using libgsf as unzipper

[Allin Cottrell <cottrell wfu edu>]

This post refers back to a discussion of libgsf from 2009. At 
that time Morten Welinder was good enough to give me a revised 
version of libgsf's test-cp-zip.c that unzips a zip file; see

https://mail.gnome.org/archives/gnumeric-list/2009-May/msg00017.html

Morten's suggestion works nicely, except that to get the unzip 
ball rolling it's necessary to use gsf_outfile_stdio_new() to 
acquire a GsfOutfile into which the contents of the zip file 
will be written (via the recursive "clone" function, which 
relies on gsf_outfile_new_child_full). That is, in effect you 
have to create a new directory for the zip contents.

That's OK in some cases, but in other cases I just need to 
unzip the zipfile's contents "here", in the current directory. 
I tried passing "." in the initial call to 
gsf_outfile_stdio_new(), but -- unsurprisingly -- that failed 
with the message that the directory already exists.

Any suggestions on how to get around this would be gratefully 
received!

--
Allin Cottrell
Department of Economics
Wake Forest University, NC