core: change top-level drop-in from -.service.d to service.d

Discussed in #13743, the -.service semantic conflicts with the
existing root mount and slice names, making this feature not
uniformly extensible to all types. Change the name to be
<type>.d instead.

Updating to this format also extends the top-level dropin to
unit types.

11 files changed, 27 insertions, 103 deletions

diff --git a/NEWS b/NEWS
index 56d05ac7ef..c9250c9eeb 100644
--- a/NEWS
+++ b/NEWS
@@ -33,10 +33,9 @@ CHANGES WITH 244 in spe:
           during early boot, so in practice this change has very little
           effect.)
 
-        * The special -.service.d dropin directory may be used to add
-          configuration that affects all services. The "-.service" service name
-          is now disallowed (though hopefully no one would use such a service
-          name. -.mount gives us enough grief.)
+        * Unit files now support top level dropin directories of the form
+          <unit_type>.d/ (e.g. service.d/) that may be used to add configuration
+          that affects all corresponding unit files.
 
         * The RuntimeMaxSec= setting is now supported by scopes, not just
           .service units. This is particularly useful for PAM sessions which
diff --git a/man/systemd.service.xml b/man/systemd.service.xml
index ce7b847420..f57e37ca5b 100644
--- a/man/systemd.service.xml
+++ b/man/systemd.service.xml
@@ -63,19 +63,6 @@
     <para>The <citerefentry><refentrytitle>systemd-run</refentrytitle><manvolnum>1</manvolnum></citerefentry>
     command allows creating <filename>.service</filename> and <filename>.scope</filename> units dynamically
     and transiently from the command line.</para>
-
-    <para>In addition to the various drop-in behaviors described in
-    <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
-    services also support a top-level drop-in with <filename>-.service.d/</filename> that allows
-    altering or adding to the settings of all services on the system.
-    The formatting and precedence of applying drop-in configurations follow what is defined in
-    <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
-    However, configurations in <filename>-.service.d/</filename> have the lowest precedence compared to settings
-    in the service specific override directories. For example, for <filename>foo-bar-baz.service</filename>,
-    drop-ins in <filename>foo-bar-baz.service.d/</filename> override the ones in
-    <filename>foo-bar-.service.d/</filename>, which override the ones <filename>foo-.service.d/</filename>,
-    which override the ones in <filename>-.service.d/</filename>.
-    </para>
   </refsect1>
 
   <refsect1>
diff --git a/man/systemd.special.xml b/man/systemd.special.xml
index afd14b977c..248fb924db 100644
--- a/man/systemd.special.xml
+++ b/man/systemd.special.xml
@@ -120,15 +120,6 @@
         </varlistentry>
 
         <varlistentry>
-          <term><filename>-.service</filename></term>
-          <listitem>
-            <para>This is a reserved unit name used to support top-level drop-ins for services. See
-            <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>
-            for details.</para>
-          </listitem>
-        </varlistentry>
-
-        <varlistentry>
           <term><filename>basic.target</filename></term>
           <listitem>
             <para>A special target unit covering basic boot-up.</para>
diff --git a/man/systemd.unit.xml b/man/systemd.unit.xml
index 5acb5951cd..616106972a 100644
--- a/man/systemd.unit.xml
+++ b/man/systemd.unit.xml
@@ -192,9 +192,14 @@
     over unit files wherever located. Multiple drop-in files with different names are applied in
     lexicographic order, regardless of which of the directories they reside in.</para>
 
-    <para>Service units also support a top-level drop-in directory for modifying the settings of all service units. See
-    <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>
-    for details.</para>
+    <para>Units also support a top-level drop-in with <filename><replaceable>type</replaceable>.d/</filename>,
+    where <replaceable>type</replaceable> may be e.g. <literal>service</literal> or <literal>socket</literal>,
+    that allows altering or adding to the settings of all corresponding unit files on the system.
+    The formatting and precedence of applying drop-in configurations follow what is defined above.
+    Configurations in <filename><replaceable>type</replaceable>.d/</filename> have the lowest precedence
+    compared to settings in the name specific override directories. So the contents of
+    <filename>foo-.service.d/10-override.conf</filename> would override
+    <filename>service.d/10-override.conf</filename>.</para>
 
     <!-- Note that we do not document .include here, as we consider it mostly obsolete, and want
          people to use .d/ drop-ins instead. -->
diff --git a/src/basic/special.h b/src/basic/special.h
index 6475501078..add1c1d507 100644
--- a/src/basic/special.h
+++ b/src/basic/special.h
@@ -105,7 +105,3 @@
 
 /* The root directory. */
 #define SPECIAL_ROOT_MOUNT "-.mount"
-
-/* Used to apply settings to all services through drop-ins.
- * Should not exist as an actual service. */
-#define SPECIAL_ROOT_SERVICE "-.service"
diff --git a/src/basic/unit-name.c b/src/basic/unit-name.c
index af8dca53cd..680e8eb4ab 100644
--- a/src/basic/unit-name.c
+++ b/src/basic/unit-name.c
@@ -669,36 +669,6 @@ good:
         return 0;
 }
 
-bool service_unit_name_is_valid(const char *name) {
-        _cleanup_free_ char *prefix = NULL, *s = NULL;
-        const char *e, *service_name = name;
-
-        if (!unit_name_is_valid(name, UNIT_NAME_ANY))
-                return false;
-
-        e = endswith(name, ".service");
-        if (!e)
-                return false;
-
-        /* If it's a template or instance, get the prefix as a service name. */
-        if (unit_name_is_valid(name, UNIT_NAME_INSTANCE|UNIT_NAME_TEMPLATE)) {
-                if (unit_name_to_prefix(name, &prefix) < 0)
-                        return false;
-
-                s = strjoin(prefix, ".service");
-                if (!s)
-                        return false;
-
-                service_name = s;
-        }
-
-        /* Reject reserved service name(s). */
-        if (streq(service_name, SPECIAL_ROOT_SERVICE))
-                return false;
-
-        return true;
-}
-
 int slice_build_parent_slice(const char *slice, char **ret) {
         char *s, *dash;
         int r;
diff --git a/src/basic/unit-name.h b/src/basic/unit-name.h
index 4a6f64cc1c..15ce4e2495 100644
--- a/src/basic/unit-name.h
+++ b/src/basic/unit-name.h
@@ -58,8 +58,6 @@ static inline int unit_name_mangle(const char *name, UnitNameMangle flags, char
         return unit_name_mangle_with_suffix(name, NULL, flags, ".service", ret);
 }
 
-bool service_unit_name_is_valid(const char *name);
-
 int slice_build_parent_slice(const char *slice, char **ret);
 int slice_build_subslice(const char *slice, const char *name, char **subslice);
 bool slice_name_is_valid(const char *name);
diff --git a/src/core/service.c b/src/core/service.c
index ebbd99a3cc..4b17889eb4 100644
--- a/src/core/service.c
+++ b/src/core/service.c
@@ -549,11 +549,6 @@ static int service_verify(Service *s) {
         assert(s);
         assert(UNIT(s)->load_state == UNIT_LOADED);
 
-        if (!service_unit_name_is_valid(UNIT(s)->id)) {
-                log_unit_error(UNIT(s), "Service name is invalid or reserved. Refusing.");
-                return -EINVAL;
-        }
-
         if (!s->exec_command[SERVICE_EXEC_START] && !s->exec_command[SERVICE_EXEC_STOP]
             && UNIT(s)->success_action == EMERGENCY_ACTION_NONE) {
                 /* FailureAction= only makes sense if one of the start or stop commands is specified.
diff --git a/src/shared/dropin.c b/src/shared/dropin.c
index 7328b7adde..ca97285c97 100644
--- a/src/shared/dropin.c
+++ b/src/shared/dropin.c
@@ -19,7 +19,6 @@
 #include "mkdir.h"
 #include "path-util.h"
 #include "set.h"
-#include "special.h"
 #include "string-util.h"
 #include "strv.h"
 #include "unit-name.h"
@@ -164,6 +163,10 @@ static int unit_file_find_dirs(
                         return r;
         }
 
+        /* Return early for top level drop-ins. */
+        if (unit_type_from_string(name) >= 0)
+                return 0;
+
         /* Let's see if there's a "-" prefix for this unit name. If so, let's invoke ourselves for it. This will then
          * recursively do the same for all our prefixes. i.e. this means given "foo-bar-waldo.service" we'll also
          * search "foo-bar-.service" and "foo-.service".
@@ -244,16 +247,15 @@ int unit_file_find_dropin_paths(
                                                name);
         }
 
-        /* Special drop in for -.service. Add this first as it's the most generic
+        /* Special top level drop in for "<unit type>.<suffix>". Add this first as it's the most generic
          * and should be able to be overridden by more specific drop-ins. */
-        if (type == UNIT_SERVICE)
-                STRV_FOREACH(p, lookup_path)
-                        (void) unit_file_find_dirs(original_root,
-                                                   unit_path_cache,
-                                                   *p,
-                                                   SPECIAL_ROOT_SERVICE,
-                                                   dir_suffix,
-                                                   &dirs);
+        STRV_FOREACH(p, lookup_path)
+                (void) unit_file_find_dirs(original_root,
+                                           unit_path_cache,
+                                           *p,
+                                           unit_type_to_string(type),
+                                           dir_suffix,
+                                           &dirs);
 
         SET_FOREACH(name, names, i)
                 STRV_FOREACH(p, lookup_path)
diff --git a/src/test/test-unit-name.c b/src/test/test-unit-name.c
index c65f6ffe08..c9bbce0d2e 100644
--- a/src/test/test-unit-name.c
+++ b/src/test/test-unit-name.c
@@ -353,24 +353,6 @@ static void test_unit_name_build(void) {
         free(t);
 }
 
-static void test_service_unit_name_is_valid(void) {
-        assert_se(service_unit_name_is_valid("foo.service"));
-        assert_se(service_unit_name_is_valid("foo@bar.service"));
-        assert_se(service_unit_name_is_valid("foo@bar@bar.service"));
-        assert_se(service_unit_name_is_valid("--.service"));
-        assert_se(service_unit_name_is_valid(".-.service"));
-        assert_se(service_unit_name_is_valid("-foo-bar.service"));
-        assert_se(service_unit_name_is_valid("-foo-bar-.service"));
-        assert_se(service_unit_name_is_valid("foo-bar-.service"));
-
-        assert_se(!service_unit_name_is_valid("-.service"));
-        assert_se(!service_unit_name_is_valid(""));
-        assert_se(!service_unit_name_is_valid("foo.slice"));
-        assert_se(!service_unit_name_is_valid("@.service"));
-        assert_se(!service_unit_name_is_valid("@bar.service"));
-        assert_se(!service_unit_name_is_valid("-@.service"));
-}
-
 static void test_slice_name_is_valid(void) {
         assert_se( slice_name_is_valid(SPECIAL_ROOT_SLICE));
         assert_se( slice_name_is_valid("foo.slice"));
@@ -856,7 +838,6 @@ int main(int argc, char* argv[]) {
         test_unit_prefix_is_valid();
         test_unit_name_change_suffix();
         test_unit_name_build();
-        test_service_unit_name_is_valid();
         test_slice_name_is_valid();
         test_build_subslice();
         test_build_parent_slice();
diff --git a/test/TEST-15-DROPIN/test-dropin.sh b/test/TEST-15-DROPIN/test-dropin.sh
index 75c36df2b8..fe424c1587 100755
--- a/test/TEST-15-DROPIN/test-dropin.sh
+++ b/test/TEST-15-DROPIN/test-dropin.sh
@@ -101,18 +101,18 @@ test_basic_dropins () {
     check_ok b Wants c.service
     systemctl stop a c
 
-    echo "*** test -.service.d/ top level drop-in"
+    echo "*** test service.d/ top level drop-in"
     create_services a b
     check_ko a ExecCondition "/bin/echo a"
     check_ko b ExecCondition "/bin/echo b"
-    mkdir -p /usr/lib/systemd/system/-.service.d
-    cat >/usr/lib/systemd/system/-.service.d/override.conf <<EOF
+    mkdir -p /usr/lib/systemd/system/service.d
+    cat >/usr/lib/systemd/system/service.d/override.conf <<EOF
 [Service]
 ExecCondition=/bin/echo %n
 EOF
     check_ok a ExecCondition "/bin/echo a"
     check_ok b ExecCondition "/bin/echo b"
-    rm -rf /usr/lib/systemd/system/-.service.d
+    rm -rf /usr/lib/systemd/system/service.d
 
     clear_services a b c
 }