Commit bb955867 authored Aug 11, 2012 by Peter Maydell Committed by Stefan Hajnoczi Aug 15, 2012

iov_send_recv(): Handle zero bytes case even if OS does not



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>

parent 9c6bb55b

iov.c

+7 −0

Original line number	Diff line number	Diff line
		@@ -146,6 +146,13 @@ ssize_t iov_send_recv(int sockfd, struct iovec *iov, unsigned iov_cnt,
		{
		ssize_t ret;
		unsigned si, ei; /* start and end indexes */
		if (bytes == 0) {
		/* Catch the do-nothing case early, as otherwise we will pass an
		* empty iovec to sendmsg/recvmsg(), and not all implementations
		* accept this.
		*/
		return 0;
		}

		/* Find the start position, skipping `offset' bytes:
		* first, skip all full-sized vector elements, */