Bug in file.copy: overwrite=FALSE ignored (PR#3529)

I am using R 1.7.1 on Windows XP Pro.

The 'overwrite=FALSE' argument appears to be ignored in
file.copy():

file.exists(c("file1.txt", "file2.txt"))

[1] TRUE TRUE

file.copy(from="file2.txt", to="file1.txt", overwrite=FALSE)

[1] TRUE


and sure enough, file1.txt has been overwritten.

Rich Raubertas
Biometrics Research, RY33-300
Merck & Co.

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Fix:

     if (!overwrite) {
         if (nt > nf)
             from <- rep(from, length = nt)
         exists <- file.exists(from)
         from <- from[exists]
         to <- to[exists]
     }
     file.create(to)
     file.append(to, from)


should be something like


     if (!overwrite) {
         if (nt > nf)
             from <- rep(from, length = nt)
         exists <- file.exists(to)
         if(sum(exists))
             warning("File(s) \"", paste(to[exists], collapse = ", "), 
"\" already exist(s)")
         from <- from[!exists]
         to <- to[!exists]
     }
     if (length(to)) {
         file.create(to)
         file.append(to, from)
     }


Uwe Ligges

On Mon, 21 Jul 2003 19:27:34 +0200 (MET DST),
richard_raubertas@merck.com wrote :

I am using R 1.7.1 on Windows XP Pro.

The 'overwrite=FALSE' argument appears to be ignored in
file.copy():

file.exists(c("file1.txt", "file2.txt"))

[1] TRUE TRUE

file.copy(from="file2.txt", to="file1.txt", overwrite=FALSE)

[1] TRUE

and sure enough, file1.txt has been overwritten.

There was a bug in the file.copy code; I'll submit a patch.

Duncan Murdoch

On Mon, 21 Jul 2003 20:02:39 +0200, Uwe Ligges
<ligges@statistik.uni-dortmund.de> wrote :

    if (!overwrite) {
        if (nt > nf)
            from <- rep(from, length = nt)
        exists <- file.exists(to)
        if(sum(exists))
            warning("File(s) \"", paste(to[exists], collapse = ", "), 
"\" already exist(s)")
        from <- from[!exists]
        to <- to[!exists]
    }
    if (length(to)) {
        file.create(to)
        file.append(to, from)
    }

I don't think that gets the return value right.  Presumably if you're
copying 5 files to 5 files, and two of the destination files already
exist, the return should consist of 3 TRUE values and 2 FALSE values.
Here's my rewrite:

file.copy <- function(from, to, overwrite=FALSE)
{
    if (!(nf <- length(from))) stop("no files to copy from")
    if (!(nt <- length(to)))   stop("no files to copy to")
    if (nt == 1 && file.exists(to) && file.info(to)$isdir)
        to <- file.path(to, from)
    else if (nf > nt)  stop("more `from' files than `to' files")
    if(nt > nf) from <- rep(from, length = nt)
    if (!overwrite) okay <- !file.exists(to)
    else okay <- rep(TRUE, length(to))
     
    file.create(to[okay])
    okay[okay] <- file.append(to[okay], from[okay])
    okay
}

Duncan Murdoch

On Mon, 21 Jul 2003 14:57:36 -0400, Duncan Murdoch <dmurdoch@pair.com>
wrote :

Here's my rewrite:

file.copy <- function(from, to, overwrite=FALSE)
{
   if (!(nf <- length(from))) stop("no files to copy from")
   if (!(nt <- length(to)))   stop("no files to copy to")
   if (nt == 1 && file.exists(to) && file.info(to)$isdir)
       to <- file.path(to, from)
   else if (nf > nt)  stop("more `from' files than `to' files")
   if(nt > nf) from <- rep(from, length = nt)
   if (!overwrite) okay <- !file.exists(to)
   else okay <- rep(TRUE, length(to))
    
   file.create(to[okay])
   okay[okay] <- file.append(to[okay], from[okay])
   okay
}

This isn't quite right either; it doesn't handle the case of no
eligible files or the case of copying a file onto itself properly.
The first is easy to fix (copying Uwe's test);  I think I'll just make
the second illegal.

Duncan Murdoch