exec: add support for Plan 9

R=paulzhol, mirtchovski, fshahriar, alex.brainman, r
CC=golang-dev
https://golang.org/cl/4386041

src/pkg/exec/Makefile

@@ -20,6 +20,9 @@ GOFILES_linux=\
 GOFILES_windows=\
 	lp_windows.go\
 
+GOFILES_plan9=\
+	lp_plan9.go\
+
 GOFILES+=$(GOFILES_$(GOOS))
 
 include ../../Make.pkg

src/pkg/exec/lp_plan9.go

+// Copyright 2011 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 exec
+
+import (
+	"os"
+	"strings"
+)
+
+// ErrNotFound is the error resulting if a path search failed to find an executable file.
+var ErrNotFound = os.ErrorString("executable file not found in $path")
+
+func findExecutable(file string) os.Error {
+	d, err := os.Stat(file)
+	if err != nil {
+		return err
+	}
+	if d.IsRegular() && d.Permission()&0111 != 0 {
+		return nil
+	}
+	return os.EPERM
+}
+
+// LookPath searches for an executable binary named file
+// in the directories named by the path environment variable.
+// If file begins with "/", "#", "./", or "../", it is tried
+// directly and the path is not consulted.
+func LookPath(file string) (string, os.Error) {
+	// skip the path lookup for these prefixes
+	skip := []string{"/", "#", "./", "../"}
+
+	for _, p := range skip {
+		if strings.HasPrefix(file, p) {
+			err := findExecutable(file)
+			if err == nil {
+				return file, nil
+			}
+			return "", &Error{file, err}
+		}
+	}
+
+	path := os.Getenv("path")
+	for _, dir := range strings.Split(path, "\000", -1) {
+		if err := findExecutable(dir + "/" + file); err == nil {
+			return dir + "/" + file, nil
+		}
+	}
+	return "", &Error{file, ErrNotFound}
+}

src/pkg/os/error_plan9.go

@@ -45,6 +45,7 @@ var (
 	EEXIST  = Eexist
 	EIO     = Eio
 	EACCES  = Eperm
+	EPERM   = Eperm
 	EISDIR  = syscall.EISDIR
 
 	ENAMETOOLONG = NewError("file name too long")

src/pkg/os/exec_plan9.go

@@ -63,7 +63,9 @@ func Exec(name string, argv []string, envv []string) Error {
 }
 
 // Waitmsg stores the information about an exited process as reported by Wait.
-type Waitmsg syscall.Waitmsg
+type Waitmsg struct {
+	syscall.Waitmsg
+}
 
 // Wait waits for the Process to exit or stop, and then returns a
 // Waitmsg describing its status and an Error, if any. The options
@@ -87,7 +89,7 @@ func (p *Process) Wait(options int) (w *Waitmsg, err Error) {
 		}
 	}
 
-	return (*Waitmsg)(&waitmsg), nil
+	return &Waitmsg{waitmsg}, nil
 }
 
 // Wait waits for process pid to exit or stop, and then returns a

src/pkg/syscall/syscall_plan9.go

@@ -35,7 +35,7 @@ var (
 	Stdout = 1
 	Stderr = 2
 
-	EISDIR Error = NewError("file is a directory")
+	EISDIR = NewError("file is a directory")
 )
 
 func Syscall(trap, a1, a2, a3 uintptr) (r1, r2 uintptr, err string)
@@ -200,6 +200,17 @@ type Waitmsg struct {
 	Msg  string
 }
 
+func (w Waitmsg) Exited() bool   { return true }
+func (w Waitmsg) Signaled() bool { return false }
+
+func (w Waitmsg) ExitStatus() int {
+	if len(w.Msg) == 0 {
+		// a normal exit returns no message
+		return 0
+	}
+	return 1
+}
+
 //sys	await(s []byte) (n int, err Error)
 func Await(w *Waitmsg) (err Error) {
 	var buf [512]byte
@@ -230,7 +241,7 @@ func Await(w *Waitmsg) (err Error) {
 	w.Time[0] = uint32(atoi(f[1]))
 	w.Time[1] = uint32(atoi(f[2]))
 	w.Time[2] = uint32(atoi(f[3]))
-	w.Msg = string(f[4])
+	w.Msg = cstring(f[4])
 	return
 }