meson: move vhost_user_blk_server to meson.build

The --enable/disable-vhost-user-blk-server options were implemented in
./configure. There has been confusion about them and part of the problem
is that the shell syntax used for setting the default value is not easy
to read. Move the option over to meson where the conditions are easier
to understand:

  have_vhost_user_blk_server = (targetos == 'linux')

  if get_option('vhost_user_blk_server').enabled()
      if targetos != 'linux'
          error('vhost_user_blk_server requires linux')
      endif
  elif get_option('vhost_user_blk_server').disabled() or not have_system
      have_vhost_user_blk_server = false
  endif

This patch does not change behavior.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-Id: <20201110171121.1265142-2-stefanha@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Tested-by: Philippe Mathieu-Daudé <philmd@redhat.com>

block/export/meson.build

@@ -1,2 +1,5 @@
 blockdev_ss.add(files('export.c'))
-blockdev_ss.add(when: 'CONFIG_VHOST_USER_BLK_SERVER', if_true: files('vhost-user-blk-server.c'))
+
+if have_vhost_user_blk_server
+    blockdev_ss.add(files('vhost-user-blk-server.c'))
+endif

configure

@@ -329,7 +329,7 @@ vhost_crypto=""
 vhost_scsi=""
 vhost_vsock=""
 vhost_user=""
-vhost_user_blk_server=""
+vhost_user_blk_server="auto"
 vhost_user_fs=""
 kvm="auto"
 hax="auto"
@@ -1247,9 +1247,9 @@ for opt do
   ;;
   --enable-vhost-vsock) vhost_vsock="yes"
   ;;
-  --disable-vhost-user-blk-server) vhost_user_blk_server="no"
+  --disable-vhost-user-blk-server) vhost_user_blk_server="disabled"
   ;;
-  --enable-vhost-user-blk-server) vhost_user_blk_server="yes"
+  --enable-vhost-user-blk-server) vhost_user_blk_server="enabled"
   ;;
   --disable-vhost-user-fs) vhost_user_fs="no"
   ;;
@@ -2390,12 +2390,6 @@ if test "$vhost_net" = ""; then
   test "$vhost_kernel" = "yes" && vhost_net=yes
 fi
 
-# libvhost-user is Linux-only
-test "$vhost_user_blk_server" = "" && vhost_user_blk_server=$linux
-if test "$vhost_user_blk_server" = "yes" && test "$linux" = "no"; then
-  error_exit "--enable-vhost-user-blk-server is only available on Linux"
-fi
-
 ##########################################
 # pkg-config probe
 
@@ -6289,9 +6283,6 @@ fi
 if test "$vhost_vdpa" = "yes" ; then
   echo "CONFIG_VHOST_VDPA=y" >> $config_host_mak
 fi
-if test "$vhost_user_blk_server" = "yes" ; then
-  echo "CONFIG_VHOST_USER_BLK_SERVER=y" >> $config_host_mak
-fi
 if test "$vhost_user_fs" = "yes" ; then
   echo "CONFIG_VHOST_USER_FS=y" >> $config_host_mak
 fi
@@ -7012,6 +7003,7 @@ NINJA=$ninja $meson setup \
         -Dcapstone=$capstone -Dslirp=$slirp -Dfdt=$fdt \
         -Diconv=$iconv -Dcurses=$curses -Dlibudev=$libudev\
         -Ddocs=$docs -Dsphinx_build=$sphinx_build -Dinstall_blobs=$blobs \
+        -Dvhost_user_blk_server=$vhost_user_blk_server \
         $cross_arg \
         "$PWD" "$source_path"
 

meson.build

@@ -751,6 +751,16 @@ statx_test = '''
 
 has_statx = cc.links(statx_test)
 
+have_vhost_user_blk_server = (targetos == 'linux')
+
+if get_option('vhost_user_blk_server').enabled()
+    if targetos != 'linux'
+        error('vhost_user_blk_server requires linux')
+    endif
+elif get_option('vhost_user_blk_server').disabled() or not have_system
+    have_vhost_user_blk_server = false
+endif
+
 #################
 # config-host.h #
 #################
@@ -775,6 +785,7 @@ config_host_data.set('CONFIG_MPATH_NEW_API', mpathpersist_new_api)
 config_host_data.set('CONFIG_CURSES', curses.found())
 config_host_data.set('CONFIG_SDL', sdl.found())
 config_host_data.set('CONFIG_SDL_IMAGE', sdl_image.found())
+config_host_data.set('CONFIG_VHOST_USER_BLK_SERVER', have_vhost_user_blk_server)
 config_host_data.set('CONFIG_VNC', vnc.found())
 config_host_data.set('CONFIG_VNC_JPEG', jpeg.found())
 config_host_data.set('CONFIG_VNC_PNG', png.found())
@@ -2103,6 +2114,7 @@ summary_info += {'vhost-crypto support': config_host.has_key('CONFIG_VHOST_CRYPT
 summary_info += {'vhost-scsi support': config_host.has_key('CONFIG_VHOST_SCSI')}
 summary_info += {'vhost-vsock support': config_host.has_key('CONFIG_VHOST_VSOCK')}
 summary_info += {'vhost-user support': config_host.has_key('CONFIG_VHOST_KERNEL')}
+summary_info += {'vhost-user-blk server support': have_vhost_user_blk_server}
 summary_info += {'vhost-user-fs support': config_host.has_key('CONFIG_VHOST_USER_FS')}
 summary_info += {'vhost-vdpa support': config_host.has_key('CONFIG_VHOST_VDPA')}
 summary_info += {'Trace backends':    config_host['TRACE_BACKENDS']}

meson_options.txt

@@ -64,6 +64,8 @@ option('xkbcommon', type : 'feature', value : 'auto',
        description: 'xkbcommon support')
 option('virtiofsd', type: 'feature', value: 'auto',
        description: 'build virtiofs daemon (virtiofsd)')
+option('vhost_user_blk_server', type: 'feature', value: 'auto',
+       description: 'build vhost-user-blk server')
 
 option('capstone', type: 'combo', value: 'auto',
        choices: ['disabled', 'enabled', 'auto', 'system', 'internal'],