Re: [Gnu-arch-users] [BUG] serious bug in vu_write_retry?

[Tom Lord]

    > From: Aaron Bentley <address@hidden>

    > I'm not so sure about the interface itself.  Shouldn't it return
    > a short count if it partially succeeds?

No.

vu_write_retry calls vu_write in a loop, ignoring EAGAIN and EINTR
errors, adding up short writes until the full amount of the original
write has been written.

What happens if some _other_ error is returned from either vu_write or
vu_read in those loops?  In those cases, we simply don't know what has
been read or written: most bets are off.  There is no portably correct
and interestingly useful short count to return for other errors.

(Besides which, the _retry functions are specifically for cases when
the caller classifies the outcomes of the read or write as either
"completely succeeded" or "failed in a way that suggests resuming the
read or write is pointless".   Allowing the _retry functions to 
return a partial count would make them the same, for nearly all
practical purposes as plain old read/write: there'd be no point to
having the _retry functions at all.)


-t