Fix exit code mismatch between wasmtime and lind-boot exit (#856)

* Fix exit code mismatch

* Update skipped list

* Skip test case

* Handle system err return

* Fix merge conflicts

Author: Yaxuan-w

src/lind-boot/src/lind_wasmtime/execute.rs

@@ -46,7 +46,7 @@ use wasmtime_wasi_threads::WasiThreadsCtx;
 /// entrypoint. On successful completion it waits for all cages to exit before
 /// shutting down RawPOSIX, ensuring runtime-wide cleanup happens only after the
 /// last process terminates.
-pub fn execute_wasmtime(lindboot_cli: CliOptions) -> anyhow::Result<Vec<Val>> {
+pub fn execute_wasmtime(lindboot_cli: CliOptions) -> anyhow::Result<i32> {
     // -- Initialize Lind + RawPOSIX + 3i runtime --
     // Initialize the Lind cage counter
     let lind_manager = Arc::new(LindCageManager::new(0));
@@ -71,16 +71,25 @@ pub fn execute_wasmtime(lindboot_cli: CliOptions) -> anyhow::Result<Vec<Val>> {
     let result = execute_with_lind(lindboot_cli, lind_manager.clone(), CAGE_START_ID as u64);
 
     match result {
-        Ok(ref _res) => {
+        Ok(ref ret_vals) => {
             // we wait until all other cage exits
             lind_manager.wait();
+            // Interpret the first return value of the Wasm entry point
+            // as the process exit code. If the module does not explicitly
+            // return an i32, we treat it as a successful exit (code = 0).
+            let exit_code = match ret_vals.first() {
+                Some(Val::I32(code)) => *code,
+                _ => 0,
+            };
+            // Propagate the exit code to the main, which will translate it
+            // into the host process exit status.
+            Ok(exit_code)
         }
         Err(e) => {
+            // Exit the process
             return Err(e);
         }
     }
-
-    result
 }
 
 /// Executes a Wasm program *within an existing Lind runtime* as part of an `exec()` path.

src/lind-boot/src/main.rs

@@ -71,9 +71,27 @@ fn main() -> Result<(), Box<dyn std::error::Error>> {
     // Initialize RawPOSIX and register RawPOSIX syscalls with 3i
     rawposix_start(0);
 
-    // Execute with user-selected runtime. Can be switched to other runtime implementation
-    // in the future (e.g.: MPK).
-    execute_wasmtime(lindboot_cli)?;
+    // Execute the selected runtime backend and translate its unified
+    // execution result into a host-level process exit status.
+    //
+    // At this layer, we intentionally do NOT interpret Wasm return
+    // conventions or runtime-specific details. All exit semantics
+    // (e.g., proc_exit, return values, traps) are already normalized
+    // inside `execute_wasmtime` into a single `i32` exit code.
+    //
+    // This design keeps the runtime backend pluggable (e.g., Wasmtime,
+    // MPK-based runtime, SGX-enclosed runtime) while preserving a
+    // consistent host process contract: exit(code) on success,
+    // If the runtime backend fails before producing a normalized
+    // program exit code, terminate with EX_SOFTWARE (70) to signal
+    // a runtime-level failure rather than a cage-provided exit code.
+    match execute_wasmtime(lindboot_cli) {
+        Ok(code) => std::process::exit(code),
+        Err(e) => {
+            eprintln!("{:?}", e);
+            std::process::exit(sysdefs::constants::EX_SOFTWARE);
+        }
+    }
 
     // after all cage exits, finalize the lind
     rawposix_shutdown();

src/sysdefs/src/constants/sys_const.rs

@@ -209,3 +209,27 @@ pub const CLONE_IO: u64 = 0x80000000; /* Clone I/O context.  */
 /* cloning flags intersect with CSIGNAL so can be used only with unshare and
 clone3 syscalls.  */
 pub const CLONE_NEWTIME: u64 = 0x00000080; /* New time namespace */
+
+// Exit code
+// Source: src/glibc/misc/sysexits.h
+pub const EX_OK: i32 = 0; /* successful termination */
+
+pub const EX__BASE: i32 = 64; /* base value for error messages */
+
+pub const EX_USAGE: i32 = 64; /* command line usage error */
+pub const EX_DATAERR: i32 = 65; /* data format error */
+pub const EX_NOINPUT: i32 = 66; /* cannot open input */
+pub const EX_NOUSER: i32 = 67; /* addressee unknown */
+pub const EX_NOHOST: i32 = 68; /* host name unknown */
+pub const EX_UNAVAILABLE: i32 = 69; /* service unavailable */
+pub const EX_SOFTWARE: i32 = 70; /* internal software error */
+pub const EX_OSERR: i32 = 71; /* system error (e.g., can't fork) */
+pub const EX_OSFILE: i32 = 72; /* critical OS file missing */
+pub const EX_CANTCREAT: i32 = 73; /* can't create (user) output file */
+pub const EX_IOERR: i32 = 74; /* input/output error */
+pub const EX_TEMPFAIL: i32 = 75; /* temp failure; user is invited to retry */
+pub const EX_PROTOCOL: i32 = 76; /* remote error in protocol */
+pub const EX_NOPERM: i32 = 77; /* permission denied */
+pub const EX_CONFIG: i32 = 78; /* configuration error */
+
+pub const EX__MAX: i32 = 78; /* maximum listed value */