If the file system doesn't handle this file it should return -1 otherwise the index of the start of the root name.
Sample: .ressource@tests/acdk/vfile/tar/acdk_dmi-src.tar@/dir/fname.c The RessourceFileSystem returns strlen(.ressource@), The TarFileSytem returns .ressource@tests/acdk/vfile/tar/acdk_dmi-src.tar@
Implemented in acdk::io::ConfigFileSystemFactory, acdk::io::RessourceFileSystemFactory, acdk::net::ftp::FTPFileSystemFactory, acdk::net::UrlFileSystemFactory, acdk::vfile::tar::TarFileSystemFactory, and acdk::vfile::zip::ZipFileSystemFactory. |