On Wed, Mar 08, 2023 at 10:53:13AM +0400, Marc-André Lureau wrote:
> Hi
>
> On Tue, Mar 7, 2023 at 6:50 PM Daniel P. Berrangé <berra...@redhat.com> wrote:
> >
> > On Mon, Mar 06, 2023 at 04:27:44PM +0400, marcandre.lur...@redhat.com wrote:
> > > From: Marc-André Lureau <marcandre.lur...@redhat.com>
> > >
> > > Manually implement a socketpair() function, using UNIX sockets and
> > > simple peer credential checking.
> > >
> > > QEMU doesn't make much use of socketpair, beside vhost-user which is not
> > > available for win32 at this point. However, I intend to use it for
> > > writing some new portable tests.
> > >
> > > Signed-off-by: Marc-André Lureau <marcandre.lur...@redhat.com>
> > > ---
> > > include/qemu/sockets.h | 2 -
> > > util/oslib-win32.c | 110 +++++++++++++++++++++++++++++++++++++++++
> > > 2 files changed, 110 insertions(+), 2 deletions(-)
> > >
> > > diff --git a/include/qemu/sockets.h b/include/qemu/sockets.h
> > > index 2b0698a7c9..d935fd80da 100644
> > > --- a/include/qemu/sockets.h
> > > +++ b/include/qemu/sockets.h
> > > @@ -15,7 +15,6 @@ int inet_aton(const char *cp, struct in_addr *ia);
> > > bool fd_is_socket(int fd);
> > > int qemu_socket(int domain, int type, int protocol);
> > >
> > > -#ifndef WIN32
> > > /**
> > > * qemu_socketpair:
> > > * @domain: specifies a communication domain, such as PF_UNIX
> > > @@ -30,7 +29,6 @@ int qemu_socket(int domain, int type, int protocol);
> > > * Return 0 on success.
> > > */
> > > int qemu_socketpair(int domain, int type, int protocol, int sv[2]);
> > > -#endif
> > >
> > > int qemu_accept(int s, struct sockaddr *addr, socklen_t *addrlen);
> > > /*
> > > diff --git a/util/oslib-win32.c b/util/oslib-win32.c
> > > index 29a667ae3d..16f8a67f7e 100644
> > > --- a/util/oslib-win32.c
> > > +++ b/util/oslib-win32.c
> > > @@ -310,6 +310,116 @@ bool qemu_socket_unselect(int sockfd, Error **errp)
> > > return qemu_socket_select(sockfd, NULL, 0, errp);
> > > }
> > >
> > > +int qemu_socketpair(int domain, int type, int protocol, int sv[2])
> > > +{
> > > + struct sockaddr_un addr = {
> > > + 0,
> > > + };
> > > + socklen_t socklen;
> > > + int listener = -1;
> > > + int client = -1;
> > > + int server = -1;
> > > + g_autofree char *path = NULL;
> > > + int tmpfd;
> > > + u_long arg;
> > > + int ret = -1;
> > > +
> > > + g_return_val_if_fail(sv != NULL, -1);
> > > +
> > > + addr.sun_family = AF_UNIX;
> > > + socklen = sizeof(addr);
> > > +
> > > + tmpfd = g_file_open_tmp(NULL, &path, NULL);
> > > + if (tmpfd == -1 || !path) {
> > > + errno = EACCES;
> > > + goto out;
> > > + }
> > > +
> > > + close(tmpfd);
> > > +
> > > + if (strlen(path) >= sizeof(addr.sun_path)) {
> > > + errno = EINVAL;
> > > + goto out;
> > > + }
> > > +
> > > + strncpy(addr.sun_path, path, sizeof(addr.sun_path) - 1);
> > > +
> > > + listener = socket(domain, type, protocol);
> > > + if (listener == -1) {
> > > + goto out;
> > > + }
> > > +
> > > + if (DeleteFile(path) == 0 && GetLastError() != ERROR_FILE_NOT_FOUND)
> > > {
> > > + errno = EACCES;
> > > + goto out;
> > > + }
> > > + g_clear_pointer(&path, g_free);
> > > +
> > > + if (bind(listener, (struct sockaddr *)&addr, socklen) == -1) {
> > > + goto out;
> > > + }
> > > +
> > > + if (listen(listener, 1) == -1) {
> > > + goto out;
> > > + }
> > > +
> > > + client = socket(domain, type, protocol);
> > > + if (client == -1) {
> > > + goto out;
> > > + }
> > > +
> > > + arg = 1;
> > > + if (ioctlsocket(client, FIONBIO, &arg) != NO_ERROR) {
> > > + goto out;
> > > + }
> > > +
> > > + if (connect(client, (struct sockaddr *)&addr, socklen) == -1 &&
> > > + WSAGetLastError() != WSAEWOULDBLOCK) {
> > > + goto out;
> > > + }
> > > +
> > > + server = accept(listener, NULL, NULL);
> > > + if (server == -1) {
> > > + goto out;
> > > + }
> >
> > In theory at this point 'client' if connect() returned WSAEWOULDBLOCK,
> > then at this point it should be fully connected. I wonder if that is
> > actually guaranteed though, or should we do something to validate
> > there's no race condition ?
> >
> > > +
> > > + arg = 0;
> > > + if (ioctlsocket(client, FIONBIO, &arg) != NO_ERROR) {
> > > + goto out;
> > > + }
> > > +
> > > + arg = 0;
> > > + if (ioctlsocket(client, SIO_AF_UNIX_GETPEERPID, &arg) != NO_ERROR) {
> > > + goto out;
> > > + }
> >
> > Maybe this will force a synchronization point ?
>
> yeah, I guess switching back to sync and getting the peer pid,
>
> I assume the unix socket pair to be ready at this point.
Ok, lets hope its ok, but remember this if we see any non-deterministic
failures
Reviewed-by: Daniel P. Berrangé <berra...@redhat.com>
With regards,
Daniel
--
|: https://berrange.com -o- https://www.flickr.com/photos/dberrange :|
|: https://libvirt.org -o- https://fstop138.berrange.com :|
|: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|
