Add interactive launch mode.

After launching a process via the server, krun immediately closes and the
launched process' std{in,out,err} go nowhere. Add a --interactive flag that
allocates a pseudo-terminal, routes it to the host and connects to it.

Somewhat like '-it' in docker/podman exec.

Signed-off-by: Sasha Finkelstein <[email protected]>

crates/muvm/src/bin/muvm.rs

@@ -16,7 +16,7 @@ use muvm::cli_options::options;
 use muvm::cpu::{get_fallback_cores, get_performance_cores};
 use muvm::env::{find_muvm_exec, prepare_env_vars};
 use muvm::hidpipe_server::spawn_hidpipe_server;
-use muvm::launch::{launch_or_lock, LaunchResult};
+use muvm::launch::{launch_or_lock, LaunchResult, DYNAMIC_PORT_RANGE};
 use muvm::monitor::spawn_monitor;
 use muvm::net::{connect_to_passt, start_passt};
 use muvm::types::MiB;
@@ -74,6 +74,7 @@ fn main() -> Result<()> {
         options.command,
         options.command_args,
         options.env,
+        options.interactive,
     )? {
         LaunchResult::LaunchRequested => {
             // There was a muvm instance already running and we've requested it
@@ -317,7 +318,7 @@ fn main() -> Result<()> {
         let socket_dir = Path::new(&run_path).join("krun/socket");
         std::fs::create_dir_all(&socket_dir)?;
         // Dynamic ports: Applications may listen on these sockets as neeeded.
-        for port in 50000..50200 {
+        for port in DYNAMIC_PORT_RANGE {
             let socket_path = socket_dir.join(format!("port-{}", port));
             let socket_path = CString::new(
                 socket_path

crates/muvm/src/cli_options.rs

@@ -17,6 +17,7 @@ pub struct Options {
     pub server_port: u32,
     pub fex_images: Vec<String>,
     pub direct_x11: bool,
+    pub interactive: bool,
     pub command: PathBuf,
     pub command_args: Vec<String>,
 }
@@ -116,7 +117,10 @@ pub fn options() -> OptionParser<Options> {
             "--direct-x11 requires the `x11bridge` crate feature",
         )
         .hide();
-
+    let interactive = long("interactive")
+        .short('i')
+        .help("Allocate a tty guest-side and connect it to the current stdin/out")
+        .switch();
     let command = positional("COMMAND").help("the command you want to execute in the vm");
     let command_args = any::<String, _, _>("COMMAND_ARGS", |arg| {
         (!["--help", "-h"].contains(&&*arg)).then_some(arg)
@@ -134,6 +138,7 @@ pub fn options() -> OptionParser<Options> {
         server_port,
         fex_images,
         direct_x11,
+        interactive,
         // positionals
         command,
         command_args,

crates/muvm/src/launch.rs

@@ -11,8 +11,14 @@ use anyhow::{anyhow, Context, Result};
 use rustix::fs::{flock, FlockOperation};
 use uuid::Uuid;
 
+use super::utils::env::find_in_path;
 use crate::env::prepare_env_vars;
 use crate::utils::launch::Launch;
+use rustix::path::Arg;
+use std::ops::Range;
+use std::process::{Child, Command};
+
+pub const DYNAMIC_PORT_RANGE: Range<u32> = 50000..50200;
 
 pub enum LaunchResult {
     LaunchRequested,
@@ -50,18 +56,79 @@ impl Display for LaunchError {
     }
 }
 
+fn start_socat() -> Result<(Child, u32)> {
+    let run_path = env::var("XDG_RUNTIME_DIR")
+        .map_err(|e| anyhow!("unable to get XDG_RUNTIME_DIR: {:?}", e))?;
+    let socket_dir = Path::new(&run_path).join("krun/socket");
+    let socat_path =
+        find_in_path("socat")?.ok_or_else(|| anyhow!("Unable to find socat in PATH"))?;
+    for port in DYNAMIC_PORT_RANGE {
+        let path = socket_dir.join(format!("port-{}", port));
+        if path.exists() {
+            continue;
+        }
+        let child = Command::new(&socat_path)
+            .arg(format!("unix-l:{}", path.as_os_str().to_string_lossy()))
+            .arg("-,raw,echo=0")
+            .spawn()?;
+        return Ok((child, port));
+    }
+    Err(anyhow!("Ran out of ports."))
+}
+
+fn escape_for_socat(s: String) -> String {
+    let mut ret = String::with_capacity(s.len());
+    for c in s.chars() {
+        match c {
+            ':' | ',' | '!' | '"' | '\'' | '\\' | '(' | '[' | '{' => {
+                ret.push('\\');
+            },
+            _ => {},
+        }
+        ret.push(c);
+    }
+    ret
+}
+
+fn wrapped_launch(
+    server_port: u32,
+    cookie: Uuid,
+    mut command: PathBuf,
+    mut command_args: Vec<String>,
+    env: HashMap<String, String>,
+    interactive: bool,
+) -> Result<()> {
+    if !interactive {
+        return request_launch(server_port, cookie, command, command_args, env);
+    }
+    let (mut socat, vsock_port) = start_socat()?;
+    command_args.insert(0, command.to_string_lossy().into_owned());
+    command_args = vec![
+        format!("vsock:2:{}", vsock_port),
+        format!(
+            "exec:{},pty,setsid,stderr",
+            escape_for_socat(command_args.join(" "))
+        ),
+    ];
+    command = "socat".into();
+    request_launch(server_port, cookie, command, command_args, env)?;
+    socat.wait()?;
+    Ok(())
+}
+
 pub fn launch_or_lock(
     server_port: u32,
     command: PathBuf,
     command_args: Vec<String>,
     env: Vec<(String, Option<String>)>,
+    interactive: bool,
 ) -> Result<LaunchResult> {
     let running_server_port = env::var("MUVM_SERVER_PORT").ok();
     if let Some(port) = running_server_port {
         let port: u32 = port.parse()?;
         let env = prepare_env_vars(env)?;
         let cookie = read_cookie()?;
-        if let Err(err) = request_launch(port, cookie, command, command_args, env) {
+        if let Err(err) = wrapped_launch(port, cookie, command, command_args, env, interactive) {
             return Err(anyhow!("could not request launch to server: {err}"));
         }
         return Ok(LaunchResult::LaunchRequested);
@@ -80,12 +147,13 @@ pub fn launch_or_lock(
             let env = prepare_env_vars(env)?;
             let mut tries = 0;
             loop {
-                match request_launch(
+                match wrapped_launch(
                     server_port,
                     cookie,
                     command.clone(),
                     command_args.clone(),
                     env.clone(),
+                    interactive,
                 ) {
                     Err(err) => match err.downcast_ref::<LaunchError>() {
                         Some(&LaunchError::Connection(_)) => {