bus: parse matches locally and allow registration of callbacks for them

This includes code to parse and split up match strings which will also
be useful to calculate bloom filter masks when the time comes.

1 files changed, 35 insertions, 0 deletions

diff --git a/src/libsystemd-bus/bus-message.c b/src/libsystemd-bus/bus-message.c
index 845e2c0040..85b9cbaae0 100644
--- a/src/libsystemd-bus/bus-message.c
+++ b/src/libsystemd-bus/bus-message.c
@@ -3002,3 +3002,38 @@ int bus_message_read_strv_extend(sd_bus_message *m, char ***l) {
 
         return 0;
 }
+
+const char* bus_message_get_arg(sd_bus_message *m, unsigned i) {
+        int r;
+        const char *t;
+        char type;
+
+        assert(m);
+
+        r = sd_bus_message_rewind(m, true);
+        if (r < 0)
+                return NULL;
+
+        while (i > 0) {
+                r = sd_bus_message_peek_type(m, &type, NULL);
+                if (r < 0)
+                        return NULL;
+
+                if (type != SD_BUS_TYPE_STRING &&
+                    type != SD_BUS_TYPE_OBJECT_PATH &&
+                    type != SD_BUS_TYPE_SIGNATURE)
+                        return NULL;
+
+                r = sd_bus_message_read_basic(m, type, &t);
+                if (r < 0)
+                        return NULL;
+
+                i--;
+        }
+
+        r = sd_bus_message_rewind(m, true);
+        if (r < 0)
+                return NULL;
+
+        return t;
+}