Added check against negative malloc and cleaned up comments

src/lxc/lxc_user_nic.c

@@ -106,6 +106,12 @@ static char **get_groupnames(void)
 	struct group *gr;
 
 	ngroups = getgroups(0, NULL);
+
+  if (ngroups == -1) {
+    fprintf(stderr, "Failed to get number of groups user belongs to\n");
+    return NULL;
+  }
+
 	group_ids = (gid_t *)malloc(sizeof(gid_t)*ngroups);
 	ret = getgroups(ngroups, group_ids);
 
@@ -242,11 +248,13 @@ static int get_alloted(char *me, char *intype, char *link, struct alloted_s **al
 		if (strcmp(link, br) != 0)
 			continue;
 
+    /* found the user with the appropriate settings, therefore finish the search.
+     * what to do if there are more than one applicable lines? not specified in the docs.
+     * since getline is implemented with realloc, we don't need to free line until exiting func.
+     */
 		append_alloted(alloted, me, n);
 		count += n;
-		break; // found the user with the appropriate settings, therefore finish the search.
-		// what to do if there are more than one applicable lines? not specified in the docs.
-		// since getline is implemented with realloc, we don't need to free line until exiting func.
+		break;
 	}
 
   // now parse any possible groups specified