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

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

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.


> ---
>  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
>