[freetds] RE: latest snapshot testing on Sun Solaris

Lowden, James K LowdenJK at bernstein.com
Tue Jun 24 14:05:53 EDT 2003


> From: Thompson, Bill D (London) [mailto:ThompBil at exchange.uk.ml.com]
> Sent: June 24, 2003 12:15 PM
> 
> AFAICT from the freetds code, we're trying to get iconv to 
> say that it will
> convert the 8859 character set (in various guises) to UTF-8 (again in
> various guises), and giving up if it won't...
> 
> Have I correctly understood the problem do you think ? 

Basically, yes.  We're not trying to convert to UTF-8 per se.  We're
assessing the client character set from nl_langinfo(3) or freetds.conf(5)
;-) and taking an agnostic point of view wrt the charsets.  That is, we
don't assume anything about who's using what charset, except that we know
TDS7+ metadata are always UCS-2LE.  

What you're bumping into is our long long long discussion about character
set names.  There's no commonly accepted name (i.e. string) for charsets.
One iconv_open(3) might use "ASCII" and another might use "646".  On Mac OS
X and Win32, they're not even strings; they're numbers.  

We chose to use GNU's names as our canonical name i.e., the name to pass to
tds_iconv_open.  To figure out what to pass to iconv(3), we use a lookup
table src/tds/alternative_character_sets.h.  Your iconv's names are
definitely not there, which is the nub.  

Freddy changed some of the logic, and I haven't looked at it closely since,
so I'm a little hazy on just exactly what happens in configure and then at
runtime.  But the notion is that if iconv rejects our canonical name, we try
all the alternatives in turn until we succeed or exhaust the set.  I think
the successful one becomes our canonical name for the duration of the
session.  

> and if  so, what's the way forward ?

You could add some/all of your names to alternative_character_sets.h.  

Or you could write replacements/iconv.c, implementing iconv_open(),
iconv_close(), and iconv() for ISO-8859-1 <-> UCS-2 conversions (and same
<-> same), leaning on the old ascii2unicode logic.  That's my grand plan for
reenabling non-iconv builds.  

Or you could install GNU iconv.

Thanks for pointing this out, Bill.  I haven't had time to work on FreeTDS
since Erika got back from school, but I dislike imposing the iconv
requirement on our Romanesque users.  

--jkl
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