From 96fb8242cc1ef6b0e28f6c86a4f57950095dd7f1 Mon Sep 17 00:00:00 2001

From: Lennart Poettering <lennart@poettering.net>

Date: Thu, 21 Aug 2014 18:50:42 +0200

Subject: [PATCH] service: allow services of Type=oneshot that specify no

 ExecStart= commands

This is useful for services that simply want to run something on

shutdown, but not at bootup. They should only set ExecStop= but leave

ExecStart= unset.

---

 man/systemd.service.xml | 44 +++++++++++++++++++++++++++-----------------

 src/core/service.c      | 39 +++++++++++++++++++++++++++++----------

 2 files changed, 56 insertions(+), 27 deletions(-)

diff --git a/man/systemd.service.xml b/man/systemd.service.xml

index 5c4bd6569f..e584a1f006 100644

--- a/man/systemd.service.xml

+++ b/man/systemd.service.xml

@@ -139,9 +139,10 @@

                                 <para>If set to

                                 <option>simple</option> (the default

-                                value if neither

+                                if neither

                                 <varname>Type=</varname> nor

-                                <varname>BusName=</varname> are

+                                <varname>BusName=</varname>, but

+                                <varname>ExecStart=</varname> are

                                 specified), it is expected that the

                                 process configured with

                                 <varname>ExecStart=</varname> is the

@@ -177,13 +178,17 @@

                                 exits.</para>

                                 <para>Behavior of

-                                <option>oneshot</option> is similar

-                                to <option>simple</option>; however,

-                                it is expected that the process has to

+                                <option>oneshot</option> is similar to

+                                <option>simple</option>; however, it

+                                is expected that the process has to

                                 exit before systemd starts follow-up

                                 units. <varname>RemainAfterExit=</varname>

                                 is particularly useful for this type

-                                of service.</para>

+                                of service. This is the implied

+                                default if neither

+                                <varname>Type=</varname> or

+                                <varname>ExecStart=</varname> are

+                                specified.</para>

                                 <para>Behavior of

                                 <option>dbus</option> is similar to

@@ -313,22 +318,27 @@

                                 <para>When <varname>Type</varname> is

                                 not <option>oneshot</option>, only one

-                                command may be given. When

+                                command may and must be given. When

                                 <varname>Type=oneshot</varname> is

-                                used, more than one command may be

-                                specified. Multiple command lines may

-                                be concatenated in a single directive

-                                by separating them with semicolons

-                                (these semicolons must be passed as

-                                separate words). Alternatively, this

-                                directive may be specified more than

-                                once with the same effect.

-                                Lone semicolons may be escaped as

+                                used, none or more than one command

+                                may be specified. Multiple command

+                                lines may be concatenated in a single

+                                directive by separating them with

+                                semicolons (these semicolons must be

+                                passed as separate

+                                words). Alternatively, this directive

+                                may be specified more than once with

+                                the same effect.  Lone semicolons may

+                                be escaped as

                                 <literal>\;</literal>. If the empty

                                 string is assigned to this option, the

                                 list of commands to start is reset,

                                 prior assignments of this option will

-                                have no effect.</para>

+                                have no effect. If no

+                                <varname>ExecStart=</varname> is

+                                specified, then the service must have

+                                <varname>RemainAfterExit=yes</varname>

+                                set.</para>

                                 <para>Each command line is split on

                                 whitespace, with the first item being

diff --git a/src/core/service.c b/src/core/service.c

index 7d6ea73e05..1b864c4c8c 100644

--- a/src/core/service.c

+++ b/src/core/service.c

@@ -313,14 +313,23 @@ static int service_verify(Service *s) {

         if (UNIT(s)->load_state != UNIT_LOADED)

                 return 0;

-        if (!s->exec_command[SERVICE_EXEC_START]) {

-                log_error_unit(UNIT(s)->id, "%s lacks ExecStart setting. Refusing.", UNIT(s)->id);

+        if (!s->exec_command[SERVICE_EXEC_START] && !s->exec_command[SERVICE_EXEC_STOP]) {

+                log_error_unit(UNIT(s)->id, "%s lacks both ExecStart= and ExecStop= setting. Refusing.", UNIT(s)->id);

                 return -EINVAL;

         }

-        if (s->type != SERVICE_ONESHOT &&

-            s->exec_command[SERVICE_EXEC_START]->command_next) {

-                log_error_unit(UNIT(s)->id, "%s has more than one ExecStart setting, which is only allowed for Type=oneshot services. Refusing.", UNIT(s)->id);

+        if (s->type != SERVICE_ONESHOT && !s->exec_command[SERVICE_EXEC_START]) {

+                log_error_unit(UNIT(s)->id, "%s has no ExecStart= setting, which is only allowed for Type=oneshot services. Refusing.", UNIT(s)->id);

+                return -EINVAL;

+        }

+

+        if (!s->remain_after_exit && !s->exec_command[SERVICE_EXEC_START]) {

+                log_error_unit(UNIT(s)->id, "%s has no ExecStart= setting, which is only allowed for RemainAfterExit=yes services. Refusing.", UNIT(s)->id);

+                return -EINVAL;

+        }

+

+        if (s->type != SERVICE_ONESHOT && s->exec_command[SERVICE_EXEC_START]->command_next) {

+                log_error_unit(UNIT(s)->id, "%s has more than one ExecStart= setting, which is only allowed for Type=oneshot services. Refusing.", UNIT(s)->id);

                 return -EINVAL;

         }

@@ -410,8 +419,15 @@ static int service_load(Unit *u) {

                 if (r < 0)

                         return r;

-                if (s->type == _SERVICE_TYPE_INVALID)

-                        s->type = s->bus_name ? SERVICE_DBUS : SERVICE_SIMPLE;

+                if (s->type == _SERVICE_TYPE_INVALID) {

+                        /* Figure out a type automatically */

+                        if (s->bus_name)

+                                s->type = SERVICE_DBUS;

+                        else if (s->exec_command[SERVICE_EXEC_START])

+                                s->type = SERVICE_SIMPLE;

+                        else

+                                s->type = SERVICE_ONESHOT;

+                }

                 /* Oneshot services have disabled start timeout by default */

                 if (s->type == SERVICE_ONESHOT && !s->start_timeout_defined)

@@ -1309,9 +1325,6 @@ static void service_enter_start(Service *s) {

         assert(s);

-        assert(s->exec_command[SERVICE_EXEC_START]);

-        assert(!s->exec_command[SERVICE_EXEC_START]->command_next || s->type == SERVICE_ONESHOT);

-

         service_unwatch_control_pid(s);

         service_unwatch_main_pid(s);

@@ -1332,6 +1345,12 @@ static void service_enter_start(Service *s) {

                 c = s->main_command = s->exec_command[SERVICE_EXEC_START];

         }

+        if (!c) {

+                assert(s->type == SERVICE_ONESHOT);

+                service_enter_start_post(s);

+                return;

+        }

+

         r = service_spawn(s,

                           c,

                           IN_SET(s->type, SERVICE_FORKING, SERVICE_DBUS, SERVICE_NOTIFY, SERVICE_ONESHOT) ? s->timeout_start_usec : 0,