FreeTDS Development Group

[ZIGLIO Frediano <Frediano.Ziglio AT vodafoneomnitel.it>]

> 
> Eric, 
> 
> Your remarks are on the money.  Please ignore my last 
> message.  I now like
> your "radical" solution best, because it's both simple and funny.  
> 
> I should have looked at cs.c, at cs_convert().  I was fixing dblib in
> tdslib, with the consequence of breaking ctlib.  The weird termination
> behavior described in the dblib docs shouldn't be embedded in a shared
> library.  dbconvert() is what needs attention.  
> 
> Brian, I'd like to suggest a policy about conversions for the 
> project; if
> you like it then it should be explicitly noted somewhere.  
> 
> <policy>
> tds_convert copies from src to dest and returns the output 
> data length,
> period.  All padding and termination is the responsibilty of 
> the API library
> and is done post conversion.  There may be some shared 
> utility padding &
> termination functions, but they're really not "conversion".  
> Trying to do
> anything nonstraightforward in tds_convert will only confuse 
> and confound
> the higher levels, us among them.  
> </policy>
> 
> An alternative would be to pass the padding & termination 
> policy argument as
> an enumerated type, which tds_convert would carry out if the basic
> conversion succeeds.  
> 
> You have more experience with this (obviously), and have some 
> idea where
> UTF-8 is taking us, so I'm curious how you see things.  
> 
Perhaps we should find a common beetween all library. Is not clear what
destlen mean. I know quite well odbc, but not other library. 
I execute some test with ms odbc with following results

Test with ODBC, 128 byte buffer

SELECT CAST('123' AS CHAR(6))
return "123   ", always terminated, indicator = 6

SELECT CAST('123' AS VARCHAR(6))
return "123", always terminated, indicator = 3

SELECT CAST('123' AS TEXT)
return "123", always terminated, indicator = 3

Test with ODBC, 2 byte buffer

SELECT CAST('123' AS CHAR(6))
return "1", always terminated, indicator = 6

SELECT CAST('123' AS VARCHAR(6))
return "1", always terminated, indicator = 3

SELECT CAST('123' AS TEXT)
return "1", always terminated, indicator = 3

Test with ODBC, 0 byte buffer

SELECT CAST('123' AS CHAR(6))
return nothing, always terminated, indicator = 6

SELECT CAST('123' AS VARCHAR(6))
return nothing, always terminated, indicator = 3

SELECT CAST('123' AS TEXT)
return nothing, always terminated, indicator = 3

Test with ODBC, 2 byte buffer

SELECT CAST(NULL AS CHAR(6))
return nothing, always terminated, indicator = -1

SELECT CAST(NULL AS VARCHAR(6))
return nothing, always terminated, indicator = -1

SELECT CAST(NULL AS TEXT)
return nothing, always terminated, indicator = -1

Test with ODBC, -1 byte buffer
Fail to bind

Test with ODBC, -2 byte buffer
Fail to bind

return nothing mean that function do not write nothing in destination
buffer. As we can see ODBC do not handle destlen of -1 or destlen of -2.
Also There destination can be only a terminated string (no difference
beetween DBCHAR, DBVARCHAR or DBTEXT)

I think ctlib and DB-Library have different destlen value and terminator
problems...
Watching some doc seem that converting to DBCHAR do not append terminator
(if destlen >=0) but pad with spaces and always terminated if
DBVARCHAR/DBTEXT.
Someone else have better info?

freddy77

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