Bug #29871 MyODBC problem with MS Query ('Memory allocation error')

Description:
The problem appears in MS Query when trying to import the data into Excel.

How to repeat:
Open MS excel > Data > new database query >pick up the DSN just configed and pick up some tables > View data or edit query in Microsoft Query > Allow editing > Modify some data field and try to return data to Excel.

Suggested fix:
When MS Query uses parameters in queries MyODBC incorrectly calculates the size of the buffer as:

if ( length > param->ValueMax )
    length = param->ValueMax;

for ValueMax == -1 the length cannot be considered as valid.

To fix the problem it is necessary to add a new condition:
if ( length > param->ValueMax && param->ValueMax > 0)
    length = param->ValueMax;

Trying to narrow the problem to a C test case

I found out that MSQuery binds the query parameters in an unusual way. It mostly affects integer columns. The value type is SQL_C_CHAR whereas the parameter type is SQL_INTEGER. This causes misinterpretation of the parameter when inserting it into the resulting SQL query.

parameter length -1 appeared due to use of a deprecated function SQLSetParam instead of SQLBindParam. I wonder why it is mapped so, that SQLBindParam is being called with SQL_SETPARAM_VALUE_MAX (-1L) whereas the direct call of SQLBindParam with this option fails:
[ HY090] [Microsoft][ODBC Driver Manager] Invalid string or buffer length

Patch and test case

Attachment: patch29871.diff (application/octet-stream, text), 1.85 KiB.

change

  if ( length > param->ValueMax && param->ValueMax > 0 )

to

  if (length != SQL_SETPARAM_VALUE_MAX && length > param->ValueMax)

and fix the formatting of the comment preceding this line.

okay to push.

The following condition does not work for MS Query:

if (length != SQL_SETPARAM_VALUE_MAX && length > param->ValueMax)

it has to be changed to:

if (param->ValueMax != SQL_SETPARAM_VALUE_MAX && length > param->ValueMax)

A note has been added to the 3.51.20 changelog: 

SQLSetParam() caused memory allocation errors due to driver manager's mapping of deprecated functions (buffer length -1).

New patch incuding SQLSetParam function (mapped to SQLBindParameter)

Attachment: patch29871v2.diff (application/octet-stream, text), 2.71 KiB.

the comment should be written in doxygen-style, and some of the code formatting fixed, but the code looks fine.

The fix for this bug was committed to the source repository, and will be in 3.51.21.

A note has been added to the 3.51.21 changelog:
 
SQLSetParam() caused memory allocation errors due to driver manager's mapping of deprecated functions (buffer length -1).

The test for this bug is failing. The function is not exported (I checked 3.51.23 release DLL).

SQLSetPos() needs to be exported. Also, the test-case should verify that the correct data was inserted.

Sorry, SQLSetParam() needs to be exported.

New version of the patch

Attachment: patch29871v6.diff (application/octet-stream, text), 2.27 KiB.

The existing changelog entry has also been tagged against the 3.51.24 release.