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.

src/syscall/syscall_nonhosted.go

@@ -0,0 +1,133 @@
+// +build baremetal js
+
+package syscall
+
+// Most code here has been copied from the Go sources:
+//   https://github.com/golang/go/blob/go1.12/src/syscall/syscall_js.go
+// It has the following copyright note:
+//
+//     Copyright 2018 The Go Authors. All rights reserved.
+//     Use of this source code is governed by a BSD-style
+//     license that can be found in the LICENSE file.
+
+// A Signal is a number describing a process signal.
+// It implements the os.Signal interface.
+type Signal int
+
+const (
+	_ Signal = iota
+	SIGCHLD
+	SIGINT
+	SIGKILL
+	SIGTRAP
+	SIGQUIT
+	SIGTERM
+)
+
+// File system
+
+const (
+	Stdin  = 0
+	Stdout = 1
+	Stderr = 2
+)
+
+const (
+	O_RDONLY = 0
+	O_WRONLY = 1
+	O_RDWR   = 2
+
+	O_CREAT  = 0100
+	O_CREATE = O_CREAT
+	O_TRUNC  = 01000
+	O_APPEND = 02000
+	O_EXCL   = 0200
+	O_SYNC   = 010000
+
+	O_CLOEXEC = 0
+)
+
+func runtime_envs() []string
+
+func Getenv(key string) (value string, found bool) {
+	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) {
+	return 0, ENOSYS
+}
+
+func Read(fd int, p []byte) (n int, err error) {
+	return 0, ENOSYS
+}
+
+func Seek(fd int, offset int64, whence int) (off int64, err error) {
+	return 0, ENOSYS
+}
+
+func Close(fd int) (err error) {
+	return ENOSYS
+}
+
+// Processes
+
+type WaitStatus uint32
+
+func (w WaitStatus) Exited() bool       { return false }
+func (w WaitStatus) ExitStatus() int    { return 0 }
+func (w WaitStatus) Signaled() bool     { return false }
+func (w WaitStatus) Signal() Signal     { return 0 }
+func (w WaitStatus) CoreDump() bool     { return false }
+func (w WaitStatus) Stopped() bool      { return false }
+func (w WaitStatus) Continued() bool    { return false }
+func (w WaitStatus) StopSignal() Signal { return 0 }
+func (w WaitStatus) TrapCause() int     { return 0 }
+
+// XXX made up
+type Rusage struct {
+	Utime Timeval
+	Stime Timeval
+}
+
+// XXX made up
+type ProcAttr struct {
+	Dir   string
+	Env   []string
+	Files []uintptr
+	Sys   *SysProcAttr
+}
+
+type SysProcAttr struct {
+}
+
+func Getgroups() ([]int, error)         { return []int{1}, nil }
+func Gettimeofday(tv *Timeval) error    { return ENOSYS }
+func Kill(pid int, signum Signal) error { return ENOSYS }
+func Sendfile(outfd int, infd int, offset *int64, count int) (written int, err error) {
+	return 0, ENOSYS
+}
+func StartProcess(argv0 string, argv []string, attr *ProcAttr) (pid int, handle uintptr, err error) {
+	return 0, 0, ENOSYS
+}
+func Wait4(pid int, wstatus *WaitStatus, options int, rusage *Rusage) (wpid int, err error) {
+	return 0, ENOSYS
+}
+
+type Timeval struct {
+	Sec  int64
+	Usec int64
+}