Regression: Invalid read in f_directory_create().

Now that this uses f_string_static_t, the string is not necessarily NULL terminated.
This new behavior resulted in an invalid read.

Redesign to use a range check instead of a NULL check and to include a NULL terminating space in the built string.

diff --git a/level_1/fl_directory/c/directory.c b/level_1/fl_directory/c/directory.c
index b7ab091882fdea3f806e213050792e47dfbc8f90..26420953c28f7545fa420eb9181d4c0bc37b898e 100644 (file)
--- a/level_1/fl_directory/c/directory.c
+++ b/level_1/fl_directory/c/directory.c
@@ -27,15 +27,16 @@ extern "C" {
       f_array_length_t at_path = 0;
       f_string_static_t tree = f_string_static_t_initialize;
 
-      char tree_string[path.used];
+      char tree_string[path.used + 1];
       tree.string = tree_string;
       tree.used = path.used;
+      tree_string[path.used] = 0;
 
-      for (; path.string[at_path]; ++at_path) {
+      for (; at_path < path.used; ++at_path) {
 
         if (at_path && path.string[at_path] == f_path_separator_s.string[0]) {
           memcpy(tree.string, path.string + at_tree, at_path - at_tree);
-          tree.string[at_path] = 0;
+          tree.string[at_path - at_tree] = 0;
 
           status = f_directory_exists(tree);
           if (F_status_is_error(status)) return status;