Load zips using real dir instead of filename

This fixes a limitation where the level filename had to be the exact
same name as the name of the zip, because the game used the name of the
level to identify the zip of which to load assets, and this also made it
impossible to use assets for more than one level in a zip.

Instead, we just look up where the level came from, so we can always
load its assets regardless of its filename.

Additionally, the zip structure checks can go away too, simplifying the
code further.

desktop_version/src/FileSystemUtils.cpp

@@ -352,157 +352,10 @@ static bool FILESYSTEM_mountAssetsFrom(const char *fname)
     return true;
 }
 
-struct ArchiveState
-{
-    const char* filename;
-    bool has_extension;
-    bool other_level_files;
-};
-
-static PHYSFS_EnumerateCallbackResult zipCheckCallback(
-    void* data,
-    const char* origdir,
-    const char* filename
-) {
-    struct ArchiveState* state = (struct ArchiveState*) data;
-    const bool has_extension = endsWith(filename, ".vvvvvv");
-    UNUSED(origdir);
-
-    if (!state->has_extension)
-    {
-        state->has_extension = has_extension;
-    }
-    if (!state->other_level_files && has_extension)
-    {
-        state->other_level_files = SDL_strcmp(
-            state->filename,
-            filename
-        ) != 0;
-    }
-
-    if (state->has_extension && state->other_level_files)
-    {
-        /* We don't need to check any more files. */
-        return PHYSFS_ENUM_STOP;
-    }
-    return PHYSFS_ENUM_OK;
-}
-
-/* For technical reasons, the level file inside a zip named LEVELNAME.zip must
- * be named LEVELNAME.vvvvvv, else its custom assets won't work;
- * if there are .vvvvvv files other than LEVELNAME.vvvvvv, they would be loaded
- * too but they won't load any assets
- *
- * For user-friendliness, we check this upfront and reject all zips that don't
- * conform to this (regardless of them containing assets or not) - otherwise a
- * level zip with assets can be played but its assets mysteriously won't work
- */
-static bool checkZipStructure(const char* filename)
-{
-    const char* real_dir = PHYSFS_getRealDir(filename);
-    char base_name[MAX_PATH];
-    char base_name_suffixed[MAX_PATH];
-    char real_path[MAX_PATH];
-    char mount_path[MAX_PATH];
-    char check_path[MAX_PATH];
-    char random_str[6 + 1];
-    bool success;
-    bool file_exists;
-    struct ArchiveState zip_state;
-
-    if (real_dir == NULL)
-    {
-        vlog_error(
-            "Could not check %s: real directory doesn't exist",
-            filename
-        );
-        return false;
-    }
-
-    SDL_snprintf(real_path, sizeof(real_path), "%s/%s", real_dir, filename);
-
-    generateBase36(random_str, sizeof(random_str));
-    SDL_snprintf(mount_path, sizeof(mount_path), ".vvv-mnt-temp-%s/", random_str);
-
-    if (!PHYSFS_mount(real_path, mount_path, 1))
-    {
-        vlog_error(
-            "Error mounting and checking %s: %s",
-            filename,
-            PHYSFS_getErrorByCode(PHYSFS_getLastErrorCode())
-        );
-        return false;
-    }
-
-    VVV_between(filename, "levels/", base_name, ".zip");
-
-    SDL_snprintf(
-        base_name_suffixed,
-        sizeof(base_name_suffixed),
-        "%s.vvvvvv",
-        base_name
-    );
-
-    SDL_snprintf(
-        check_path,
-        sizeof(check_path),
-        "%s%s",
-        mount_path,
-        base_name_suffixed
-    );
-
-    file_exists = PHYSFS_exists(check_path);
-    success = file_exists;
-
-    SDL_zero(zip_state);
-    zip_state.filename = base_name_suffixed;
-
-    PHYSFS_enumerate(mount_path, zipCheckCallback, (void*) &zip_state);
-
-    /* If no .vvvvvv files in zip, don't print warning. */
-    if (!success && zip_state.has_extension)
-    {
-        setLevelDirError(
-            "%s.zip is not structured correctly! It is missing %s.vvvvvv.",
-            base_name,
-            base_name
-        );
-    }
-
-    success &= !zip_state.other_level_files;
-
-    /* ...But if other .vvvvvv file(s), do print warning. */
-    /* This message is redundant if the correct file already DOESN'T exist. */
-    if (file_exists && zip_state.other_level_files)
-    {
-        setLevelDirError(
-            "%s.zip is not structured correctly! It has .vvvvvv file(s) other than %s.vvvvvv.",
-            base_name,
-            base_name
-        );
-    }
-
-    if (!PHYSFS_unmount(real_path))
-    {
-        vlog_error(
-            "Could not unmount %s: %s",
-            mount_path,
-            PHYSFS_getErrorByCode(PHYSFS_getLastErrorCode())
-        );
-    }
-
-    return success;
-}
-
 void FILESYSTEM_loadZip(const char* filename)
 {
     PHYSFS_File* zip = PHYSFS_openRead(filename);
 
-    if (!checkZipStructure(filename))
-    {
-        return;
-    }
-
     if (!PHYSFS_mountHandle(zip, filename, "levels", 1))
     {
         vlog_error(
@@ -517,23 +370,16 @@ void FILESYSTEM_unmountAssets(void);
 
 bool FILESYSTEM_mountAssets(const char* path)
 {
-    char filename[MAX_PATH];
+    const char* real_dir = PHYSFS_getRealDir(path);
-    char virtual_path[MAX_PATH];
 
-    VVV_between(path, "levels/", filename, ".vvvvvv");
+    if (real_dir != NULL &&
-
+    SDL_strncmp(real_dir, "levels/", sizeof("levels/") - 1) == 0 &&
-    SDL_snprintf(
+    endsWith(real_dir, ".zip"))
-        virtual_path,
-        sizeof(virtual_path),
-        "levels/%s.zip",
-        filename
-    );
-    if (FILESYSTEM_exists(virtual_path))
     {
-        /* This is a full zipped-up level including assets */
+        /* This is a level zip */
-        vlog_info("Asset directory is .zip at %s", virtual_path);
+        vlog_info("Asset directory is .zip at %s", real_dir);
 
-        if (!FILESYSTEM_mountAssetsFrom(virtual_path))
+        if (!FILESYSTEM_mountAssetsFrom(real_dir))
         {
             return false;
         }
@@ -542,13 +388,19 @@ bool FILESYSTEM_mountAssets(const char* path)
     }
     else
     {
-        /* If it's not a level, look for a level folder */
+        /* If it's not a zip, look for a level folder */
+        char filename[MAX_PATH];
+        char virtual_path[MAX_PATH];
+
+        VVV_between(path, "levels/", filename, ".vvvvvv");
+
         SDL_snprintf(
             virtual_path,
             sizeof(virtual_path),
             "levels/%s/",
             filename
         );
+
         if (FILESYSTEM_exists(virtual_path))
         {
             vlog_info("Asset directory exists at %s", virtual_path);