sendfile() breakage was Re: SO_SNDTIMEO: 2.4 kernel bugs

[Chris Evans]

On Mon, 19 Feb 2001, Chris Evans wrote:

> > BTW, if you have enough fast network, you probably can observe
> > that sendfile() is even not interrupted by signals. 8) But this
> > is possible to fix at least. BTW the same fix will repair SO_*TIMEO
> > partially, i.e. it will timeout after n*timeo, where n is an arbitrary
> > number not exceeding size/sndbuf.
>
> Hi Alexey,
>
> You are right - our sendfile() implementation is broken. I have fixed it
> (patch at end of mail).

Actually the whole mess stems from our broken internal ->write() and
->read() APIs.

The _single_ return value is trying to convery _two_ pieces of information
- always a bad move. They are:
1) Success/failure (and error code if it's a failure)
2) Amount of bytes read or written

This bogon does not allow for the following information to be returned
(assume I asked for 8192 bytes to be written):
"4096 bytes were written, and the operation was aborted due to EINTR"

Cheers
Chris