On 2019-Dec-07, Tom Lane wrote:
> 0001:
> It is a very bad idea that this is truncating text without regard to
> multibyte character boundaries.
Hmm. So it turns out that we recently made stringinfo.c exported to
frontends in libpgcommon. Clipping strings at a given character size
means we need some facility like pg_encoding_mbcliplen.
However, 1) pgcommon does not have wchar.c (libpq does have it), and 2)
mbcliplen is not in wchar.c anyway.
I see four possible ways forward, with nuances. In order of preference:
1. change enough of the build system so that pg_encoding_mbcliplen is
available. (Offhand I see no reason why we couldn't move the
function from mbutils.c to wchar.c, but I haven't tried.)
2. in frontend, ignore the specified length; always copy the whole
string.
3. don't allow length clipping in frontend. (We have no use for it
in the near future.)
3a. Throw a run-time error if it's requested.
3b. throw a compile-time error if requested
4. don't provide this new function #if FRONTEND
--
Álvaro Herrera https://www.2ndQuadrant.com/
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