[PULL 49/66] libvhost-user: check memfd API

[Michael S. Tsirkin]

From: Marc-André Lureau <marcandre.lureau@redhat.com>

Do not compile potentially panicking code, instead check memfd API is
present during configure time.

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <20201125100640.366523-7-marcandre.lureau@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---
 subprojects/libvhost-user/libvhost-user.c |  6 ------
 subprojects/libvhost-user/meson.build     | 12 ++++++++++++
 2 files changed, 12 insertions(+), 6 deletions(-)

diff --git a/subprojects/libvhost-user/libvhost-user.c 
b/subprojects/libvhost-user/libvhost-user.c
index fab7ca17ee..09741a7b49 100644
--- a/subprojects/libvhost-user/libvhost-user.c
+++ b/subprojects/libvhost-user/libvhost-user.c
@@ -1616,7 +1616,6 @@ vu_inflight_queue_size(uint16_t queue_size)
            sizeof(uint16_t), INFLIGHT_ALIGNMENT);
 }
 
-#ifdef MFD_ALLOW_SEALING
 static void *
 memfd_alloc(const char *name, size_t size, unsigned int flags, int *fd)
 {
@@ -1648,7 +1647,6 @@ memfd_alloc(const char *name, size_t size, unsigned int 
flags, int *fd)
 
     return ptr;
 }
-#endif
 
 static bool
 vu_get_inflight_fd(VuDev *dev, VhostUserMsg *vmsg)
@@ -1672,13 +1670,9 @@ vu_get_inflight_fd(VuDev *dev, VhostUserMsg *vmsg)
 
     mmap_size = vu_inflight_queue_size(queue_size) * num_queues;
 
-#ifdef MFD_ALLOW_SEALING
     addr = memfd_alloc("vhost-inflight", mmap_size,
                        F_SEAL_GROW | F_SEAL_SHRINK | F_SEAL_SEAL,
                        &fd);
-#else
-    vu_panic(dev, "Not implemented: memfd support is missing");
-#endif
 
     if (!addr) {
         vu_panic(dev, "Failed to alloc vhost inflight area");
diff --git a/subprojects/libvhost-user/meson.build 
b/subprojects/libvhost-user/meson.build
index f9ecc534cf..ac228b5ba6 100644
--- a/subprojects/libvhost-user/meson.build
+++ b/subprojects/libvhost-user/meson.build
@@ -2,7 +2,19 @@ project('libvhost-user', 'c',
         license: 'GPL-2.0-or-later',
         default_options: ['c_std=gnu99'])
 
+cc = meson.get_compiler('c')
+
 glib = dependency('glib-2.0')
+foreach h, syms: {
+  'sys/mman.h': ['memfd_create', 'MFD_ALLOW_SEALING'],
+  'sys/fcntl.h': ['F_SEAL_GROW', 'F_SEAL_SHRINK', 'F_SEAL_SEAL'] }
+  foreach sym: syms
+    cc.has_header_symbol(h, sym,
+                         args: ['-D_GNU_SOURCE'],
+                         required: true)
+  endforeach
+endforeach
+
 inc = include_directories('../../include', '../../linux-headers')
 
 vhost_user = static_library('vhost-user',
-- 
MST