Change proc_exit to unwind the stack rather than exiting the host process. (#1646)

* Remove Cranelift's OutOfBounds trap, which is no longer used.

* Change proc_exit to unwind instead of exit the host process.

This implements the semantics in https://github.com/WebAssembly/WASI/pull/235.

Fixes #783.
Fixes #993.

* Fix exit-status tests on Windows.

* Revert the wiggle changes and re-introduce the wasi-common implementations.

* Move `wasi_proc_exit` into the wasmtime-wasi crate.

* Revert the spec_testsuite change.

* Remove the old proc_exit implementations.

* Make `TrapReason` an implementation detail.

* Allow exit status 2 on Windows too.

* Fix a documentation link.

* Really fix a documentation link.

tests/all/cli_tests.rs

@@ -182,3 +182,77 @@ fn timeout_in_invoke() -> Result<()> {
     );
     Ok(())
 }
+
+// Exit with a valid non-zero exit code, snapshot0 edition.
+#[test]
+fn exit2_wasi_snapshot0() -> Result<()> {
+    let wasm = build_wasm("tests/wasm/exit2_wasi_snapshot0.wat")?;
+    let output = run_wasmtime_for_output(&[wasm.path().to_str().unwrap(), "--disable-cache"])?;
+    assert_eq!(output.status.code().unwrap(), 2);
+    Ok(())
+}
+
+// Exit with a valid non-zero exit code, snapshot1 edition.
+#[test]
+fn exit2_wasi_snapshot1() -> Result<()> {
+    let wasm = build_wasm("tests/wasm/exit2_wasi_snapshot1.wat")?;
+    let output = run_wasmtime_for_output(&[wasm.path().to_str().unwrap(), "--disable-cache"])?;
+    assert_eq!(output.status.code().unwrap(), 2);
+    Ok(())
+}
+
+// Exit with a valid non-zero exit code, snapshot0 edition.
+#[test]
+fn exit125_wasi_snapshot0() -> Result<()> {
+    let wasm = build_wasm("tests/wasm/exit125_wasi_snapshot0.wat")?;
+    let output = run_wasmtime_for_output(&[wasm.path().to_str().unwrap(), "--disable-cache"])?;
+    if cfg!(windows) {
+        assert_eq!(output.status.code().unwrap(), 1);
+    } else {
+        assert_eq!(output.status.code().unwrap(), 125);
+    }
+    Ok(())
+}
+
+// Exit with a valid non-zero exit code, snapshot1 edition.
+#[test]
+fn exit125_wasi_snapshot1() -> Result<()> {
+    let wasm = build_wasm("tests/wasm/exit125_wasi_snapshot1.wat")?;
+    let output = run_wasmtime_for_output(&[wasm.path().to_str().unwrap(), "--disable-cache"])?;
+    if cfg!(windows) {
+        assert_eq!(output.status.code().unwrap(), 1);
+    } else {
+        assert_eq!(output.status.code().unwrap(), 125);
+    }
+    Ok(())
+}
+
+// Exit with an invalid non-zero exit code, snapshot0 edition.
+#[test]
+fn exit126_wasi_snapshot0() -> Result<()> {
+    let wasm = build_wasm("tests/wasm/exit126_wasi_snapshot0.wat")?;
+    let output = run_wasmtime_for_output(&[wasm.path().to_str().unwrap(), "--disable-cache"])?;
+    if cfg!(windows) {
+        assert_eq!(output.status.code().unwrap(), 3);
+    } else {
+        assert_eq!(output.status.code().unwrap(), 128 + libc::SIGABRT);
+    }
+    assert!(output.stdout.is_empty());
+    assert!(String::from_utf8_lossy(&output.stderr).contains("invalid exit status"));
+    Ok(())
+}
+
+// Exit with an invalid non-zero exit code, snapshot1 edition.
+#[test]
+fn exit126_wasi_snapshot1() -> Result<()> {
+    let wasm = build_wasm("tests/wasm/exit126_wasi_snapshot1.wat")?;
+    let output = run_wasmtime_for_output(&[wasm.path().to_str().unwrap(), "--disable-cache"])?;
+    if cfg!(windows) {
+        assert_eq!(output.status.code().unwrap(), 3);
+    } else {
+        assert_eq!(output.status.code().unwrap(), 128 + libc::SIGABRT);
+    }
+    assert!(output.stdout.is_empty());
+    assert!(String::from_utf8_lossy(&output.stderr).contains("invalid exit status"));
+    Ok(())
+}

tests/all/func.rs

@@ -182,6 +182,7 @@ fn trap_smoke() -> Result<()> {
     let f = Func::wrap(&store, || -> Result<(), Trap> { Err(Trap::new("test")) });
     let err = f.call(&[]).unwrap_err().downcast::<Trap>()?;
     assert_eq!(err.message(), "test");
+    assert!(err.i32_exit_status().is_none());
     Ok(())
 }
 

tests/all/iloop.rs

@@ -30,7 +30,7 @@ fn loops_interruptable() -> anyhow::Result<()> {
     let iloop = instance.get_func("loop").unwrap().get0::<()>()?;
     store.interrupt_handle()?.interrupt();
     let trap = iloop().unwrap_err();
-    assert!(trap.message().contains("wasm trap: interrupt"));
+    assert!(trap.to_string().contains("wasm trap: interrupt"));
     Ok(())
 }
 
@@ -44,9 +44,9 @@ fn functions_interruptable() -> anyhow::Result<()> {
     store.interrupt_handle()?.interrupt();
     let trap = iloop().unwrap_err();
     assert!(
-        trap.message().contains("wasm trap: interrupt"),
+        trap.to_string().contains("wasm trap: interrupt"),
         "{}",
-        trap.message()
+        trap.to_string()
     );
     Ok(())
 }
@@ -91,9 +91,9 @@ fn loop_interrupt_from_afar() -> anyhow::Result<()> {
     let trap = iloop().unwrap_err();
     thread.join().unwrap();
     assert!(
-        trap.message().contains("wasm trap: interrupt"),
+        trap.to_string().contains("wasm trap: interrupt"),
         "bad message: {}",
-        trap.message()
+        trap.to_string()
     );
     Ok(())
 }
@@ -127,9 +127,9 @@ fn function_interrupt_from_afar() -> anyhow::Result<()> {
     let trap = iloop().unwrap_err();
     thread.join().unwrap();
     assert!(
-        trap.message().contains("wasm trap: interrupt"),
+        trap.to_string().contains("wasm trap: interrupt"),
         "bad message: {}",
-        trap.message()
+        trap.to_string()
     );
     Ok(())
 }

tests/all/stack_overflow.rs

@@ -30,9 +30,9 @@ fn host_always_has_some_stack() -> anyhow::Result<()> {
     // has been exhausted.
     let trap = foo().unwrap_err();
     assert!(
-        trap.message().contains("call stack exhausted"),
+        trap.to_string().contains("call stack exhausted"),
         "{}",
-        trap.message()
+        trap.to_string()
     );
 
     // Additionally, however, and this is the crucial test, make sure that the

tests/wasm/exit125_wasi_snapshot0.wat

@@ -0,0 +1,8 @@
+(module
+  (import "wasi_unstable" "proc_exit"
+    (func $__wasi_proc_exit (param i32)))
+  (func $_start
+    (call $__wasi_proc_exit (i32.const 125))
+  )
+  (export "_start" (func $_start))
+)

tests/wasm/exit125_wasi_snapshot1.wat

@@ -0,0 +1,8 @@
+(module
+  (import "wasi_snapshot_preview1" "proc_exit"
+    (func $__wasi_proc_exit (param i32)))
+  (func $_start
+    (call $__wasi_proc_exit (i32.const 125))
+  )
+  (export "_start" (func $_start))
+)

tests/wasm/exit126_wasi_snapshot0.wat

@@ -0,0 +1,8 @@
+(module
+  (import "wasi_unstable" "proc_exit"
+    (func $__wasi_proc_exit (param i32)))
+  (func $_start
+    (call $__wasi_proc_exit (i32.const 126))
+  )
+  (export "_start" (func $_start))
+)

tests/wasm/exit126_wasi_snapshot1.wat

@@ -0,0 +1,8 @@
+(module
+  (import "wasi_snapshot_preview1" "proc_exit"
+    (func $__wasi_proc_exit (param i32)))
+  (func $_start
+    (call $__wasi_proc_exit (i32.const 126))
+  )
+  (export "_start" (func $_start))
+)

tests/wasm/exit2_wasi_snapshot0.wat

@@ -0,0 +1,8 @@
+(module
+  (import "wasi_unstable" "proc_exit"
+    (func $__wasi_proc_exit (param i32)))
+  (func $_start
+    (call $__wasi_proc_exit (i32.const 2))
+  )
+  (export "_start" (func $_start))
+)

tests/wasm/exit2_wasi_snapshot1.wat

@@ -0,0 +1,8 @@
+(module
+  (import "wasi_snapshot_preview1" "proc_exit"
+    (func $__wasi_proc_exit (param i32)))
+  (func $_start
+    (call $__wasi_proc_exit (i32.const 2))
+  )
+  (export "_start" (func $_start))
+)