readBin differences on Windows and Linux/mac

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

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