differing sizes of wchar_t (client vs server)

From: Henry Townsend (henry.townsend_at_not.here)
Date: 09/25/05 

Date: Sun, 25 Sep 2005 17:12:31 -0400

I hope I'm missing something obvious here ...

My app reads text data over a socket. It's actually done via libcurl
(http://curl.haxx.se) but that doesn't matter here; the point is that I
am presented with a void * pointing to a block of raw data and a long
giving the number of bytes in the block, and that's it.

However, since my app comprises both server and client the client knows
the data is line-oriented text. All it needs to do is break it into
lines and print them to stdout, skipping certain lines. This is not
hard, using a bunch of <string.h> routines like strchr and strstr, plus
fputs(). I have this all working - when the text is 8-bit ASCII.

But for full generality I'd like the server to deliver text in the UCS-2
charset (Unicode). I figured handling this on the client side would be a
simple matter of transposing char to wchar_t and strlen() to wcslen(),
etc. But it turns out that wchar_t on my platform (and on many,
including Linux and Solaris) is 4 bytes wide. So I've got a stream of
16-bit characters from the server and mechanisms for handling 8- and
32-bit - but not 16-bit - character streams on the client!

Is there a common/elegant solution? I could allocate a buffer twice as
big as the incoming data and promote to 4-byte chars before operating on
it but that would be inelegant to say the least. Not to mention the
platforms where wchar_t is 2 bytes. I guess I could pass sizeof(wchar_t)
to the server and have it respond with 2- or 4-byte data based on that,
but that would mean a doubling of bandwidth consumption. What do people
usually do about this "impedance mismatch"?

Background: the data is basically just a list of filenames. I want to
store them in a Unicode format (which is easy on the server side since
it's written in Java where UTF-16 is the native format) because Windows
pathnames technically are Unicode. But there's not a lot of I18N stuff
to deal with here - I just want to be able to store and regurgitate
strings of 16-bit characters.

Thanks,
Henry Townsend

[PS I posted this to comp.lang.java.softwaretools first but that was
just a finger fumble. I meant to come here all along so please don't
accuse me of multiposting.]

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