Add argument 'force' to dos2unix() and unix2dos()

NEWS.md

@@ -8,10 +8,11 @@
 * Added function taf.libraries() to load all packages from TAF library. Code
   contributed by Iago Mosqueira.
 
+* Added argument 'force' to dos2unix() and unix2dos().
+
 * Added argument 'quiet' to make(). Renamed argument 'debug' to 'details'.
 
-* Added argument 'gitignore' to taf.skeleton() for writing a .gitignore file,
-  enabled by default.
+* Added argument 'gitignore' to taf.skeleton().
 
 * Improved draft.software() so it supports packages from r-universe. Code
   contributed by Iago Mosqueira.

R/dos2unix.R

@@ -3,6 +3,14 @@
 #' Convert line endings in a text file between Dos (CRLF) and Unix (LF) format.
 #'
 #' @param file a filename.
+#' @param force whether to proceed with the conversion when the file is not a
+#'        standard text file.
+#'
+#' @details
+#' The default value of \code{force = FALSE} is a safety feature that can avoid
+#' corrupting files that are not standard text files, such as binary files. A
+#' standard text file is one that can be read using \code{\link{readLines}}
+#' without producing warnings.
 #'
 #' @return No return value, called for side effects.
 #'
@@ -27,9 +35,18 @@
 #'
 #' @export
 
-dos2unix <- function(file)
+dos2unix <- function(file, force=FALSE)
 {
-  txt <- readLines(file)
+  if(!force)
+  {
+    owarn <- options(warn=2)  # treat warnings from readLines() as errors
+    on.exit(options(owarn))
+  }
+
+  txt <- try(readLines(file), silent=TRUE)
+  if(inherits(txt, "try-error"))
+    stop("file is not a standard text file")
+
   con <- file(file, open="wb")
   writeLines(txt, con, sep="\n")
   close(con)

R/unix2dos.R

@@ -2,9 +2,18 @@
 #'
 #' @export
 
-unix2dos <- function(file)
+unix2dos <- function(file, force=FALSE)
 {
-  txt <- readLines(file)
+  if(!force)
+  {
+    owarn <- options(warn=2)  # treat warnings from readLines() as errors
+    on.exit(options(owarn))
+  }
+
+  txt <- try(readLines(file), silent=TRUE)
+  if(inherits(txt, "try-error"))
+    stop("file is not a standard text file")
+
   con <- file(file, open="wb")
   writeLines(txt, con, sep="\r\n")
   close(con)