api: in constructor function calls, always put the returned object pointer first (or second)

Previously the returned object of constructor functions where sometimes
returned as last, sometimes as first and sometimes as second parameter.
Let's clean this up a bit. Here are the new rules:

1. The object the new object is derived from is put first, if there is any

2. The object we are creating will be returned in the next arguments

3. This is followed by any additional arguments

Rationale:

For functions that operate on an object we always put that object first.
Constructors should probably not be too different in this regard. Also,
if the additional parameters might want to use varargs which suggests to
put them last.

Note that this new scheme only applies to constructor functions, not to
all other functions. We do give a lot of freedom for those.

Note that this commit only changes the order of the new functions we
added, for old ones we accept the wrong order and leave it like that.

4 files changed, 29 insertions, 31 deletions

diff --git a/src/libsystemd/sd-rtnl/rtnl-message.c b/src/libsystemd/sd-rtnl/rtnl-message.c
index 5d4dc71810..8c20b8e765 100644
--- a/src/libsystemd/sd-rtnl/rtnl-message.c
+++ b/src/libsystemd/sd-rtnl/rtnl-message.c
@@ -85,9 +85,8 @@ int sd_rtnl_message_route_set_dst_prefixlen(sd_rtnl_message *m, unsigned char pr
         return 0;
 }
 
-int sd_rtnl_message_new_route(sd_rtnl *rtnl, uint16_t nlmsg_type,
-                              unsigned char rtm_family,
-                              sd_rtnl_message **ret) {
+int sd_rtnl_message_new_route(sd_rtnl *rtnl, sd_rtnl_message **ret,
+                              uint16_t nlmsg_type, unsigned char rtm_family) {
         struct rtmsg *rtm;
         int r;
 
@@ -147,8 +146,8 @@ int sd_rtnl_message_link_set_type(sd_rtnl_message *m, unsigned type) {
         return 0;
 }
 
-int sd_rtnl_message_new_link(sd_rtnl *rtnl, uint16_t nlmsg_type, int index,
-                             sd_rtnl_message **ret) {
+int sd_rtnl_message_new_link(sd_rtnl *rtnl, sd_rtnl_message **ret,
+                             uint16_t nlmsg_type, int index) {
         struct ifinfomsg *ifi;
         int r;
 
@@ -222,9 +221,9 @@ int sd_rtnl_message_addr_set_scope(sd_rtnl_message *m, unsigned char scope) {
         return 0;
 }
 
-int sd_rtnl_message_new_addr(sd_rtnl *rtnl, uint16_t nlmsg_type, int index,
-                             unsigned char family,
-                             sd_rtnl_message **ret) {
+int sd_rtnl_message_new_addr(sd_rtnl *rtnl, sd_rtnl_message **ret,
+                             uint16_t nlmsg_type, int index,
+                             unsigned char family) {
         struct ifaddrmsg *ifa;
         int r;
 
diff --git a/src/libsystemd/sd-rtnl/rtnl-util.c b/src/libsystemd/sd-rtnl/rtnl-util.c
index ec1a92e01f..fc834e9554 100644
--- a/src/libsystemd/sd-rtnl/rtnl-util.c
+++ b/src/libsystemd/sd-rtnl/rtnl-util.c
@@ -34,7 +34,7 @@ int rtnl_set_link_name(sd_rtnl *rtnl, int ifindex, const char *name) {
         assert(ifindex > 0);
         assert(name);
 
-        r = sd_rtnl_message_new_link(rtnl, RTM_SETLINK, ifindex, &message);
+        r = sd_rtnl_message_new_link(rtnl, &message, RTM_SETLINK, ifindex);
         if (r < 0)
                 return r;
 
@@ -61,7 +61,7 @@ int rtnl_set_link_properties(sd_rtnl *rtnl, int ifindex, const char *alias,
         if (!alias && !mac && mtu == 0)
                 return 0;
 
-        r = sd_rtnl_message_new_link(rtnl, RTM_SETLINK, ifindex, &message);
+        r = sd_rtnl_message_new_link(rtnl, &message, RTM_SETLINK, ifindex);
         if (r < 0)
                 return r;
 
diff --git a/src/libsystemd/sd-rtnl/sd-rtnl.c b/src/libsystemd/sd-rtnl/sd-rtnl.c
index 05889656f9..1b9f583726 100644
--- a/src/libsystemd/sd-rtnl/sd-rtnl.c
+++ b/src/libsystemd/sd-rtnl/sd-rtnl.c
@@ -70,7 +70,7 @@ static bool rtnl_pid_changed(sd_rtnl *rtnl) {
         return rtnl->original_pid != getpid();
 }
 
-int sd_rtnl_open(uint32_t groups, sd_rtnl **ret) {
+int sd_rtnl_open(sd_rtnl **ret, uint32_t groups) {
         _cleanup_rtnl_unref_ sd_rtnl *rtnl = NULL;
         socklen_t addrlen;
         int r;
@@ -774,7 +774,7 @@ int sd_rtnl_attach_event(sd_rtnl *rtnl, sd_event *event, int priority) {
                         return r;
         }
 
-        r = sd_event_add_io(rtnl->event, rtnl->fd, 0, io_callback, rtnl, &rtnl->io_event_source);
+        r = sd_event_add_io(rtnl->event, &rtnl->io_event_source, rtnl->fd, 0, io_callback, rtnl);
         if (r < 0)
                 goto fail;
 
@@ -786,7 +786,7 @@ int sd_rtnl_attach_event(sd_rtnl *rtnl, sd_event *event, int priority) {
         if (r < 0)
                 goto fail;
 
-        r = sd_event_add_monotonic(rtnl->event, 0, 0, time_callback, rtnl, &rtnl->time_event_source);
+        r = sd_event_add_monotonic(rtnl->event, &rtnl->time_event_source, 0, 0, time_callback, rtnl);
         if (r < 0)
                 goto fail;
 
@@ -794,7 +794,7 @@ int sd_rtnl_attach_event(sd_rtnl *rtnl, sd_event *event, int priority) {
         if (r < 0)
                 goto fail;
 
-        r = sd_event_add_exit(rtnl->event, exit_callback, rtnl, &rtnl->exit_event_source);
+        r = sd_event_add_exit(rtnl->event, &rtnl->exit_event_source, exit_callback, rtnl);
         if (r < 0)
                 goto fail;
 
diff --git a/src/libsystemd/sd-rtnl/test-rtnl.c b/src/libsystemd/sd-rtnl/test-rtnl.c
index 5ab06d5bad..497cefd4f9 100644
--- a/src/libsystemd/sd-rtnl/test-rtnl.c
+++ b/src/libsystemd/sd-rtnl/test-rtnl.c
@@ -37,7 +37,7 @@ static void test_link_configure(sd_rtnl *rtnl, int ifindex) {
         void *data;
 
         /* we'd really like to test NEWLINK, but let's not mess with the running kernel */
-        assert(sd_rtnl_message_new_link(rtnl, RTM_GETLINK, ifindex, &message) >= 0);
+        assert(sd_rtnl_message_new_link(rtnl, &message, RTM_GETLINK, ifindex) >= 0);
         assert(sd_rtnl_message_append_string(message, IFLA_IFNAME, name) >= 0);
         assert(sd_rtnl_message_append_ether_addr(message, IFLA_ADDRESS, ether_aton(mac)) >= 0);
         assert(sd_rtnl_message_append_u32(message, IFLA_MTU, mtu) >= 0);
@@ -57,7 +57,6 @@ static void test_link_configure(sd_rtnl *rtnl, int ifindex) {
         assert(mtu == *(unsigned int *) data);
 }
 
-
 static void test_link_get(sd_rtnl *rtnl, int ifindex) {
         sd_rtnl_message *m;
         sd_rtnl_message *r;
@@ -66,7 +65,7 @@ static void test_link_get(sd_rtnl *rtnl, int ifindex) {
         void *data;
         uint16_t type;
 
-        assert(sd_rtnl_message_new_link(rtnl, RTM_GETLINK, ifindex, &m) >= 0);
+        assert(sd_rtnl_message_new_link(rtnl, &m, RTM_GETLINK, ifindex) >= 0);
         assert(m);
 
         /* u8 test cases  */
@@ -137,7 +136,7 @@ static void test_route(void) {
         void *data;
         int r;
 
-        r = sd_rtnl_message_new_route(NULL, RTM_NEWROUTE, AF_INET, &req);
+        r = sd_rtnl_message_new_route(NULL, &req, RTM_NEWROUTE, AF_INET);
         if (r < 0) {
                 log_error("Could not create RTM_NEWROUTE message: %s", strerror(-r));
                 return;
@@ -171,8 +170,8 @@ static void test_route(void) {
 static void test_multiple(void) {
         sd_rtnl *rtnl1, *rtnl2;
 
-        assert(sd_rtnl_open(0, &rtnl1) >= 0);
-        assert(sd_rtnl_open(0, &rtnl2) >= 0);
+        assert(sd_rtnl_open(&rtnl1, 0) >= 0);
+        assert(sd_rtnl_open(&rtnl2, 0) >= 0);
 
         rtnl1 = sd_rtnl_unref(rtnl1);
         rtnl2 = sd_rtnl_unref(rtnl2);
@@ -215,8 +214,8 @@ static void test_event_loop(int ifindex) {
         ifname = strdup("lo2");
         assert(ifname);
 
-        assert(sd_rtnl_open(0, &rtnl) >= 0);
-        assert(sd_rtnl_message_new_link(rtnl, RTM_GETLINK, ifindex, &m) >= 0);
+        assert(sd_rtnl_open(&rtnl, 0) >= 0);
+        assert(sd_rtnl_message_new_link(rtnl, &m, RTM_GETLINK, ifindex) >= 0);
 
         assert(sd_rtnl_call_async(rtnl, m, &link_handler, ifname, 0, NULL) >= 0);
 
@@ -248,9 +247,9 @@ static void test_async(int ifindex) {
         ifname = strdup("lo");
         assert(ifname);
 
-        assert(sd_rtnl_open(0, &rtnl) >= 0);
+        assert(sd_rtnl_open(&rtnl, 0) >= 0);
 
-        assert(sd_rtnl_message_new_link(rtnl, RTM_GETLINK, ifindex, &m) >= 0);
+        assert(sd_rtnl_message_new_link(rtnl, &m, RTM_GETLINK, ifindex) >= 0);
 
         assert(sd_rtnl_call_async(rtnl, m, &link_handler, ifname, 0, &serial) >= 0);
 
@@ -263,10 +262,10 @@ static void test_pipe(int ifindex) {
         _cleanup_rtnl_message_unref_ sd_rtnl_message *m1 = NULL, *m2 = NULL;
         int counter = 0;
 
-        assert(sd_rtnl_open(0, &rtnl) >= 0);
+        assert(sd_rtnl_open(&rtnl, 0) >= 0);
 
-        assert(sd_rtnl_message_new_link(rtnl, RTM_GETLINK, ifindex, &m1) >= 0);
-        assert(sd_rtnl_message_new_link(rtnl, RTM_GETLINK, ifindex, &m2) >= 0);
+        assert(sd_rtnl_message_new_link(rtnl, &m1, RTM_GETLINK, ifindex) >= 0);
+        assert(sd_rtnl_message_new_link(rtnl, &m2, RTM_GETLINK, ifindex) >= 0);
 
         counter ++;
         assert(sd_rtnl_call_async(rtnl, m1, &pipe_handler, &counter, 0, NULL) >= 0);
@@ -285,7 +284,7 @@ static void test_container(void) {
         uint16_t type;
         void *data;
 
-        assert(sd_rtnl_message_new_link(NULL, RTM_NEWLINK, 0, &m) >= 0);
+        assert(sd_rtnl_message_new_link(NULL, &m, RTM_NEWLINK, 0) >= 0);
 
         assert(sd_rtnl_message_open_container(m, IFLA_LINKINFO) >= 0);
         assert(sd_rtnl_message_open_container(m, IFLA_LINKINFO) == -ENOTSUP);
@@ -325,7 +324,7 @@ static void test_container(void) {
 static void test_match(void) {
         _cleanup_rtnl_unref_ sd_rtnl *rtnl = NULL;
 
-        assert(sd_rtnl_open(0, &rtnl) >= 0);
+        assert(sd_rtnl_open(&rtnl, 0) >= 0);
 
         assert(sd_rtnl_add_match(rtnl, RTM_NEWLINK, &link_handler, NULL) >= 0);
         assert(sd_rtnl_add_match(rtnl, RTM_NEWLINK, &link_handler, NULL) >= 0);
@@ -351,7 +350,7 @@ int main(void) {
 
         test_container();
 
-        assert(sd_rtnl_open(0, &rtnl) >= 0);
+        assert(sd_rtnl_open(&rtnl, 0) >= 0);
         assert(rtnl);
 
         if_loopback = (int) if_nametoindex("lo");
@@ -365,7 +364,7 @@ int main(void) {
 
         test_link_configure(rtnl, if_loopback);
 
-        assert(sd_rtnl_message_new_link(rtnl, RTM_GETLINK, if_loopback, &m) >= 0);
+        assert(sd_rtnl_message_new_link(rtnl, &m, RTM_GETLINK, if_loopback) >= 0);
         assert(m);
 
         assert(sd_rtnl_message_get_type(m, &type) >= 0);