tree-wide: expose "p"-suffix unref calls in public APIs to make gcc cleanup easy

GLIB has recently started to officially support the gcc cleanup
attribute in its public API, hence let's do the same for our APIs.

With this patch we'll define an xyz_unrefp() call for each public
xyz_unref() call, to make it easy to use inside a
__attribute__((cleanup())) expression. Then, all code is ported over to
make use of this.

The new calls are also documented in the man pages, with examples how to
use them (well, I only added docs where the _unref() call itself already
had docs, and the examples, only cover sd_bus_unrefp() and
sd_event_unrefp()).

This also renames sd_lldp_free() to sd_lldp_unref(), since that's how we
tend to call our destructors these days.

Note that this defines no public macro that wraps gcc's attribute and
makes it easier to use. While I think it's our duty in the library to
make our stuff easy to use, I figure it's not our duty to make gcc's own
features easy to use on its own. Most likely, client code which wants to
make use of this should define its own:

       #define _cleanup_(function) __attribute__((cleanup(function)))

Or similar, to make the gcc feature easier to use.

Making this logic public has the benefit that we can remove three header
files whose only purpose was to define these functions internally.

See #2008.

2 files changed, 7 insertions, 8 deletions

diff --git a/src/hostname/hostnamectl.c b/src/hostname/hostnamectl.c
index bf09fb8fbb..940f6f7e23 100644
--- a/src/hostname/hostnamectl.c
+++ b/src/hostname/hostnamectl.c
@@ -127,8 +127,8 @@ static void print_status_info(StatusInfo *i) {
 }
 
 static int show_one_name(sd_bus *bus, const char* attr) {
-        _cleanup_bus_message_unref_ sd_bus_message *reply = NULL;
-        _cleanup_bus_error_free_ sd_bus_error error = SD_BUS_ERROR_NULL;
+        _cleanup_(sd_bus_message_unrefp) sd_bus_message *reply = NULL;
+        _cleanup_(sd_bus_error_free) sd_bus_error error = SD_BUS_ERROR_NULL;
         const char *s;
         int r;
 
@@ -233,7 +233,7 @@ static int show_status(sd_bus *bus, char **args, unsigned n) {
 }
 
 static int set_simple_string(sd_bus *bus, const char *method, const char *value) {
-        _cleanup_bus_error_free_ sd_bus_error error = SD_BUS_ERROR_NULL;
+        _cleanup_(sd_bus_error_free) sd_bus_error error = SD_BUS_ERROR_NULL;
         int r = 0;
 
         polkit_agent_open_if_enabled();
@@ -507,7 +507,7 @@ static int hostnamectl_main(sd_bus *bus, int argc, char *argv[]) {
 }
 
 int main(int argc, char *argv[]) {
-        _cleanup_bus_flush_close_unref_ sd_bus *bus = NULL;
+        _cleanup_(sd_bus_flush_close_unrefp) sd_bus *bus = NULL;
         int r;
 
         setlocale(LC_ALL, "");
diff --git a/src/hostname/hostnamed.c b/src/hostname/hostnamed.c
index dde2baf661..e1fbacd11b 100644
--- a/src/hostname/hostnamed.c
+++ b/src/hostname/hostnamed.c
@@ -28,7 +28,6 @@
 #include "bus-util.h"
 #include "def.h"
 #include "env-util.h"
-#include "event-util.h"
 #include "fileio-label.h"
 #include "hostname-util.h"
 #include "parse-util.h"
@@ -665,7 +664,7 @@ static const sd_bus_vtable hostname_vtable[] = {
 };
 
 static int connect_bus(Context *c, sd_event *event, sd_bus **_bus) {
-        _cleanup_bus_flush_close_unref_ sd_bus *bus = NULL;
+        _cleanup_(sd_bus_flush_close_unrefp) sd_bus *bus = NULL;
         int r;
 
         assert(c);
@@ -696,8 +695,8 @@ static int connect_bus(Context *c, sd_event *event, sd_bus **_bus) {
 
 int main(int argc, char *argv[]) {
         Context context = {};
-        _cleanup_event_unref_ sd_event *event = NULL;
-        _cleanup_bus_flush_close_unref_ sd_bus *bus = NULL;
+        _cleanup_(sd_event_unrefp) sd_event *event = NULL;
+        _cleanup_(sd_bus_flush_close_unrefp) sd_bus *bus = NULL;
         int r;
 
         log_set_target(LOG_TARGET_AUTO);