Re: [Qemu-devel] [PATCH v2 3/3] socket: unlink unix socket on remove

["Michael S. Tsirkin" <mst@redhat.com>]

On Thu, Jun 23, 2016 at 07:41:55AM +0300, Michael S. Tsirkin wrote:
> On Thu, Jun 16, 2016 at 09:28:52PM +0200, marcandre.lureau@redhat.com wrote:
> > From: Marc-André Lureau <marcandre.lureau@redhat.com>
> > 
> > qemu leaves unix socket files behind when removing a listening chardev
> > or leaving. qemu could clean that up, even if doing so isn't race-free.
> > 
> > Fixes:
> > https://bugzilla.redhat.com/show_bug.cgi?id=1347077
> > 
> > Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
> 
> We normally only unlink what we created.
> 
> unlinking files we didn't create
> looks like a silent change that might easily break
> existing users.

Maybe what you want is a need_unlink feature.
Set it for unix sockets only, that would make some sense.


> 
> > ---
> >  include/qemu/sockets.h         |  1 +
> >  io/channel-socket.c            | 10 ++++++++++
> >  tests/test-io-channel-socket.c |  2 +-
> >  util/qemu-sockets.c            | 18 ++++++++++++++++++
> >  4 files changed, 30 insertions(+), 1 deletion(-)
> > 
> > diff --git a/include/qemu/sockets.h b/include/qemu/sockets.h
> > index 1bd9218..5dd2648 100644
> > --- a/include/qemu/sockets.h
> > +++ b/include/qemu/sockets.h
> > @@ -51,6 +51,7 @@ SocketAddress *socket_parse(const char *str, Error **errp);
> >  int socket_connect(SocketAddress *addr, Error **errp,
> >                     NonBlockingConnectHandler *callback, void *opaque);
> >  int socket_listen(SocketAddress *addr, Error **errp);
> > +void socket_listen_cleanup(int fd, Error **errp);
> >  int socket_dgram(SocketAddress *remote, SocketAddress *local, Error **errp);
> >  
> >  /* Old, ipv4 only bits.  Don't use for new code. */
> > diff --git a/io/channel-socket.c b/io/channel-socket.c
> > index 1cd5848..6ec87f8 100644
> > --- a/io/channel-socket.c
> > +++ b/io/channel-socket.c
> > @@ -400,7 +400,17 @@ static void qio_channel_socket_init(Object *obj)
> >  static void qio_channel_socket_finalize(Object *obj)
> >  {
> >      QIOChannelSocket *ioc = QIO_CHANNEL_SOCKET(obj);
> > +
> >      if (ioc->fd != -1) {
> > +        if (QIO_CHANNEL(ioc)->features & QIO_CHANNEL_FEATURE_LISTEN) {
> > +            Error *err = NULL;
> > +
> > +            socket_listen_cleanup(ioc->fd, &err);
> > +            if (err) {
> > +                error_report_err(err);
> > +                err = NULL;
> > +            }
> > +        }
> >  #ifdef WIN32
> >          WSAEventSelect(ioc->fd, NULL, 0);
> >  #endif
> > diff --git a/tests/test-io-channel-socket.c b/tests/test-io-channel-socket.c
> > index 855306b..f73e063 100644
> > --- a/tests/test-io-channel-socket.c
> > +++ b/tests/test-io-channel-socket.c
> > @@ -383,7 +383,7 @@ static void test_io_channel_unix(bool async)
> >  
> >      qapi_free_SocketAddress(listen_addr);
> >      qapi_free_SocketAddress(connect_addr);
> > -    unlink(TEST_SOCKET);
> > +    g_assert(g_file_test(TEST_SOCKET, G_FILE_TEST_EXISTS) == FALSE);
> >  }
> >  
> >  
> > diff --git a/util/qemu-sockets.c b/util/qemu-sockets.c
> > index 0d6cd1f..5d03695 100644
> > --- a/util/qemu-sockets.c
> > +++ b/util/qemu-sockets.c
> > @@ -997,6 +997,24 @@ int socket_listen(SocketAddress *addr, Error **errp)
> >      return fd;
> >  }
> >  
> > +void socket_listen_cleanup(int fd, Error **errp)
> > +{
> > +    SocketAddress *addr;
> > +
> > +    addr = socket_local_address(fd, errp);
> > +
> > +    if (addr->type == SOCKET_ADDRESS_KIND_UNIX
> > +        && addr->u.q_unix.data->path) {
> > +        if (unlink(addr->u.q_unix.data->path) < 0 && errno != ENOENT) {
> > +            error_setg_errno(errp, errno,
> > +                             "Failed to unlink socket %s",
> > +                             addr->u.q_unix.data->path);
> > +        }
> > +    }
> > +
> > +    g_free(addr);
> > +}
> > +
> >  int socket_dgram(SocketAddress *remote, SocketAddress *local, Error **errp)
> >  {
> >      int fd;
> > -- 
> > 2.7.4
> >