
index 0000000000..3f8220d9ac
--- /dev/null
+++ b/src/shared/offline-passwd.c
@@ -0,0 +1,158 @@
+/* SPDX-License-Identifier: LGPL-2.1+ */
+
+#include "fd-util.h"
+#include "offline-passwd.h"
+#include "path-util.h"
+#include "user-util.h"
+
+DEFINE_PRIVATE_HASH_OPS_WITH_KEY_DESTRUCTOR(uid_gid_hash_ops, char, string_hash_func, string_compare_func, free);
+
+static int open_passwd_file(const char *root, const char *fname, FILE **ret_file) {
+        const char *p = prefix_roota(root, fname);
+        if (!p)
+                return -ENOMEM;
+
+        FILE *f = fopen(p, "re");
+        if (!f)
+                return -errno;
+
+        log_debug("Reading %s entries from %s...", basename(fname), p);
+
+        *ret_file = f;
+        return 0;
+}
+
+static int populate_uid_cache(const char *root, Hashmap **ret) {
+        _cleanup_(hashmap_freep) Hashmap *cache = NULL;
+        int r;
+
+        cache = hashmap_new(&uid_gid_hash_ops);
+        if (!cache)
+                return -ENOMEM;
+
+        /* The directory list is harcoded here: /etc is the standard, and rpm-ostree uses /usr/lib. This
+         * could be made configurable, but I don't see the point right now. */
+
+        const char *fname;
+        FOREACH_STRING(fname, "/etc/passwd", "/usr/lib/passwd") {
+                _cleanup_fclose_ FILE *f = NULL;
+
+                r = open_passwd_file(root, fname, &f);
+                if (r == -ENOENT)
+                        continue;
+                if (r < 0)
+                        return r;
+
+                struct passwd *pw;
+                while ((r = fgetpwent_sane(f, &pw)) > 0) {
+                        _cleanup_free_ char *n = NULL;
+
+                        n = strdup(pw->pw_name);
+                        if (!n)
+                                return -ENOMEM;
+
+                        r = hashmap_put(cache, n, UID_TO_PTR(pw->pw_uid));
+                        if (IN_SET(r, 0 -EEXIST))
+                                continue;
+                        if (r < 0)
+                                return r;
+                        TAKE_PTR(n);
+                }
+        }
+
+        *ret = TAKE_PTR(cache);
+        return 0;
+}
+
+static int populate_gid_cache(const char *root, Hashmap **ret) {
+        _cleanup_(hashmap_freep) Hashmap *cache = NULL;
+        int r;
+
+        cache = hashmap_new(&uid_gid_hash_ops);
+        if (!cache)
+                return -ENOMEM;
+
+        const char *fname;
+        FOREACH_STRING(fname, "/etc/group", "/usr/lib/group") {
+                _cleanup_fclose_ FILE *f = NULL;
+
+                r = open_passwd_file(root, fname, &f);
+                if (r == -ENOENT)
+                        continue;
+                if (r < 0)
+                        return r;
+
+                struct group *gr;
+                while ((r = fgetgrent_sane(f, &gr)) > 0) {
+                        _cleanup_free_ char *n = NULL;
+
+                        n = strdup(gr->gr_name);
+                        if (!n)
+                                return -ENOMEM;
+
+                        r = hashmap_put(cache, n, GID_TO_PTR(gr->gr_gid));
+                        if (IN_SET(r, 0, -EEXIST))
+                                continue;
+                        if (r < 0)
+                                return r;
+                        TAKE_PTR(n);
+                }
+        }
+
+        *ret = TAKE_PTR(cache);
+        return 0;
+}
+
+int name_to_uid_offline(
+                const char *root,
+                const char *user,
+                uid_t *ret_uid,
+                Hashmap **cache) {
+
+        void *found;
+        int r;
+
+        assert(user);
+        assert(ret_uid);
+        assert(cache);
+
+        if (!*cache) {
+                r = populate_uid_cache(root, cache);
+                if (r < 0)
+                        return r;
+        }
+
+        found = hashmap_get(*cache, user);
+        if (!found)
+                return -ESRCH;
+
+        *ret_uid = PTR_TO_UID(found);
+        return 0;
+}
+
+int name_to_gid_offline(
+                const char *root,
+                const char *group,
+                gid_t *ret_gid,
+                Hashmap **cache) {
+
+        void *found;
+        int r;
+
+        assert(group);
+        assert(ret_gid);
+        assert(cache);
+
+        if (!*cache) {
+                r = populate_gid_cache(root, cache);
+                if (r < 0)
+                        return r;
+        }
+
+        found = hashmap_get(*cache, group);
+        if (!found)
+                return -ESRCH;
+
+        *ret_gid = PTR_TO_GID(found);
+        return 0;
+}
diff --git a/src/tmpfiles/offline-passwd.h b/src/shared/offline-passwd.h
similarity index 100%
rename from src/tmpfiles/offline-passwd.h
rename to src/shared/offline-passwd.h
diff --git a/src/test/meson.build b/src/test/meson.build
index d3fc803088..4affcd647f 100644
--- a/src/test/meson.build
+++ b/src/test/meson.build
@@ -301,6 +301,12 @@ tests += [
          [],
          []],
 
+        [['src/test/test-offline-passwd.c',
+          'src/shared/offline-passwd.c',
+          'src/shared/offline-passwd.h'],
+         [],
+         []],
+
         [['src/test/test-escape.c'],
          [],
          []],
diff --git a/src/test/test-offline-passwd.c b/src/test/test-offline-passwd.c
new file mode 100644
index 0000000000..5933ec28a3
--- /dev/null
+++ b/src/test/test-offline-passwd.c
@@ -0,0 +1,85 @@
+/* SPDX-License-Identifier: LGPL-2.1+ */
+
+#include <getopt.h>
+
+#include "offline-passwd.h"
+#include "user-util.h"
+#include "format-util.h"
+#include "tests.h"
+
+static char *arg_root = NULL;
+
+static void test_resolve_one(const char *name) {
+        bool relaxed = name || arg_root;
+
+        if (!name)
+                name = "root";
+
+        log_info("/* %s(\"%s\") */", __func__, name);
+
+        _cleanup_(hashmap_freep) Hashmap *uid_cache = NULL, *gid_cache = NULL;
+        uid_t uid = UID_INVALID;
+        gid_t gid = GID_INVALID;
+        int r;
+
+        r = name_to_uid_offline(arg_root, name, &uid, &uid_cache);
+        log_info_errno(r, "name_to_uid_offline: %s → "UID_FMT": %m", name, uid);
+        assert_se(relaxed || r == 0);
+
+        r = name_to_uid_offline(arg_root, name, &uid, &uid_cache);
+        log_info_errno(r, "name_to_uid_offline: %s → "UID_FMT": %m", name, uid);
+        assert_se(relaxed || r == 0);
+
+        r = name_to_gid_offline(arg_root, name, &gid, &gid_cache);
+        log_info_errno(r, "name_to_gid_offline: %s → "GID_FMT": %m", name, gid);
+        assert_se(relaxed || r == 0);
+
+        r = name_to_gid_offline(arg_root, name, &gid, &gid_cache);
+        log_info_errno(r, "name_to_gid_offline: %s → "GID_FMT": %m", name, gid);
+        assert_se(relaxed || r == 0);
+}
+
+static int parse_argv(int argc, char *argv[]) {
+        static const struct option options[] = {
+                { "root",           required_argument,   NULL, 'r' },
+                {}
+        };
+
+        int c;
+
+        assert(argc >= 0);
+        assert(argv);
+
+        while ((c = getopt_long(argc, argv, "r:", options, NULL)) >= 0)
+                switch(c) {
+                case 'r':
+                        arg_root = optarg;
+                        break;
+
+                case '?':
+                        return -EINVAL;
+
+                default:
+                        assert_not_reached("Unhandled option");
+                }
+
+        return 0;
+}
+
+int main(int argc, char **argv) {
+        int r;
+
+        test_setup_logging(LOG_DEBUG);
+
+        r = parse_argv(argc, argv);
+        if (r < 0)
+                return r;
+
+        if (optind >= argc)
+                test_resolve_one(NULL);
+        else
+                while (optind < argc)
+                        test_resolve_one(argv[optind++]);
+
+        return 0;
+}
diff --git a/src/tmpfiles/meson.build b/src/tmpfiles/meson.build
index 2f8fb29bd9..434dcf800d 100644
--- a/src/tmpfiles/meson.build
+++ b/src/tmpfiles/meson.build
@@ -2,6 +2,6 @@
 
 systemd_tmpfiles_sources = [
         'src/tmpfiles/tmpfiles.c',
-        'src/tmpfiles/offline-passwd.c',
-        'src/tmpfiles/offline-passwd.h',
+        'src/shared/offline-passwd.c',
+        'src/shared/offline-passwd.h',
 ]
diff --git a/src/tmpfiles/offline-passwd.c b/src/tmpfiles/offline-passwd.c
deleted file mode 100644
index 8ac5431c66..0000000000
--- a/src/tmpfiles/offline-passwd.c
+++ /dev/null
@@ -1,122 +0,0 @@
-/* SPDX-License-Identifier: LGPL-2.1+ */
-
-#include "fd-util.h"
-#include "offline-passwd.h"
-#include "path-util.h"
-#include "user-util.h"
-
-DEFINE_PRIVATE_HASH_OPS_WITH_KEY_DESTRUCTOR(uid_gid_hash_ops, char, string_hash_func, string_compare_func, free);
-
-int name_to_uid_offline(
-                const char *root,
-                const char *user,
-                uid_t *ret_uid,
-                Hashmap **cache) {
-
-        void *found;
-        int r;
-
-        assert(user);
-        assert(ret_uid);
-        assert(cache);
-
-        if (!*cache) {
-                _cleanup_(hashmap_freep) Hashmap *uid_by_name = NULL;
-                _cleanup_fclose_ FILE *f = NULL;
-                struct passwd *pw;
-                const char *passwd_path;
-
-                passwd_path = prefix_roota(root, "/etc/passwd");
-                f = fopen(passwd_path, "re");
-                if (!f)
-                        return errno == ENOENT ? -ESRCH : -errno;
-
-                uid_by_name = hashmap_new(&uid_gid_hash_ops);
-                if (!uid_by_name)
-                        return -ENOMEM;
-
-                while ((r = fgetpwent_sane(f, &pw)) > 0) {
-                        _cleanup_free_ char *n = NULL;
-
-                        n = strdup(pw->pw_name);
-                        if (!n)
-                                return -ENOMEM;
-
-                        r = hashmap_put(uid_by_name, n, UID_TO_PTR(pw->pw_uid));
-                        if (r == -EEXIST) {
-                                log_warning_errno(r, "Duplicate entry in %s for %s: %m", passwd_path, pw->pw_name);
-                                continue;
-                        }
-                        if (r < 0)
-                                return r;
-
-                        TAKE_PTR(n);
-                }
-
-                *cache = TAKE_PTR(uid_by_name);
-        }
-
-        found = hashmap_get(*cache, user);
-        if (!found)
-                return -ESRCH;
-
-        *ret_uid = PTR_TO_UID(found);
-        return 0;
-}
-
-int name_to_gid_offline(
-                const char *root,
-                const char *group,
-                gid_t *ret_gid,
-                Hashmap **cache) {
-
-        void *found;
-        int r;
-
-        assert(group);
-        assert(ret_gid);
-        assert(cache);
-
-        if (!*cache) {
-                _cleanup_(hashmap_freep) Hashmap *gid_by_name = NULL;
-                _cleanup_fclose_ FILE *f = NULL;
-                struct group *gr;
-                const char *group_path;
-
-                group_path = prefix_roota(root, "/etc/group");
-                f = fopen(group_path, "re");
-                if (!f)
-                        return errno == ENOENT ? -ESRCH : -errno;
-
-                gid_by_name = hashmap_new(&uid_gid_hash_ops);
-                if (!gid_by_name)
-                        return -ENOMEM;
-
-                while ((r = fgetgrent_sane(f, &gr)) > 0) {
-                        _cleanup_free_ char *n = NULL;
-
-                        n = strdup(gr->gr_name);
-                        if (!n)
-                                return -ENOMEM;
-
-                        r = hashmap_put(gid_by_name, n, GID_TO_PTR(gr->gr_gid));
-                        if (r == -EEXIST) {
-                                log_warning_errno(r, "Duplicate entry in %s for %s: %m", group_path, gr->gr_name);
-                                continue;
-                        }
-                        if (r < 0)
-                                return r;
-
-                        TAKE_PTR(n);
-                }
-
-                *cache = TAKE_PTR(gid_by_name);
-        }
-
-        found = hashmap_get(*cache, group);
-        if (!found)
-                return -ESRCH;
-
-        *ret_gid = PTR_TO_GID(found);
-        return 0;
-}