bus: wrap KDBUS_CMD_BYEBYE with a high-level call sd_bus_try_close()

src/libsystemd-bus/bus-kernel.c

@@ -1266,3 +1266,13 @@ int bus_kernel_create_monitor(const char *bus) {
 
         return fd;
 }
+
+int bus_kernel_try_close(sd_bus *bus) {
+        assert(bus);
+        assert(bus->is_kernel);
+
+        if (ioctl(bus->input_fd, KDBUS_CMD_BYEBYE) < 0)
+                return -errno;
+
+        return 0;
+}

src/libsystemd-bus/bus-kernel.h

@@ -75,3 +75,5 @@ int bus_kernel_parse_unique_name(const char *s, uint64_t *id);
 
 int kdbus_translate_request_name_flags(uint64_t sd_bus_flags, uint64_t *kdbus_flags);
 int kdbus_translate_attach_flags(uint64_t sd_bus_flags, uint64_t *kdbus_flags);
+
+int bus_kernel_try_close(sd_bus *bus);

src/libsystemd-bus/libsystemd-bus.sym

@@ -31,6 +31,7 @@ global:
         sd_bus_negotiate_attach_creds;
         sd_bus_start;
         sd_bus_close;
+        sd_bus_try_close;
         sd_bus_ref;
         sd_bus_unref;
         sd_bus_is_open;

src/libsystemd-bus/sd-bus.c

@@ -2956,3 +2956,19 @@ _public_ int sd_bus_get_peer_creds(sd_bus *bus, uint64_t mask, sd_bus_creds **re
         *ret = c;
         return 0;
 }
+
+_public_ int sd_bus_try_close(sd_bus *bus) {
+        int r;
+
+        assert_return(bus, -EINVAL);
+        assert_return(BUS_IS_OPEN(bus->state), -ENOTCONN);
+        assert_return(!bus_pid_changed(bus), -ECHILD);
+        assert_return(bus->is_kernel, -ENOTSUP);
+
+        r = bus_kernel_try_close(bus);
+        if (r < 0)
+                return r;
+
+        sd_bus_close(bus);
+        return 0;
+}

src/libsystemd-bus/test-bus-kernel.c

@@ -95,6 +95,9 @@ int main(int argc, char *argv[]) {
         r = sd_bus_emit_signal(a, "/foo/bar/waldo", "waldo.com", "Piep", "sss", "I am a string", "/this/is/a/path", "and.this.a.domain.name");
         assert_se(r >= 0);
 
+        r = sd_bus_try_close(b);
+        assert_se(r == -EBUSY);
+
         r = sd_bus_process(b, &m);
         assert_se(r > 0);
         assert_se(m);
@@ -160,6 +163,9 @@ int main(int argc, char *argv[]) {
         r = sd_bus_release_name(a, "net.x0pointer.foobar");
         assert_se(r == -ESRCH);
 
+        r = sd_bus_try_close(a);
+        assert_se(r >= 0);
+
         sd_bus_unref(a);
         sd_bus_unref(b);
 

src/systemd/sd-bus.h

@@ -115,6 +115,7 @@ int sd_bus_negotiate_attach_timestamp(sd_bus *bus, int b);
 int sd_bus_negotiate_attach_creds(sd_bus *bus, uint64_t creds_mask);
 int sd_bus_start(sd_bus *ret);
 
+int sd_bus_try_close(sd_bus *bus);
 void sd_bus_close(sd_bus *bus);
 
 sd_bus *sd_bus_ref(sd_bus *bus);