Re: sendfile and EAGAIN

[H. Peter Anvin]

On 02/25/2013 09:22 AM, Ulrich Drepper wrote:
> When using sendfile with a non-blocking output file descriptor for a
> socket the operation can cause a partial write because of capacity
> issues.  This is nothing critical and the operation could resume after
> the output queue is cleared.  The problem is: there is no way to
> determine where to resume.
> 
> The system call just returns -EAGAIN without any further indication.
> The caller doesn't know what to resend.

This is IMO just a bug.  EAGAIN should only be used in the zero-byte
case and in other cases it should return the number of bytes
transferred, just like all the read/write system calls.

This was clearly also the intent.

	-hpa

-- 
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel.  I don't speak on their behalf.

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/