MEDIUM: server: introduce srv_alloc()/srv_free() to alloc/free a server

It happens that we free servers at various places in the code, both
on error paths and at runtime thanks to the "server delete" feature. In
order to switch to an aligned struct, we'll need to change the calloc()
and free() calls. Let's first spot them and switch them to srv_alloc()
and srv_free() instead of using calloc() and either free() or ha_free().
An easy trap to fall into is that some of them are default-server
entries. The new srv_free() function also resets the pointer like
ha_free() does.

This was done by running the following coccinelle script all over the
code:

  @@
  struct server *srv;
  @@
  (
  - free(srv)
  + srv_free(&srv)
  |
  - ha_free(&srv)
  + srv_free(&srv)
  )
  @@
  struct server *srv;
  expression e1;
  expression e2;
  @@
  (
  - srv = malloc(e1)
  + srv = srv_alloc()
  |
  - srv = calloc(e1, e2)
  + srv = srv_alloc()
  )

This is marked medium because despite spotting all call places, we can
never rule out the possibility that some out-of-tree patches would
allocate their own servers and continue to use the old API... at their
own risk.

include/haproxy/server.h

@@ -179,6 +179,23 @@ void srv_set_dyncookie(struct server *s);
 int srv_check_reuse_ws(struct server *srv);
 const struct mux_ops *srv_get_ws_proto(struct server *srv);
 
+/* allocate a new server and return it (or NULL on failure). The structure is
+ * zeroed.
+ */
+static inline struct server *srv_alloc(void)
+{
+	struct server *srv;
+
+	srv = calloc(1, sizeof(*srv));
+	return srv;
+}
+
+/* free a previously allocated server an nullifies the pointer */
+static inline void srv_free(struct server **srv_ptr)
+{
+	ha_free(srv_ptr);
+}
+
 /* increase the number of cumulated streams on the designated server */
 static inline void srv_inc_sess_ctr(struct server *s)
 {

src/cli.c

@@ -3726,7 +3726,7 @@ error:
 	list_for_each_entry(child, &proc_list, list) {
 		free((char *)child->srv->conf.file); /* cast because of const char *  */
 		free(child->srv->id);
-		ha_free(&child->srv);
+		srv_free(&child->srv);
 	}
 	free(msg);
 

src/proxy.c

@@ -388,7 +388,7 @@ void deinit_proxy(struct proxy *p)
 	 */
 	if (p->defsrv) {
 		srv_free_params(p->defsrv);
-		ha_free(&p->defsrv);
+		srv_free(&p->defsrv);
 	}
 
 	if (p->lbprm.proxy_deinit)
@@ -1560,7 +1560,7 @@ void proxy_free_defaults(struct proxy *defproxy)
 	if (defproxy->defsrv)
 		ha_free((char **)&defproxy->defsrv->conf.file);
 	ha_free(&defproxy->defbe.name);
-	ha_free(&defproxy->defsrv);
+	srv_free(&defproxy->defsrv);
 
 	h = defproxy->req_cap;
 	while (h) {
@@ -1708,7 +1708,7 @@ int setup_new_proxy(struct proxy *px, const char *name, unsigned int cap, char *
 	if (name)
 		memprintf(errmsg, "proxy '%s': %s", name, *errmsg);
 
-	ha_free(&px->defsrv);
+	srv_free(&px->defsrv);
 	ha_free(&px->id);
 	counters_fe_shared_drop(&px->fe_counters.shared);
 	counters_be_shared_drop(&px->be_counters.shared);
@@ -1740,7 +1740,7 @@ struct proxy *alloc_new_proxy(const char *name, unsigned int cap, char **errmsg)
 	 * quitting.
 	 */
 	if (curproxy)
-		free(curproxy->defsrv);
+		srv_free(&curproxy->defsrv);
 	free(curproxy);
 	return NULL;
 }
@@ -1802,7 +1802,7 @@ static int proxy_defproxy_cpy(struct proxy *curproxy, const struct proxy *defpro
 			 * none allocated yet in the current proxy so we have
 			 * to allocate and pre-initialize it right now.
 			 */
-			curproxy->defsrv = calloc(1, sizeof(*curproxy->defsrv));
+			curproxy->defsrv = srv_alloc();
 			if (!curproxy->defsrv) {
 				memprintf(errmsg, "proxy '%s': out of memory allocating default-server", curproxy->id);
 				return 1;
@@ -2833,7 +2833,7 @@ static int post_section_px_cleanup()
 
 		if (curproxy->defsrv) {
 			ha_free((char **)&curproxy->defsrv->conf.file);
-			ha_free(&curproxy->defsrv);
+			srv_free(&curproxy->defsrv);
 		}
 	}
 	return 0;

src/server.c

@@ -3042,7 +3042,7 @@ struct server *new_server(struct proxy *proxy)
 {
 	struct server *srv;
 
-	srv = calloc(1, sizeof *srv);
+	srv = srv_alloc();
 	if (!srv)
 		return NULL;
 
@@ -3202,7 +3202,7 @@ struct server *srv_drop(struct server *srv)
 
 	EXTRA_COUNTERS_FREE(srv->extra_counters);
 
-	ha_free(&srv);
+	srv_free(&srv);
 
  end:
 	return next;
@@ -3354,7 +3354,7 @@ static int _srv_parse_tmpl_init(struct server *srv, struct proxy *px)
 		free_check(&newsrv->check);
 		MT_LIST_DELETE(&newsrv->global_list);
 	}
-	free(newsrv);
+	srv_free(&newsrv);
 	return i - srv->tmpl_info.nb_low;
 }
 
@@ -3712,7 +3712,7 @@ static int _srv_parse_init(struct server **srv, char **args, int *cur_arg,
 		 */
 		newsrv = curproxy->defsrv;
 		if (!newsrv) {
-			newsrv = calloc(1, sizeof(*newsrv));
+			newsrv = srv_alloc();
 			if (!newsrv) {
 				ha_alert("out of memory.\n");
 				err_code |= ERR_ALERT | ERR_ABORT;