[Libguestfs] [PATCH libnbd v2 1/3] lib/crypto: Use GNUTLS_NO_SIGNAL if available

[Eric Blake]

On Thu, Jul 28, 2022 at 03:19:08PM +0100, Richard W.M. Jones wrote:
> libnbd has long used MSG_NOSIGNAL to avoid receiving SIGPIPE if we
> accidentally write on a closed socket, which is a nice alternative to
> using a SIGPIPE signal handler.  However with TLS connections, gnutls
> did not use this flag and so programs using libnbd + TLS would receive
> SIGPIPE in some situations, notably if the server closed the
> connection abruptly while we were trying to write something.
> 
> GnuTLS 3.4.2 introduces GNUTLS_NO_SIGNAL which does the same thing.
> Use this flag if available.
> 
> RHEL 7 has an older gnutls which lacks this flag.  To avoid qemu-nbd
> interop tests failing (rarely, but more often with a forthcoming
> change to TLS shutdown behaviour), register a SIGPIPE signal handler
> in the test if the flag is missing.

Stale comment in the parenthesis?

> ---
>  interop/interop.c | 8 ++++++++
>  lib/crypto.c      | 7 ++++++-
>  2 files changed, 14 insertions(+), 1 deletion(-)

Reviewed-by: Eric Blake <eblake at redhat.com>

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3266
Virtualization:  qemu.org | libvirt.org