lio_read should return the number of bytes actually read

[PerilousApricot]

Currently, lio_read just kicks back the same size that the user passed in, even if that read would go beyond the end of the file:

https://github.com/accre/lstore/blob/master/src/lio/lio_core_io.c#L963

That means there's no way to know "where" the EOF was hit, just that the next time you read you'll get zero bytes

[tacketar]

Good catch. It's looks to be a pretty easy fix. I'll take care of it
next week when I write the example GOP and open/write/read/close
examples. It can be one of the examples. It's complicated by the read
ahead cache buffering but it looks like _gop_lio_read() calculates the
actual number of bytes dumped in the buffer excluding any read ahead.
That just needs to get passed back and returned as the actual number of
bytes instead of what the user passes in.

[PerilousApricot]

Prolly worth checking the write variant. Gridftp plugin is blocking on
this, FWIW

It's dark in this basement.

[tacketar]

Write looks fine.

[PerilousApricot]

Any chance you could pop out a quick patch to the read path? I can't find a good way around it for the gridftp plugin.

[tacketar]

Sure. I'll knock it out this afternoon.

[PerilousApricot]

cheers.