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, 0 insertions, 303 deletions

diff --git a/src/core/snapshot.c b/src/core/snapshot.c
deleted file mode 100644
index ba3135f401..0000000000
--- a/src/core/snapshot.c
+++ /dev/null
@@ -1,303 +0,0 @@
-/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
-
-/***
-  This file is part of systemd.
-
-  Copyright 2010 Lennart Poettering
-
-  systemd is free software; you can redistribute it and/or modify it
-  under the terms of the GNU Lesser General Public License as published by
-  the Free Software Foundation; either version 2.1 of the License, or
-  (at your option) any later version.
-
-  systemd is distributed in the hope that it will be useful, but
-  WITHOUT ANY WARRANTY; without even the implied warranty of
-  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
-  Lesser General Public License for more details.
-
-  You should have received a copy of the GNU Lesser General Public License
-  along with systemd; If not, see <http://www.gnu.org/licenses/>.
-***/
-
-#include <errno.h>
-
-#include "alloc-util.h"
-#include "bus-common-errors.h"
-#include "dbus-snapshot.h"
-#include "parse-util.h"
-#include "parse-util.h"
-#include "snapshot.h"
-#include "string-util.h"
-#include "unit-name.h"
-#include "unit.h"
-
-static const UnitActiveState state_translation_table[_SNAPSHOT_STATE_MAX] = {
-        [SNAPSHOT_DEAD] = UNIT_INACTIVE,
-        [SNAPSHOT_ACTIVE] = UNIT_ACTIVE
-};
-
-static void snapshot_init(Unit *u) {
-        Snapshot *s = SNAPSHOT(u);
-
-        assert(s);
-        assert(UNIT(s)->load_state == UNIT_STUB);
-
-        UNIT(s)->ignore_on_isolate = true;
-        UNIT(s)->ignore_on_snapshot = true;
-        UNIT(s)->allow_isolate = true;
-}
-
-static void snapshot_set_state(Snapshot *s, SnapshotState state) {
-        SnapshotState old_state;
-        assert(s);
-
-        old_state = s->state;
-        s->state = state;
-
-        if (state != old_state)
-                log_unit_debug(UNIT(s), "Changed %s -> %s", snapshot_state_to_string(old_state), snapshot_state_to_string(state));
-
-        unit_notify(UNIT(s), state_translation_table[old_state], state_translation_table[state], true);
-}
-
-static int snapshot_load(Unit *u) {
-        Snapshot *s = SNAPSHOT(u);
-
-        assert(u);
-        assert(u->load_state == UNIT_STUB);
-
-        /* Make sure that only snapshots created via snapshot_create()
-         * can be loaded */
-        if (!u->transient && UNIT(s)->manager->n_reloading <= 0)
-                return -ENOENT;
-
-        u->load_state = UNIT_LOADED;
-        return 0;
-}
-
-static int snapshot_coldplug(Unit *u) {
-        Snapshot *s = SNAPSHOT(u);
-
-        assert(s);
-        assert(s->state == SNAPSHOT_DEAD);
-
-        if (s->deserialized_state != s->state)
-                snapshot_set_state(s, s->deserialized_state);
-
-        return 0;
-}
-
-static void snapshot_dump(Unit *u, FILE *f, const char *prefix) {
-        Snapshot *s = SNAPSHOT(u);
-
-        assert(s);
-        assert(f);
-
-        fprintf(f,
-                "%sSnapshot State: %s\n"
-                "%sClean Up: %s\n",
-                prefix, snapshot_state_to_string(s->state),
-                prefix, yes_no(s->cleanup));
-}
-
-static int snapshot_start(Unit *u) {
-        Snapshot *s = SNAPSHOT(u);
-
-        assert(s);
-        assert(s->state == SNAPSHOT_DEAD);
-
-        snapshot_set_state(s, SNAPSHOT_ACTIVE);
-
-        if (s->cleanup)
-                unit_add_to_cleanup_queue(u);
-
-        return 1;
-}
-
-static int snapshot_stop(Unit *u) {
-        Snapshot *s = SNAPSHOT(u);
-
-        assert(s);
-        assert(s->state == SNAPSHOT_ACTIVE);
-
-        snapshot_set_state(s, SNAPSHOT_DEAD);
-        return 1;
-}
-
-static int snapshot_serialize(Unit *u, FILE *f, FDSet *fds) {
-        Snapshot *s = SNAPSHOT(u);
-        Unit *other;
-        Iterator i;
-
-        assert(s);
-        assert(f);
-        assert(fds);
-
-        unit_serialize_item(u, f, "state", snapshot_state_to_string(s->state));
-        unit_serialize_item(u, f, "cleanup", yes_no(s->cleanup));
-        SET_FOREACH(other, u->dependencies[UNIT_WANTS], i)
-                unit_serialize_item(u, f, "wants", other->id);
-
-        return 0;
-}
-
-static int snapshot_deserialize_item(Unit *u, const char *key, const char *value, FDSet *fds) {
-        Snapshot *s = SNAPSHOT(u);
-        int r;
-
-        assert(u);
-        assert(key);
-        assert(value);
-        assert(fds);
-
-        if (streq(key, "state")) {
-                SnapshotState state;
-
-                state = snapshot_state_from_string(value);
-                if (state < 0)
-                        log_unit_debug(u, "Failed to parse state value: %s", value);
-                else
-                        s->deserialized_state = state;
-
-        } else if (streq(key, "cleanup")) {
-
-                r = parse_boolean(value);
-                if (r < 0)
-                        log_unit_debug(u, "Failed to parse cleanup value: %s", value);
-                else
-                        s->cleanup = r;
-
-        } else if (streq(key, "wants")) {
-
-                r = unit_add_two_dependencies_by_name(u, UNIT_AFTER, UNIT_WANTS, value, NULL, true);
-                if (r < 0)
-                        return r;
-        } else
-                log_unit_debug(u, "Unknown serialization key: %s", key);
-
-        return 0;
-}
-
-_pure_ static UnitActiveState snapshot_active_state(Unit *u) {
-        assert(u);
-
-        return state_translation_table[SNAPSHOT(u)->state];
-}
-
-_pure_ static const char *snapshot_sub_state_to_string(Unit *u) {
-        assert(u);
-
-        return snapshot_state_to_string(SNAPSHOT(u)->state);
-}
-
-int snapshot_create(Manager *m, const char *name, bool cleanup, sd_bus_error *e, Snapshot **_s) {
-        _cleanup_free_ char *n = NULL;
-        Unit *other, *u = NULL;
-        Iterator i;
-        int r;
-        const char *k;
-
-        assert(m);
-        assert(_s);
-
-        if (name) {
-                if (!unit_name_is_valid(name, UNIT_NAME_PLAIN))
-                        return sd_bus_error_setf(e, SD_BUS_ERROR_INVALID_ARGS, "Unit name %s is not valid.", name);
-
-                if (!endswith(name, ".snapshot"))
-                        return sd_bus_error_setf(e, SD_BUS_ERROR_INVALID_ARGS, "Unit name %s lacks snapshot suffix.", name);
-
-                if (manager_get_unit(m, name))
-                        return sd_bus_error_setf(e, BUS_ERROR_UNIT_EXISTS, "Snapshot %s exists already.", name);
-
-        } else {
-
-                for (;;) {
-                        if (asprintf(&n, "snapshot-%u.snapshot", ++ m->n_snapshots) < 0)
-                                return -ENOMEM;
-
-                        if (!manager_get_unit(m, n)) {
-                                name = n;
-                                break;
-                        }
-
-                        n = mfree(n);
-                }
-        }
-
-        r = manager_load_unit_prepare(m, name, NULL, e, &u);
-        if (r < 0)
-                goto fail;
-
-        u->transient = true;
-        manager_dispatch_load_queue(m);
-        assert(u->load_state == UNIT_LOADED);
-
-        HASHMAP_FOREACH_KEY(other, k, m->units, i) {
-
-                if (other->ignore_on_snapshot ||
-                    other->transient)
-                        continue;
-
-                if (k != other->id)
-                        continue;
-
-                if (UNIT_VTABLE(other)->check_snapshot)
-                        if (!UNIT_VTABLE(other)->check_snapshot(other))
-                            continue;
-
-                if (!UNIT_IS_ACTIVE_OR_ACTIVATING(unit_active_state(other)))
-                        continue;
-
-                r = unit_add_two_dependencies(u, UNIT_AFTER, UNIT_WANTS, other, true);
-                if (r < 0)
-                        goto fail;
-        }
-
-        SNAPSHOT(u)->cleanup = cleanup;
-        *_s = SNAPSHOT(u);
-
-        log_unit_info(u, "Created snapshot.");
-
-        return 0;
-
-fail:
-        if (u)
-                unit_add_to_cleanup_queue(u);
-
-        return r;
-}
-
-void snapshot_remove(Snapshot *s) {
-        assert(s);
-
-        log_unit_info(UNIT(s), "Removing snapshot.");
-
-        unit_add_to_cleanup_queue(UNIT(s));
-}
-
-const UnitVTable snapshot_vtable = {
-        .object_size = sizeof(Snapshot),
-
-        .no_alias = true,
-        .no_instances = true,
-        .no_gc = true,
-
-        .init = snapshot_init,
-        .load = snapshot_load,
-
-        .coldplug = snapshot_coldplug,
-
-        .dump = snapshot_dump,
-
-        .start = snapshot_start,
-        .stop = snapshot_stop,
-
-        .serialize = snapshot_serialize,
-        .deserialize_item = snapshot_deserialize_item,
-
-        .active_state = snapshot_active_state,
-        .sub_state_to_string = snapshot_sub_state_to_string,
-
-        .bus_vtable = bus_snapshot_vtable
-};