Archive_Tar::addModify in core/modules/system/system.tar.inc

This method add the files / directories listed in $p_filelist at the end of the existing archive. If the archive does not yet exists it is created. The $p_filelist parameter can be an array of string, each string representing a filename or a directory…

Archive_Tar::addString in core/modules/system/system.tar.inc

This method add a single string as a file at the end of the existing archive. If the archive does not yet exists it is created.

Archive_Tar::_addFile in core/modules/system/system.tar.inc