R/lightWeightCopy.R

In jbrzusto/motus-R-package: Operate a server to process data for http://motus.org

#' Make a light-weight recursive copy of a folder.
#'
#' This uses hard (or symbolic) links wherever possible, so that file
#' data are not copied, but falls back to normal copy where necessary.
#'
#' @param src character vector; paths to source files / folders
#'
#' @param dst character scalar; path to target folder
#'
#' @param sym logical scalar; if TRUE, use symbolic links instead
#' of hard links.  Default: FALSE
#'
#' @return TRUE on success, FALSE otherwise.
#'
#' @export
#'
#' @author John Brzustowski \email{jbrzusto@@REMOVE_THIS_PART_fastmail.fm}

lightWeightCopy = function(src, dst, sym=FALSE) {
    ## try with hard-links first
    rv = safeSys("cp", "--recursive", if (sym) "--symbolic-link" else "--link", src, dst, minErrorCode=10000)
    if (attr(rv, "exitCode") == 0)
        return(TRUE)

    ## fallback to normal copying
    rv = safeSys("cp", "--recursive", src, dst, minErrorCode=10000)
    return (attr(rv, "exitCode") == 0)
}