io: Add a read flag for relaxed EOF

Add a read flag that can inform a channel that it's ok to receive an
EOF at any moment. Channels that have some form of strict EOF
tracking, such as TLS session termination, may choose to ignore EOF
errors with the use of this flag.

This is being added for compatibility with older migration streams
that do not include a TLS termination step.

Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Signed-off-by: Fabiano Rosas <farosas@suse.de>

include/io/channel.h

@@ -35,6 +35,7 @@ OBJECT_DECLARE_TYPE(QIOChannel, QIOChannelClass,
 #define QIO_CHANNEL_WRITE_FLAG_ZERO_COPY 0x1
 
 #define QIO_CHANNEL_READ_FLAG_MSG_PEEK 0x1
+#define QIO_CHANNEL_READ_FLAG_RELAXED_EOF 0x2
 
 typedef enum QIOChannelFeature QIOChannelFeature;
 

io/channel-tls.c

@@ -359,6 +359,7 @@ static ssize_t qio_channel_tls_readv(QIOChannel *ioc,
             tioc->session,
             iov[i].iov_base,
             iov[i].iov_len,
+            flags & QIO_CHANNEL_READ_FLAG_RELAXED_EOF ||
             qatomic_load_acquire(&tioc->shutdown) & QIO_CHANNEL_SHUTDOWN_READ,
             errp);
         if (ret == QCRYPTO_TLS_SESSION_ERR_BLOCK) {