Description:
Hi!
If one updates a row so that the size of some column value changes, but the value of a
BLOB or a TEXT column does not change, then a consistent read of the previous version of
the BLOB or TEXT will bring at most 532 bytes of data, of which 512 bytes is good data,
and the remaining 20 bytes the 'external storage header', that is, nonprintable
characters.
This bug was found by a user.
Will be fixed in 4.0.22.
Regards,
Heikki
How to repeat:
See above.
Suggested fix:
Do not forget columns with the external bit set in the original row:
if (row_upd_changes_field_size_or_external(rec, index, update)) {
entry = row_rec_to_index_entry(ROW_COPY_DATA, index, rec,
heap);
row_upd_index_replace_new_col_vals(entry, index, update, heap);
buf = mem_heap_alloc(heap, rec_get_converted_size(entry));
*old_vers = rec_convert_dtuple_to_rec(buf, entry);
} else {
buf = mem_heap_alloc(heap, rec_get_size(rec));
*old_vers = rec_copy(buf, rec);
row_upd_rec_in_place(*old_vers, update);
}
for (i = 0; i < upd_get_n_fields(update); i++) {
if (upd_get_nth_field(update, i)->extern_storage) {
rec_set_nth_field_extern_bit(*old_vers,
upd_get_nth_field(update, i)->field_no,
TRUE, NULL);
}
}
return(DB_SUCCESS);
Description: Hi! If one updates a row so that the size of some column value changes, but the value of a BLOB or a TEXT column does not change, then a consistent read of the previous version of the BLOB or TEXT will bring at most 532 bytes of data, of which 512 bytes is good data, and the remaining 20 bytes the 'external storage header', that is, nonprintable characters. This bug was found by a user. Will be fixed in 4.0.22. Regards, Heikki How to repeat: See above. Suggested fix: Do not forget columns with the external bit set in the original row: if (row_upd_changes_field_size_or_external(rec, index, update)) { entry = row_rec_to_index_entry(ROW_COPY_DATA, index, rec, heap); row_upd_index_replace_new_col_vals(entry, index, update, heap); buf = mem_heap_alloc(heap, rec_get_converted_size(entry)); *old_vers = rec_convert_dtuple_to_rec(buf, entry); } else { buf = mem_heap_alloc(heap, rec_get_size(rec)); *old_vers = rec_copy(buf, rec); row_upd_rec_in_place(*old_vers, update); } for (i = 0; i < upd_get_n_fields(update); i++) { if (upd_get_nth_field(update, i)->extern_storage) { rec_set_nth_field_extern_bit(*old_vers, upd_get_nth_field(update, i)->field_no, TRUE, NULL); } } return(DB_SUCCESS);