From: Peter Maydell <peter.mayd...@linaro.org>
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.mayd...@linaro.org>
Acked-by: Michael Tokarev <m...@tls.msk.ru>
Signed-off-by: Stefan Hajnoczi <stefa...@linux.vnet.ibm.com>
---
iov.c | 7 +++++++
1 file changed, 7 insertions(+)
diff --git a/iov.c b/iov.c
index b333061..60705c7 100644
--- a/iov.c
+++ b/iov.c
@@ -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, */
--
1.7.10.4
