POSIX allows sendmsg() and recvmsg() to fail EMSGSIZE if passed a zero
msg.msg_iovlen (in particular the MacOS X implementation will do this).
Handle the case where iov_send_recv() is passed a zero byte count
explicitly, to avoid accidentally depending on the OS to treat zero
msg_iovlen as a no-op.
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Acked-by: Michael Tokarev <mjt@tls.msk.ru>
Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Commit 25e5e4c7 broke compilation for non POSIX hosts (e.g. MinGW)
because it partially replaced "ret" by "count".
It also changed the handling of EINTR in a wrong way.
The patch restores the old code for these two changes.
Signed-off-by: Stefan Weil <sw@weilnetz.de>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
Make it much more understandable, add a missing
iov_cnt argument (number of iovs in the iov), and
add comments to it.
The new implementation has been extensively tested
by splitting a large buffer into many small
randomly-sized chunks, sending it over socket to
another, slow process and verifying the receiving
data is the same.
Also add a unit test for iov_send_recv(), sending/
receiving data between two processes over a socketpair
using random vectors and random sizes.
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
This changes implementations of all iov_*
functions, completing the previous step.
All iov_* functions now ensure that this offset
argument is within the iovec (using assertion),
but lets to specify `bytes' value larger than
actual length of the iovec - in this case they
stops at the actual end of iovec. It is also
suggested to use convinient `-1' value as `bytes'
to mean just this -- "up to the end".
There's one very minor semantic change here: new
requiriment is that `offset' points to inside of
iovec. This is checked just at the end of functions
(assert()), it does not actually need to be enforced,
but using any of these functions with offset pointing
past the end of iovec is wrong anyway.
Note: the new code in iov.c uses arithmetic with
void pointers. I thought this is not supported
everywhere and is a GCC extension (indeed, the C
standard does not define void arithmetic). However,
the original code already use void arith in
iov_from_buf() function:
(memcpy(..., buf + buf_off,...)
which apparently works well so far (it is this
way in qemu 1.0). So I left it this way and used
it in other places.
While at it, add a unit-test file test-iov.c,
to check various corner cases with iov_from_buf(),
iov_to_buf() and iov_memset().
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
Reorder arguments to be more natural, readable and
consistent with other iov_* functions, and change
argument names, from:
iov_from_buf(iov, iov_cnt, buf, iov_off, size)
to
iov_from_buf(iov, iov_cnt, offset, buf, bytes)
The result becomes natural English:
copy data to this `iov' vector with `iov_cnt'
elements starting at byte offset `offset'
from memory buffer `buf', processing `bytes'
bytes max.
(Try to read the original prototype this way).
Also change iov_clear() to more general iov_memset()
(it uses memset() internally anyway).
While at it, add comments to the header file
describing what the routines actually does.
The patch only renames argumens in the header, but
keeps old names in the implementation. The next
patch will touch actual code to match.
Now, it might look wrong to pay so much attention
to so small things. But we've so many badly designed
interfaces already so the whole thing becomes rather
confusing or error prone. One example of this is
previous commit and small discussion which emerged
from it, with an outcome that the utility functions
like these aren't well-understdandable, leading to
strange usage cases. That's why I paid quite some
attention to this set of functions and a few
others in subsequent patches.
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
All files under GPLv2 will get GPLv2+ changes starting tomorrow.
event_notifier.c and exec-obsolete.h were only ever touched by Red Hat
employees and can be relicensed now.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
iov_to_buf() has an 'offset' parameter, iov_from_buf() hasn't.
This patch adds the missing parameter to iov_from_buf().
It also renames the 'offset' parameter to 'iov_off' to
emphasize it's the offset into the iovec and not the buffer.
Signed-off-by: Hannes Reinecke <hare@suse.de>
Acked-by: Alexander Graf <agraf@suse.de>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
The iov functions can be useful to other code as well.
Signed-off-by: Amit Shah <amit.shah@redhat.com>
CC: Christoph Hellwig <hch@lst.de>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
Michael S. Tsirkin
Peter Maydell
Stefan Weil
Michael Tokarev
Paolo Bonzini
Gerd Hoffmann
Hannes Reinecke
Amit Shah