Re: [PATCH 4/5] util/qemu-sockets: Enable unix socket support on Windows

[Yan Vugenfirer <yvugenfi@redhat.com>]

On Wed, Jul 27, 2022 at 10:46 AM Bin Meng <bmeng.cn@gmail.com> wrote:
>
> From: Bin Meng <bin.meng@windriver.com>
>
> Support for the unix socket has existed both in BSD and Linux for the
> longest time, but not on Windows. Since Windows 10 build 17063 [1],
> the native support for the unix socket has came to Windows. Starting
> this build, two Win32 processes can use the AF_UNIX address family
> over Winsock API to communicate with each other.
>
> Introduce a new build time config option CONFIG_AF_UNIX when the build
> host has such a capability, and a run-time check afunix_available() for
> Windows host in the QEMU sockets util codes.
>
> [1] https://devblogs.microsoft.com/commandline/af_unix-comes-to-windows/
>
> Signed-off-by: Xuzhou Cheng <xuzhou.cheng@windriver.com>
> Signed-off-by: Bin Meng <bin.meng@windriver.com>
> ---
>
>  meson.build         |  6 ++++++
>  util/qemu-sockets.c | 48 ++++++++++++++++++++++++++++++++++++++-------
>  2 files changed, 47 insertions(+), 7 deletions(-)
>
> diff --git a/meson.build b/meson.build
> index 75aaca8462..73e5de5957 100644
> --- a/meson.build
> +++ b/meson.build
> @@ -2327,6 +2327,12 @@ have_afalg = get_option('crypto_afalg') \
>    '''), error_message: 'AF_ALG requested but could not be detected').allowed()
>  config_host_data.set('CONFIG_AF_ALG', have_afalg)
>
> +if targetos != 'windows'
> +  config_host_data.set('CONFIG_AF_UNIX', true)
> +else
> +  config_host_data.set('CONFIG_AF_UNIX', cc.has_header('afunix.h'))
> +endif
> +
>  config_host_data.set('CONFIG_AF_VSOCK', cc.has_header_symbol(
>    'linux/vm_sockets.h', 'AF_VSOCK',
>    prefix: '#include <sys/socket.h>',
> diff --git a/util/qemu-sockets.c b/util/qemu-sockets.c
> index 0e2298278f..d85f3ea3ee 100644
> --- a/util/qemu-sockets.c
> +++ b/util/qemu-sockets.c
> @@ -17,6 +17,15 @@
>   */
>  #include "qemu/osdep.h"
>
> +#if defined(CONFIG_WIN32) && defined(CONFIG_AF_UNIX)
> +# include <afunix.h>
> +/*
> + * AF_UNIX support is available since Windows 10 build 17063
> + * See https://devblogs.microsoft.com/commandline/af_unix-comes-to-windows/
> + */
> +# define WIN_BUILD_AF_UNIX 17063
> +#endif /* CONFIG_WIN32 && CONFIG_AF_UNIX */
> +
>  #ifdef CONFIG_AF_VSOCK
>  #include <linux/vm_sockets.h>
>  #endif /* CONFIG_AF_VSOCK */
> @@ -880,7 +889,7 @@ static int vsock_parse(VsockSocketAddress *addr, const char *str,
>  }
>  #endif /* CONFIG_AF_VSOCK */
>
> -#ifndef _WIN32
> +#ifdef CONFIG_AF_UNIX
>
>  static bool saddr_is_abstract(UnixSocketAddress *saddr)
>  {
> @@ -900,6 +909,17 @@ static bool saddr_is_tight(UnixSocketAddress *saddr)
>  #endif
>  }
>
> +#ifdef CONFIG_WIN32
> +static bool afunix_available(void)
> +{
> +    OSVERSIONINFOEXW os_version = { 0 };
> +
> +    os_get_win_version(&os_version);
> +
> +    return os_version.dwBuildNumber >= WIN_BUILD_AF_UNIX;
It can be that CONFIG_WIN32 is defined,but CONFIG_AF_UNIX is not. In
this case WIN_BUILD_AF_UNIX will be undefined.
Also, WIN_BUILD_AF_UNIX is just a build constant, why not define it
always under CONFIG_WIN32?

Best regards,
Yan.


> +}
> +#endif
> +
>  static int unix_listen_saddr(UnixSocketAddress *saddr,
>                               int num,
>                               Error **errp)
> @@ -912,6 +932,13 @@ static int unix_listen_saddr(UnixSocketAddress *saddr,
>      size_t pathlen;
>      size_t addrlen;
>
> +#ifdef CONFIG_WIN32
> +    if (!afunix_available()) {
> +        error_setg(errp, "AF_UNIX is not available on your Windows");
> +        return -1;
> +    }
> +#endif
> +
>      sock = qemu_socket(PF_UNIX, SOCK_STREAM, 0);
>      if (sock < 0) {
>          error_setg_errno(errp, errno, "Failed to create Unix socket");
> @@ -1004,6 +1031,13 @@ static int unix_connect_saddr(UnixSocketAddress *saddr, Error **errp)
>          return -1;
>      }
>
> +#ifdef CONFIG_WIN32
> +    if (!afunix_available()) {
> +        error_setg(errp, "AF_UNIX is not available on your Windows");
> +        return -1;
> +    }
> +#endif
> +
>      sock = qemu_socket(PF_UNIX, SOCK_STREAM, 0);
>      if (sock < 0) {
>          error_setg_errno(errp, errno, "Failed to create socket");
> @@ -1060,14 +1094,14 @@ static int unix_listen_saddr(UnixSocketAddress *saddr,
>                               int num,
>                               Error **errp)
>  {
> -    error_setg(errp, "unix sockets are not available on windows");
> +    error_setg(errp, "unix sockets are not available on your host");
>      errno = ENOTSUP;
>      return -1;
>  }
>
>  static int unix_connect_saddr(UnixSocketAddress *saddr, Error **errp)
>  {
> -    error_setg(errp, "unix sockets are not available on windows");
> +    error_setg(errp, "unix sockets are not available on your host");
>      errno = ENOTSUP;
>      return -1;
>  }
> @@ -1335,7 +1369,7 @@ socket_sockaddr_to_address_inet(struct sockaddr_storage *sa,
>  }
>
>
> -#ifndef WIN32
> +#ifdef CONFIG_AF_UNIX
>  static SocketAddress *
>  socket_sockaddr_to_address_unix(struct sockaddr_storage *sa,
>                                  socklen_t salen,
> @@ -1362,7 +1396,7 @@ socket_sockaddr_to_address_unix(struct sockaddr_storage *sa,
>      addr->u.q_unix.path = g_strndup(su->sun_path, salen);
>      return addr;
>  }
> -#endif /* WIN32 */
> +#endif /* CONFIG_AF_UNIX */
>
>  #ifdef CONFIG_AF_VSOCK
>  static SocketAddress *
> @@ -1394,10 +1428,10 @@ socket_sockaddr_to_address(struct sockaddr_storage *sa,
>      case AF_INET6:
>          return socket_sockaddr_to_address_inet(sa, salen, errp);
>
> -#ifndef WIN32
> +#ifdef CONFIG_AF_UNIX
>      case AF_UNIX:
>          return socket_sockaddr_to_address_unix(sa, salen, errp);
> -#endif /* WIN32 */
> +#endif
>
>  #ifdef CONFIG_AF_VSOCK
>      case AF_VSOCK:
> --
> 2.34.1
>
>