PQconndefaults() error, don't show PGCLIENTENCODING

Hello

I work on small patch for pg_dump, which adds information about
used encoding into dump file. I can get current encoding via SQL "SHOW
client_encoding", but I can (propably) PQconndefaults too? Is it true?

I wrote small program which show env vars from PQconninfoOption struct.
But env PGCLIENTENCODING didn't showed? Maybe its error?

[stehule(at)stehule public_html]$ set|grep PG
PGCLIENTENCODING=windows1250
PGDATABASE=testdb011
[stehule(at)stehule public_html]$ ./testcninfo
[stehule(at)stehule public_html]$ ./testcninfo
PGAUTHTYPE=
PGSERVICE=(null)
PGUSER=stehule
PGPASSWORD=(null)
PGCONNECT_TIMEOUT=(null)
PGDATABASE=testdb011
PGHOST=(null)
PGHOSTADDR=(null)
PGPORT=5432
PGTTY=
PGOPTIONS=
PGSSLMODE=disable

Next questions? I don't think so I can use PQconndefaults for getting
informations about current connection now. Can I get this informations
by different way than sql?

Regards

Pavel Stehule