[core] configparser: error on duplicate keys in array merge (fixes #2685)

From: Glenn Strauss <gstrauss@gluelogic.com>

git-svn-id: svn://svn.lighttpd.net/lighttpd/branches/lighttpd-1.4.x@3103 152afb58-edef-0310-8abb-c4023f1b3aa9

NEWS

@@ -31,6 +31,7 @@ NEWS
   * [core] refactor array search; raise array size limit to SSIZE_MAX
   * [core] fix memory leak in configparser_merge_data
   * [core] provide array_extract_element and use it
+  * [core] configparser: error on duplicate keys in array merge (fixes #2685)
 
 - 1.4.39 - 2016-01-02
   * [core] fix memset_s call (fixes #2698)

src/configparser.y

@@ -92,7 +92,13 @@ data_unset *configparser_merge_data(data_unset *op1, const data_unset *op2) {
       for (i = 0; i < src->used; i ++) {
         du = (data_unset *)src->data[i];
         if (du) {
-          array_insert_unique(dst, du->copy(du));
+          if (du->is_index_key || buffer_is_empty(du->key) || !array_get_element(dst, du->key->ptr)) {
+            array_insert_unique(dst, du->copy(du));
+          } else {
+            fprintf(stderr, "Duplicate array-key '%s'\n", du->key->ptr);
+            op1->free(op1);
+            return NULL;
+          }
         }
       }
       break;