Let's make the code more portable by adding defines from
block/file-posix.c to support O_DIRECT in other systems (e.g. macOS).

vhost-user-server.c is a dependency, let's enable it for any POSIX
system.

Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Tested-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
---
v6:
- reverted v5 changes since we can't move O_DSYNC and O_DIRECT in osdep
  [Daniel, failing tests on Windows]
v5:
- O_DSYNC and O_DIRECT definition are now in osdep [Phil]
- commit updated since we moved out all code changes
v4:
- moved using of "qemu/bswap.h" API in a separate patch [Phil]
---
 meson.build                             |  2 --
 contrib/vhost-user-blk/vhost-user-blk.c | 14 ++++++++++++++
 util/meson.build                        |  4 +++-
 3 files changed, 17 insertions(+), 3 deletions(-)

diff --git a/meson.build b/meson.build
index 48e476b237..c89ee7b578 100644
--- a/meson.build
+++ b/meson.build
@@ -1981,8 +1981,6 @@ has_statx = cc.has_header_symbol('sys/stat.h', 'STATX_BASIC_STATS', prefix: gnu_
 has_statx_mnt_id = cc.has_header_symbol('sys/stat.h', 'STATX_MNT_ID', prefix: gnu_source_prefix)
 
 have_vhost_user_blk_server = get_option('vhost_user_blk_server') \
-  .require(host_os == 'linux',
-           error_message: 'vhost_user_blk_server requires linux') \
   .require(have_vhost_user,
            error_message: 'vhost_user_blk_server requires vhost-user support') \
   .disable_auto_if(not have_tools and not have_system) \
diff --git a/contrib/vhost-user-blk/vhost-user-blk.c b/contrib/vhost-user-blk/vhost-user-blk.c
index 9492146855..a450337685 100644
--- a/contrib/vhost-user-blk/vhost-user-blk.c
+++ b/contrib/vhost-user-blk/vhost-user-blk.c
@@ -25,6 +25,20 @@
 #include <sys/ioctl.h>
 #endif
 
+/* OS X does not have O_DSYNC */
+#ifndef O_DSYNC
+#ifdef O_SYNC
+#define O_DSYNC O_SYNC
+#elif defined(O_FSYNC)
+#define O_DSYNC O_FSYNC
+#endif
+#endif
+
+/* Approximate O_DIRECT with O_DSYNC if O_DIRECT isn't available */
+#ifndef O_DIRECT
+#define O_DIRECT O_DSYNC
+#endif
+
 enum {
     VHOST_USER_BLK_MAX_QUEUES = 8,
 };
diff --git a/util/meson.build b/util/meson.build
index 72b505df11..c414178ace 100644
--- a/util/meson.build
+++ b/util/meson.build
@@ -112,10 +112,12 @@ if have_block
     util_ss.add(files('filemonitor-stub.c'))
   endif
   if host_os == 'linux'
-    util_ss.add(files('vhost-user-server.c'), vhost_user)
     util_ss.add(files('vfio-helpers.c'))
     util_ss.add(files('chardev_open.c'))
   endif
+  if host_os != 'windows'
+    util_ss.add(files('vhost-user-server.c'), vhost_user)
+  endif
   util_ss.add(files('yank.c'))
 endif
 
-- 
2.45.1