[PATCH v4 2/4] util/qemu-sockets: Enable unix socket support on Windows

[Bin Meng <bmeng.cn@gmail.com>]

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 come to Windows. Starting
this build, two Win32 processes can use the AF_UNIX address family
over Winsock API to communicate with each other.

[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>
---

Changes in v4:
- instead of introducing CONFIG_AF_UNIX, add fallback afunix.h header
  in os-win32.h, and compile the AF_UNIX stuff for all Windows hosts

Changes in v3:
- drop the run-time check afunix_available()

Changes in v2:
- move #include <afunix.h> to os-win32.h
- define WIN_BUILD_AF_UNIX only when CONFIG_WIN32

 meson.build               |  3 +++
 include/sysemu/os-win32.h | 17 +++++++++++++++++
 util/qemu-sockets.c       | 25 -------------------------
 3 files changed, 20 insertions(+), 25 deletions(-)

diff --git a/meson.build b/meson.build
index 294e9a8f32..6749223f1a 100644
--- a/meson.build
+++ b/meson.build
@@ -1890,6 +1890,9 @@ config_host_data.set('HAVE_PTY_H', cc.has_header('pty.h'))
 config_host_data.set('HAVE_SYS_DISK_H', cc.has_header('sys/disk.h'))
 config_host_data.set('HAVE_SYS_IOCCOM_H', cc.has_header('sys/ioccom.h'))
 config_host_data.set('HAVE_SYS_KCOV_H', cc.has_header('sys/kcov.h'))
+if targetos == 'windows'
+  config_host_data.set('HAVE_AFUNIX_H', cc.has_header('afunix.h'))
+endif
 
 # has_function
 config_host_data.set('CONFIG_ACCEPT4', cc.has_function('accept4'))
diff --git a/include/sysemu/os-win32.h b/include/sysemu/os-win32.h
index edc3b38a57..5b38c7bd04 100644
--- a/include/sysemu/os-win32.h
+++ b/include/sysemu/os-win32.h
@@ -30,6 +30,23 @@
 #include <windows.h>
 #include <ws2tcpip.h>
 
+#ifdef HAVE_AFUNIX_H
+#include <afunix.h>
+#else
+/*
+ * Fallback definitions of things we need in afunix.h, if not available from
+ * the used Windows SDK or MinGW headers.
+ */
+#define UNIX_PATH_MAX 108
+
+typedef struct sockaddr_un {
+    ADDRESS_FAMILY sun_family;
+    char sun_path[UNIX_PATH_MAX];
+} SOCKADDR_UN, *PSOCKADDR_UN;
+
+#define SIO_AF_UNIX_GETPEERPID _WSAIOR(IOC_VENDOR, 256)
+#endif
+
 #ifdef __cplusplus
 extern "C" {
 #endif
diff --git a/util/qemu-sockets.c b/util/qemu-sockets.c
index 0e2298278f..83f4bd6fd2 100644
--- a/util/qemu-sockets.c
+++ b/util/qemu-sockets.c
@@ -880,8 +880,6 @@ static int vsock_parse(VsockSocketAddress *addr, const char *str,
 }
 #endif /* CONFIG_AF_VSOCK */
 
-#ifndef _WIN32
-
 static bool saddr_is_abstract(UnixSocketAddress *saddr)
 {
 #ifdef CONFIG_LINUX
@@ -1054,25 +1052,6 @@ static int unix_connect_saddr(UnixSocketAddress *saddr, Error **errp)
     return -1;
 }
 
-#else
-
-static int unix_listen_saddr(UnixSocketAddress *saddr,
-                             int num,
-                             Error **errp)
-{
-    error_setg(errp, "unix sockets are not available on windows");
-    errno = ENOTSUP;
-    return -1;
-}
-
-static int unix_connect_saddr(UnixSocketAddress *saddr, Error **errp)
-{
-    error_setg(errp, "unix sockets are not available on windows");
-    errno = ENOTSUP;
-    return -1;
-}
-#endif
-
 /* compatibility wrapper */
 int unix_listen(const char *str, Error **errp)
 {
@@ -1335,7 +1314,6 @@ socket_sockaddr_to_address_inet(struct sockaddr_storage *sa,
 }
 
 
-#ifndef WIN32
 static SocketAddress *
 socket_sockaddr_to_address_unix(struct sockaddr_storage *sa,
                                 socklen_t salen,
@@ -1362,7 +1340,6 @@ socket_sockaddr_to_address_unix(struct sockaddr_storage *sa,
     addr->u.q_unix.path = g_strndup(su->sun_path, salen);
     return addr;
 }
-#endif /* WIN32 */
 
 #ifdef CONFIG_AF_VSOCK
 static SocketAddress *
@@ -1394,10 +1371,8 @@ socket_sockaddr_to_address(struct sockaddr_storage *sa,
     case AF_INET6:
         return socket_sockaddr_to_address_inet(sa, salen, errp);
 
-#ifndef WIN32
     case AF_UNIX:
         return socket_sockaddr_to_address_unix(sa, salen, errp);
-#endif /* WIN32 */
 
 #ifdef CONFIG_AF_VSOCK
     case AF_VSOCK:
-- 
2.34.1