From 201c651eaaf886064987272cc88b03995fd2715d Mon Sep 17 00:00:00 2001

From: Mike Yuan <me@yhndnzj.com>

Date: Fri, 18 Nov 2022 15:43:34 +0800

Subject: [PATCH] systemctl: warn if trying to disable a unit with no install

 info

Trying to disable a unit with no install info is mostly useless, so

adding a warning like we do for enable (with the new dbus method

'DisableUnitFilesWithFlagsAndInstallInfo()'). Note that it would

still find and remove symlinks to the unit in /etc, regardless of

whether it has install info or not, just like before. And if there are

actually files to remove, we suppress the warning.

Fixes #17689

(cherry picked from commit bf1bea43f15b04152a3948702ba1695a0835c2bf)

Related: #2141979

---

 man/org.freedesktop.systemd1.xml | 13 ++++++++++++-

 src/core/dbus-manager.c          | 21 ++++++++++++++++-----

 src/shared/install.c             | 21 +++++++++++++++++----

 src/systemctl/systemctl-enable.c | 15 ++++++++++-----

 4 files changed, 55 insertions(+), 15 deletions(-)

diff --git a/man/org.freedesktop.systemd1.xml b/man/org.freedesktop.systemd1.xml

index 5e08b35234..c2f70870c7 100644

--- a/man/org.freedesktop.systemd1.xml

+++ b/man/org.freedesktop.systemd1.xml

@@ -209,6 +209,10 @@ node /org/freedesktop/systemd1 {

       DisableUnitFilesWithFlags(in  as files,

                                 in  t flags,

                                 out a(sss) changes);

+      DisableUnitFilesWithFlagsAndInstallInfo(in  as files,

+                                              in  t flags,

+                                              out b carries_install_info,

+                                              out a(sss) changes);

       ReenableUnitFiles(in  as files,

                         in  b runtime,

                         in  b force,

@@ -916,6 +920,8 @@ node /org/freedesktop/systemd1 {

     <variablelist class="dbus-method" generated="True" extra-ref="DisableUnitFilesWithFlags()"/>

+    <variablelist class="dbus-method" generated="True" extra-ref="DisableUnitFilesWithFlagsAndInstallInfo()"/>

+

     <variablelist class="dbus-method" generated="True" extra-ref="ReenableUnitFiles()"/>

     <variablelist class="dbus-method" generated="True" extra-ref="LinkUnitFiles()"/>

@@ -1417,7 +1423,7 @@ node /org/freedesktop/systemd1 {

       enabled for runtime only (true, <filename>/run/</filename>), or persistently (false,

       <filename>/etc/</filename>). The second one controls whether symlinks pointing to other units shall be

       replaced if necessary. This method returns one boolean and an array of the changes made. The boolean

-      signals whether the unit files contained any enablement information (i.e. an [Install]) section. The

+      signals whether the unit files contained any enablement information (i.e. an [Install] section). The

       changes array consists of structures with three strings: the type of the change (one of

       <literal>symlink</literal> or <literal>unlink</literal>), the file name of the symlink and the

       destination of the symlink. Note that most of the following calls return a changes list in the same

@@ -1440,6 +1446,11 @@ node /org/freedesktop/systemd1 {

       replaced if necessary. <varname>SD_SYSTEMD_UNIT_PORTABLE</varname> will add or remove the symlinks in

       <filename>/etc/systemd/system.attached</filename> and <filename>/run/systemd/system.attached</filename>.</para>

+      <para><function>DisableUnitFilesWithFlagsAndInstallInfo()</function> is similar to

+      <function>DisableUnitFilesWithFlags()</function> and takes the same arguments, but returns

+      a boolean to indicate whether the unit files contain any enablement information, like

+      <function>EnableUnitFiles()</function>. The changes made are still returned in an array.</para>

+

       <para>Similarly, <function>ReenableUnitFiles()</function> applies the changes to one or more units that

       would result from disabling and enabling the unit quickly one after the other in an atomic

       fashion. This is useful to apply updated [Install] information contained in unit files.</para>

diff --git a/src/core/dbus-manager.c b/src/core/dbus-manager.c

index 88f098ec86..2db12721a1 100644

--- a/src/core/dbus-manager.c

+++ b/src/core/dbus-manager.c

@@ -2425,6 +2425,7 @@ static int method_disable_unit_files_generic(

                 sd_bus_message *message,

                 Manager *m,

                 int (*call)(LookupScope scope, UnitFileFlags flags, const char *root_dir, char *files[], InstallChange **changes, size_t *n_changes),

+                bool carries_install_info,

                 sd_bus_error *error) {

         _cleanup_strv_free_ char **l = NULL;

@@ -2440,7 +2441,8 @@ static int method_disable_unit_files_generic(

         if (r < 0)

                 return r;

-        if (sd_bus_message_is_method_call(message, NULL, "DisableUnitFilesWithFlags")) {

+        if (sd_bus_message_is_method_call(message, NULL, "DisableUnitFilesWithFlags") ||

+            sd_bus_message_is_method_call(message, NULL, "DisableUnitFilesWithFlagsAndInstallInfo")) {

                 uint64_t raw_flags;

                 r = sd_bus_message_read(message, "t", &raw_flags);

@@ -2469,19 +2471,23 @@ static int method_disable_unit_files_generic(

         if (r < 0)

                 return install_error(error, r, changes, n_changes);

-        return reply_install_changes_and_free(m, message, -1, changes, n_changes, error);

+        return reply_install_changes_and_free(m, message, carries_install_info ? r : -1, changes, n_changes, error);

 }

 static int method_disable_unit_files_with_flags(sd_bus_message *message, void *userdata, sd_bus_error *error) {

-        return method_disable_unit_files_generic(message, userdata, unit_file_disable, error);

+        return method_disable_unit_files_generic(message, userdata, unit_file_disable, /* carries_install_info = */ false, error);

+}

+

+static int method_disable_unit_files_with_flags_and_install_info(sd_bus_message *message, void *userdata, sd_bus_error *error) {

+        return method_disable_unit_files_generic(message, userdata, unit_file_disable, /* carries_install_info = */ true, error);

 }

 static int method_disable_unit_files(sd_bus_message *message, void *userdata, sd_bus_error *error) {

-        return method_disable_unit_files_generic(message, userdata, unit_file_disable, error);

+        return method_disable_unit_files_generic(message, userdata, unit_file_disable, /* carries_install_info = */ false, error);

 }

 static int method_unmask_unit_files(sd_bus_message *message, void *userdata, sd_bus_error *error) {

-        return method_disable_unit_files_generic(message, userdata, unit_file_unmask, error);

+        return method_disable_unit_files_generic(message, userdata, unit_file_unmask, /* carries_install_info = */ false, error);

 }

 static int method_revert_unit_files(sd_bus_message *message, void *userdata, sd_bus_error *error) {

@@ -3194,6 +3200,11 @@ const sd_bus_vtable bus_manager_vtable[] = {

                                 SD_BUS_RESULT("a(sss)", changes),

                                 method_disable_unit_files_with_flags,

                                 SD_BUS_VTABLE_UNPRIVILEGED),

+        SD_BUS_METHOD_WITH_ARGS("DisableUnitFilesWithFlagsAndInstallInfo",

+                                SD_BUS_ARGS("as", files, "t", flags),

+                                SD_BUS_RESULT("b", carries_install_info, "a(sss)", changes),

+                                method_disable_unit_files_with_flags_and_install_info,

+                                SD_BUS_VTABLE_UNPRIVILEGED),

         SD_BUS_METHOD_WITH_ARGS("ReenableUnitFiles",

                                 SD_BUS_ARGS("as", files, "b", runtime, "b", force),

                                 SD_BUS_RESULT("b", carries_install_info, "a(sss)", changes),

diff --git a/src/shared/install.c b/src/shared/install.c

index 834a1c59e3..4b610b20a5 100644

--- a/src/shared/install.c

+++ b/src/shared/install.c

@@ -2790,25 +2790,38 @@ static int do_unit_file_disable(

         _cleanup_(install_context_done) InstallContext ctx = { .scope = scope };

         _cleanup_set_free_free_ Set *remove_symlinks_to = NULL;

+        InstallInfo *info;

+        bool has_install_info = false;

         int r;

         STRV_FOREACH(name, names) {

                 if (!unit_name_is_valid(*name, UNIT_NAME_ANY))

                         return install_changes_add(changes, n_changes, -EUCLEAN, *name, NULL);

-                r = install_info_add(&ctx, *name, NULL, lp->root_dir, /* auxiliary= */ false, NULL);

+                r = install_info_add(&ctx, *name, NULL, lp->root_dir, /* auxiliary= */ false, &info;;

+                if (r >= 0)

+                        r = install_info_traverse(&ctx, lp, info, SEARCH_LOAD|SEARCH_FOLLOW_CONFIG_SYMLINKS, NULL);

+

                 if (r < 0)

-                        return r;

+                        return install_changes_add(changes, n_changes, r, *name, NULL);

+

+                /* If we enable multiple units, some with install info and others without,

+                 * the "empty [Install] section" warning is not shown. Let's make the behavior

+                 * of disable align with that. */

+                has_install_info = has_install_info || install_info_has_rules(info) || install_info_has_also(info);

         }

         r = install_context_mark_for_removal(&ctx, lp, &remove_symlinks_to, config_path, changes, n_changes);

+        if (r >= 0)

+                r = remove_marked_symlinks(remove_symlinks_to, config_path, lp, flags & UNIT_FILE_DRY_RUN, changes, n_changes);

+

         if (r < 0)

                 return r;

-        return remove_marked_symlinks(remove_symlinks_to, config_path, lp, flags & UNIT_FILE_DRY_RUN, changes, n_changes);

+        /* The warning is shown only if it's a no-op */

+        return install_changes_have_modification(*changes, *n_changes) || has_install_info;

 }

-

 int unit_file_disable(

                 LookupScope scope,

                 UnitFileFlags flags,

diff --git a/src/systemctl/systemctl-enable.c b/src/systemctl/systemctl-enable.c

index 5be4c0c725..aea66872de 100644

--- a/src/systemctl/systemctl-enable.c

+++ b/src/systemctl/systemctl-enable.c

@@ -109,9 +109,10 @@ int verb_enable(int argc, char *argv[], void *userdata) {

                 if (streq(verb, "enable")) {

                         r = unit_file_enable(arg_scope, flags, arg_root, names, &changes, &n_changes);

                         carries_install_info = r;

-                } else if (streq(verb, "disable"))

+                } else if (streq(verb, "disable")) {

                         r = unit_file_disable(arg_scope, flags, arg_root, names, &changes, &n_changes);

-                else if (streq(verb, "reenable")) {

+                        carries_install_info = r;

+                } else if (streq(verb, "reenable")) {

                         r = unit_file_reenable(arg_scope, flags, arg_root, names, &changes, &n_changes);

                         carries_install_info = r;

                 } else if (streq(verb, "link"))

@@ -165,7 +166,8 @@ int verb_enable(int argc, char *argv[], void *userdata) {

                         method = "EnableUnitFiles";

                         expect_carries_install_info = true;

                 } else if (streq(verb, "disable")) {

-                        method = "DisableUnitFiles";

+                        method = "DisableUnitFilesWithFlagsAndInstallInfo";

+                        expect_carries_install_info = true;

                         send_force = false;

                 } else if (streq(verb, "reenable")) {

                         method = "ReenableUnitFiles";

@@ -208,7 +210,10 @@ int verb_enable(int argc, char *argv[], void *userdata) {

                 }

                 if (send_runtime) {

-                        r = sd_bus_message_append(m, "b", arg_runtime);

+                        if (streq(method, "DisableUnitFilesWithFlagsAndInstallInfo"))

+                                r = sd_bus_message_append(m, "t", arg_runtime ? UNIT_FILE_RUNTIME : 0);

+                        else

+                                r = sd_bus_message_append(m, "b", arg_runtime);

                         if (r < 0)

                                 return bus_log_create_error(r);

                 }

@@ -245,7 +250,7 @@ int verb_enable(int argc, char *argv[], void *userdata) {

         if (carries_install_info == 0 && !ignore_carries_install_info)

                 log_notice("The unit files have no installation config (WantedBy=, RequiredBy=, Also=,\n"

                            "Alias= settings in the [Install] section, and DefaultInstance= for template\n"

-                           "units). This means they are not meant to be enabled using systemctl.\n"

+                           "units). This means they are not meant to be enabled or disabled using systemctl.\n"

                            " \n" /* trick: the space is needed so that the line does not get stripped from output */

                            "Possible reasons for having this kind of units are:\n"

                            "%1$s A unit may be statically enabled by being symlinked from another unit's\n"