[Rd] readBin differences on Windows and Linux/mac

[Uwe Ligges]

I see. It is either a bug or something related to the following 
paragraph from ?seek:

      We have found so many errors in the Windows implementation of file
      positioning that users are advised to use it only at their own
      risk, and asked not to waste the R developers' time with bug
      reports on Windows' deficiencies.

I will investigate more closely when I am back in office end of this week.

Best,
Uwe




Sean Davis wrote:
> Sorry, Uwe.  Of course:
> 
> Both in relatively recent R-devel (one mac, one windows):
> 
> ### gunzip pulled from R.utils to be a simple function
> ### In R.utils, implemented as a method
> gunzip <- function(filename, destname=gsub("[.]gz$", "", filename), 
> overwrite=FALSE, remove=TRUE, BFR.SIZE=1e7) {
>   if (filename == destname)
>     stop(sprintf("Argument 'filename' and 'destname' are identical: %s", 
> filename));
>   if (!overwrite && file.exists(destname))
>     stop(sprintf("File already exists: %s", destname));
> 
>   inn <- gzfile(filename, "rb");
>   on.exit(if (!is.null(inn)) close(inn));
> 
>   out <- file(destname, "wb");
>   on.exit(close(out), add=TRUE);
> 
>   nbytes <- 0;
>   repeat {
>     bfr <- readBin(inn, what=raw(0), size=1, n=BFR.SIZE);
>     n <- length(bfr);
>     if (n == 0)
>       break;
>     nbytes <- nbytes + n;
>     writeBin(bfr, con=out, size=1);
>   };
> 
>   if (remove) {
>     close(inn);
>     inn <- NULL;
>     file.remove(filename);
>   }
>    
>   invisible(nbytes);
> }
> download.file(' 
> ftp://ftp.ncbi.nih.gov/pub/geo/DATA/SeriesMatrix/GSE1/GSE1_series_matrix.txt.gz','test.txt.gz' 
> <ftp://ftp.ncbi.nih.gov/pub/geo/DATA/SeriesMatrix/GSE1/GSE1_series_matrix.txt.gz','test.txt.gz'>)
> gunzip('test.txt.gz')
> 
> Under windows, this results in the error reported below.  Under mac and 
> linux, results in test.txt being created in the current working 
> directory.  The actual gunzip function is pretty bare bones, so I don't 
> think it complicates matters much to use it in this example. 
> 
> Sean
> 
> 
> On Dec 31, 2007 1:24 PM, Uwe Ligges <ligges at statistik.uni-dortmund.de 
> <mailto:ligges at statistik.uni-dortmund.de>> wrote:
> 
>     Can you give a reproducible example, pelase?
> 
>     Uwe Ligges
> 
> 
>     Sean Davis wrote:
>      > I have been trying to use the gunzip function in the R.utils
>     package.  It
>      > opens a connection to a gzfile, uses readBin to read from that
>     connection,
>      > and then uses writeBin to write out the raw data to a new file.
>      This works
>      > as expected under linux/mac, but under Windows, I get:
>      >
>      > Error in readBin(inn, what= raw(0), size = 1, n=BFR.SIZE)  :
>      >   negative length vectors are not allowed
>      >
>      > A simple traceback shows the error in readBin.  I wouldn't be
>     surprised if
>      > this is a programming issue not located in readBin, but I am
>     confused about
>      > the difference in behaviors on Windows versus mac/linux.  Any
>     insight into
>      > what I can do to remedy the issue and have a cross-platform gunzip()?
>      >
>      > Thanks,
>      > Sean
>      >
>      >       [[alternative HTML version deleted]]
>      >
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> 
>