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

[Bin Meng]

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;
+}
+#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