Remove snapshot unit type

Snapshots were never useful or used for anything. Many systemd
developers that I spoke to at systemd.conf2015, didn't even know they
existed, so it is fairly safe to assume that this type can be deleted
without harm.

The fundamental problem with snapshots is that the state of the system
is dynamic, devices come and go, users log in and out, timers fire...
and restoring all units to some state from the past would "undo"
those changes, which isn't really possible.

Tested by creating a snapshot, running the new binary, and checking
that the transition did not cause errors, and the snapshot is gone,
and snapshots cannot be created anymore.

New systemctl says:
Unknown operation snapshot.
Old systemctl says:
Failed to create snapshot: Support for snapshots has been removed.

IgnoreOnSnaphost settings are warned about and ignored:
Support for option IgnoreOnSnapshot= has been removed and it is ignored

http://lists.freedesktop.org/archives/systemd-devel/2015-November/034872.html

1 files changed, 4 insertions, 63 deletions

diff --git a/src/core/dbus-manager.c b/src/core/dbus-manager.c
index 1f9f25093d..eaa0fb2b37 100644
--- a/src/core/dbus-manager.c
+++ b/src/core/dbus-manager.c
@@ -31,7 +31,6 @@
 #include "dbus-execute.h"
 #include "dbus-job.h"
 #include "dbus-manager.h"
-#include "dbus-snapshot.h"
 #include "dbus-unit.h"
 #include "dbus.h"
 #include "env-util.h"
@@ -1101,66 +1100,8 @@ static int method_dump(sd_bus_message *message, void *userdata, sd_bus_error *er
         return sd_bus_reply_method_return(message, "s", dump);
 }
 
-static int method_create_snapshot(sd_bus_message *message, void *userdata, sd_bus_error *error) {
-        _cleanup_free_ char *path = NULL;
-        Manager *m = userdata;
-        const char *name;
-        int cleanup;
-        Snapshot *s = NULL;
-        int r;
-
-        assert(message);
-        assert(m);
-
-        r = mac_selinux_access_check(message, "start", error);
-        if (r < 0)
-                return r;
-
-        r = sd_bus_message_read(message, "sb", &name, &cleanup);
-        if (r < 0)
-                return r;
-
-        if (isempty(name))
-                name = NULL;
-
-        r = bus_verify_manage_units_async(m, message, error);
-        if (r < 0)
-                return r;
-        if (r == 0)
-                return 1; /* No authorization for now, but the async polkit stuff will call us again when it has it */
-
-        r = snapshot_create(m, name, cleanup, error, &s);
-        if (r < 0)
-                return r;
-
-        path = unit_dbus_path(UNIT(s));
-        if (!path)
-                return -ENOMEM;
-
-        return sd_bus_reply_method_return(message, "o", path);
-}
-
-static int method_remove_snapshot(sd_bus_message *message, void *userdata, sd_bus_error *error) {
-        Manager *m = userdata;
-        const char *name;
-        Unit *u;
-        int r;
-
-        assert(message);
-        assert(m);
-
-        r = sd_bus_message_read(message, "s", &name);
-        if (r < 0)
-                return r;
-
-        u = manager_get_unit(m, name);
-        if (!u)
-                return sd_bus_error_setf(error, BUS_ERROR_NO_SUCH_UNIT, "Unit %s does not exist.", name);
-
-        if (u->type != UNIT_SNAPSHOT)
-                return sd_bus_error_setf(error, BUS_ERROR_NO_SUCH_UNIT, "Unit %s is not a snapshot", name);
-
-        return bus_snapshot_method_remove(message, u, error);
+static int method_refuse_snapshot(sd_bus_message *message, void *userdata, sd_bus_error *error) {
+        return sd_bus_error_setf(error, SD_BUS_ERROR_NOT_SUPPORTED, "Support for snapshots has been removed.");
 }
 
 static int method_reload(sd_bus_message *message, void *userdata, sd_bus_error *error) {
@@ -2042,8 +1983,8 @@ const sd_bus_vtable bus_manager_vtable[] = {
         SD_BUS_METHOD("Subscribe", NULL, NULL, method_subscribe, SD_BUS_VTABLE_UNPRIVILEGED),
         SD_BUS_METHOD("Unsubscribe", NULL, NULL, method_unsubscribe, SD_BUS_VTABLE_UNPRIVILEGED),
         SD_BUS_METHOD("Dump", NULL, "s", method_dump, SD_BUS_VTABLE_UNPRIVILEGED),
-        SD_BUS_METHOD("CreateSnapshot", "sb", "o", method_create_snapshot, SD_BUS_VTABLE_UNPRIVILEGED),
-        SD_BUS_METHOD("RemoveSnapshot", "s", NULL, method_remove_snapshot, SD_BUS_VTABLE_UNPRIVILEGED),
+        SD_BUS_METHOD("CreateSnapshot", "sb", "o", method_refuse_snapshot, SD_BUS_VTABLE_UNPRIVILEGED),
+        SD_BUS_METHOD("RemoveSnapshot", "s", NULL, method_refuse_snapshot, SD_BUS_VTABLE_UNPRIVILEGED),
         SD_BUS_METHOD("Reload", NULL, NULL, method_reload, SD_BUS_VTABLE_UNPRIVILEGED),
         SD_BUS_METHOD("Reexecute", NULL, NULL, method_reexecute, SD_BUS_VTABLE_UNPRIVILEGED),
         SD_BUS_METHOD("Exit", NULL, NULL, method_exit, 0),