On Thu, Jul 9, 2026 at 12:04 AM Peter Eisentraut <[email protected]> wrote: > > On 08.07.26 21:24, Haibo Yan wrote: > > I noticed a few places in ecpg that use strncpy() even though the code > > already > > knows how many bytes to copy. > > > > For example, some paths copy N bytes into a temporary buffer and then add > > the > > terminating NUL explicitly. There is also one small substring copy in > > pgtypeslib/datetime.c. memcpy() seems a better fit for those cases. > > Why is it better? At least strncpy() enforces that the target is a char > array, which memcpy() doesn't.
Thank you. I should have explained that better. I am not arguing that memcpy() is generally better for string handling. The sites I changed already have an explicit byte count, and some of them add the terminating NUL immediately afterwards. So they are not relying on strncpy()’s padding behavior. > > At a quick glance, strlcpy() might be more suitable in some of the cases > you found. > I don’t think strlcpy() fits these cases well. It would reserve space for a terminator, which would change exact-fit/truncation behavior in some output paths. It also treats the source as a NUL-terminated C string, while the ECPG VARCHAR case is an arr/len buffer, not just a plain C string. I left other strncpy() calls unchanged where the source may be shorter than the fixed-size destination, because there the stop-at-NUL and padding behavior is still useful. Thanks, Haibo
