tmpfiles: add new 'r' line type to add UIDs/GIDs to the pool to allocate UIDs/GIDs from

This way we can guarantee a limited amount of compatibility with
login.defs, by generate an appopriate "r" line out of it, on package
installation.

7 files changed, 507 insertions, 73 deletions

diff --git a/.gitignore b/.gitignore
index a3d8c4ea91..8189da71f0 100644
--- a/.gitignore
+++ b/.gitignore
@@ -228,6 +228,7 @@
 /test-time
 /test-tmpfiles
 /test-udev
+/test-uid-range
 /test-unifont
 /test-unit-file
 /test-unit-name
diff --git a/Makefile.am b/Makefile.am
index 3ef9c24313..d4d5775475 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -862,6 +862,8 @@ libsystemd_shared_la_SOURCES = \
 	src/shared/base-filesystem.h \
 	src/shared/memfd.c \
 	src/shared/memfd.h \
+	src/shared/uid-range.c \
+	src/shared/uid-range.h \
 	src/shared/nss-util.h
 
 nodist_libsystemd_shared_la_SOURCES = \
@@ -1322,7 +1324,8 @@ tests += \
 	test-capability \
 	test-async \
 	test-ratelimit \
-	test-condition-util
+	test-condition-util \
+	test-uid-range
 
 EXTRA_DIST += \
 	test/a.service \
@@ -1487,6 +1490,12 @@ test_util_SOURCES = \
 test_util_LDADD = \
 	libsystemd-core.la
 
+test_uid_range_SOURCES = \
+	src/test/test-uid-range.c
+
+test_uid_range_LDADD = \
+	libsystemd-core.la
+
 test_socket_util_SOURCES = \
 	src/test/test-socket-util.c
 
diff --git a/man/sysusers.d.xml b/man/sysusers.d.xml
index 1832ecf0e6..18c71db63e 100644
--- a/man/sysusers.d.xml
+++ b/man/sysusers.d.xml
@@ -134,6 +134,25 @@ u root 0 "Superuser" /root</programlisting>
                                         will be implicitly
                                         created.</para></listitem>
                                 </varlistentry>
+
+                                <varlistentry>
+                                        <term><varname>r</varname></term>
+                                        <listitem><para>Add a range of
+                                        numeric UIDs/GIDs to the pool
+                                        to allocate new UIDs and GIDs
+                                        from. If no line of this type
+                                        is specified the range of
+                                        UIDs/GIDs is set to some
+                                        compiled-in default. Note that
+                                        both UIDs and GIDs are
+                                        allocated from the same pool,
+                                        in order to ensure that users
+                                        and groups of the same name
+                                        are likely to carry the same
+                                        numeric UID and
+                                        GID.</para></listitem>
+                                </varlistentry>
+
                         </variablelist>
                 </refsect2>
 
@@ -154,6 +173,10 @@ u root 0 "Superuser" /root</programlisting>
                         <para>For <varname>m</varname> lines this
                         field should contain the user name to add to a
                         group.</para>
+
+                        <para>For lines of type <varname>r</varname>
+                        this field should be set to
+                        <literal>-</literal>.</para>
                 </refsect2>
 
                 <refsect2>
@@ -175,6 +198,14 @@ u root 0 "Superuser" /root</programlisting>
                         <para>For <varname>m</varname> lines this
                         field should contain the group name to add to
                         a user to.</para>
+
+                        <para>For lines of type <varname>r</varname>
+                        this field should be set to a UID/GID range in
+                        the format <literal>FROM-TO</literal> where
+                        both values are formatted as decimal ASCII
+                        numbers. Alternatively, a single UID/GID may
+                        be specified formatted as decimal ASCII
+                        numbers.</para>
                 </refsect2>
 
                 <refsect2>
diff --git a/src/shared/uid-range.c b/src/shared/uid-range.c
new file mode 100644
index 0000000000..74c3be4a13
--- /dev/null
+++ b/src/shared/uid-range.c
@@ -0,0 +1,205 @@
+/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
+
+/***
+  This file is part of systemd.
+
+  Copyright 2014 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 "util.h"
+#include "uid-range.h"
+
+static bool uid_range_intersect(UidRange *range, uid_t start, uid_t nr) {
+        assert(range);
+
+        return range->start <= start + nr &&
+                range->start + range->nr >= start;
+}
+
+static void uid_range_coalesce(UidRange **p, unsigned *n) {
+        unsigned i, j;
+
+        assert(p);
+        assert(n);
+
+        for (i = 0; i < *n; i++) {
+                for (j = i + 1; j < *n; j++) {
+                        UidRange *x = (*p)+i, *y = (*p)+j;
+
+                        if (uid_range_intersect(x, y->start, y->nr)) {
+                                uid_t begin, end;
+
+                                begin = MIN(x->start, y->start);
+                                end = MAX(x->start + x->nr, y->start + y->nr);
+
+                                x->start = begin;
+                                x->nr = end - begin;
+
+                                if (*n > j+1)
+                                        memmove(y, y+1, sizeof(UidRange) * (*n - j -1));
+
+                                (*n) --;
+                                j--;
+                        }
+                }
+        }
+
+}
+
+static int uid_range_compare(const void *a, const void *b) {
+        const UidRange *x = a, *y = b;
+
+        if (x->start < y->start)
+                return -1;
+        if (x->start > y->start)
+                return 1;
+
+        if (x->nr < y->nr)
+                return -1;
+        if (x->nr > y->nr)
+                return 1;
+
+        return 0;
+}
+
+int uid_range_add(UidRange **p, unsigned *n, uid_t start, uid_t nr) {
+        bool found = false;
+        UidRange *x;
+        unsigned i;
+
+        assert(p);
+        assert(n);
+
+        if (nr <= 0)
+                return 0;
+
+        for (i = 0; i < *n; i++) {
+                x = (*p) + i;
+                if (uid_range_intersect(x, start, nr)) {
+                        found = true;
+                        break;
+                }
+        }
+
+        if (found) {
+                uid_t begin, end;
+
+                begin = MIN(x->start, start);
+                end = MAX(x->start + x->nr, start + nr);
+
+                x->start = begin;
+                x->nr = end - begin;
+        } else {
+                UidRange *t;
+
+                t = realloc(*p, sizeof(UidRange) * (*n + 1));
+                if (!t)
+                        return -ENOMEM;
+
+                *p = t;
+                x = t + ((*n) ++);
+
+                x->start = start;
+                x->nr = nr;
+        }
+
+        qsort(*p, *n, sizeof(UidRange), uid_range_compare);
+        uid_range_coalesce(p, n);
+
+        return *n;
+}
+
+int uid_range_add_str(UidRange **p, unsigned *n, const char *s) {
+        uid_t start, nr;
+        const char *t;
+        int r;
+
+        assert(p);
+        assert(n);
+        assert(s);
+
+        t = strchr(s, '-');
+        if (t) {
+                char *b;
+                uid_t end;
+
+                b = strndupa(s, t - s);
+                r = parse_uid(b, &start);
+                if (r < 0)
+                        return r;
+
+                r = parse_uid(t+1, &end);
+                if (r < 0)
+                        return r;
+
+                if (end < start)
+                        return -EINVAL;
+
+                nr = end - start + 1;
+        } else {
+                r = parse_uid(s, &start);
+                if (r < 0)
+                        return r;
+
+                nr = 1;
+        }
+
+        return uid_range_add(p, n, start, nr);
+}
+
+int uid_range_next_lower(const UidRange *p, unsigned n, uid_t *uid) {
+        uid_t closest = (uid_t) -1, candidate;
+        unsigned i;
+
+        assert(p);
+        assert(uid);
+
+        candidate = *uid - 1;
+
+        for (i = 0; i < n; i++) {
+                uid_t begin, end;
+
+                begin = p[i].start;
+                end = p[i].start + p[i].nr - 1;
+
+                if (candidate >= begin && candidate <= end) {
+                        *uid = candidate;
+                        return 1;
+                }
+
+                if (end < candidate)
+                        closest = end;
+        }
+
+        if (closest == (uid_t) -1)
+                return -EBUSY;
+
+        *uid = closest;
+        return 1;
+}
+
+bool uid_range_contains(const UidRange *p, unsigned n, uid_t uid) {
+        unsigned i;
+
+        assert(p);
+        assert(uid);
+
+        for (i = 0; i < n; i++)
+                if (uid >= p[i].start && uid < p[i].start + p[i].nr)
+                        return true;
+
+        return false;
+}
diff --git a/src/shared/uid-range.h b/src/shared/uid-range.h
new file mode 100644
index 0000000000..d3dac8df63
--- /dev/null
+++ b/src/shared/uid-range.h
@@ -0,0 +1,34 @@
+/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
+
+#pragma once
+
+/***
+  This file is part of systemd.
+
+  Copyright 2014 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 <sys/types.h>
+
+typedef struct UidRange {
+        uid_t start, nr;
+} UidRange;
+
+int uid_range_add(UidRange **p, unsigned *n, uid_t start, uid_t nr);
+int uid_range_add_str(UidRange **p, unsigned *n, const char *s);
+
+int uid_range_next_lower(const UidRange *p, unsigned n, uid_t *uid);
+bool uid_range_contains(const UidRange *p, unsigned n, uid_t uid);
diff --git a/src/sysusers/sysusers.c b/src/sysusers/sysusers.c
index eedc1e067e..1ff0e21a06 100644
--- a/src/sysusers/sysusers.c
+++ b/src/sysusers/sysusers.c
@@ -38,11 +38,13 @@
 #include "utf8.h"
 #include "label.h"
 #include "fileio-label.h"
+#include "uid-range.h"
 
 typedef enum ItemType {
         ADD_USER = 'u',
         ADD_GROUP = 'g',
         ADD_MEMBER = 'm',
+        ADD_RANGE = 'r',
 } ItemType;
 typedef struct Item {
         ItemType type;
@@ -82,8 +84,9 @@ static Hashmap *members = NULL;
 static Hashmap *database_uid = NULL, *database_user = NULL;
 static Hashmap *database_gid = NULL, *database_group = NULL;
 
-static uid_t search_uid = SYSTEM_UID_MAX;
-static gid_t search_gid = SYSTEM_GID_MAX;
+static uid_t search_uid = (uid_t) -1;
+static UidRange *uid_range = NULL;
+static unsigned n_uid_range = 0;
 
 #define UID_TO_PTR(u) (ULONG_TO_PTR(u+1))
 #define PTR_TO_UID(u) ((uid_t) (PTR_TO_ULONG(u)-1))
@@ -916,7 +919,7 @@ static int add_user(Item *i) {
 
                 if (read_id_from_file(i, &c, NULL) > 0) {
 
-                        if (c <= 0 || c > SYSTEM_UID_MAX)
+                        if (c <= 0 || !uid_range_contains(uid_range, n_uid_range, c))
                                 log_debug("User ID " UID_FMT " of file not suitable for %s.", c, i->name);
                         else {
                                 r = uid_is_ok(c, i->name);
@@ -947,7 +950,12 @@ static int add_user(Item *i) {
 
         /* And if that didn't work either, let's try to find a free one */
         if (!i->uid_set) {
-                for (; search_uid > 0; search_uid--) {
+                for (;;) {
+                        r = uid_range_next_lower(uid_range, n_uid_range, &search_uid);
+                        if (r < 0) {
+                                log_error("No free user ID available for %s.", i->name);
+                                return r;
+                        }
 
                         r = uid_is_ok(search_uid, i->name);
                         if (r < 0) {
@@ -957,15 +965,8 @@ static int add_user(Item *i) {
                                 break;
                 }
 
-                if (search_uid <= 0) {
-                        log_error("No free user ID available for %s.", i->name);
-                        return -E2BIG;
-                }
-
                 i->uid_set = true;
                 i->uid = search_uid;
-
-                search_uid--;
         }
 
         r = hashmap_ensure_allocated(&todo_uids, trivial_hash_func, trivial_compare_func);
@@ -1083,7 +1084,7 @@ static int add_group(Item *i) {
 
                 if (read_id_from_file(i, NULL, &c) > 0) {
 
-                        if (c <= 0 || c > SYSTEM_GID_MAX)
+                        if (c <= 0 || !uid_range_contains(uid_range, n_uid_range, c))
                                 log_debug("Group ID " GID_FMT " of file not suitable for %s.", c, i->name);
                         else {
                                 r = gid_is_ok(c);
@@ -1101,8 +1102,15 @@ static int add_group(Item *i) {
 
         /* And if that didn't work either, let's try to find a free one */
         if (!i->gid_set) {
-                for (; search_gid > 0; search_gid--) {
-                        r = gid_is_ok(search_gid);
+                for (;;) {
+                        /* We look for new GIDs in the UID pool! */
+                        r = uid_range_next_lower(uid_range, n_uid_range, &search_uid);
+                        if (r < 0) {
+                                log_error("No free group ID available for %s.", i->name);
+                                return r;
+                        }
+
+                        r = gid_is_ok(search_uid);
                         if (r < 0) {
                                 log_error("Failed to verify gid " GID_FMT ": %s", i->gid, strerror(-r));
                                 return r;
@@ -1110,15 +1118,8 @@ static int add_group(Item *i) {
                                 break;
                 }
 
-                if (search_gid <= 0) {
-                        log_error("No free group ID available for %s.", i->name);
-                        return -E2BIG;
-                }
-
                 i->gid_set = true;
-                i->gid = search_gid;
-
-                search_gid--;
+                i->gid = search_uid;
         }
 
         r = hashmap_ensure_allocated(&todo_gids, trivial_hash_func, trivial_compare_func);
@@ -1384,7 +1385,7 @@ static int parse_line(const char *fname, unsigned line, const char *buffer) {
                 {}
         };
 
-        _cleanup_free_ char *action = NULL, *name = NULL, *id = NULL, *resolved_name = NULL, *description = NULL, *home = NULL;
+        _cleanup_free_ char *action = NULL, *name = NULL, *id = NULL, *resolved_name = NULL, *resolved_id = NULL, *description = NULL, *home = NULL;
         _cleanup_(item_freep) Item *i = NULL;
         Item *existing;
         Hashmap *h;
@@ -1417,66 +1418,113 @@ static int parse_line(const char *fname, unsigned line, const char *buffer) {
                 return -EINVAL;
         }
 
-        if (!IN_SET(action[0], ADD_USER, ADD_GROUP, ADD_MEMBER)) {
+        if (!IN_SET(action[0], ADD_USER, ADD_GROUP, ADD_MEMBER, ADD_RANGE)) {
                 log_error("[%s:%u] Unknown command command type '%c'.", fname, line, action[0]);
                 return -EBADMSG;
         }
 
         /* Verify name */
-        r = specifier_printf(name, specifier_table, NULL, &resolved_name);
-        if (r < 0) {
-                log_error("[%s:%u] Failed to replace specifiers: %s", fname, line, name);
-                return r;
+        if (isempty(name) || streq(name, "-")) {
+                free(name);
+                name = NULL;
         }
 
-        if (!valid_user_group_name(resolved_name)) {
-                log_error("[%s:%u] '%s' is not a valid user or group name.", fname, line, resolved_name);
-                return -EINVAL;
+        if (name) {
+                r = specifier_printf(name, specifier_table, NULL, &resolved_name);
+                if (r < 0) {
+                        log_error("[%s:%u] Failed to replace specifiers: %s", fname, line, name);
+                        return r;
+                }
+
+                if (!valid_user_group_name(resolved_name)) {
+                        log_error("[%s:%u] '%s' is not a valid user or group name.", fname, line, resolved_name);
+                        return -EINVAL;
+                }
         }
 
-        /* Simplify remaining columns */
+        /* Verify id */
         if (isempty(id) || streq(id, "-")) {
                 free(id);
                 id = NULL;
         }
 
+        if (id) {
+                r = specifier_printf(id, specifier_table, NULL, &resolved_id);
+                if (r < 0) {
+                        log_error("[%s:%u] Failed to replace specifiers: %s", fname, line, name);
+                        return r;
+                }
+        }
+
+        /* Verify description */
         if (isempty(description) || streq(description, "-")) {
                 free(description);
                 description = NULL;
         }
 
+        if (description) {
+                if (!valid_gecos(description)) {
+                        log_error("[%s:%u] '%s' is not a valid GECOS field.", fname, line, description);
+                        return -EINVAL;
+                }
+        }
+
+        /* Verify home */
         if (isempty(home) || streq(home, "-")) {
                 free(home);
                 home = NULL;
         }
 
+        if (home) {
+                if (!valid_home(home)) {
+                        log_error("[%s:%u] '%s' is not a valid home directory field.", fname, line, home);
+                        return -EINVAL;
+                }
+        }
+
         switch (action[0]) {
 
-        case ADD_MEMBER: {
-                _cleanup_free_ char *resolved_id = NULL;
-                char **l;
+        case ADD_RANGE:
+                if (resolved_name) {
+                        log_error("[%s:%u] Lines of type 'r' don't take a name field.", fname, line);
+                        return -EINVAL;
+                }
 
-                /* Try to extend an existing member or group item */
+                if (!resolved_id) {
+                        log_error("[%s:%u] Lines of type 'r' require a ID range in the third field.", fname, line);
+                        return -EINVAL;
+                }
 
                 if (description) {
-                        log_error("[%s:%u] Lines of type 'm' don't take a GECOS field.", fname, line);
+                        log_error("[%s:%u] Lines of type 'r' don't take a GECOS field.", fname, line);
                         return -EINVAL;
                 }
 
                 if (home) {
-                        log_error("[%s:%u] Lines of type 'm' don't take a home directory field.", fname, line);
+                        log_error("[%s:%u] Lines of type 'r' don't take a home directory field.", fname, line);
                         return -EINVAL;
                 }
 
-                if (!id) {
-                        log_error("[%s:%u] Lines of type 'm' require a group name in the third field.", fname, line);
+                r = uid_range_add_str(&uid_range, &n_uid_range, resolved_id);
+                if (r < 0) {
+                        log_error("[%s:%u] Invalid UID range %s.", fname, line, resolved_id);
                         return -EINVAL;
                 }
 
-                r = specifier_printf(id, specifier_table, NULL, &resolved_id);
-                if (r < 0) {
-                        log_error("[%s:%u] Failed to replace specifiers: %s", fname, line, name);
-                        return r;
+                return 0;
+
+        case ADD_MEMBER: {
+                char **l;
+
+                /* Try to extend an existing member or group item */
+                if (!name) {
+                        log_error("[%s:%u] Lines of type 'm' require a user name in the second field.", fname, line);
+                        return -EINVAL;
+                }
+
+                if (!resolved_id) {
+                        log_error("[%s:%u] Lines of type 'm' require a group name in the third field.", fname, line);
+                        return -EINVAL;
                 }
 
                 if (!valid_user_group_name(resolved_id)) {
@@ -1484,6 +1532,16 @@ static int parse_line(const char *fname, unsigned line, const char *buffer) {
                         return -EINVAL;
                 }
 
+                if (description) {
+                        log_error("[%s:%u] Lines of type 'm' don't take a GECOS field.", fname, line);
+                        return -EINVAL;
+                }
+
+                if (home) {
+                        log_error("[%s:%u] Lines of type 'm' don't take a home directory field.", fname, line);
+                        return -EINVAL;
+                }
+
                 r = hashmap_ensure_allocated(&members, string_hash_func, string_compare_func);
                 if (r < 0)
                         return log_oom();
@@ -1521,6 +1579,11 @@ static int parse_line(const char *fname, unsigned line, const char *buffer) {
         }
 
         case ADD_USER:
+                if (!name) {
+                        log_error("[%s:%u] Lines of type 'u' require a user name in the second field.", fname, line);
+                        return -EINVAL;
+                }
+
                 r = hashmap_ensure_allocated(&users, string_hash_func, string_compare_func);
                 if (r < 0)
                         return log_oom();
@@ -1529,14 +1592,14 @@ static int parse_line(const char *fname, unsigned line, const char *buffer) {
                 if (!i)
                         return log_oom();
 
-                if (id) {
-                        if (path_is_absolute(id)) {
-                                i->uid_path = id;
-                                id = NULL;
+                if (resolved_id) {
+                        if (path_is_absolute(resolved_id)) {
+                                i->uid_path = resolved_id;
+                                resolved_id = NULL;
 
                                 path_kill_slashes(i->uid_path);
                         } else {
-                                r = parse_uid(id, &i->uid);
+                                r = parse_uid(resolved_id, &i->uid);
                                 if (r < 0) {
                                         log_error("Failed to parse UID: %s", id);
                                         return -EBADMSG;
@@ -1546,30 +1609,20 @@ static int parse_line(const char *fname, unsigned line, const char *buffer) {
                         }
                 }
 
-                if (description) {
-                        if (!valid_gecos(description)) {
-                                log_error("[%s:%u] '%s' is not a valid GECOS field.", fname, line, description);
-                                return -EINVAL;
-                        }
-
-                        i->description = description;
-                        description = NULL;
-                }
-
-                if (home) {
-                        if (!valid_home(home)) {
-                                log_error("[%s:%u] '%s' is not a valid home directory field.", fname, line, home);
-                                return -EINVAL;
-                        }
+                i->description = description;
+                description = NULL;
 
-                        i->home = home;
-                        home = NULL;
-                }
+                i->home = home;
+                home = NULL;
 
                 h = users;
                 break;
 
         case ADD_GROUP:
+                if (!name) {
+                        log_error("[%s:%u] Lines of type 'g' require a user name in the second field.", fname, line);
+                        return -EINVAL;
+                }
 
                 if (description) {
                         log_error("[%s:%u] Lines of type 'g' don't take a GECOS field.", fname, line);
@@ -1589,14 +1642,14 @@ static int parse_line(const char *fname, unsigned line, const char *buffer) {
                 if (!i)
                         return log_oom();
 
-                if (id) {
-                        if (path_is_absolute(id)) {
-                                i->gid_path = id;
-                                id = NULL;
+                if (resolved_id) {
+                        if (path_is_absolute(resolved_id)) {
+                                i->gid_path = resolved_id;
+                                resolved_id = NULL;
 
                                 path_kill_slashes(i->gid_path);
                         } else {
-                                r = parse_gid(id, &i->gid);
+                                r = parse_gid(resolved_id, &i->gid);
                                 if (r < 0) {
                                         log_error("Failed to parse GID: %s", id);
                                         return -EBADMSG;
@@ -1608,6 +1661,7 @@ static int parse_line(const char *fname, unsigned line, const char *buffer) {
 
                 h = groups;
                 break;
+
         default:
                 return -EBADMSG;
         }
@@ -1812,6 +1866,15 @@ int main(int argc, char *argv[]) {
                 }
         }
 
+        if (!uid_range) {
+                /* Default to default range of 1..SYSTEMD_UID_MAX */
+                r = uid_range_add(&uid_range, &n_uid_range, 1, SYSTEM_UID_MAX);
+                if (r < 0) {
+                        log_oom();
+                        goto finish;
+                }
+        }
+
         r = add_implicit();
         if (r < 0)
                 goto finish;
diff --git a/src/test/test-uid-range.c b/src/test/test-uid-range.c
new file mode 100644
index 0000000000..5f3d871b6c
--- /dev/null
+++ b/src/test/test-uid-range.c
@@ -0,0 +1,91 @@
+/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
+
+/***
+  This file is part of systemd.
+
+  Copyright 2014 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 <stddef.h>
+
+#include "util.h"
+#include "uid-range.h"
+
+int main(int argc, char *argv[]) {
+        _cleanup_free_ UidRange *p = NULL;
+        unsigned n = 0;
+        uid_t search;
+
+        assert_se(uid_range_add_str(&p, &n, "500-999") >= 0);
+        assert_se(n == 1);
+        assert_se(p[0].start == 500);
+        assert_se(p[0].nr = 500);
+
+        assert_se(!uid_range_contains(p, n, 499));
+        assert_se(uid_range_contains(p, n, 500));
+        assert_se(uid_range_contains(p, n, 999));
+        assert_se(!uid_range_contains(p, n, 1000));
+
+        search = (uid_t) -1;
+        assert_se(uid_range_next_lower(p, n, &search));
+        assert_se(search == 999);
+        assert_se(uid_range_next_lower(p, n, &search));
+        assert_se(search == 998);
+        search = 501;
+        assert_se(uid_range_next_lower(p, n, &search));
+        assert_se(search == 500);
+        assert_se(uid_range_next_lower(p, n, &search) == -EBUSY);
+
+        assert_se(uid_range_add_str(&p, &n, "1000") >= 0);
+        assert_se(n == 1);
+        assert_se(p[0].start == 500);
+        assert_se(p[0].nr = 501);
+
+        assert_se(uid_range_add_str(&p, &n, "30-40") >= 0);
+        assert_se(n == 2);
+        assert_se(p[0].start == 30);
+        assert_se(p[0].nr = 11);
+        assert_se(p[1].start == 500);
+        assert_se(p[1].nr = 501);
+
+        assert_se(uid_range_add_str(&p, &n, "60-70") >= 0);
+        assert_se(n == 3);
+        assert_se(p[0].start == 30);
+        assert_se(p[0].nr = 11);
+        assert_se(p[1].start == 60);
+        assert_se(p[1].nr = 11);
+        assert_se(p[2].start == 500);
+        assert_se(p[2].nr = 501);
+
+        assert_se(uid_range_add_str(&p, &n, "20-2000") >= 0);
+        assert_se(n == 1);
+        assert_se(p[0].start == 20);
+        assert_se(p[0].nr = 1981);
+
+        assert_se(uid_range_add_str(&p, &n, "2002") >= 0);
+        assert_se(n == 2);
+        assert_se(p[0].start == 20);
+        assert_se(p[0].nr = 1981);
+        assert_se(p[1].start == 2002);
+        assert_se(p[1].nr = 1);
+
+        assert_se(uid_range_add_str(&p, &n, "2001") >= 0);
+        assert_se(n == 1);
+        assert_se(p[0].start == 20);
+        assert_se(p[0].nr = 1983);
+
+        return 0;
+}