Don't depend on the USER environment variable

Instead of reading $USER variable and finding the user based on that,
use uid to lookup the user.

Signed-off-by: Nikodem Rabuliński <[email protected]>

Author: nrabulinski

crates/muvm/src/bin/muvm.rs

@@ -346,11 +346,12 @@ fn main() -> Result<ExitCode> {
         }
     }
 
-    let username = env::var("USER").context("Failed to get username from environment")?;
-    let user = User::from_name(&username)
+    let uid = getuid().as_raw();
+    let user = User::from_uid(uid.into())
         .map_err(Into::into)
         .and_then(|user| user.ok_or_else(|| anyhow!("requested entry not found")))
-        .with_context(|| format!("Failed to get user `{username}` from user database"))?;
+        .with_context(|| format!("Failed to get user `{uid}` from user database"))?;
+
     let workdir_path = CString::new(
         user.dir
             .to_str()
@@ -389,8 +390,7 @@ fn main() -> Result<ExitCode> {
             tty: false,
             privileged: false,
         },
-        username,
-        uid: getuid().as_raw(),
+        uid,
         gid: getgid().as_raw(),
         host_display: display,
         merged_rootfs: options.merged_rootfs,

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

@@ -96,11 +96,7 @@ fn main() -> Result<()> {
 
     configure_network()?;
 
-    let run_path = match setup_user(
-        options.username,
-        Uid::from(options.uid),
-        Gid::from(options.gid),
-    ) {
+    let run_path = match setup_user(Uid::from(options.uid), Gid::from(options.gid)) {
         Ok(p) => p,
         Err(err) => return Err(err).context("Failed to set up user, bailing out"),
     };

crates/muvm/src/guest/user.rs

@@ -8,7 +8,7 @@ use anyhow::{anyhow, Context, Result};
 use nix::sys::wait::{waitpid, WaitStatus};
 use nix::unistd::{fork, setresgid, setresuid, ForkResult, Gid, Uid, User};
 
-pub fn setup_user(username: String, uid: Uid, gid: Gid) -> Result<PathBuf> {
+pub fn setup_user(uid: Uid, gid: Gid) -> Result<PathBuf> {
     setup_directories(uid, gid)?;
 
     setresgid(gid, gid, Gid::from(0)).context("Failed to setgid")?;
@@ -24,10 +24,10 @@ pub fn setup_user(username: String, uid: Uid, gid: Gid) -> Result<PathBuf> {
     // See https://doc.rust-lang.org/std/env/fn.set_var.html#safety
     env::set_var("XDG_RUNTIME_DIR", &path);
 
-    let user = User::from_name(&username)
+    let user = User::from_uid(uid)
         .map_err(Into::into)
         .and_then(|user| user.ok_or_else(|| anyhow!("requested entry not found")))
-        .with_context(|| format!("Failed to get user `{username}` from user database"))?;
+        .with_context(|| format!("Failed to get user `{uid}` from user database"))?;
 
     {
         // SAFETY: Safe if and only if `muvm-guest` program is not multithreaded.

crates/muvm/src/utils/launch.rs

@@ -38,7 +38,6 @@ impl FromStr for Emulator {
 #[derive(Clone, Eq, PartialEq, Debug, Deserialize, Serialize)]
 pub struct GuestConfiguration {
     pub command: Launch,
-    pub username: String,
     pub uid: u32,
     pub gid: u32,
     pub host_display: Option<String>,