1 files changed, 495 insertions, 0 deletions
diff --git a/src/libsystemd/sd-bus/bus-track.c b/src/libsystemd/sd-bus/bus-track.c
new file mode 100644
index 0000000..f9c59a1
--- /dev/null
+++ b/src/libsystemd/sd-bus/bus-track.c
@@ -0,0 +1,495 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+#include "sd-bus.h"
+
+#include "alloc-util.h"
+#include "bus-internal.h"
+#include "bus-track.h"
+#include "string-util.h"
+
+struct track_item {
+        unsigned n_ref;
+        char *name;
+        sd_bus_slot *slot;
+};
+
+struct sd_bus_track {
+        unsigned n_ref;
+        unsigned n_adding; /* are we in the process of adding a new name? */
+        sd_bus *bus;
+        sd_bus_track_handler_t handler;
+        void *userdata;
+        Hashmap *names;
+        LIST_FIELDS(sd_bus_track, queue);
+        Iterator iterator;
+        bool in_list:1;    /* In bus->tracks? */
+        bool in_queue:1;   /* In bus->track_queue? */
+        bool modified:1;
+        bool recursive:1;
+        sd_bus_destroy_t destroy_callback;
+
+        LIST_FIELDS(sd_bus_track, tracks);
+};
+
+#define MATCH_FOR_NAME(name)                            \
+        strjoina("type='signal',"                       \
+                 "sender='org.freedesktop.DBus',"       \
+                 "path='/org/freedesktop/DBus',"        \
+                 "interface='org.freedesktop.DBus',"    \
+                 "member='NameOwnerChanged',"           \
+                 "arg0='", name, "'")
+
+static struct track_item* track_item_free(struct track_item *i) {
+        if (!i)
+                return NULL;
+
+        sd_bus_slot_unref(i->slot);
+        free(i->name);
+        return mfree(i);
+}
+
+DEFINE_PRIVATE_TRIVIAL_UNREF_FUNC(struct track_item, track_item, track_item_free);
+DEFINE_TRIVIAL_CLEANUP_FUNC(struct track_item*, track_item_unref);
+DEFINE_PRIVATE_HASH_OPS_WITH_VALUE_DESTRUCTOR(track_item_hash_ops, char, string_hash_func, string_compare_func,
+                                              struct track_item, track_item_free);
+
+static void bus_track_add_to_queue(sd_bus_track *track) {
+        assert(track);
+
+        /* Adds the bus track object to the queue of objects we should dispatch next, subject to a number of
+         * conditions. */
+
+        /* Already in the queue? */
+        if (track->in_queue)
+                return;
+
+        /* if we are currently in the process of adding a new name, then let's not enqueue this just yet, let's wait
+         * until the addition is complete. */
+        if (track->n_adding > 0)
+                return;
+
+        /* still referenced? */
+        if (hashmap_size(track->names) > 0)
+                return;
+
+        /* Nothing to call? */
+        if (!track->handler)
+                return;
+
+        /* Already closed? */
+        if (!track->in_list)
+                return;
+
+        LIST_PREPEND(queue, track->bus->track_queue, track);
+        track->in_queue = true;
+}
+
+static void bus_track_remove_from_queue(sd_bus_track *track) {
+        assert(track);
+
+        if (!track->in_queue)
+                return;
+
+        LIST_REMOVE(queue, track->bus->track_queue, track);
+        track->in_queue = false;
+}
+
+static int bus_track_remove_name_fully(sd_bus_track *track, const char *name) {
+        struct track_item *i;
+
+        assert(track);
+        assert(name);
+
+        i = hashmap_remove(track->names, name);
+        if (!i)
+                return 0;
+
+        track_item_free(i);
+
+        bus_track_add_to_queue(track);
+
+        track->modified = true;
+        return 1;
+}
+
+_public_ int sd_bus_track_new(
+                sd_bus *bus,
+                sd_bus_track **track,
+                sd_bus_track_handler_t handler,
+                void *userdata) {
+
+        sd_bus_track *t;
+
+        assert_return(bus, -EINVAL);
+        assert_return(bus = bus_resolve(bus), -ENOPKG);
+        assert_return(track, -EINVAL);
+
+        if (!bus->bus_client)
+                return -EINVAL;
+
+        t = new0(sd_bus_track, 1);
+        if (!t)
+                return -ENOMEM;
+
+        t->n_ref = 1;
+        t->handler = handler;
+        t->userdata = userdata;
+        t->bus = sd_bus_ref(bus);
+
+        LIST_PREPEND(tracks, bus->tracks, t);
+        t->in_list = true;
+
+        bus_track_add_to_queue(t);
+
+        *track = t;
+        return 0;
+}
+
+static sd_bus_track *track_free(sd_bus_track *track) {
+        assert(track);
+
+        if (track->in_list)
+                LIST_REMOVE(tracks, track->bus->tracks, track);
+
+        bus_track_remove_from_queue(track);
+        track->names = hashmap_free(track->names);
+        track->bus = sd_bus_unref(track->bus);
+
+        if (track->destroy_callback)
+                track->destroy_callback(track->userdata);
+
+        return mfree(track);
+}
+
+DEFINE_PUBLIC_TRIVIAL_REF_UNREF_FUNC(sd_bus_track, sd_bus_track, track_free);
+
+static int on_name_owner_changed(sd_bus_message *message, void *userdata, sd_bus_error *error) {
+        sd_bus_track *track = ASSERT_PTR(userdata);
+        const char *name;
+        int r;
+
+        assert(message);
+
+        r = sd_bus_message_read(message, "sss", &name, NULL, NULL);
+        if (r < 0)
+                return 0;
+
+        bus_track_remove_name_fully(track, name);
+        return 0;
+}
+
+_public_ int sd_bus_track_add_name(sd_bus_track *track, const char *name) {
+        _cleanup_(track_item_unrefp) struct track_item *n = NULL;
+        struct track_item *i;
+        const char *match;
+        int r;
+
+        assert_return(track, -EINVAL);
+        assert_return(service_name_is_valid(name), -EINVAL);
+
+        i = hashmap_get(track->names, name);
+        if (i) {
+                if (track->recursive) {
+                        assert(i->n_ref > 0);
+
+                        /* Manual overflow check (instead of a DEFINE_TRIVIAL_REF_FUNC() helper or so), so
+                         * that we can return a proper error, given this is almost always called in a
+                         * directly client controllable way, and thus better should never hit an assertion
+                         * here. */
+                        if (i->n_ref >= UINT_MAX)
+                                return -EOVERFLOW;
+
+                        i->n_ref++;
+                }
+
+                bus_track_remove_from_queue(track);
+                return 0;
+        }
+
+        r = hashmap_ensure_allocated(&track->names, &track_item_hash_ops);
+        if (r < 0)
+                return r;
+
+        n = new(struct track_item, 1);
+        if (!n)
+                return -ENOMEM;
+
+        *n = (struct track_item) {
+                .n_ref = 1,
+        };
+
+        n->name = strdup(name);
+        if (!n->name)
+                return -ENOMEM;
+
+        /* First, subscribe to this name */
+        match = MATCH_FOR_NAME(name);
+
+        bus_track_remove_from_queue(track); /* don't dispatch this while we work in it */
+
+        r = sd_bus_add_match_async(track->bus, &n->slot, match, on_name_owner_changed, NULL, track);
+        if (r < 0) {
+                bus_track_add_to_queue(track);
+                return r;
+        }
+
+        r = hashmap_put(track->names, n->name, n);
+        if (r < 0) {
+                bus_track_add_to_queue(track);
+                return r;
+        }
+
+        /* Second, check if it is currently existing, or maybe doesn't, or maybe disappeared already. */
+        track->n_adding++; /* again, make sure this isn't dispatch while we are working in it */
+        r = sd_bus_get_name_creds(track->bus, name, 0, NULL);
+        track->n_adding--;
+        if (r < 0) {
+                hashmap_remove(track->names, name);
+                bus_track_add_to_queue(track);
+                return r;
+        }
+
+        TAKE_PTR(n);
+
+        bus_track_remove_from_queue(track);
+        track->modified = true;
+
+        return 1;
+}
+
+_public_ int sd_bus_track_remove_name(sd_bus_track *track, const char *name) {
+        struct track_item *i;
+
+        assert_return(name, -EINVAL);
+
+        if (!track) /* Treat a NULL track object as an empty track object */
+                return 0;
+
+        i = hashmap_get(track->names, name);
+        if (!i)
+                return 0;
+
+        assert(i->n_ref >= 1);
+        if (i->n_ref <= 1)
+                return bus_track_remove_name_fully(track, name);
+
+        track_item_unref(i);
+
+        return 1;
+}
+
+_public_ unsigned sd_bus_track_count(sd_bus_track *track) {
+
+        if (!track) /* Let's consider a NULL object equivalent to an empty object */
+                return 0;
+
+        /* This signature really should have returned an int, so that we can propagate errors. But well, ... Also, note
+         * that this returns the number of names being watched, and multiple references to the same name are not
+         * counted. */
+
+        return hashmap_size(track->names);
+}
+
+_public_ const char* sd_bus_track_contains(sd_bus_track *track, const char *name) {
+        assert_return(name, NULL);
+
+        if (!track) /* Let's consider a NULL object equivalent to an empty object */
+                return NULL;
+
+        return hashmap_contains(track->names, name) ? name : NULL;
+}
+
+_public_ const char* sd_bus_track_first(sd_bus_track *track) {
+        const char *n = NULL;
+
+        if (!track)
+                return NULL;
+
+        track->modified = false;
+        track->iterator = ITERATOR_FIRST;
+
+        (void) hashmap_iterate(track->names, &track->iterator, NULL, (const void**) &n);
+        return n;
+}
+
+_public_ const char* sd_bus_track_next(sd_bus_track *track) {
+        const char *n = NULL;
+
+        if (!track)
+                return NULL;
+
+        if (track->modified)
+                return NULL;
+
+        (void) hashmap_iterate(track->names, &track->iterator, NULL, (const void**) &n);
+        return n;
+}
+
+_public_ int sd_bus_track_add_sender(sd_bus_track *track, sd_bus_message *m) {
+        const char *sender;
+
+        assert_return(track, -EINVAL);
+        assert_return(m, -EINVAL);
+
+        if (sd_bus_message_get_bus(m) != track->bus)
+                return -EINVAL;
+
+        sender = sd_bus_message_get_sender(m);
+        if (!sender)
+                return -EINVAL;
+
+        return sd_bus_track_add_name(track, sender);
+}
+
+_public_ int sd_bus_track_remove_sender(sd_bus_track *track, sd_bus_message *m) {
+        const char *sender;
+
+        assert_return(m, -EINVAL);
+
+        if (!track) /* Treat a NULL track object as an empty track object */
+                return 0;
+
+        if (sd_bus_message_get_bus(m) != track->bus)
+                return -EINVAL;
+
+        sender = sd_bus_message_get_sender(m);
+        if (!sender)
+                return -EINVAL;
+
+        return sd_bus_track_remove_name(track, sender);
+}
+
+_public_ sd_bus* sd_bus_track_get_bus(sd_bus_track *track) {
+        assert_return(track, NULL);
+
+        return track->bus;
+}
+
+void bus_track_dispatch(sd_bus_track *track) {
+        int r;
+
+        assert(track);
+        assert(track->handler);
+
+        bus_track_remove_from_queue(track);
+
+        sd_bus_track_ref(track);
+
+        r = track->handler(track, track->userdata);
+        if (r < 0)
+                log_debug_errno(r, "Failed to process track handler: %m");
+        else if (r == 0)
+                bus_track_add_to_queue(track);
+
+        sd_bus_track_unref(track);
+}
+
+void bus_track_close(sd_bus_track *track) {
+        assert(track);
+
+        /* Called whenever our bus connected is closed. If so, and our track object is non-empty, dispatch it
+         * immediately, as we are closing now, but first flush out all names. */
+
+        if (!track->in_list)
+                return; /* We already closed this one, don't close it again. */
+
+        /* Remember that this one is closed now */
+        LIST_REMOVE(tracks, track->bus->tracks, track);
+        track->in_list = false;
+
+        /* If there's no name in this one anyway, we don't have to dispatch */
+        if (hashmap_isempty(track->names))
+                return;
+
+        /* Let's flush out all names */
+        hashmap_clear(track->names);
+
+        /* Invoke handler */
+        if (track->handler)
+                bus_track_dispatch(track);
+}
+
+_public_ void *sd_bus_track_get_userdata(sd_bus_track *track) {
+        assert_return(track, NULL);
+
+        return track->userdata;
+}
+
+_public_ void *sd_bus_track_set_userdata(sd_bus_track *track, void *userdata) {
+        void *ret;
+
+        assert_return(track, NULL);
+
+        ret = track->userdata;
+        track->userdata = userdata;
+
+        return ret;
+}
+
+_public_ int sd_bus_track_set_destroy_callback(sd_bus_track *track, sd_bus_destroy_t callback) {
+        assert_return(track, -EINVAL);
+
+        track->destroy_callback = callback;
+        return 0;
+}
+
+_public_ int sd_bus_track_get_destroy_callback(sd_bus_track *track, sd_bus_destroy_t *ret) {
+        assert_return(track, -EINVAL);
+
+        if (ret)
+                *ret = track->destroy_callback;
+
+        return !!track->destroy_callback;
+}
+
+_public_ int sd_bus_track_set_recursive(sd_bus_track *track, int b) {
+        assert_return(track, -EINVAL);
+
+        if (track->recursive == !!b)
+                return 0;
+
+        if (!hashmap_isempty(track->names))
+                return -EBUSY;
+
+        track->recursive = b;
+        return 0;
+}
+
+_public_ int sd_bus_track_get_recursive(sd_bus_track *track) {
+        assert_return(track, -EINVAL);
+
+        return track->recursive;
+}
+
+_public_ int sd_bus_track_count_sender(sd_bus_track *track, sd_bus_message *m) {
+        const char *sender;
+
+        assert_return(m, -EINVAL);
+
+        if (!track) /* Let's consider a NULL object equivalent to an empty object */
+                return 0;
+
+        if (sd_bus_message_get_bus(m) != track->bus)
+                return -EINVAL;
+
+        sender = sd_bus_message_get_sender(m);
+        if (!sender)
+                return -EINVAL;
+
+        return sd_bus_track_count_name(track, sender);
+}
+
+_public_ int sd_bus_track_count_name(sd_bus_track *track, const char *name) {
+        struct track_item *i;
+
+        assert_return(service_name_is_valid(name), -EINVAL);
+
+        if (!track) /* Let's consider a NULL object equivalent to an empty object */
+                return 0;
+
+        i = hashmap_get(track->names, name);
+        if (!i)
+                return 0;
+
+        return i->n_ref;
+}