os: start processes with posix_spawn

src/os/exec.go

@@ -5,6 +5,9 @@ import (
 	"syscall"
 )
 
+// Errors StartProcess returns for a ProcAttr that it cannot honour. On a
+// hosted OS only ErrNotImplementedSys is reachable. The other two stay because
+// they are part of the exported API of this package.
 var (
 	ErrNotImplementedDir   = errors.New("directory setting not implemented")
 	ErrNotImplementedSys   = errors.New("sys setting not implemented")
@@ -36,35 +39,12 @@ type ProcAttr struct {
 // ErrProcessDone indicates a Process has finished.
 var ErrProcessDone = errors.New("os: process already finished")
 
-type ProcessState struct {
-}
-
-func (p *ProcessState) String() string {
-	return "" // TODO
-}
-func (p *ProcessState) Success() bool {
-	return false // TODO
-}
-
-// Sys returns system-dependent exit information about
-// the process. Convert it to the appropriate underlying
-// type, such as syscall.WaitStatus on Unix, to access its contents.
-func (p *ProcessState) Sys() interface{} {
-	return nil // TODO
-}
-
-func (p *ProcessState) Exited() bool {
-	return false // TODO
-}
-
-// ExitCode returns the exit code of the exited process, or -1
-// if the process hasn't exited or was terminated by a signal.
-func (p *ProcessState) ExitCode() int {
-	return -1 // TODO
-}
-
 type Process struct {
 	Pid int
+
+	// done reports whether Wait reaped this process. A signal to a reaped pid
+	// is unsafe, because the number can belong to an unrelated process.
+	done int32
 }
 
 // StartProcess starts a new process with the program, arguments and attributes specified by name, argv and attr.
@@ -73,21 +53,6 @@ func StartProcess(name string, argv []string, attr *ProcAttr) (*Process, error)
 	return startProcess(name, argv, attr)
 }
 
-func (p *Process) Wait() (*ProcessState, error) {
-	if p.Pid == -1 {
-		return nil, syscall.EINVAL
-	}
-	return nil, ErrNotImplemented
-}
-
-func (p *Process) Kill() error {
-	return ErrNotImplemented
-}
-
-func (p *Process) Signal(sig Signal) error {
-	return ErrNotImplemented
-}
-
 func Ignore(sig ...Signal) {
 	// leave all the signals unaltered
 	return

src/os/exec_other.go

@@ -1,4 +1,4 @@
-//go:build (!aix && !android && !freebsd && !linux && !netbsd && !openbsd && !plan9 && !solaris) || baremetal || tinygo.wasm || nintendoswitch
+//go:build (!aix && !android && !darwin && !freebsd && !linux && !netbsd && !openbsd && !plan9 && !solaris) || baremetal || tinygo.wasm || nintendoswitch
 
 package os
 
@@ -18,6 +18,49 @@ func (p *Process) release() error {
 	return nil
 }
 
+// ProcessState is a placeholder on targets that have no process model.
+type ProcessState struct {
+}
+
+func (p *ProcessState) String() string {
+	return "" // TODO
+}
+func (p *ProcessState) Success() bool {
+	return false // TODO
+}
+
+// Sys returns system-dependent exit information about
+// the process. Convert it to the appropriate underlying
+// type, such as syscall.WaitStatus on Unix, to access its contents.
+func (p *ProcessState) Sys() interface{} {
+	return nil // TODO
+}
+
+func (p *ProcessState) Exited() bool {
+	return false // TODO
+}
+
+// ExitCode returns the exit code of the exited process, or -1
+// if the process hasn't exited or was terminated by a signal.
+func (p *ProcessState) ExitCode() int {
+	return -1 // TODO
+}
+
+func (p *Process) Wait() (*ProcessState, error) {
+	if p.Pid == -1 {
+		return nil, syscall.EINVAL
+	}
+	return nil, ErrNotImplemented
+}
+
+func (p *Process) Kill() error {
+	return ErrNotImplemented
+}
+
+func (p *Process) Signal(sig Signal) error {
+	return ErrNotImplemented
+}
+
 func forkExec(_ string, _ []string, _ *ProcAttr) (pid int, err error) {
 	return 0, ErrNotImplemented
 }