Re: [PATCH] fix defaults for cursor type and concurrency in ctlib

Applied to 0.91 and HEAD

Frediano

2012/10/26  <[email protected]>:
> Hello,
>
> I have a problem using python-sybase with a MS-SQL Server data base (TDS 7.1).
> cursor.execute() aborts with the error message
> "sp_cursoropen: The value of the parameter 'scrollopt' is invalid.".
>
> The same problem has been reported a long time ago already:
> https://sourceforge.net/mailarchive/forum.php?thread_name=5c06fa770907291200w5e7aeb3akaba12ab95d419785%40mail.gmail.com&forum_name=python-sybase-misc
>
> As correctly stated there, the problem occurs with python-sybase v0.39 and
> later only. This is due to the fact that python-sybase started to use
> the ct_cursor() API in 0.39. But that's not a bug of python-sybase.
>
> I analyzed the problem and I found that FreeTDS ctlib code sends a value
> of 0 for cursor->type and cursor->concurrency to the server, which is
> invalid. It appears that these two fields are never properly initialized
> in ctlib. The ODBC code (odbc.c) has code that initializes these fields.
>
> Below is a suggested patch that sets the default values as documented.
> in  http://jtds.sourceforge.net/apiCursors.html. Please review.
>
> The patch was made against FreeTDS 0.91-3 (Fedora 17).
>
> Best regards
> Martin
>
> diff -rup freetds-0.91.orig/include/tds.h freetds-0.91/include/tds.h
> --- freetds-0.91.orig/include/tds.h     2011-08-18 03:54:41.000000000 +0200
> +++ freetds-0.91/include/tds.h  2012-10-26 15:50:08.000000000 +0200
> @@ -378,6 +378,25 @@ enum {
>         TDS_CUR_ISTAT_DEALLOC   = 0x40
>  };
>
> +/* http://jtds.sourceforge.net/apiCursors.html */
> +/* Cursor scroll option, must be one of 0x01 - 0x10, OR'd with other bits */
> +enum {
> +       TDS_CUR_TYPE_KEYSET          = 0x0001, /* default */
> +       TDS_CUR_TYPE_DYNAMIC         = 0x0002,
> +       TDS_CUR_TYPE_FORWARD         = 0x0004,
> +       TDS_CUR_TYPE_STATIC          = 0x0008,
> +       TDS_CUR_TYPE_FASTFORWARDONLY = 0x0010,
> +       TDS_CUR_TYPE_PARAMETERIZED   = 0x1000,
> +       TDS_CUR_TYPE_AUTO_FETCH      = 0x2000
> +};
> +
> +enum {
> +       TDS_CUR_CONCUR_READ_ONLY         = 1,
> +       TDS_CUR_CONCUR_SCROLL_LOCKS      = 2,
> +       TDS_CUR_CONCUR_OPTIMISTIC        = 4, /* default */
> +       TDS_CUR_CONCUR_OPTIMISTIC_VALUES = 8
> +};
> +
>  /* environment type field */
>  #define TDS_ENV_DATABASE       1
>  #define TDS_ENV_LANG           2
> Only in freetds-0.91/include: tds.h~
> diff -rup freetds-0.91.orig/src/ctlib/ct.c freetds-0.91/src/ctlib/ct.c
> --- freetds-0.91.orig/src/ctlib/ct.c    2010-10-05 10:36:36.000000000 +0200
> +++ freetds-0.91/src/ctlib/ct.c 2012-10-26 15:55:38.000000000 +0200
> @@ -3704,6 +3704,8 @@ ct_cursor(CS_COMMAND * cmd, CS_INT type,
>                 cursor->status.fetch      = _CS_CURS_TYPE_UNACTIONED;
>                 cursor->status.close      = _CS_CURS_TYPE_UNACTIONED;
>                 cursor->status.dealloc    = _CS_CURS_TYPE_UNACTIONED;
> +               cursor->type              = TDS_CUR_TYPE_KEYSET;
> +               cursor->concurrency       = TDS_CUR_CONCUR_OPTIMISTIC;
>
>                 cmd->cursor = cursor;
>                 ct_set_command_state(cmd, _CS_COMMAND_READY);
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