Fixed memory checks and faulty loop in get_alloted according to comments

doc/lxc-usernet.sgml.in

@@ -133,12 +133,12 @@ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
       </variablelist>
 
       <para>
-        Since a user can be be specified both by username as well as one or 
-        more usergroups, it is possible that several configuration lines 
-        enable that user to create network interfaces. In such cases, any 
-        interfaces create are counted towards the quotas of the user or group 
-        in the order in which they appear in the file. If the quota of one 
-        line is full, the rest will be parsed until one is found or the end of 
+        Since a user can be be specified both by username as well as one or
+        more usergroups, it is possible that several configuration lines
+        enable that user to create network interfaces. In such cases, any
+        interfaces create are counted towards the quotas of the user or group
+        in the order in which they appear in the file. If the quota of one
+        line is full, the rest will be parsed until one is found or the end of
         the file.
       </para>
     </refsect2>

src/lxc/lxc_user_nic.c

@@ -97,42 +97,63 @@ static char *get_username(void)
 	return pwd->pw_name;
 }
 
+static void free_groupnames(char **groupnames)
+{
+	char **group;
+	for (group=groupnames; group != NULL; group++)
+		free(*group);
+	free(groupnames);
+}
+
 static char **get_groupnames(void)
 {
 	int ngroups;
 	gid_t *group_ids;
-	int ret, i, j;
+	int ret, i;
 	char **groupnames;
 	struct group *gr;
 
 	ngroups = getgroups(0, NULL);
 
 	if (ngroups == -1) {
-		fprintf(stderr, "Failed to get number of groups user belongs to\n");
+		fprintf(stderr, "Failed to get number of groups user belongs to: %s\n", strerror(errno));
 		return NULL;
 	}
+	if (ngroups == 0)
+		return NULL;
 
 	group_ids = (gid_t *)malloc(sizeof(gid_t)*ngroups);
+
+	if (group_ids == NULL) {
+		fprintf(stderr, "Out of memory while getting groups the user belongs to\n");
+		return NULL;
+	}
+
 	ret = getgroups(ngroups, group_ids);
 
 	if (ret < 0) {
 		free(group_ids);
-		fprintf(stderr, "Failed to get process groups\n");
+		fprintf(stderr, "Failed to get process groups: %s\n", strerror(errno));
 		return NULL;
 	}
 
 	groupnames = (char **)malloc(sizeof(char *)*(ngroups+1));
 
+	if (groupnames == NULL) {
+		free(group_ids);
+		fprintf(stderr, "Out of memory while getting group names\n");
+		return NULL;
+	}
+
+	memset(groupnames, 0, sizeof(char *)*(ngroups+1));
+
 	for (i=0; i<ngroups; i++ ) {
 		gr = getgrgid(group_ids[i]);
 
 		if (gr == NULL) {
 			fprintf(stderr, "Failed to get group name\n");
 			free(group_ids);
-			for (j=0; j<i; j++) {
-				free(groupnames[j]);
-			}
-			free(groupnames);
+			free_groupnames(groupnames);
 			return NULL;
 		}
 
@@ -141,29 +162,16 @@ static char **get_groupnames(void)
 		if (groupnames[i] == NULL) {
 			fprintf(stderr, "Failed to copy group name: %s", gr->gr_name);
 			free(group_ids);
-			for (j=0; j<i; j++) {
-				free(groupnames[j]);
-			}
-			free(groupnames);
+			free_groupnames(groupnames);
 			return NULL;
 		}
 	}
 
-	groupnames[ngroups] = NULL;
-
 	free(group_ids);
 
 	return groupnames;
 }
 
-static void free_groupnames(char **groupnames)
-{
-	char **group;
-	for (group=groupnames; group != NULL; group++)
-		free(*group);
-	free(groupnames);
-}
-
 static bool name_is_in_groupnames(char *name, char **groupnames)
 {
 	while (groupnames != NULL) {
@@ -197,6 +205,12 @@ static struct alloted_s *append_alloted(struct alloted_s **head, char *name, int
 	}
 
 	al->name = strdup(name);
+
+	if (al->name == NULL) {
+		free(al);
+		return NULL;
+	}
+
 	al->allowed = n;
 	al->next = NULL;
 
@@ -283,12 +297,13 @@ static int get_alloted(char *me, char *intype, char *link, struct alloted_s **al
 		 */
 		append_alloted(alloted, name, n);
 		count += n;
-		break;
 	}
 
 	free_groupnames(groups);
 	fclose(fin);
 	free(line);
+
+	// now return the total number of nics that this user can create
 	return count;
 }