From b8172408f824fd6e7301a4d837183e755ff0649d Mon Sep 17 00:00:00 2001
From: Wei Liu <liuwe@microsoft.com>
Date: Fri, 13 Jan 2023 00:57:20 +0000
Subject: [PATCH] vhost_user_net: add --version

Signed-off-by: Wei Liu <liuwe@microsoft.com>
---
 vhost_user_net/Cargo.toml  |  1 +
 vhost_user_net/src/main.rs | 18 ++++++++++++++++--
 2 files changed, 17 insertions(+), 2 deletions(-)

diff --git a/vhost_user_net/Cargo.toml b/vhost_user_net/Cargo.toml
index 2d835ae48..1c621e0b7 100644
--- a/vhost_user_net/Cargo.toml
+++ b/vhost_user_net/Cargo.toml
@@ -3,6 +3,7 @@ name = "vhost_user_net"
 version = "0.1.0"
 authors = ["The Cloud Hypervisor Authors"]
 edition = "2021"
+build = "../build.rs"
 
 [dependencies]
 argh = "0.1.9"
diff --git a/vhost_user_net/src/main.rs b/vhost_user_net/src/main.rs
index e7bc81336..d00cfeff1 100644
--- a/vhost_user_net/src/main.rs
+++ b/vhost_user_net/src/main.rs
@@ -15,7 +15,11 @@ struct TopLevel {
     #[argh(option, long = "net-backend")]
     /// vhost-user-net backend parameters
     /// ip=<ip_addr>,mask=<net_mask>,socket=<socket_path>,client=on|off,num_queues=<number_of_queues>,queue_size=<size_of_each_queue>,tap=<if_name>
-    backend_command: String,
+    backend_command: Option<String>,
+
+    #[argh(switch, short = 'V', long = "version")]
+    /// print version information
+    version: bool,
 }
 
 fn main() {
@@ -23,5 +27,15 @@ fn main() {
 
     let toplevel: TopLevel = argh::from_env();
 
-    start_net_backend(&toplevel.backend_command);
+    if toplevel.version {
+        println!("{} {}", env!("CARGO_BIN_NAME"), env!("BUILT_VERSION"));
+        return;
+    }
+
+    if toplevel.backend_command.is_none() {
+        println!("Please specify --net-backend");
+        std::process::exit(1)
+    }
+
+    start_net_backend(&toplevel.backend_command.unwrap());
 }