FreeTDS Development Group

["Lowden, James K" <LowdenJK AT bernstein.com>]

> From: Thompson, Bill D (London) [mailto:ThompBil AT exchange.uk.ml.com]
> Sent: June 25, 2003 7:56 AM
> 
> I discovered that my iconv() would convert ISO-8859 to UTF-8 (despite
> circumstantial evidence to the contrary), so I did this and 
> got past that
> stage. However I then fell over on the ISO-8859 / UCS-2 
> conversions. My
> iconv was having none of that.

I'd look once more, Bill.  It seems very unlikely to me that it would
support UTF-8 and not UCS-2, because UCS-2 was the first of the Unicode
standards.  It might be called UCS-2LE or something more peculiar.  I can't
see how a UTF-8 conversion could be accomplished without full knowledge of
UCS-2.  (After all, UTF-8 is a multibyte "transitional" representation of
UCS-4 values.)

> If I code a replacements/iconv.c , will it have to replace my 
> existing iconv in all cases ?

Yes.  

> If so, will I also have to cater for other conversions - like the
> 8859->ASCII and the 8859->UTF-8 ?

No.  replacements/iconv.c will enable FreeTDS to do only what it used to do
without iconv: add a zero high byte to create UCS-2, and strip the high byte
to create ISO-8859-1.  It also has to support the trivial pass-through case,
because in some cases we expect iconv to copy the buffer even when it's not
strictly necessary (think tdsconvert).  

> Any Idea what an iconv_t is ? 

$ grep iconv_t /usr/pkg/include/i*.h |egrep 'type|def' |tail -1

typedef void* iconv_t;

> or at least some ideas about what I'll need to put in my own 
> version of it ?

I think you'll need 

        #if !HAVE_ICONV
        typedef void* iconv_t;
        #endif 

in tds.h.  

Another thought, Bill:  Maybe you could rip the minimum code right out of
GNU iconv.  Use their headers, their handle generation/lookup method, etc.
Probably replace just the conversion algorithm.  They're LGPL, too, same as
we use.  

--jkl
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