Re: UTF16 surrogate pairs in UTF8 encoding

On 8/22/10, Peter Eisentraut <peter_e@gmx.net> wrote:
> On sön, 2010-08-22 at 14:29 -0400, Tom Lane wrote:
>  > I just noticed that we are now advertising the ability to insert UTF16
>  > surrogate pairs in strings and identifiers (see section 4.1.2.2 in
>  > current docs, in particular).  Is this really wise?  I thought that
>  > surrogate pairs were specifically prohibited in UTF8 strings, because
>  > of the security hazards implicit in having more than one way to
>  > represent the same code point.
>
>
> We combine the surrogate pair components to a single code point and
>  encode that in UTF-8.  We don't encode the components separately; that
>  would be wrong.

AFAICS our UTF8 validator (pg_utf8_islegal) detects and rejects
such sequences, if they are inserted via any means, eg. \x

Although it's not very obvious...

--
marko