libpq endless loop if client_min_messages=debug1

My Deja wrote:

>
>> I am trying to get some query trees to appear in the PostgreSQL log
>> and in order to that I have set
>> client_min_messages = DEBUG1 in order to use the following settings
>> debug_print_parse, debug_print_rewritten, or debug_print_plan which
>> are required for the query tree to show up in the log.
>>
>> pgAdmin crashes whenever I set that option. I tried a few times and I
>> am sure of it.
>> I am using PostgreSQL 7.4 under Cygwin on a Windows 2000 machine, but
>> I don't think that has any relevance.
>
I reproduced this problem with 7.5 head backend and libpq under win32
and Linux, and found that the problem is pqParseInput3 expecting a
message length >= 30000 only for message types 'T', 'D' and 'd', but not
'N'. In the case tested above, the message will be 49336 bytes long,
causing an endless loop in PQexecFinish because PQgetResult will deliver
the same broken message forever.

The attached patch fixes this. I wonder if there are additional message
types that might be longer?

Regards,
Andreas