os: implement new Process api
Fixes #1004.
Fixes #1460.
R=mattn, r, niemeyer, rog, rsc
CC=golang-dev
https://golang.org/cl/4029053
diff --git a/src/pkg/os/exec_unix.go b/src/pkg/os/exec_unix.go
new file mode 100644
index 0000000..8990d6a
--- /dev/null
+++ b/src/pkg/os/exec_unix.go
@@ -0,0 +1,63 @@
+// Copyright 2009 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.
+
+package os
+
+import (
+ "runtime"
+ "syscall"
+)
+
+// Options for Wait.
+const (
+ WNOHANG = syscall.WNOHANG // Don't wait if no process has exited.
+ WSTOPPED = syscall.WSTOPPED // If set, status of stopped subprocesses is also reported.
+ WUNTRACED = syscall.WUNTRACED // Usually an alias for WSTOPPED.
+ WRUSAGE = 1 << 20 // Record resource usage.
+)
+
+// WRUSAGE must not be too high a bit, to avoid clashing with Linux's
+// WCLONE, WALL, and WNOTHREAD flags, which sit in the top few bits of
+// the options
+
+// Wait waits for the Process to exit or stop, and then returns a
+// Waitmsg describing its status and an Error, if any. The options
+// (WNOHANG etc.) affect the behavior of the Wait call.
+func (p *Process) Wait(options int) (w *Waitmsg, err Error) {
+ if p.Pid == -1 {
+ return nil, EINVAL
+ }
+ var status syscall.WaitStatus
+ var rusage *syscall.Rusage
+ if options&WRUSAGE != 0 {
+ rusage = new(syscall.Rusage)
+ options ^= WRUSAGE
+ }
+ pid1, e := syscall.Wait4(p.Pid, &status, options, rusage)
+ if e != 0 {
+ return nil, NewSyscallError("wait", e)
+ }
+ w = new(Waitmsg)
+ w.Pid = pid1
+ w.WaitStatus = status
+ w.Rusage = rusage
+ return w, nil
+}
+
+// Release releases any resources associated with the Process.
+func (p *Process) Release() Error {
+ // NOOP for unix.
+ p.Pid = -1
+ // no need for a finalizer anymore
+ runtime.SetFinalizer(p, nil)
+ return nil
+}
+
+// FindProcess looks for a running process by its pid.
+// The Process it returns can be used to obtain information
+// about the underlying operating system process.
+func FindProcess(pid int) (p *Process, err Error) {
+ // NOOP for unix.
+ return newProcess(pid, 0), nil
+}
