Re: Fix handling of copy_file_range() return value

Hi,

On Mon, 22 Jun 2026 at 10:20, Peter Eisentraut <peter(at)eisentraut(dot)org> wrote:
>
> While checking return/error handling of file system calls, I found that
> the copy_file_range() call in pg_combinebackup has a potential problem.
> If copy_file_range() returns 0, which is a documented condition, then
> the loop never makes progress and could spin forever.
>
> The other uses of copy_file_range() in the tree are surrounded by
> different logic and don't appear to have this problem.
>
> My suggested fix is to make a return value of 0 an error. It most
> likely indicates that the source file has an unexpected size.

You are right, that is a problem only with this use of
copy_file_range(), and your patch fixes it; LGTM.

--
Regards,
Nazir Bilal Yavuz
Microsoft