baremetal,wasm: support command line params and environment variables

This is mainly useful to be able to run `tinygo test`, for example:

    tinygo test -target=cortex-m-qemu -v math

This is not currently supported, but will be in the future.

loader/goroot.go

@@ -208,7 +208,7 @@ func mergeDirectory(goroot, tinygoroot, tmpgoroot, importPath string, overrides
 // with the TinyGo version. This is the case on some targets.
 func needsSyscallPackage(buildTags []string) bool {
 	for _, tag := range buildTags {
-		if tag == "baremetal" || tag == "darwin" || tag == "nintendoswitch" || tag == "wasi" {
+		if tag == "baremetal" || tag == "darwin" || tag == "nintendoswitch" || tag == "tinygo.wasm" {
 			return true
 		}
 	}

main_test.go

@@ -162,15 +162,15 @@ func runPlatTests(target string, tests []string, t *testing.T) {
 			runTest(name, target, t, nil, nil)
 		})
 	}
+	t.Run("env.go", func(t *testing.T) {
+		t.Parallel()
+		runTest("env.go", target, t, []string{"first", "second"}, []string{"ENV1=VALUE1", "ENV2=VALUE2"})
+	})
 	if target == "" || target == "wasi" {
 		t.Run("filesystem.go", func(t *testing.T) {
 			t.Parallel()
 			runTest("filesystem.go", target, t, nil, nil)
 		})
-		t.Run("env.go", func(t *testing.T) {
-			t.Parallel()
-			runTest("env.go", target, t, []string{"first", "second"}, []string{"ENV1=VALUE1", "ENV2=VALUE2"})
-		})
 	}
 	if target == "" || target == "wasi" || target == "wasm" {
 		t.Run("rand.go", func(t *testing.T) {
@@ -233,6 +233,42 @@ func runTestWithConfig(name, target string, t *testing.T, options compileopts.Op
 		}
 	}()
 
+	// Determine whether we're on a system that supports environment variables
+	// and command line parameters (operating systems, WASI) or not (baremetal,
+	// WebAssembly in the browser). If we're on a system without an environment,
+	// we need to pass command line arguments and environment variables through
+	// global variables (built into the binary directly) instead of the
+	// conventional way.
+	spec, err := compileopts.LoadTarget(target)
+	if err != nil {
+		t.Fatal("failed to load target spec:", err)
+	}
+	needsEnvInVars := spec.GOOS == "js"
+	for _, tag := range spec.BuildTags {
+		if tag == "baremetal" {
+			needsEnvInVars = true
+		}
+	}
+	if needsEnvInVars {
+		runtimeGlobals := make(map[string]string)
+		if len(cmdArgs) != 0 {
+			runtimeGlobals["osArgs"] = strings.Join(cmdArgs, "\x00")
+		}
+		if len(environmentVars) != 0 {
+			runtimeGlobals["osEnv"] = strings.Join(environmentVars, "\x00")
+		}
+		if len(runtimeGlobals) != 0 {
+			// This sets the global variables like they would be set with
+			// `-ldflags="-X=runtime.osArgs=first\x00second`.
+			// The runtime package has two variables (osArgs and osEnv) that are
+			// both strings, from which the parameters and environment variables
+			// are read.
+			options.GlobalValues = map[string]map[string]string{
+				"runtime": runtimeGlobals,
+			}
+		}
+	}
+
 	// Build the test binary.
 	binary := filepath.Join(tmpdir, "test")
 	err = runBuild("./"+path, binary, &options)
@@ -242,26 +278,14 @@ func runTestWithConfig(name, target string, t *testing.T, options compileopts.Op
 		return
 	}
 
-	// Run the test.
+	// Create the test command, taking care of emulators etc.
-	runComplete := make(chan struct{})
 	var cmd *exec.Cmd
-	ranTooLong := false
-	if target == "" {
-		cmd = exec.Command(binary)
-		cmd.Env = append(cmd.Env, environmentVars...)
-		cmd.Args = append(cmd.Args, cmdArgs...)
-	} else {
-		spec, err := compileopts.LoadTarget(target)
-		if err != nil {
-			t.Fatal("failed to load target spec:", err)
-		}
 	if len(spec.Emulator) == 0 {
 		cmd = exec.Command(binary)
 	} else {
 		args := append(spec.Emulator[1:], binary)
 		cmd = exec.Command(spec.Emulator[0], args...)
 	}
-
 	if len(spec.Emulator) != 0 && spec.Emulator[0] == "wasmtime" {
 		// Allow reading from the current directory.
 		cmd.Args = append(cmd.Args, "--dir=.")
@@ -270,9 +294,15 @@ func runTestWithConfig(name, target string, t *testing.T, options compileopts.Op
 		}
 		cmd.Args = append(cmd.Args, cmdArgs...)
 	} else {
+		if !needsEnvInVars {
+			cmd.Args = append(cmd.Args, cmdArgs...) // works on qemu-aarch64 etc
 			cmd.Env = append(cmd.Env, environmentVars...)
 		}
 	}
+
+	// Run the test.
+	runComplete := make(chan struct{})
+	ranTooLong := false
 	stdout := &bytes.Buffer{}
 	cmd.Stdout = stdout
 	cmd.Stderr = os.Stderr

src/runtime/nonhosted.go

@@ -0,0 +1,48 @@
+// +build baremetal js
+
+package runtime
+
+// This file is for non-hosted environments, that don't support command line
+// parameters or environment variables. To still be able to run certain tests,
+// command line parameters and environment variables can be passed to the binary
+// by setting the variables `runtime.osArgs` and `runtime.osEnv`, both of which
+// are strings separated by newlines.
+//
+// The primary use case is `tinygo test`, which takes some parameters (such as
+// -test.v).
+
+var env []string
+
+//go:linkname syscall_runtime_envs syscall.runtime_envs
+func syscall_runtime_envs() []string {
+	return env
+}
+
+var osArgs string
+var osEnv string
+
+func init() {
+	if osArgs != "" {
+		s := osArgs
+		start := 0
+		for i := 0; i < len(s); i++ {
+			if s[i] == 0 {
+				args = append(args, s[start:i])
+				start = i + 1
+			}
+		}
+		args = append(args, s[start:])
+	}
+
+	if osEnv != "" {
+		s := osEnv
+		start := 0
+		for i := 0; i < len(s); i++ {
+			if s[i] == 0 {
+				env = append(env, s[start:i])
+				start = i + 1
+			}
+		}
+		env = append(env, s[start:])
+	}
+}

src/runtime/runtime_wasm_js.go

@@ -15,11 +15,6 @@ func _start() {
 	run()
 }
 
-//go:linkname syscall_runtime_envs syscall.runtime_envs
-func syscall_runtime_envs() []string {
-	return nil
-}
-
 var handleEvent func()
 
 //go:linkname setEventHandler syscall/js.setEventHandler

src/syscall/syscall_nonhosted.go

@@ -1,4 +1,4 @@
-// +build baremetal
+// +build baremetal js
 
 package syscall
 
@@ -47,8 +47,24 @@ const (
 	O_CLOEXEC = 0
 )
 
+func runtime_envs() []string
+
 func Getenv(key string) (value string, found bool) {
-	return "", false // stub
+	env := runtime_envs()
+	for _, keyval := range env {
+		// Split at '=' character.
+		var k, v string
+		for i := 0; i < len(keyval); i++ {
+			if keyval[i] == '=' {
+				k = keyval[:i]
+				v = keyval[i+1:]
+			}
+		}
+		if k == key {
+			return v, true
+		}
+	}
+	return "", false
 }
 
 func Open(path string, mode int, perm uint32) (fd int, err error) {

src/syscall/tables_nonhosted.go

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build baremetal nintendoswitch
+// +build baremetal nintendoswitch js
 
 package syscall