mountd: move most of get_exportlist() into helpers

From: J. Bruce Fields <bfields@citi.umich.edu>

I needed to understand get_exportlist() recently, and it gave me
trouble.

Move detail work into helper functions to make the basic logic clear,
and to remove need for excessive nesting (and fix inconsistent
indentation levels).  Also remove unnecessary casts of void returns from
xmalloc().

Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
---
 utils/mountd/mountd.c |  142 +++++++++++++++++++++++++++++---------------------
 1 file changed, 84 insertions(+), 58 deletions(-)

--- nfs-utils-1.2.1.orig/utils/mountd/mountd.c
+++ nfs-utils-1.2.1/utils/mountd/mountd.c
@@ -509,12 +509,89 @@ get_rootfh(struct svc_req *rqstp, dirpat
 	return fh;
 }
 
+static void remove_all_clients(exportnode *e)
+{
+	struct groupnode *g, *ng;
+
+	for (g = e->ex_groups; g; g = ng) {
+		ng = g->gr_next;
+		xfree(g->gr_name);
+		xfree(g);
+	}
+	e->ex_groups = NULL;
+}
+
+static void free_exportlist(exports *elist)
+{
+	struct exportnode *e, *ne;
+
+	for (e = *elist; e != NULL; e = ne) {
+		ne = e->ex_next;
+		remove_all_clients(e);
+		xfree(e->ex_dir);
+		xfree(e);
+	}
+	*elist = NULL;
+}
+
+static void prune_clients(nfs_export *exp, struct exportnode *e)
+{
+	struct hostent 	*hp;
+	struct groupnode *c, **cp;
+
+	cp = &e->ex_groups;
+	while ((c = *cp) != NULL) {
+		if (client_gettype(c->gr_name) == MCL_FQDN
+				&& (hp = gethostbyname(c->gr_name))) {
+			hp = hostent_dup(hp);
+			if (client_check(exp->m_client, hp)) {
+				*cp = c->gr_next;
+				xfree(c->gr_name);
+				xfree(c);
+				xfree (hp);
+				continue;
+			}
+			xfree (hp);
+		}
+		cp = &(c->gr_next);
+	}
+}
+
+static exportnode *lookup_or_create_elist_entry(exports *elist, nfs_export *exp)
+{
+	exportnode *e;
+
+	for (e = *elist; e != NULL; e = e->ex_next) {
+		if (!strcmp(exp->m_export.e_path, e->ex_dir))
+			return e;
+	}
+	e = xmalloc(sizeof(*e));
+	e->ex_next = *elist;
+	e->ex_groups = NULL;
+	e->ex_dir = xstrdup(exp->m_export.e_path);
+	*elist = e;
+	return e;
+}
+
+static void insert_group(struct exportnode *e, char *newname)
+{
+	struct groupnode *g;
+
+	for (g = e->ex_groups; g; g = g->gr_next)
+		if (!strcmp(g->gr_name, newname))
+			return;
+
+	g = xmalloc(sizeof(*g));
+	g->gr_name = xstrdup(newname);
+	g->gr_next = e->ex_groups;
+	e->ex_groups = g;
+}
+
 static exports
 get_exportlist(void)
 {
 	static exports		elist = NULL;
-	struct exportnode	*e, *ne;
-	struct groupnode	*g, *ng, *c, **cp;
+	struct exportnode	*e;
 	nfs_export		*exp;
 	int			i;
 	static unsigned int	ecounter;
@@ -526,76 +603,25 @@ get_exportlist(void)
 
 	ecounter = acounter;
 
-	for (e = elist; e != NULL; e = ne) {
-		ne = e->ex_next;
-		for (g = e->ex_groups; g != NULL; g = ng) {
-			ng = g->gr_next;
-			xfree(g->gr_name);
-			xfree(g);
-		}
-		xfree(e->ex_dir);
-		xfree(e);
-	}
-	elist = NULL;
+	free_exportlist(&elist);
 
 	for (i = 0; i < MCL_MAXTYPES; i++) {
 		for (exp = exportlist[i].p_head; exp; exp = exp->m_next) {
-			for (e = elist; e != NULL; e = e->ex_next) {
-				if (!strcmp(exp->m_export.e_path, e->ex_dir))
-					break;
-			}
-			if (!e) {
-				e = (struct exportnode *) xmalloc(sizeof(*e));
-				e->ex_next = elist;
-				e->ex_groups = NULL;
-				e->ex_dir = xstrdup(exp->m_export.e_path);
-				elist = e;
-			}
+			e = lookup_or_create_elist_entry(&elist, exp);
 
 			/* We need to check if we should remove
 			   previous ones. */
 			if (i == MCL_ANONYMOUS && e->ex_groups) {
-				for (g = e->ex_groups; g; g = ng) {
-					ng = g->gr_next;
-					xfree(g->gr_name);
-					xfree(g);
-				}
-				e->ex_groups = NULL;
+				remove_all_clients(e);
 				continue;
 			}
 
 			if (i != MCL_FQDN && e->ex_groups) {
-			  struct hostent 	*hp;
-
-			  cp = &e->ex_groups;
-			  while ((c = *cp) != NULL) {
-			    if (client_gettype (c->gr_name) == MCL_FQDN
-			        && (hp = gethostbyname(c->gr_name))) {
-			      hp = hostent_dup (hp);
-			      if (client_check(exp->m_client, hp)) {
-				*cp = c->gr_next;
-				xfree(c->gr_name);
-				xfree(c);
-				xfree (hp);
-				continue;
-			      }
-			      xfree (hp);
-			    }
-			    cp = &(c->gr_next);
-			  }
+				prune_clients(exp, e);
 			}
 
 			if (exp->m_export.e_hostname [0] != '\0') {
-				for (g = e->ex_groups; g; g = g->gr_next)
-					if (strcmp (exp->m_export.e_hostname,
-						    g->gr_name) == 0)
-						break;
-				if (g)
-					continue;
-				g = (struct groupnode *) xmalloc(sizeof(*g));
-				g->gr_name = xstrdup(exp->m_export.e_hostname);
-				g->gr_next = e->ex_groups;
-				e->ex_groups = g;
+				insert_group(e, exp->m_export.e_hostname);
 			}
 		}
 	}