muvm-guest: Reopen the system tty (hvc0)

This fixes the classic:

-bash: cannot set terminal process group (-1): Inappropriate ioctl for device
-bash: no job control in this shell

I'm not entirely sure why this doesn't happen with our main shell, but it
happens with things like sudo. (There are a bunch of other things needed
to make sudo work, of course)

Signed-off-by: Asahi Lina <[email protected]>

Author: hoshinolina

crates/muvm/Cargo.toml

@@ -16,7 +16,7 @@ env_logger = { version = "0.11.3", default-features = false, features = ["auto-c
 krun-sys = { path = "../krun-sys", version = "1.9.1", default-features = false, features = [] }
 log = { version = "0.4.21", default-features = false, features = ["kv"] }
 nix = { version = "0.28.0", default-features = false, features = ["user"] }
-rustix = { version = "0.38.34", default-features = false, features = ["fs", "mount", "process", "std", "system", "use-libc-auxv"] }
+rustix = { version = "0.38.34", default-features = false, features = ["fs", "mount", "process", "std", "stdio", "system", "use-libc-auxv"] }
 serde = { version = "1.0.203", default-features = false, features = ["derive"] }
 serde_json = { version = "1.0.117", default-features = false, features = ["std"] }
 tempfile = { version = "3.10.1", default-features = false, features = [] }

crates/muvm/src/guest/bin/muvm-guest.rs

@@ -1,4 +1,5 @@
 use std::cmp;
+use std::os::fd::AsFd;
 use std::os::unix::process::CommandExt as _;
 use std::process::Command;
 
@@ -38,6 +39,17 @@ fn main() -> Result<()> {
     if let Err(err) = mount_filesystems() {
         return Err(err).context("Failed to mount filesystems, bailing out");
     }
+
+    // Use the correct TTY, which fixes pty issues etc. (/dev/console cannot be a controlling tty)
+    let console = std::fs::OpenOptions::new()
+        .read(true)
+        .write(true)
+        .create(false)
+        .open("/dev/hvc0")?;
+    rustix::stdio::dup2_stdin(console.as_fd())?;
+    rustix::stdio::dup2_stdout(console.as_fd())?;
+    rustix::stdio::dup2_stderr(console.as_fd())?;
+
     Command::new("/usr/lib/systemd/systemd-udevd").spawn()?;
 
     setup_fex()?;