nbd: Improve error messages

This patch makes use of the Error object for nbd_receive_negotiate() so
that errors during negotiation look nicer.

Furthermore, this patch adds an additional error message if the received
magic was wrong, but would be correct for the other protocol version,
respectively: So if an export name was specified, but the NBD server
magic corresponds to an old handshake, this condition is explicitly
signaled to the user, and vice versa.

As these messages are now part of the "Could not open image" error
message, additional filtering has to be employed in iotest 083, which
this patch does as well.

Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

1 files changed, 1 insertions, 1 deletions

diff --git a/include/block/nbd.h b/include/block/nbd.h
index 348302c90b..b75959556c 100644
--- a/include/block/nbd.h
+++ b/include/block/nbd.h
@@ -75,7 +75,7 @@ enum {
 
 ssize_t nbd_wr_sync(int fd, void *buffer, size_t size, bool do_read);
 int nbd_receive_negotiate(int csock, const char *name, uint32_t *flags,
-                          off_t *size, size_t *blocksize);
+                          off_t *size, size_t *blocksize, Error **errp);
 int nbd_init(int fd, int csock, uint32_t flags, off_t size, size_t blocksize);
 ssize_t nbd_send_request(int csock, struct nbd_request *request);
 ssize_t nbd_receive_reply(int csock, struct nbd_reply *reply);