Unhardcode user IDs

Cargo.lock

@@ -635,9 +635,9 @@ checksum = "bbd2bcb4c963f2ddae06a2efc7e9f3591312473c50c6685e1f298068316e66fe"
 
 [[package]]
 name = "libc"
-version = "0.2.174"
+version = "0.2.178"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "1171693293099992e19cddea4e8b849964e9846f4acee11b3948bcc337be8776"
+checksum = "37c93d8daa9d8a012fd8ab92f088405fb202ea0b6ab73ee2482ae66af4f42091"
 
 [[package]]
 name = "linux-raw-sys"
@@ -1026,6 +1026,7 @@ dependencies = [
  "clap",
  "eyre",
  "futures",
+ "libc",
  "rand",
  "rustix",
  "sidebus-common",

sidebus-broker/Cargo.toml

@@ -18,3 +18,4 @@ rustix = { version = "1.0.8", features = ["fs"] }
 url = "2.5.4"
 rand = "0.9.2"
 futures = "0.3.31"
+libc = "0.2.178"

sidebus-broker/src/main.rs

@@ -43,6 +43,14 @@ struct BrokerCli {
     /// Unix socket path to listen on for the VM bus
     #[clap(long)]
     unix_path: Option<PathBuf>,
+
+    /// The user ID for the appvm user inside of the guest
+    #[clap(long, default_value = "1337")]
+    guest_uid: u32,
+
+    /// The group ID for the appvm group inside of the guest
+    #[clap(long, default_value = "1337")]
+    guest_gid: u32,
 }
 
 async fn new_hosted_bus() -> eyre::Result<(
@@ -129,9 +137,9 @@ async fn main() -> eyre::Result<()> {
                 "--socket-path",
                 cli.runtime_dir.join("fs.sock").to_str().unwrap(),
                 "--uid-map",
-                ":1000:1001:1:",
+                &format!(":{}:{}:1:", cli.guest_uid, unsafe { libc::getuid() }),
                 "--gid-map",
-                ":100:100:1:",
+                &format!(":{}:{}:1:", cli.guest_gid, unsafe { libc::getgid() }),
                 "--log-level",
                 "debug",
             ])