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authorLennart Poettering <lennart@poettering.net>2013-04-05 03:55:58 +0200
committerLennart Poettering <lennart@poettering.net>2013-04-05 03:55:58 +0200
commit7286037fd438e93137571fa68a741cc894d8e549 (patch)
treef34cbc20ec29ca10e1d866859c0f0289ed14fb72
parent6807947e56d7d1b40ec4e984a5f631fb6d5a6834 (diff)
bus: properly detect and handle if a callback is installed/removed from within a callback
-rw-r--r--src/libsystemd-bus/bus-internal.h8
-rw-r--r--src/libsystemd-bus/bus-match.c13
-rw-r--r--src/libsystemd-bus/bus-match.h3
-rw-r--r--src/libsystemd-bus/sd-bus.c106
-rw-r--r--src/systemd/sd-bus.h2
5 files changed, 103 insertions, 29 deletions
diff --git a/src/libsystemd-bus/bus-internal.h b/src/libsystemd-bus/bus-internal.h
index 9cc1c9c899..6ff3163cfd 100644
--- a/src/libsystemd-bus/bus-internal.h
+++ b/src/libsystemd-bus/bus-internal.h
@@ -46,6 +46,8 @@ struct filter_callback {
sd_bus_message_handler_t callback;
void *userdata;
+ unsigned last_iteration;
+
LIST_FIELDS(struct filter_callback, callbacks);
};
@@ -55,6 +57,8 @@ struct object_callback {
char *path;
bool is_fallback;
+
+ unsigned last_iteration;
};
enum bus_state {
@@ -86,6 +90,9 @@ struct sd_bus {
bool prefer_readv:1;
bool prefer_writev:1;
bool processing:1;
+ bool match_callbacks_modified:1;
+ bool filter_callbacks_modified:1;
+ bool object_callbacks_modified:1;
void *rbuffer;
size_t rbuffer_size;
@@ -139,6 +146,7 @@ struct sd_bus {
char **exec_argv;
uint64_t hello_serial;
+ unsigned iteration_counter;
};
static inline void bus_unrefp(sd_bus **b) {
diff --git a/src/libsystemd-bus/bus-match.c b/src/libsystemd-bus/bus-match.c
index 972ac8e00e..fed25c1a2a 100644
--- a/src/libsystemd-bus/bus-match.c
+++ b/src/libsystemd-bus/bus-match.c
@@ -212,6 +212,9 @@ int bus_match_run(
if (!node)
return 0;
+ if (bus && bus->match_callbacks_modified)
+ return 0;
+
/* Not these special semantics: when traversing the tree we
* usually let bus_match_run() when called for a node
* recursively invoke bus_match_run(). There's are two
@@ -241,6 +244,13 @@ int bus_match_run(
case BUS_MATCH_LEAF:
+ if (bus) {
+ if (node->leaf.last_iteration == bus->iteration_counter)
+ return 0;
+
+ node->leaf.last_iteration = bus->iteration_counter;
+ }
+
/* Run the callback. And then invoke siblings. */
assert(node->leaf.callback);
r = node->leaf.callback(bus, ret, m, node->leaf.userdata);
@@ -323,6 +333,9 @@ int bus_match_run(
}
}
+ if (bus && bus->match_callbacks_modified)
+ return 0;
+
/* And now, let's invoke our siblings */
return bus_match_run(bus, node->next, ret, m);
}
diff --git a/src/libsystemd-bus/bus-match.h b/src/libsystemd-bus/bus-match.h
index a31c5d67dc..075f1a9e3a 100644
--- a/src/libsystemd-bus/bus-match.h
+++ b/src/libsystemd-bus/bus-match.h
@@ -54,12 +54,13 @@ struct bus_match_node {
union {
struct {
- uint8_t u8;
char *str;
+ uint8_t u8;
} value;
struct {
sd_bus_message_handler_t callback;
void *userdata;
+ unsigned last_iteration;
} leaf;
struct {
/* If this is set, then the child is NULL */
diff --git a/src/libsystemd-bus/sd-bus.c b/src/libsystemd-bus/sd-bus.c
index 8daf922ded..943cd43cb1 100644
--- a/src/libsystemd-bus/sd-bus.c
+++ b/src/libsystemd-bus/sd-bus.c
@@ -1517,20 +1517,47 @@ static int process_filter(sd_bus *bus, sd_bus_message *m) {
assert(bus);
assert(m);
- LIST_FOREACH(callbacks, l, bus->filter_callbacks) {
- r = l->callback(bus, 0, m, l->userdata);
- if (r != 0)
- return r;
- }
+ do {
+ bus->filter_callbacks_modified = false;
+
+ LIST_FOREACH(callbacks, l, bus->filter_callbacks) {
+
+ if (bus->filter_callbacks_modified)
+ break;
+
+ /* Don't run this more than once per iteration */
+ if (l->last_iteration == bus->iteration_counter)
+ continue;
+
+ l->last_iteration = bus->iteration_counter;
+
+ r = l->callback(bus, 0, m, l->userdata);
+ if (r != 0)
+ return r;
+
+ }
+
+ } while (bus->filter_callbacks_modified);
return 0;
}
static int process_match(sd_bus *bus, sd_bus_message *m) {
+ int r;
+
assert(bus);
assert(m);
- return bus_match_run(bus, &bus->match_callbacks, 0, m);
+ do {
+ bus->match_callbacks_modified = false;
+
+ r = bus_match_run(bus, &bus->match_callbacks, 0, m);
+ if (r != 0)
+ return r;
+
+ } while (bus->match_callbacks_modified);
+
+ return 0;
}
static int process_builtin(sd_bus *bus, sd_bus_message *m) {
@@ -1588,9 +1615,9 @@ static int process_object(sd_bus *bus, sd_bus_message *m) {
_cleanup_bus_error_free_ sd_bus_error error = SD_BUS_ERROR_INIT;
_cleanup_bus_message_unref_ sd_bus_message *reply = NULL;
struct object_callback *c;
- char *p;
int r;
bool found = false;
+ size_t pl;
assert(bus);
assert(m);
@@ -1601,35 +1628,53 @@ static int process_object(sd_bus *bus, sd_bus_message *m) {
if (hashmap_isempty(bus->object_callbacks))
return 0;
- c = hashmap_get(bus->object_callbacks, m->path);
- if (c) {
- r = c->callback(bus, 0, m, c->userdata);
- if (r != 0)
- return r;
+ pl = strlen(m->path);
- found = true;
- }
+ do {
+ char p[pl+1];
- /* Look for fallback prefixes */
- p = strdupa(m->path);
- for (;;) {
- char *e;
+ bus->object_callbacks_modified = false;
- e = strrchr(p, '/');
- if (e == p || !e)
- break;
+ c = hashmap_get(bus->object_callbacks, m->path);
+ if (c && c->last_iteration != bus->iteration_counter) {
- *e = 0;
+ c->last_iteration = bus->iteration_counter;
- c = hashmap_get(bus->object_callbacks, p);
- if (c && c->is_fallback) {
r = c->callback(bus, 0, m, c->userdata);
if (r != 0)
return r;
found = true;
}
- }
+
+ /* Look for fallback prefixes */
+ strcpy(p, m->path);
+ for (;;) {
+ char *e;
+
+ if (bus->object_callbacks_modified)
+ break;
+
+ e = strrchr(p, '/');
+ if (e == p || !e)
+ break;
+
+ *e = 0;
+
+ c = hashmap_get(bus->object_callbacks, p);
+ if (c && c->last_iteration != bus->iteration_counter && c->is_fallback) {
+
+ c->last_iteration = bus->iteration_counter;
+
+ r = c->callback(bus, 0, m, c->userdata);
+ if (r != 0)
+ return r;
+
+ found = true;
+ }
+ }
+
+ } while (bus->object_callbacks_modified);
/* We found some handlers but none wanted to take this, then
* return this -- with one exception, we can handle
@@ -1750,6 +1795,8 @@ static int process_message(sd_bus *bus, sd_bus_message *m) {
assert(bus);
assert(m);
+ bus->iteration_counter++;
+
r = process_hello(bus, m);
if (r != 0)
return r;
@@ -1995,6 +2042,7 @@ int sd_bus_add_filter(sd_bus *bus, sd_bus_message_handler_t callback, void *user
f->callback = callback;
f->userdata = userdata;
+ bus->filter_callbacks_modified = true;
LIST_PREPEND(struct filter_callback, callbacks, bus->filter_callbacks, f);
return 0;
}
@@ -2009,6 +2057,7 @@ int sd_bus_remove_filter(sd_bus *bus, sd_bus_message_handler_t callback, void *u
LIST_FOREACH(callbacks, f, bus->filter_callbacks) {
if (f->callback == callback && f->userdata == userdata) {
+ bus->filter_callbacks_modified = true;
LIST_REMOVE(struct filter_callback, callbacks, bus->filter_callbacks, f);
free(f);
return 1;
@@ -2053,6 +2102,7 @@ static int bus_add_object(
c->userdata = userdata;
c->is_fallback = fallback;
+ bus->object_callbacks_modified = true;
r = hashmap_put(bus->object_callbacks, c->path, c);
if (r < 0) {
free(c->path);
@@ -2086,6 +2136,7 @@ static int bus_remove_object(
if (c->callback != callback || c->userdata != userdata || c->is_fallback != fallback)
return 0;
+ bus->object_callbacks_modified = true;
assert_se(c == hashmap_remove(bus->object_callbacks, c->path));
free(c->path);
@@ -2125,6 +2176,7 @@ int sd_bus_add_match(sd_bus *bus, const char *match, sd_bus_message_handler_t ca
}
if (callback) {
+ bus->match_callbacks_modified = true;
r = bus_match_add(&bus->match_callbacks, match, callback, userdata, NULL);
if (r < 0) {
@@ -2147,8 +2199,10 @@ int sd_bus_remove_match(sd_bus *bus, const char *match, sd_bus_message_handler_t
if (bus->bus_client)
r = bus_remove_match_internal(bus, match);
- if (callback)
+ if (callback) {
+ bus->match_callbacks_modified = true;
q = bus_match_remove(&bus->match_callbacks, match, callback, userdata);
+ }
if (r < 0)
return r;
diff --git a/src/systemd/sd-bus.h b/src/systemd/sd-bus.h
index b89394e974..057931d0df 100644
--- a/src/systemd/sd-bus.h
+++ b/src/systemd/sd-bus.h
@@ -33,8 +33,6 @@ extern "C" {
#endif
/* TODO:
- * - allow registration/removl of callbacks from within callbacks
- *
* - add page donation logic
* - api for appending/reading fixed arrays
* - merge busctl into systemctl or so?