bus: properly detect and handle if a callback is installed/removed from within a callback
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6807947e56
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7286037fd4
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@ -46,6 +46,8 @@ struct filter_callback {
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sd_bus_message_handler_t callback;
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void *userdata;
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unsigned last_iteration;
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LIST_FIELDS(struct filter_callback, callbacks);
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};
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@ -55,6 +57,8 @@ struct object_callback {
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char *path;
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bool is_fallback;
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unsigned last_iteration;
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};
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enum bus_state {
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@ -86,6 +90,9 @@ struct sd_bus {
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bool prefer_readv:1;
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bool prefer_writev:1;
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bool processing:1;
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bool match_callbacks_modified:1;
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bool filter_callbacks_modified:1;
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bool object_callbacks_modified:1;
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void *rbuffer;
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size_t rbuffer_size;
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@ -139,6 +146,7 @@ struct sd_bus {
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char **exec_argv;
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uint64_t hello_serial;
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unsigned iteration_counter;
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};
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static inline void bus_unrefp(sd_bus **b) {
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@ -212,6 +212,9 @@ int bus_match_run(
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if (!node)
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return 0;
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if (bus && bus->match_callbacks_modified)
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return 0;
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/* Not these special semantics: when traversing the tree we
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* usually let bus_match_run() when called for a node
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* recursively invoke bus_match_run(). There's are two
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@ -241,6 +244,13 @@ int bus_match_run(
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case BUS_MATCH_LEAF:
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if (bus) {
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if (node->leaf.last_iteration == bus->iteration_counter)
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return 0;
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node->leaf.last_iteration = bus->iteration_counter;
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}
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/* Run the callback. And then invoke siblings. */
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assert(node->leaf.callback);
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r = node->leaf.callback(bus, ret, m, node->leaf.userdata);
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@ -323,6 +333,9 @@ int bus_match_run(
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}
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}
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if (bus && bus->match_callbacks_modified)
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return 0;
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/* And now, let's invoke our siblings */
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return bus_match_run(bus, node->next, ret, m);
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}
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@ -54,12 +54,13 @@ struct bus_match_node {
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union {
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struct {
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uint8_t u8;
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char *str;
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uint8_t u8;
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} value;
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struct {
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sd_bus_message_handler_t callback;
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void *userdata;
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unsigned last_iteration;
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} leaf;
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struct {
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/* If this is set, then the child is NULL */
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@ -1517,20 +1517,47 @@ static int process_filter(sd_bus *bus, sd_bus_message *m) {
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assert(bus);
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assert(m);
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LIST_FOREACH(callbacks, l, bus->filter_callbacks) {
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r = l->callback(bus, 0, m, l->userdata);
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if (r != 0)
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return r;
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}
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do {
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bus->filter_callbacks_modified = false;
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LIST_FOREACH(callbacks, l, bus->filter_callbacks) {
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if (bus->filter_callbacks_modified)
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break;
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/* Don't run this more than once per iteration */
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if (l->last_iteration == bus->iteration_counter)
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continue;
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l->last_iteration = bus->iteration_counter;
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r = l->callback(bus, 0, m, l->userdata);
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if (r != 0)
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return r;
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}
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} while (bus->filter_callbacks_modified);
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return 0;
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}
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static int process_match(sd_bus *bus, sd_bus_message *m) {
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int r;
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assert(bus);
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assert(m);
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return bus_match_run(bus, &bus->match_callbacks, 0, m);
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do {
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bus->match_callbacks_modified = false;
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r = bus_match_run(bus, &bus->match_callbacks, 0, m);
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if (r != 0)
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return r;
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} while (bus->match_callbacks_modified);
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return 0;
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}
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static int process_builtin(sd_bus *bus, sd_bus_message *m) {
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@ -1588,9 +1615,9 @@ static int process_object(sd_bus *bus, sd_bus_message *m) {
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_cleanup_bus_error_free_ sd_bus_error error = SD_BUS_ERROR_INIT;
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_cleanup_bus_message_unref_ sd_bus_message *reply = NULL;
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struct object_callback *c;
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char *p;
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int r;
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bool found = false;
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size_t pl;
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assert(bus);
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assert(m);
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@ -1601,35 +1628,53 @@ static int process_object(sd_bus *bus, sd_bus_message *m) {
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if (hashmap_isempty(bus->object_callbacks))
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return 0;
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c = hashmap_get(bus->object_callbacks, m->path);
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if (c) {
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r = c->callback(bus, 0, m, c->userdata);
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if (r != 0)
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return r;
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pl = strlen(m->path);
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found = true;
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}
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do {
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char p[pl+1];
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/* Look for fallback prefixes */
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p = strdupa(m->path);
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for (;;) {
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char *e;
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bus->object_callbacks_modified = false;
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e = strrchr(p, '/');
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if (e == p || !e)
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break;
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c = hashmap_get(bus->object_callbacks, m->path);
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if (c && c->last_iteration != bus->iteration_counter) {
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*e = 0;
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c->last_iteration = bus->iteration_counter;
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c = hashmap_get(bus->object_callbacks, p);
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if (c && c->is_fallback) {
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r = c->callback(bus, 0, m, c->userdata);
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if (r != 0)
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return r;
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found = true;
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}
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}
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/* Look for fallback prefixes */
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strcpy(p, m->path);
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for (;;) {
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char *e;
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if (bus->object_callbacks_modified)
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break;
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e = strrchr(p, '/');
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if (e == p || !e)
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break;
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*e = 0;
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c = hashmap_get(bus->object_callbacks, p);
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if (c && c->last_iteration != bus->iteration_counter && c->is_fallback) {
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c->last_iteration = bus->iteration_counter;
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r = c->callback(bus, 0, m, c->userdata);
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if (r != 0)
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return r;
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found = true;
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}
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}
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} while (bus->object_callbacks_modified);
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/* We found some handlers but none wanted to take this, then
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* return this -- with one exception, we can handle
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@ -1750,6 +1795,8 @@ static int process_message(sd_bus *bus, sd_bus_message *m) {
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assert(bus);
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assert(m);
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bus->iteration_counter++;
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r = process_hello(bus, m);
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if (r != 0)
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return r;
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@ -1995,6 +2042,7 @@ int sd_bus_add_filter(sd_bus *bus, sd_bus_message_handler_t callback, void *user
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f->callback = callback;
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f->userdata = userdata;
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bus->filter_callbacks_modified = true;
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LIST_PREPEND(struct filter_callback, callbacks, bus->filter_callbacks, f);
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return 0;
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}
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@ -2009,6 +2057,7 @@ int sd_bus_remove_filter(sd_bus *bus, sd_bus_message_handler_t callback, void *u
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LIST_FOREACH(callbacks, f, bus->filter_callbacks) {
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if (f->callback == callback && f->userdata == userdata) {
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bus->filter_callbacks_modified = true;
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LIST_REMOVE(struct filter_callback, callbacks, bus->filter_callbacks, f);
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free(f);
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return 1;
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@ -2053,6 +2102,7 @@ static int bus_add_object(
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c->userdata = userdata;
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c->is_fallback = fallback;
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bus->object_callbacks_modified = true;
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r = hashmap_put(bus->object_callbacks, c->path, c);
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if (r < 0) {
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free(c->path);
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@ -2086,6 +2136,7 @@ static int bus_remove_object(
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if (c->callback != callback || c->userdata != userdata || c->is_fallback != fallback)
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return 0;
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bus->object_callbacks_modified = true;
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assert_se(c == hashmap_remove(bus->object_callbacks, c->path));
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free(c->path);
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@ -2125,6 +2176,7 @@ int sd_bus_add_match(sd_bus *bus, const char *match, sd_bus_message_handler_t ca
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}
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if (callback) {
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bus->match_callbacks_modified = true;
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r = bus_match_add(&bus->match_callbacks, match, callback, userdata, NULL);
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if (r < 0) {
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@ -2147,8 +2199,10 @@ int sd_bus_remove_match(sd_bus *bus, const char *match, sd_bus_message_handler_t
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if (bus->bus_client)
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r = bus_remove_match_internal(bus, match);
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if (callback)
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if (callback) {
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bus->match_callbacks_modified = true;
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q = bus_match_remove(&bus->match_callbacks, match, callback, userdata);
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}
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if (r < 0)
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return r;
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@ -33,8 +33,6 @@ extern "C" {
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#endif
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/* TODO:
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* - allow registration/removl of callbacks from within callbacks
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*
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* - add page donation logic
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* - api for appending/reading fixed arrays
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* - merge busctl into systemctl or so?
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