muvm: Add a --passt-args argument to pass args to passt

crates/muvm/Cargo.toml

@@ -24,6 +24,7 @@ procfs = { version = "0.18.0", default-features = false, features = [] }
 rustix = { version = "0.38.34", default-features = false, features = ["fs", "mount", "process", "pty", "std", "stdio", "system", "termios", "use-libc-auxv"] }
 serde = { version = "1.0.203", default-features = false, features = ["derive"] }
 serde_json = { version = "1.0.117", default-features = false, features = ["std"] }
+shell-words = { version = "1.1.1", default-features = false, features = ["std"] }
 tempfile = { version = "3.10.1", default-features = false, features = [] }
 tokio = { version = "1.38.0", default-features = false, features = ["io-util", "macros", "net", "process", "rt-multi-thread", "sync"] }
 tokio-stream = { version = "0.1.15", default-features = false, features = ["net", "sync"] }

crates/muvm/src/bin/muvm.rs

@@ -278,7 +278,7 @@ fn main() -> Result<ExitCode> {
                 .context("Failed to connect to `passt`")?
                 .into()
         } else {
-            start_passt(&options.publish_ports)
+            start_passt(&options.publish_ports, &options.passt_args)
                 .context("Failed to start `passt`")?
                 .into()
         };

crates/muvm/src/cli_options.rs

@@ -37,6 +37,7 @@ pub struct Options {
     pub mem: Option<MiB>,
     pub vram: Option<MiB>,
     pub passt_socket: Option<PathBuf>,
+    pub passt_args: Vec<String>,
     pub fex_images: Vec<String>,
     pub merged_rootfs: bool,
     pub interactive: bool,
@@ -135,6 +136,15 @@ pub fn options() -> OptionParser<Options> {
         .help("Instead of starting passt, connect to passt socket at PATH")
         .argument("PATH")
         .optional();
+    let passt_args = long("passt-args")
+        .help(
+            "When starting passt, append the given arguments.
+            May contain shell-quoted args, like so: --passt-args '-l \"my log file.txt\"'",
+        )
+        .argument::<String>("ARGS")
+        .parse(|s| shell_words::split(&s))
+        .many()
+        .map(|nested| nested.into_iter().flatten().collect());
     let interactive = long("interactive")
         .short('i')
         .help("Attach to the command's stdin/out after starting it")
@@ -192,6 +202,7 @@ pub fn options() -> OptionParser<Options> {
         mem,
         vram,
         passt_socket,
+        passt_args,
         fex_images,
         merged_rootfs,
         interactive,

crates/muvm/src/net.rs

@@ -82,7 +82,7 @@ where
     Ok(UnixStream::connect(passt_socket_path)?)
 }
 
-pub fn start_passt(publish_ports: &[String]) -> Result<UnixStream> {
+pub fn start_passt(publish_ports: &[String], passt_args: &[String]) -> Result<UnixStream> {
     // SAFETY: The child process should not inherit the file descriptor of
     // `parent_socket`. There is no documented guarantee of this, but the
     // implementation as of writing atomically sets `SOCK_CLOEXEC`.
@@ -112,6 +112,9 @@ pub fn start_passt(publish_ports: &[String]) -> Result<UnixStream> {
     for spec in publish_ports {
         cmd.args(PublishSpec::parse(spec)?.to_args());
     }
+    for arg in passt_args {
+        cmd.arg(arg);
+    }
     let child = cmd.spawn();
     if let Err(err) = child {
         return Err(err).context("Failed to execute `passt` as child process");