unit: drop the Names= option

Names= is a source of errors, simply because alias names specified like
this only become relevant after a unit has been loaded but cannot be
used to load a unit.

Let's get rid of the confusion and drop this field. To establish alias
names peope should use symlinks, which have the the benefit of being
useful as key to load a unit, even though they are not taken into
account if unit names are listed but they haven't been explicitly
referenced before.

TODO

@@ -399,5 +399,3 @@ Regularly:
 Scheduled for removal (or fixing):
 
 * xxxOverridable dependencies
-
-* Names= unit option

man/systemd.unit.xml

@@ -869,35 +869,6 @@
                                 symlinks.</para></listitem>
                         </varlistentry>
 
-                        <varlistentry>
-                                <term><varname>Names=</varname></term>
-
-                                <listitem><para>Additional names for
-                                this unit. The names listed here must
-                                have the same suffix (i.e. type) as
-                                the unit file name. This option may be
-                                specified more than once, in which
-                                case all listed names are used. Note
-                                that this option is different from the
-                                <varname>Alias=</varname> option from
-                                the [Install] section mentioned
-                                below. See below for details. Note
-                                that in almost all cases this option
-                                is not what you want. A symlink alias
-                                in the file system is generally
-                                preferable since it can be used as
-                                lookup key. If a unit with a symlinked
-                                alias name is not loaded and needs to
-                                be it is easily found via the
-                                symlink. However, if a unit with an
-                                alias name configured with this
-                                setting is not loaded it will not be
-                                discovered. This settings' only use is
-                                in conjunction with service
-                                instances.</para>
-                                </listitem>
-                        </varlistentry>
-
                         <varlistentry>
                                 <term><varname>SourcePath=</varname></term>
                                 <listitem><para>A path to a
@@ -936,30 +907,7 @@
                                 time,
                                 <command>systemctl enable</command>
                                 will create symlinks from these names
-                                to the unit file name. Note that this
+                                to the unit file name.</para></listitem>
-                                is different from the
-                                <varname>Names=</varname> option from
-                                the [Unit] section mentioned above:
-                                The names from
-                                <varname>Names=</varname> apply
-                                unconditionally if the unit is
-                                loaded. The names from
-                                <varname>Alias=</varname> apply only
-                                if the unit has actually been
-                                installed with the
-                                <command>systemctl enable</command>
-                                command.  Also, if systemd searches for a
-                                unit, it will discover symlinked alias
-                                names as configured with
-                                <varname>Alias=</varname>, but not
-                                names configured with
-                                <varname>Names=</varname> only. It is
-                                a common pattern to list a name in
-                                both options. In this case, a unit
-                                will be active under all names if
-                                installed, but also if not installed
-                                but requested explicitly under its
-                                main name.</para></listitem>
                         </varlistentry>
 
                         <varlistentry>

src/core/load-fragment-gperf.gperf.m4

@@ -90,7 +90,6 @@ $1.UtmpIdentifier,               config_parse_unit_string_printf,    0,
 $1.ControlGroupModify,           config_parse_bool,                  0,                             offsetof($1, exec_context.control_group_modify)
 $1.ControlGroupPersistent,       config_parse_tristate,              0,                             offsetof($1, exec_context.control_group_persistent)'
 )m4_dnl
-Unit.Names,                      config_parse_unit_names,            0,                             0
 Unit.Description,                config_parse_unit_string_printf,    0,                             offsetof(Unit, description)
 Unit.Documentation,              config_parse_documentation,         0,                             offsetof(Unit, documentation)
 Unit.SourcePath,                 config_parse_path,                  0,                             offsetof(Unit, source_path)

src/core/load-fragment.c

@@ -105,49 +105,6 @@ int config_parse_unit_deps(
         return 0;
 }
 
-int config_parse_unit_names(
-                const char *filename,
-                unsigned line,
-                const char *section,
-                const char *lvalue,
-                int ltype,
-                const char *rvalue,
-                void *data,
-                void *userdata) {
-
-        Unit *u = userdata;
-        char *w;
-        size_t l;
-        char *state;
-
-        assert(filename);
-        assert(lvalue);
-        assert(rvalue);
-        assert(data);
-
-        FOREACH_WORD_QUOTED(w, l, rvalue, state) {
-                char *t, *k;
-                int r;
-
-                t = strndup(w, l);
-                if (!t)
-                        return -ENOMEM;
-
-                k = unit_name_printf(u, t);
-                free(t);
-                if (!k)
-                        return -ENOMEM;
-
-                r = unit_merge_by_name(u, k);
-                if (r < 0)
-                        log_error("Failed to add name %s, ignoring: %s", k, strerror(-r));
-
-                free(k);
-        }
-
-        return 0;
-}
-
 int config_parse_unit_string_printf(
                 const char *filename,
                 unsigned line,
@@ -2395,7 +2352,6 @@ void unit_dump_config_items(FILE *f) {
                 { config_parse_limit,                 "LIMIT" },
                 { config_parse_unit_cgroup,           "CGROUP [...]" },
                 { config_parse_unit_deps,             "UNIT [...]" },
-                { config_parse_unit_names,            "UNIT [...]" },
                 { config_parse_exec,                  "PATH [ARGUMENT [...]]" },
                 { config_parse_service_type,          "SERVICETYPE" },
                 { config_parse_service_restart,       "SERVICERESTART" },

src/core/load-fragment.h

@@ -32,7 +32,6 @@ void unit_dump_config_items(FILE *f);
 
 int config_parse_warn_compat(const char *filename, unsigned line, const char *section, const char *lvalue, int ltype, const char *rvalue, void *data, void *userdata);
 int config_parse_unit_deps(const char *filename, unsigned line, const char *section, const char *lvalue, int ltype, const char *rvalue, void *data, void *userdata);
-int config_parse_unit_names(const char *filename, unsigned line, const char *section, const char *lvalue, int ltype, const char *rvalue, void *data, void *userdata);
 int config_parse_unit_string_printf(const char *filename, unsigned line, const char *section, const char *lvalue, int ltype, const char *rvalue, void *data, void *userdata);
 int config_parse_unit_strv_printf(const char *filename, unsigned line, const char *section, const char *lvalue, int ltype, const char *rvalue, void *data, void *userdata);
 int config_parse_unit_path_printf(const char *filename, unsigned line, const char *section, const char *lvalue, int ltype, const char *rvalue, void *data, void *userdata);