Heh, rereading the same basic code in your implementation made me realize that there is another minor bug. SvSETMAGIC() doesn't get called if the 'read' is successful but returns no data. That suggests the following simplification: 

void odbc_lob_read(sth, colno, bufsv, length, attr = NULL)
     SV *sth
     int colno
     SV *bufsv
     UV  length
     SV *attr;
    PROTOTYPE: $$$$;$
    PREINIT:
     char *buf;
     UV ret_len;
     IV sql_type = 0;
    CODE:
     if (length == 0) {
         croak("Cannot retrieve 0 length lob");
     }
     if (SvROK(bufsv)) {
         bufsv = SvRV(bufsv);
     }
     if (attr) {
         SV **svp;
         DBD_ATTRIBS_CHECK("odbc_lob_read", sth, attr);
         DBD_ATTRIB_GET_IV(attr, "Type", 4, svp, sql_type);
     }
     sv_setpvn(bufsv, "", 0);                   /* ensure we can grow 
+ok */
     buf = SvGROW(bufsv, length + 1);
     ret_len = odbc_st_lob_read(sth, colno, bufsv, length, sql_type);
     if (ret_len < 0) {
         ST(0) = &PL_sv_undef;
     } else {
         SvCUR_set(bufsv, ret_len);      /* set length in SV */
         *SvEND(bufsv) = '\0';           /* NUL terminate */
         SvSETMAGIC(bufsv);
         ST(0) = sv_2mortal(newSViv(ret_len));
     }
     XSRETURN(1);

[download]

(Update: Added XSRETURN(1) after prompting in the chatterbox from ikegami.)

- tye        

In reply to Re^3: Perl XS - is this code required in DBD::Pg? (empty) by tye
in thread Perl XS - is this code required in DBD::Pg? by mje

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