Use copy_file_range system call for copying on Linux systems

[Alan Bateman]

On 16/02/2022 20:03, Brian Burkhalter wrote:
>
>> On Feb 16, 2022, at 9:51 AM, Ilya Starchenko <redux1234567 at mail.ru> 
>> wrote:
>>
>> I think we can just check if syscall return ENOSYS and if it’s true 
>> fail back to more generic code.
>
> The code would not even build without the syscall in the headers so I 
> don’t think so.
>
I suspect Ilya meant using syscall(2) with the NR. We had code in libnio 
that used approach for the *at functions before they were added to the 
glibc header files. It's a bit fragile as they are architecture specific.

-Alan