vhost_iommu: handle opendir() failure

Change-Id: I82ce702ab1af83c2f5c0197a9766437f0f728dce
Signed-off-by: Daniel Verkamp <daniel.verkamp@intel.com>
Reviewed-on: https://review.gerrithub.io/365067
Tested-by: SPDK Automated Test System <sys_sgsw@intel.com>
Reviewed-by: Ben Walker <benjamin.walker@intel.com>
Reviewed-by: Jim Harris <james.r.harris@intel.com>

lib/vhost/vhost_iommu.c

@@ -91,6 +91,11 @@ vfio_cfg_init(void)
 	}
 
 	dir = opendir("/proc/self/fd");
+	if (!dir) {
+		SPDK_ERRLOG("Failed to open /proc/self/fd (%d)\n", errno);
+		return -1;
+	}
+
 	while ((d = readdir(dir)) != NULL) {
 		if (d->d_type != DT_LNK)
 			continue;