Get files of a directory as DataPack for SourceMod

files_of_dir.sp

// For path "dir_path", get files that match the "filter_by_extension" filter,
// and pass them by reference to a valid DataPack "out_datapack".
// Optionally supports SM's OpenDirectory parameters.
// Returns the number of files passed by reference.
// Caller is responsible for initializing and freeing the DataPack memory.
int GetFilesOfDir(const char[] dir_path, DataPack out_datapack,
	const char[] filter_by_extension="",
	bool use_valve_fs=false, const char[] valve_path_id="GAME")
{
	int num_files_found = 0;

	DirectoryListing dir = OpenDirectory(dir_path, use_valve_fs,
		valve_path_id);
	if (dir == null)
	{
		LogError("Failed to open directory");
		return 0;
	}

	char filename[PLATFORM_MAX_PATH];
	FileType ft;
	int extension_len = strlen(filter_by_extension);
	while(dir.GetNext(filename, sizeof(filename), ft))
	{
		if (ft != FileType_File)
		{
			continue;
		}

		if (extension_len > 0)
		{
			int pos = StrContains(filename, filter_by_extension);
			if (pos <= 0)
			{
				continue;
			}

			int extpos = strlen(filename) - extension_len;
			if (pos != extpos)
			{
				continue;
			}
		}

		out_datapack.WriteString(filename);
		++num_files_found;
	}

	return num_files_found;
}