FreeTDS Development Group

[Michal Seliga <michal.seliga AT visicom.sk>]

problem is in function SQLGetData in odbc.c on line 4715 (in my version)

its this context, error line is marked with /*!!!*/

switch (nSybType) {
case SYBCHAR:
case SYBVARCHAR:
case SYBTEXT:
case XSYBCHAR:
case XSYBVARCHAR:
/*!!!*/ nread = (src[0] == '0' && toupper(src[1]) == 'X')? 2 : 0;  /*!!!*/
                
        while ((nread < colinfo->column_cur_size) && (src[nread] == ' ' || 
src[nread]
== '\0'))
                nread++;

        nread += colinfo->column_text_sqlgetdatapos * 2;
        
        if (nread && nread >= colinfo->column_cur_size)
                ODBC_RETURN(stmt, SQL_NO_DATA);


problem is that on my database i get:
nSybType = 35
colinfo.column_cur_size=0
src= 0x0

but its not recognized as empty or null value, instead it tries to read src[0]
and it causes crash

attached is patch which fixed issue for me, but of course i didn't studied
internals of freetds before doing it and i can't guarantee its correct, 
please,
someone review it...


--- odbc.c.orig 2009-12-04 14:47:39.000000000 +0100
+++ odbc.c      2009-12-07 12:26:23.709681867 +0100
@@ -4623,7 +4623,7 @@
        }
        colinfo = resinfo->columns[icol - 1];
 
-       if (colinfo->column_cur_size < 0) {
+       if (colinfo->column_cur_size <= 0) {
                *pcbValue = SQL_NULL_DATA;
        } else {
                nSybType = tds_get_conversion_type(colinfo->column_type, 
colinfo->column_size);