Menu support for loading directories as content if a core indicates supports for that (#17142)

A core needs to have "/" in its list of supported extensions to indicate support for loading directories.
If a core additionally supports the disk control interface, also support loading of directories as disk images.

core_info.c

@@ -2207,13 +2207,23 @@ static bool core_info_does_support_any_file(const core_info_t *core,
 static bool core_info_does_support_file(
       const core_info_t *core, const char *path)
 {
+   const char *basename, *ext;
+
    if (!core || !core->supported_extensions_list)
       return false;
    if (string_is_empty(path))
       return false;
 
+   basename = path_basename(path);
+
+   /* if a core has / in its list of supported extensions, the core
+      supports loading of directories on the host file system */
+   if (string_is_empty(basename))
+      return string_list_find_elem(core->supported_extensions_list, "/");
+
+   ext = strrchr(basename, '.');
    return string_list_find_elem_prefix(
-         core->supported_extensions_list, ".", path_get_extension(path));
+         core->supported_extensions_list, ".", (ext ? ext + 1 : ""));
 }
 
 /* qsort_r() is not in standard C, sadly. */
@@ -2452,10 +2462,19 @@ void core_info_list_get_supported_cores(core_info_list_t *core_info_list,
    struct string_list *list      = NULL;
 #endif
    core_info_state_t *p_coreinfo = &core_info_st;
+   char dir_path[PATH_MAX_LENGTH];
 
    if (!core_info_list)
       return;
 
+   if (path_is_directory(path))
+   {
+      /* Add a slash so core_info_does_support_file can know it is
+         a directory without having to check the file system again. */
+      fill_pathname_join_special(dir_path, path, "", sizeof(dir_path));
+      path = dir_path;
+   }
+
    p_coreinfo->tmp_path          = path;
 
 #ifdef HAVE_COMPRESSION

menu/cbs/menu_cbs_ok.c

@@ -2014,6 +2014,17 @@ static int file_load_with_detect_core_wrapper(
 
       core_info_get_list(&list);
 
+      /* If loading a directory, use only path */
+      if (path == NULL && !string_is_empty(menu_path_new))
+      {
+         strlcpy(menu->deferred_path, menu_path_new,
+                 sizeof(menu->deferred_path));
+         strlcpy(menu->detect_content_path, menu_path_new,
+                 sizeof(menu->detect_content_path));
+         path = menu->detect_content_path;
+         menu_path_new[0] = '\0';
+      }
+
       def_info.data       = list;
       def_info.dir        = menu_path_new;
       def_info.path       = path;
@@ -2101,6 +2112,10 @@ static int action_ok_file_load_with_detect_core_carchive(
 static int action_ok_file_load_with_detect_core(const char *path,
       const char *label, unsigned type, size_t idx, size_t entry_idx)
 {
+   bool is_dir = (entry_idx == FILE_TYPE_USE_DIRECTORY
+         && string_is_equal(label,
+                  msg_hash_to_str(MENU_ENUM_LABEL_USE_THIS_DIRECTORY)));
+   if (is_dir) path = NULL;
 
    type  = 0;
    label = NULL;
@@ -7985,7 +8000,17 @@ static int action_ok_disk_image_append(const char *path,
 
    if (!string_is_empty(menu_path))
    {
-      if (!string_is_empty(path))
+      bool is_dir = (entry_idx == FILE_TYPE_USE_DIRECTORY
+            && string_is_equal(label,
+                     msg_hash_to_str(MENU_ENUM_LABEL_USE_THIS_DIRECTORY)));
+      if (is_dir)
+      {
+         size_t past_slash;
+         strlcpy(image_path, menu_path, sizeof(image_path));
+         past_slash = fill_pathname_slash(image_path, sizeof(image_path));
+         if (past_slash > 1) image_path[past_slash - 1] = '\0';
+      }
+      else if (!string_is_empty(path))
          fill_pathname_join_special(image_path,
                menu_path, path, sizeof(image_path));
       else

menu/menu_displaylist.c

@@ -310,6 +310,14 @@ static int filebrowser_parse(
                FILE_TYPE_USE_DIRECTORY, 0 ,0);
          break;
       default:
+         /* if a core has / in its list of supported extensions, the core
+            supports loading of directories on the host file system */
+         if (exts && strchr(exts, '/'))
+            menu_entries_prepend(info_list,
+                  msg_hash_to_str(MENU_ENUM_LABEL_VALUE_USE_THIS_DIRECTORY),
+                  msg_hash_to_str(MENU_ENUM_LABEL_USE_THIS_DIRECTORY),
+                  MSG_UNKNOWN,
+                  FILE_TYPE_PLAIN, 0, FILE_TYPE_USE_DIRECTORY);
          break;
    }