os: Plan 9 support.

R=rsc, ality, r, r2
CC=golang-dev
https://golang.org/cl/4149046

16 files changed, 1400 insertions, 447 deletions

diff --git a/src/pkg/os/Makefile b/src/pkg/os/Makefile
index 3a81afe39a..985fd11d15 100644
--- a/src/pkg/os/Makefile
+++ b/src/pkg/os/Makefile
@@ -19,29 +19,48 @@ GOFILES=\
 	types.go\
 
 GOFILES_freebsd=\
+	error_posix.go\
 	env_unix.go\
+	file_posix.go\
 	file_unix.go\
 	sys_bsd.go\
+	exec_posix.go\
 	exec_unix.go\
 
 GOFILES_darwin=\
+	error_posix.go\
 	env_unix.go\
+	file_posix.go\
 	file_unix.go\
 	sys_bsd.go\
+	exec_posix.go\
 	exec_unix.go\
 
 GOFILES_linux=\
+	error_posix.go\
 	env_unix.go\
+	file_posix.go\
 	file_unix.go\
 	sys_linux.go\
+	exec_posix.go\
 	exec_unix.go\
 
 GOFILES_windows=\
+	error_posix.go\
 	env_windows.go\
+	file_posix.go\
 	file_windows.go\
 	sys_windows.go\
+	exec_posix.go\
 	exec_windows.go\
 
+GOFILES_plan9=\
+	error_plan9.go\
+	env_plan9.go\
+	file_plan9.go\
+	sys_plan9.go\
+	exec_plan9.go\
+
 GOFILES+=$(GOFILES_$(GOOS))
 
 include ../../Make.pkg
diff --git a/src/pkg/os/dir_plan9.go b/src/pkg/os/dir_plan9.go
new file mode 100644
index 0000000000..7bb0642e47
--- /dev/null
+++ b/src/pkg/os/dir_plan9.go
@@ -0,0 +1,300 @@
+// 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 (
+	"syscall"
+)
+
+type dirInfo int
+
+var markDirectory dirInfo = ^0
+
+// Readdir reads the contents of the directory associated with file and
+// returns an array of up to count FileInfo structures, as would be returned
+// by Lstat, in directory order.  Subsequent calls on the same file will yield
+// further FileInfos. A negative count means to read the entire directory.
+// Readdir returns the array and an Error, if any.
+func (file *File) Readdir(count int) (fi []FileInfo, err Error) {
+	// If this file has no dirinfo, create one.
+	if file.dirinfo == nil {
+		file.dirinfo = &markDirectory
+	}
+
+	size := count
+	if size < 0 {
+		size = 100
+	}
+
+	result := make([]FileInfo, 0, size)
+	var buf [syscall.STATMAX]byte
+
+	for {
+		n, e := file.Read(buf[:])
+
+		if e != nil {
+			if e == EOF {
+				break
+			}
+
+			return []FileInfo{}, &PathError{"readdir", file.name, e}
+		}
+
+		if n < syscall.STATFIXLEN {
+			return []FileInfo{}, &PathError{"readdir", file.name, Eshortstat}
+		}
+
+		for i := 0; i < n; {
+			m, _ := gbit16(buf[i:])
+			m += 2
+
+			if m < syscall.STATFIXLEN {
+				return []FileInfo{}, &PathError{"readdir", file.name, Eshortstat}
+			}
+
+			d, e := UnmarshalDir(buf[i : i+int(m)])
+
+			if e != nil {
+				return []FileInfo{}, &PathError{"readdir", file.name, e}
+			}
+
+			var f FileInfo
+			fileInfoFromStat(&f, d)
+
+			result = append(result, f)
+
+			// a negative count means to read until EOF.
+			if count > 0 && len(result) >= count {
+				break
+			}
+
+			i += int(m)
+		}
+	}
+
+	return result, nil
+}
+
+// Readdirnames returns an array of up to count file names residing in the 
+// directory associated with file. A negative count will return all of them.
+// Readdir returns the array and an Error, if any.
+func (file *File) Readdirnames(count int) (names []string, err Error) {
+	fi, e := file.Readdir(count)
+
+	if e != nil {
+		return []string{}, e
+	}
+
+	names = make([]string, len(fi))
+	err = nil
+
+	for i, _ := range fi {
+		names[i] = fi[i].Name
+	}
+
+	return
+}
+
+type Dir struct {
+	// system-modified data
+	Type uint16 // server type
+	Dev  uint32 // server subtype
+	// file data
+	Qid    Qid    // unique id from server
+	Mode   uint32 // permissions
+	Atime  uint32 // last read time
+	Mtime  uint32 // last write time
+	Length uint64 // file length
+	Name   string // last element of path
+	Uid    string // owner name
+	Gid    string // group name
+	Muid   string // last modifier name
+}
+
+type Qid struct {
+	Path uint64 // the file server's unique identification for the file
+	Vers uint32 // version number for given Path
+	Type uint8  // the type of the file (syscall.QTDIR for example)
+}
+
+var nullDir = Dir{
+	^uint16(0),
+	^uint32(0),
+	Qid{^uint64(0), ^uint32(0), ^uint8(0)},
+	^uint32(0),
+	^uint32(0),
+	^uint32(0),
+	^uint64(0),
+	"",
+	"",
+	"",
+	"",
+}
+
+// Null assigns members of d with special "don't care" values indicating
+// they should not be written by syscall.Wstat. 
+func (d *Dir) Null() {
+	*d = nullDir
+}
+
+// pdir appends a 9P Stat message based on the contents of Dir d to a byte slice b.
+func pdir(b []byte, d *Dir) []byte {
+	n := len(b)
+	b = pbit16(b, 0) // length, filled in later	
+	b = pbit16(b, d.Type)
+	b = pbit32(b, d.Dev)
+	b = pqid(b, d.Qid)
+	b = pbit32(b, d.Mode)
+	b = pbit32(b, d.Atime)
+	b = pbit32(b, d.Mtime)
+	b = pbit64(b, d.Length)
+	b = pstring(b, d.Name)
+	b = pstring(b, d.Uid)
+	b = pstring(b, d.Gid)
+	b = pstring(b, d.Muid)
+	pbit16(b[0:n], uint16(len(b)-(n+2)))
+	return b
+}
+
+// UnmarshalDir reads a 9P Stat message from a 9P protocol message strored in b,
+// returning the corresponding Dir struct.
+func UnmarshalDir(b []byte) (d *Dir, err Error) {
+	n := uint16(0)
+	n, b = gbit16(b)
+
+	if int(n) != len(b) {
+		return nil, Ebadstat
+	}
+
+	d = new(Dir)
+	d.Type, b = gbit16(b)
+	d.Dev, b = gbit32(b)
+	d.Qid, b = gqid(b)
+	d.Mode, b = gbit32(b)
+	d.Atime, b = gbit32(b)
+	d.Mtime, b = gbit32(b)
+	d.Length, b = gbit64(b)
+	d.Name, b = gstring(b)
+	d.Uid, b = gstring(b)
+	d.Gid, b = gstring(b)
+	d.Muid, b = gstring(b)
+
+	if len(b) != 0 {
+		return nil, Ebadstat
+	}
+
+	return d, nil
+}
+
+// gqid reads the qid part of a 9P Stat message from a 9P protocol message strored in b,
+// returning the corresponding Qid struct and the remaining slice of b.
+func gqid(b []byte) (Qid, []byte) {
+	var q Qid
+	q.Path, b = gbit64(b)
+	q.Vers, b = gbit32(b)
+	q.Type, b = gbit8(b)
+	return q, b
+}
+
+// pqid appends a Qid struct q to a 9P message b.
+func pqid(b []byte, q Qid) []byte {
+	b = pbit64(b, q.Path)
+	b = pbit32(b, q.Vers)
+	b = pbit8(b, q.Type)
+	return b
+}
+
+// gbit8 reads a byte-sized numeric value from a 9P protocol message strored in b,
+// returning the value and the remaining slice of b.
+func gbit8(b []byte) (uint8, []byte) {
+	return uint8(b[0]), b[1:]
+}
+
+// gbit16 reads a 16-bit numeric value from a 9P protocol message strored in b,
+// returning the value and the remaining slice of b.
+func gbit16(b []byte) (uint16, []byte) {
+	return uint16(b[0]) | uint16(b[1])<<8, b[2:]
+}
+
+// gbit32 reads a 32-bit numeric value from a 9P protocol message strored in b,
+// returning the value and the remaining slice of b.
+func gbit32(b []byte) (uint32, []byte) {
+	return uint32(b[0]) | uint32(b[1])<<8 | uint32(b[2])<<16 | uint32(b[3])<<24, b[4:]
+}
+
+// gbit64 reads a 64-bit numeric value from a 9P protocol message strored in b,
+// returning the value and the remaining slice of b.
+func gbit64(b []byte) (uint64, []byte) {
+	lo, b := gbit32(b)
+	hi, b := gbit32(b)
+	return uint64(hi)<<32 | uint64(lo), b
+}
+
+// gstring reads a string from a 9P protocol message strored in b,
+// returning the value as a Go string and the remaining slice of b.
+func gstring(b []byte) (string, []byte) {
+	n, b := gbit16(b)
+	return string(b[0:n]), b[n:]
+}
+
+// pbit8 appends a byte-sized numeric value x to a 9P message b.
+func pbit8(b []byte, x uint8) []byte {
+	n := len(b)
+	if n+1 > cap(b) {
+		nb := make([]byte, n, 100+2*cap(b))
+		copy(nb, b)
+		b = nb
+	}
+	b = b[0 : n+1]
+	b[n] = x
+	return b
+}
+
+// pbit16 appends a 16-bit numeric value x to a 9P message b.
+func pbit16(b []byte, x uint16) []byte {
+	n := len(b)
+	if n+2 > cap(b) {
+		nb := make([]byte, n, 100+2*cap(b))
+		copy(nb, b)
+		b = nb
+	}
+	b = b[0 : n+2]
+	b[n] = byte(x)
+	b[n+1] = byte(x >> 8)
+	return b
+}
+
+// pbit32 appends a 32-bit numeric value x to a 9P message b.
+func pbit32(b []byte, x uint32) []byte {
+	n := len(b)
+	if n+4 > cap(b) {
+		nb := make([]byte, n, 100+2*cap(b))
+		copy(nb, b)
+		b = nb
+	}
+	b = b[0 : n+4]
+	b[n] = byte(x)
+	b[n+1] = byte(x >> 8)
+	b[n+2] = byte(x >> 16)
+	b[n+3] = byte(x >> 24)
+	return b
+}
+
+// pbit64 appends a 64-bit numeric value x to a 9P message b.
+func pbit64(b []byte, x uint64) []byte {
+	b = pbit32(b, uint32(x))
+	b = pbit32(b, uint32(x>>32))
+	return b
+}
+
+// pstring appends a Go string s to a 9P message b.
+func pstring(b []byte, s string) []byte {
+	if len(s) >= 1<<16 {
+		panic(NewError("string too long"))
+	}
+	b = pbit16(b, uint16(len(s)))
+	b = append(b, []byte(s)...)
+	return b
+}
diff --git a/src/pkg/os/env_plan9.go b/src/pkg/os/env_plan9.go
new file mode 100644
index 0000000000..a73f5d8079
--- /dev/null
+++ b/src/pkg/os/env_plan9.go
@@ -0,0 +1,91 @@
+// 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.
+
+// Plan 9 environment variables.
+
+package os
+
+import "syscall"
+
+// ENOENV is the Error indicating that an environment variable does not exist.
+var ENOENV = NewError("no such environment variable")
+
+// Getenverror retrieves the value of the environment variable named by the key.
+// It returns the value and an error, if any.
+func Getenverror(key string) (value string, err Error) {
+	if len(key) == 0 {
+		return "", EINVAL
+	}
+	f, e := Open("/env/"+key, O_RDONLY, 0)
+	if iserror(e) {
+		return "", ENOENV
+	}
+	defer f.Close()
+
+	var buf [4096]byte
+	n, e := f.Read(buf[:len(buf)-1])
+	if iserror(e) {
+		return "", ENOENV
+	}
+	buf[n] = 0
+	return string(buf[0:n]), nil
+}
+
+// Getenv retrieves the value of the environment variable named by the key.
+// It returns the value, which will be empty if the variable is not present.
+func Getenv(key string) string {
+	v, _ := Getenverror(key)
+	return v
+}
+
+// Setenv sets the value of the environment variable named by the key.
+// It returns an Error, if any.
+func Setenv(key, value string) Error {
+	if len(key) == 0 {
+		return EINVAL
+	}
+
+	f, e := Open("/env/"+key, O_WRONLY|O_CREAT, 0666)
+	if iserror(e) {
+		return e
+	}
+	defer f.Close()
+
+	_, e = f.Write(syscall.StringByteSlice(value))
+	return nil
+}
+
+// Clearenv deletes all environment variables.
+func Clearenv() {
+	syscall.RawSyscall(syscall.SYS_RFORK, syscall.RFCENVG, 0, 0)
+}
+
+// Environ returns an array of strings representing the environment,
+// in the form "key=value".
+func Environ() []string {
+	env := make([]string, 0, 100)
+
+	f, e := Open("/env", O_RDONLY, 0)
+	if iserror(e) {
+		panic(e)
+	}
+	defer f.Close()
+
+	names, e := f.Readdirnames(-1)
+	if iserror(e) {
+		panic(e)
+	}
+
+	for _, k := range names {
+		if v, e := Getenverror(k); !iserror(e) {
+			env = append(env, k+"="+v)
+		}
+	}
+	return env[0:len(env)]
+}
+
+// TempDir returns the default directory to use for temporary files.
+func TempDir() string {
+	return "/tmp"
+}
diff --git a/src/pkg/os/error.go b/src/pkg/os/error.go
index 635a3fe50a..2c4516ca7d 100644
--- a/src/pkg/os/error.go
+++ b/src/pkg/os/error.go
@@ -4,8 +4,6 @@
 
 package os
 
-import syscall "syscall"
-
 // An Error can represent any printable error condition.
 type Error interface {
 	String() string
@@ -26,63 +24,6 @@ func (e ErrorString) Timeout() bool   { return false }
 // NewError converts s to an ErrorString, which satisfies the Error interface.
 func NewError(s string) Error { return ErrorString(s) }
 
-// Errno is the Unix error number.  Names such as EINVAL are simple
-// wrappers to convert the error number into an Error.
-type Errno int64
-
-func (e Errno) String() string { return syscall.Errstr(int(e)) }
-
-func (e Errno) Temporary() bool {
-	return e == Errno(syscall.EINTR) || e.Timeout()
-}
-
-func (e Errno) Timeout() bool {
-	return e == Errno(syscall.EAGAIN) || e == Errno(syscall.EWOULDBLOCK) || e == Errno(syscall.ETIMEDOUT)
-}
-
-// Commonly known Unix errors.
-var (
-	EPERM        Error = Errno(syscall.EPERM)
-	ENOENT       Error = Errno(syscall.ENOENT)
-	ESRCH        Error = Errno(syscall.ESRCH)
-	EINTR        Error = Errno(syscall.EINTR)
-	EIO          Error = Errno(syscall.EIO)
-	ENXIO        Error = Errno(syscall.ENXIO)
-	E2BIG        Error = Errno(syscall.E2BIG)
-	ENOEXEC      Error = Errno(syscall.ENOEXEC)
-	EBADF        Error = Errno(syscall.EBADF)
-	ECHILD       Error = Errno(syscall.ECHILD)
-	EDEADLK      Error = Errno(syscall.EDEADLK)
-	ENOMEM       Error = Errno(syscall.ENOMEM)
-	EACCES       Error = Errno(syscall.EACCES)
-	EFAULT       Error = Errno(syscall.EFAULT)
-	EBUSY        Error = Errno(syscall.EBUSY)
-	EEXIST       Error = Errno(syscall.EEXIST)
-	EXDEV        Error = Errno(syscall.EXDEV)
-	ENODEV       Error = Errno(syscall.ENODEV)
-	ENOTDIR      Error = Errno(syscall.ENOTDIR)
-	EISDIR       Error = Errno(syscall.EISDIR)
-	EINVAL       Error = Errno(syscall.EINVAL)
-	ENFILE       Error = Errno(syscall.ENFILE)
-	EMFILE       Error = Errno(syscall.EMFILE)
-	ENOTTY       Error = Errno(syscall.ENOTTY)
-	EFBIG        Error = Errno(syscall.EFBIG)
-	ENOSPC       Error = Errno(syscall.ENOSPC)
-	ESPIPE       Error = Errno(syscall.ESPIPE)
-	EROFS        Error = Errno(syscall.EROFS)
-	EMLINK       Error = Errno(syscall.EMLINK)
-	EPIPE        Error = Errno(syscall.EPIPE)
-	EAGAIN       Error = Errno(syscall.EAGAIN)
-	EDOM         Error = Errno(syscall.EDOM)
-	ERANGE       Error = Errno(syscall.ERANGE)
-	EADDRINUSE   Error = Errno(syscall.EADDRINUSE)
-	ECONNREFUSED Error = Errno(syscall.ECONNREFUSED)
-	ENAMETOOLONG Error = Errno(syscall.ENAMETOOLONG)
-	EAFNOSUPPORT Error = Errno(syscall.EAFNOSUPPORT)
-	ETIMEDOUT    Error = Errno(syscall.ETIMEDOUT)
-	ENOTCONN     Error = Errno(syscall.ENOTCONN)
-)
-
 // PathError records an error and the operation and file path that caused it.
 type PathError struct {
 	Op    string
@@ -91,25 +32,3 @@ type PathError struct {
 }
 
 func (e *PathError) String() string { return e.Op + " " + e.Path + ": " + e.Error.String() }
-
-// SyscallError records an error from a specific system call.
-type SyscallError struct {
-	Syscall string
-	Errno   Errno
-}
-
-func (e *SyscallError) String() string { return e.Syscall + ": " + e.Errno.String() }
-
-// Note: If the name of the function NewSyscallError changes,
-// pkg/go/doc/doc.go should be adjusted since it hardwires
-// this name in a heuristic.
-
-// NewSyscallError returns, as an Error, a new SyscallError
-// with the given system call name and error number.
-// As a convenience, if errno is 0, NewSyscallError returns nil.
-func NewSyscallError(syscall string, errno int) Error {
-	if errno == 0 {
-		return nil
-	}
-	return &SyscallError{syscall, Errno(errno)}
-}
diff --git a/src/pkg/os/error_plan9.go b/src/pkg/os/error_plan9.go
new file mode 100644
index 0000000000..0f34f04a4d
--- /dev/null
+++ b/src/pkg/os/error_plan9.go
@@ -0,0 +1,53 @@
+// 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 os
+
+import syscall "syscall"
+
+// SyscallError records an error from a specific system call.
+type SyscallError struct {
+	Syscall string
+	Err     string
+}
+
+func (e *SyscallError) String() string { return e.Syscall + ": " + e.Err }
+
+// Note: If the name of the function NewSyscallError changes,
+// pkg/go/doc/doc.go should be adjusted since it hardwires
+// this name in a heuristic.
+
+// NewSyscallError returns, as an Error, a new SyscallError
+// with the given system call name and error details.
+// As a convenience, if err is nil, NewSyscallError returns nil.
+func NewSyscallError(syscall string, err syscall.Error) Error {
+	if err == nil {
+		return nil
+	}
+	return &SyscallError{syscall, err.String()}
+}
+
+var (
+	Eshortstat = NewError("stat buffer too small")
+	Ebadstat   = NewError("malformed stat buffer")
+	Ebadfd     = NewError("fd out of range or not open")
+	Ebadarg    = NewError("bad arg in system call")
+	Enotdir    = NewError("not a directory")
+	Enonexist  = NewError("file does not exist")
+
+	EINVAL  = Ebadarg
+	ENOTDIR = Enotdir
+	ENOENT  = Enonexist
+
+	ENAMETOOLONG = NewError("file name too long")
+	ERANGE       = NewError("math result not representable")
+	EPIPE        = NewError("Broken Pipe")
+	EPLAN9       = NewError("not supported by plan 9")
+)
+
+func iserror(err syscall.Error) bool {
+	return err != nil
+}
+
+func Errno(e syscall.Error) syscall.Error { return e }
diff --git a/src/pkg/os/error_posix.go b/src/pkg/os/error_posix.go
new file mode 100644
index 0000000000..0ee34e4b0e
--- /dev/null
+++ b/src/pkg/os/error_posix.go
@@ -0,0 +1,90 @@
+// 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 syscall "syscall"
+
+// Errno is the Unix error number.  Names such as EINVAL are simple
+// wrappers to convert the error number into an Error.
+type Errno int64
+
+func (e Errno) String() string { return syscall.Errstr(int(e)) }
+
+func (e Errno) Temporary() bool {
+	return e == Errno(syscall.EINTR) || e.Timeout()
+}
+
+func (e Errno) Timeout() bool {
+	return e == Errno(syscall.EAGAIN) || e == Errno(syscall.EWOULDBLOCK) || e == Errno(syscall.ETIMEDOUT)
+}
+
+// Commonly known Unix errors.
+var (
+	EPERM        Error = Errno(syscall.EPERM)
+	ENOENT       Error = Errno(syscall.ENOENT)
+	ESRCH        Error = Errno(syscall.ESRCH)
+	EINTR        Error = Errno(syscall.EINTR)
+	EIO          Error = Errno(syscall.EIO)
+	ENXIO        Error = Errno(syscall.ENXIO)
+	E2BIG        Error = Errno(syscall.E2BIG)
+	ENOEXEC      Error = Errno(syscall.ENOEXEC)
+	EBADF        Error = Errno(syscall.EBADF)
+	ECHILD       Error = Errno(syscall.ECHILD)
+	EDEADLK      Error = Errno(syscall.EDEADLK)
+	ENOMEM       Error = Errno(syscall.ENOMEM)
+	EACCES       Error = Errno(syscall.EACCES)
+	EFAULT       Error = Errno(syscall.EFAULT)
+	EBUSY        Error = Errno(syscall.EBUSY)
+	EEXIST       Error = Errno(syscall.EEXIST)
+	EXDEV        Error = Errno(syscall.EXDEV)
+	ENODEV       Error = Errno(syscall.ENODEV)
+	ENOTDIR      Error = Errno(syscall.ENOTDIR)
+	EISDIR       Error = Errno(syscall.EISDIR)
+	EINVAL       Error = Errno(syscall.EINVAL)
+	ENFILE       Error = Errno(syscall.ENFILE)
+	EMFILE       Error = Errno(syscall.EMFILE)
+	ENOTTY       Error = Errno(syscall.ENOTTY)
+	EFBIG        Error = Errno(syscall.EFBIG)
+	ENOSPC       Error = Errno(syscall.ENOSPC)
+	ESPIPE       Error = Errno(syscall.ESPIPE)
+	EROFS        Error = Errno(syscall.EROFS)
+	EMLINK       Error = Errno(syscall.EMLINK)
+	EPIPE        Error = Errno(syscall.EPIPE)
+	EAGAIN       Error = Errno(syscall.EAGAIN)
+	EDOM         Error = Errno(syscall.EDOM)
+	ERANGE       Error = Errno(syscall.ERANGE)
+	EADDRINUSE   Error = Errno(syscall.EADDRINUSE)
+	ECONNREFUSED Error = Errno(syscall.ECONNREFUSED)
+	ENAMETOOLONG Error = Errno(syscall.ENAMETOOLONG)
+	EAFNOSUPPORT Error = Errno(syscall.EAFNOSUPPORT)
+	ETIMEDOUT    Error = Errno(syscall.ETIMEDOUT)
+	ENOTCONN     Error = Errno(syscall.ENOTCONN)
+)
+
+// SyscallError records an error from a specific system call.
+type SyscallError struct {
+	Syscall string
+	Errno   Errno
+}
+
+func (e *SyscallError) String() string { return e.Syscall + ": " + e.Errno.String() }
+
+// Note: If the name of the function NewSyscallError changes,
+// pkg/go/doc/doc.go should be adjusted since it hardwires
+// this name in a heuristic.
+
+// NewSyscallError returns, as an Error, a new SyscallError
+// with the given system call name and error details.
+// As a convenience, if errno is 0, NewSyscallError returns nil.
+func NewSyscallError(syscall string, errno int) Error {
+	if errno == 0 {
+		return nil
+	}
+	return &SyscallError{syscall, Errno(errno)}
+}
+
+func iserror(errno int) bool {
+	return errno != 0
+}
diff --git a/src/pkg/os/exec.go b/src/pkg/os/exec.go
index 9d80ccfbed..f62caf9a06 100644
--- a/src/pkg/os/exec.go
+++ b/src/pkg/os/exec.go
@@ -39,126 +39,6 @@ type ProcAttr struct {
 	Files []*File
 }
 
-// StartProcess starts a new process with the program, arguments and attributes
-// specified by name, argv and attr.
-func StartProcess(name string, argv []string, attr *ProcAttr) (p *Process, err Error) {
-	sysattr := &syscall.ProcAttr{
-		Dir: attr.Dir,
-		Env: attr.Env,
-	}
-	if sysattr.Env == nil {
-		sysattr.Env = Environ()
-	}
-	// Create array of integer (system) fds.
-	intfd := make([]int, len(attr.Files))
-	for i, f := range attr.Files {
-		if f == nil {
-			intfd[i] = -1
-		} else {
-			intfd[i] = f.Fd()
-		}
-	}
-	sysattr.Files = intfd
-
-	pid, h, e := syscall.StartProcess(name, argv, sysattr)
-	if e != 0 {
-		return nil, &PathError{"fork/exec", name, Errno(e)}
-	}
-	return newProcess(pid, h), nil
-}
-
-// Exec replaces the current process with an execution of the
-// named binary, with arguments argv and environment envv.
-// If successful, Exec never returns.  If it fails, it returns an Error.
-// StartProcess is almost always a better way to execute a program.
-func Exec(name string, argv []string, envv []string) Error {
-	if envv == nil {
-		envv = Environ()
-	}
-	e := syscall.Exec(name, argv, envv)
-	if e != 0 {
-		return &PathError{"exec", name, Errno(e)}
-	}
-	return nil
-}
-
-// TODO(rsc): Should os implement its own syscall.WaitStatus
-// wrapper with the methods, or is exposing the underlying one enough?
-//
-// TODO(rsc): Certainly need to have Rusage struct,
-// since syscall one might have different field types across
-// different OS.
-
-// Waitmsg stores the information about an exited process as reported by Wait.
-type Waitmsg struct {
-	Pid                int             // The process's id.
-	syscall.WaitStatus                 // System-dependent status info.
-	Rusage             *syscall.Rusage // System-dependent resource usage info.
-}
-
-// Wait waits for process pid 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.
-// Wait is equivalent to calling FindProcess and then Wait
-// and Release on the result.
-func Wait(pid int, options int) (w *Waitmsg, err Error) {
-	p, e := FindProcess(pid)
-	if e != nil {
-		return nil, e
-	}
-	defer p.Release()
-	return p.Wait(options)
-}
-
-// Convert i to decimal string.
-func itod(i int) string {
-	if i == 0 {
-		return "0"
-	}
-
-	u := uint64(i)
-	if i < 0 {
-		u = -u
-	}
-
-	// Assemble decimal in reverse order.
-	var b [32]byte
-	bp := len(b)
-	for ; u > 0; u /= 10 {
-		bp--
-		b[bp] = byte(u%10) + '0'
-	}
-
-	if i < 0 {
-		bp--
-		b[bp] = '-'
-	}
-
-	return string(b[bp:])
-}
-
-func (w Waitmsg) String() string {
-	// TODO(austin) Use signal names when possible?
-	res := ""
-	switch {
-	case w.Exited():
-		res = "exit status " + itod(w.ExitStatus())
-	case w.Signaled():
-		res = "signal " + itod(w.Signal())
-	case w.Stopped():
-		res = "stop signal " + itod(w.StopSignal())
-		if w.StopSignal() == syscall.SIGTRAP && w.TrapCause() != 0 {
-			res += " (trap " + itod(w.TrapCause()) + ")"
-		}
-	case w.Continued():
-		res = "continued"
-	}
-	if w.CoreDump() {
-		res += " (core dumped)"
-	}
-	return res
-}
-
 // Getpid returns the process id of the caller.
 func Getpid() int { return syscall.Getpid() }
 
diff --git a/src/pkg/os/exec_plan9.go b/src/pkg/os/exec_plan9.go
new file mode 100644
index 0000000000..11874aba67
--- /dev/null
+++ b/src/pkg/os/exec_plan9.go
@@ -0,0 +1,114 @@
+// 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"
+)
+
+// StartProcess starts a new process with the program, arguments and attributes
+// specified by name, argv and attr.
+func StartProcess(name string, argv []string, attr *ProcAttr) (p *Process, err Error) {
+	sysattr := &syscall.ProcAttr{
+		Dir: attr.Dir,
+		Env: attr.Env,
+	}
+
+	// Create array of integer (system) fds.
+	intfd := make([]int, len(attr.Files))
+	for i, f := range attr.Files {
+		if f == nil {
+			intfd[i] = -1
+		} else {
+			intfd[i] = f.Fd()
+		}
+	}
+
+	sysattr.Files = intfd
+
+	pid, h, e := syscall.StartProcess(name, argv, sysattr)
+	if iserror(e) {
+		return nil, &PathError{"fork/exec", name, e}
+	}
+
+	return newProcess(pid, h), nil
+}
+
+// Exec replaces the current process with an execution of the
+// named binary, with arguments argv and environment envv.
+// If successful, Exec never returns.  If it fails, it returns an Error.
+// ForkExec is almost always a better way to execute a program.
+func Exec(name string, argv []string, envv []string) Error {
+	e := syscall.Exec(name, argv, envv)
+	if iserror(e) {
+		return &PathError{"exec", name, e}
+	}
+
+	return nil
+}
+
+// Waitmsg stores the information about an exited process as reported by Wait.
+type Waitmsg 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
+// (WNOHANG etc.) affect the behavior of the Wait call.
+func (p *Process) Wait(options int) (w *Waitmsg, err Error) {
+	var waitmsg syscall.Waitmsg
+
+	if p.Pid == -1 {
+		return nil, EINVAL
+	}
+
+	for true {
+		err = syscall.Await(&waitmsg)
+
+		if iserror(err) {
+			return nil, NewSyscallError("wait", err)
+		}
+
+		if waitmsg.Pid == p.Pid {
+			break
+		}
+	}
+
+	return (*Waitmsg)(&waitmsg), nil
+}
+
+// Wait waits for process pid 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.
+// Wait is equivalent to calling FindProcess and then Wait
+// and Release on the result.
+func Wait(pid int, options int) (w *Waitmsg, err Error) {
+	p, e := FindProcess(pid)
+	if e != nil {
+		return nil, e
+	}
+	defer p.Release()
+	return p.Wait(options)
+}
+
+// Release releases any resources associated with the Process.
+func (p *Process) Release() Error {
+	// NOOP for Plan 9.
+	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 Plan 9.
+	return newProcess(pid, 0), nil
+}
+
+func (w Waitmsg) String() string {
+	return "exit status: " + w.Msg
+}
diff --git a/src/pkg/os/exec_posix.go b/src/pkg/os/exec_posix.go
new file mode 100644
index 0000000000..9102dc0a4c
--- /dev/null
+++ b/src/pkg/os/exec_posix.go
@@ -0,0 +1,127 @@
+// 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 "syscall"
+
+// StartProcess starts a new process with the program, arguments and attributes
+// specified by name, argv and attr.
+func StartProcess(name string, argv []string, attr *ProcAttr) (p *Process, err Error) {
+	sysattr := &syscall.ProcAttr{
+		Dir: attr.Dir,
+		Env: attr.Env,
+	}
+	if sysattr.Env == nil {
+		sysattr.Env = Environ()
+	}
+	// Create array of integer (system) fds.
+	intfd := make([]int, len(attr.Files))
+	for i, f := range attr.Files {
+		if f == nil {
+			intfd[i] = -1
+		} else {
+			intfd[i] = f.Fd()
+		}
+	}
+	sysattr.Files = intfd
+
+	pid, h, e := syscall.StartProcess(name, argv, sysattr)
+	if iserror(e) {
+		return nil, &PathError{"fork/exec", name, Errno(e)}
+	}
+	return newProcess(pid, h), nil
+}
+
+// Exec replaces the current process with an execution of the
+// named binary, with arguments argv and environment envv.
+// If successful, Exec never returns.  If it fails, it returns an Error.
+// StartProcess is almost always a better way to execute a program.
+func Exec(name string, argv []string, envv []string) Error {
+	if envv == nil {
+		envv = Environ()
+	}
+	e := syscall.Exec(name, argv, envv)
+	if iserror(e) {
+		return &PathError{"exec", name, Errno(e)}
+	}
+	return nil
+}
+
+// TODO(rsc): Should os implement its own syscall.WaitStatus
+// wrapper with the methods, or is exposing the underlying one enough?
+//
+// TODO(rsc): Certainly need to have Rusage struct,
+// since syscall one might have different field types across
+// different OS.
+
+// Waitmsg stores the information about an exited process as reported by Wait.
+type Waitmsg struct {
+	Pid                int             // The process's id.
+	syscall.WaitStatus                 // System-dependent status info.
+	Rusage             *syscall.Rusage // System-dependent resource usage info.
+}
+
+// Wait waits for process pid 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.
+// Wait is equivalent to calling FindProcess and then Wait
+// and Release on the result.
+func Wait(pid int, options int) (w *Waitmsg, err Error) {
+	p, e := FindProcess(pid)
+	if e != nil {
+		return nil, e
+	}
+	defer p.Release()
+	return p.Wait(options)
+}
+
+// Convert i to decimal string.
+func itod(i int) string {
+	if i == 0 {
+		return "0"
+	}
+
+	u := uint64(i)
+	if i < 0 {
+		u = -u
+	}
+
+	// Assemble decimal in reverse order.
+	var b [32]byte
+	bp := len(b)
+	for ; u > 0; u /= 10 {
+		bp--
+		b[bp] = byte(u%10) + '0'
+	}
+
+	if i < 0 {
+		bp--
+		b[bp] = '-'
+	}
+
+	return string(b[bp:])
+}
+
+func (w Waitmsg) String() string {
+	// TODO(austin) Use signal names when possible?
+	res := ""
+	switch {
+	case w.Exited():
+		res = "exit status " + itod(w.ExitStatus())
+	case w.Signaled():
+		res = "signal " + itod(w.Signal())
+	case w.Stopped():
+		res = "stop signal " + itod(w.StopSignal())
+		if w.StopSignal() == syscall.SIGTRAP && w.TrapCause() != 0 {
+			res += " (trap " + itod(w.TrapCause()) + ")"
+		}
+	case w.Continued():
+		res = "continued"
+	}
+	if w.CoreDump() {
+		res += " (core dumped)"
+	}
+	return res
+}
diff --git a/src/pkg/os/file.go b/src/pkg/os/file.go
index 3f73f1dffe..e916d16058 100644
--- a/src/pkg/os/file.go
+++ b/src/pkg/os/file.go
@@ -83,10 +83,10 @@ func (file *File) Read(b []byte) (n int, err Error) {
 	if n < 0 {
 		n = 0
 	}
-	if n == 0 && e == 0 {
+	if n == 0 && !iserror(e) {
 		return 0, EOF
 	}
-	if e != 0 {
+	if iserror(e) {
 		err = &PathError{"read", file.name, Errno(e)}
 	}
 	return n, err
@@ -102,10 +102,10 @@ func (file *File) ReadAt(b []byte, off int64) (n int, err Error) {
 	}
 	for len(b) > 0 {
 		m, e := syscall.Pread(file.fd, b, off)
-		if m == 0 && e == 0 {
+		if m == 0 && !iserror(e) {
 			return n, EOF
 		}
-		if e != 0 {
+		if iserror(e) {
 			err = &PathError{"read", file.name, Errno(e)}
 			break
 		}
@@ -127,15 +127,10 @@ func (file *File) Write(b []byte) (n int, err Error) {
 	if n < 0 {
 		n = 0
 	}
-	if e == syscall.EPIPE {
-		file.nepipe++
-		if file.nepipe >= 10 {
-			Exit(syscall.EPIPE)
-		}
-	} else {
-		file.nepipe = 0
-	}
-	if e != 0 {
+
+	epipecheck(file, e)
+
+	if iserror(e) {
 		err = &PathError{"write", file.name, Errno(e)}
 	}
 	return n, err
@@ -150,7 +145,7 @@ func (file *File) WriteAt(b []byte, off int64) (n int, err Error) {
 	}
 	for len(b) > 0 {
 		m, e := syscall.Pwrite(file.fd, b, off)
-		if e != 0 {
+		if iserror(e) {
 			err = &PathError{"write", file.name, Errno(e)}
 			break
 		}
@@ -167,10 +162,10 @@ func (file *File) WriteAt(b []byte, off int64) (n int, err Error) {
 // It returns the new offset and an Error, if any.
 func (file *File) Seek(offset int64, whence int) (ret int64, err Error) {
 	r, e := syscall.Seek(file.fd, offset, whence)
-	if e == 0 && file.dirinfo != nil && r != 0 {
+	if !iserror(e) && file.dirinfo != nil && r != 0 {
 		e = syscall.EISDIR
 	}
-	if e != 0 {
+	if iserror(e) {
 		return 0, &PathError{"seek", file.name, Errno(e)}
 	}
 	return r, nil
@@ -187,71 +182,19 @@ func (file *File) WriteString(s string) (ret int, err Error) {
 	return file.Write(b)
 }
 
-// Pipe returns a connected pair of Files; reads from r return bytes written to w.
-// It returns the files and an Error, if any.
-func Pipe() (r *File, w *File, err Error) {
-	var p [2]int
-
-	// See ../syscall/exec.go for description of lock.
-	syscall.ForkLock.RLock()
-	e := syscall.Pipe(p[0:])
-	if e != 0 {
-		syscall.ForkLock.RUnlock()
-		return nil, nil, NewSyscallError("pipe", e)
-	}
-	syscall.CloseOnExec(p[0])
-	syscall.CloseOnExec(p[1])
-	syscall.ForkLock.RUnlock()
-
-	return NewFile(p[0], "|0"), NewFile(p[1], "|1"), nil
-}
-
 // Mkdir creates a new directory with the specified name and permission bits.
 // It returns an error, if any.
 func Mkdir(name string, perm uint32) Error {
 	e := syscall.Mkdir(name, perm)
-	if e != 0 {
+	if iserror(e) {
 		return &PathError{"mkdir", name, Errno(e)}
 	}
 	return nil
 }
 
-// Stat returns a FileInfo structure describing the named file and an error, if any.
-// If name names a valid symbolic link, the returned FileInfo describes
-// the file pointed at by the link and has fi.FollowedSymlink set to true.
-// If name names an invalid symbolic link, the returned FileInfo describes
-// the link itself and has fi.FollowedSymlink set to false.
-func Stat(name string) (fi *FileInfo, err Error) {
-	var lstat, stat syscall.Stat_t
-	e := syscall.Lstat(name, &lstat)
-	if e != 0 {
-		return nil, &PathError{"stat", name, Errno(e)}
-	}
-	statp := &lstat
-	if lstat.Mode&syscall.S_IFMT == syscall.S_IFLNK {
-		e := syscall.Stat(name, &stat)
-		if e == 0 {
-			statp = &stat
-		}
-	}
-	return fileInfoFromStat(name, new(FileInfo), &lstat, statp), nil
-}
-
-// Lstat returns the FileInfo structure describing the named file and an
-// error, if any.  If the file is a symbolic link, the returned FileInfo
-// describes the symbolic link.  Lstat makes no attempt to follow the link.
-func Lstat(name string) (fi *FileInfo, err Error) {
-	var stat syscall.Stat_t
-	e := syscall.Lstat(name, &stat)
-	if e != 0 {
-		return nil, &PathError{"lstat", name, Errno(e)}
-	}
-	return fileInfoFromStat(name, new(FileInfo), &stat, &stat), nil
-}
-
 // Chdir changes the current working directory to the named directory.
 func Chdir(dir string) Error {
-	if e := syscall.Chdir(dir); e != 0 {
+	if e := syscall.Chdir(dir); iserror(e) {
 		return &PathError{"chdir", dir, Errno(e)}
 	}
 	return nil
@@ -260,179 +203,8 @@ func Chdir(dir string) Error {
 // Chdir changes the current working directory to the file,
 // which must be a directory.
 func (f *File) Chdir() Error {
-	if e := syscall.Fchdir(f.fd); e != 0 {
+	if e := syscall.Fchdir(f.fd); iserror(e) {
 		return &PathError{"chdir", f.name, Errno(e)}
 	}
 	return nil
 }
-
-// Remove removes the named file or directory.
-func Remove(name string) Error {
-	// System call interface forces us to know
-	// whether name is a file or directory.
-	// Try both: it is cheaper on average than
-	// doing a Stat plus the right one.
-	e := syscall.Unlink(name)
-	if e == 0 {
-		return nil
-	}
-	e1 := syscall.Rmdir(name)
-	if e1 == 0 {
-		return nil
-	}
-
-	// Both failed: figure out which error to return.
-	// OS X and Linux differ on whether unlink(dir)
-	// returns EISDIR, so can't use that.  However,
-	// both agree that rmdir(file) returns ENOTDIR,
-	// so we can use that to decide which error is real.
-	// Rmdir might also return ENOTDIR if given a bad
-	// file path, like /etc/passwd/foo, but in that case,
-	// both errors will be ENOTDIR, so it's okay to
-	// use the error from unlink.
-	// For windows syscall.ENOTDIR is set
-	// to syscall.ERROR_DIRECTORY, hopefully it should
-	// do the trick.
-	if e1 != syscall.ENOTDIR {
-		e = e1
-	}
-	return &PathError{"remove", name, Errno(e)}
-}
-
-// LinkError records an error during a link or symlink or rename
-// system call and the paths that caused it.
-type LinkError struct {
-	Op    string
-	Old   string
-	New   string
-	Error Error
-}
-
-func (e *LinkError) String() string {
-	return e.Op + " " + e.Old + " " + e.New + ": " + e.Error.String()
-}
-
-// Link creates a hard link.
-func Link(oldname, newname string) Error {
-	e := syscall.Link(oldname, newname)
-	if e != 0 {
-		return &LinkError{"link", oldname, newname, Errno(e)}
-	}
-	return nil
-}
-
-// Symlink creates a symbolic link.
-func Symlink(oldname, newname string) Error {
-	e := syscall.Symlink(oldname, newname)
-	if e != 0 {
-		return &LinkError{"symlink", oldname, newname, Errno(e)}
-	}
-	return nil
-}
-
-// Readlink reads the contents of a symbolic link: the destination of
-// the link.  It returns the contents and an Error, if any.
-func Readlink(name string) (string, Error) {
-	for len := 128; ; len *= 2 {
-		b := make([]byte, len)
-		n, e := syscall.Readlink(name, b)
-		if e != 0 {
-			return "", &PathError{"readlink", name, Errno(e)}
-		}
-		if n < len {
-			return string(b[0:n]), nil
-		}
-	}
-	// Silence 6g.
-	return "", nil
-}
-
-// Rename renames a file.
-func Rename(oldname, newname string) Error {
-	e := syscall.Rename(oldname, newname)
-	if e != 0 {
-		return &LinkError{"rename", oldname, newname, Errno(e)}
-	}
-	return nil
-}
-
-// Chmod changes the mode of the named file to mode.
-// If the file is a symbolic link, it changes the mode of the link's target.
-func Chmod(name string, mode uint32) Error {
-	if e := syscall.Chmod(name, mode); e != 0 {
-		return &PathError{"chmod", name, Errno(e)}
-	}
-	return nil
-}
-
-// Chmod changes the mode of the file to mode.
-func (f *File) Chmod(mode uint32) Error {
-	if e := syscall.Fchmod(f.fd, mode); e != 0 {
-		return &PathError{"chmod", f.name, Errno(e)}
-	}
-	return nil
-}
-
-// Chown changes the numeric uid and gid of the named file.
-// If the file is a symbolic link, it changes the uid and gid of the link's target.
-func Chown(name string, uid, gid int) Error {
-	if e := syscall.Chown(name, uid, gid); e != 0 {
-		return &PathError{"chown", name, Errno(e)}
-	}
-	return nil
-}
-
-// Lchown changes the numeric uid and gid of the named file.
-// If the file is a symbolic link, it changes the uid and gid of the link itself.
-func Lchown(name string, uid, gid int) Error {
-	if e := syscall.Lchown(name, uid, gid); e != 0 {
-		return &PathError{"lchown", name, Errno(e)}
-	}
-	return nil
-}
-
-// Chown changes the numeric uid and gid of the named file.
-func (f *File) Chown(uid, gid int) Error {
-	if e := syscall.Fchown(f.fd, uid, gid); e != 0 {
-		return &PathError{"chown", f.name, Errno(e)}
-	}
-	return nil
-}
-
-// Truncate changes the size of the file.
-// It does not change the I/O offset.
-func (f *File) Truncate(size int64) Error {
-	if e := syscall.Ftruncate(f.fd, size); e != 0 {
-		return &PathError{"truncate", f.name, Errno(e)}
-	}
-	return nil
-}
-
-// Sync commits the current contents of the file to stable storage.
-// Typically, this means flushing the file system's in-memory copy
-// of recently written data to disk.
-func (file *File) Sync() (err Error) {
-	if file == nil {
-		return EINVAL
-	}
-	if e := syscall.Fsync(file.fd); e != 0 {
-		return NewSyscallError("fsync", e)
-	}
-	return nil
-}
-
-// Chtimes changes the access and modification times of the named
-// file, similar to the Unix utime() or utimes() functions.
-//
-// The argument times are in nanoseconds, although the underlying
-// filesystem may truncate or round the values to a more
-// coarse time unit.
-func Chtimes(name string, atime_ns int64, mtime_ns int64) Error {
-	var utimes [2]syscall.Timeval
-	utimes[0] = syscall.NsecToTimeval(atime_ns)
-	utimes[1] = syscall.NsecToTimeval(mtime_ns)
-	if e := syscall.Utimes(name, utimes[0:]); e != 0 {
-		return &PathError{"chtimes", name, Errno(e)}
-	}
-	return nil
-}
diff --git a/src/pkg/os/file_plan9.go b/src/pkg/os/file_plan9.go
new file mode 100644
index 0000000000..2de9efc643
--- /dev/null
+++ b/src/pkg/os/file_plan9.go
@@ -0,0 +1,231 @@
+// 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 os
+
+import (
+	"runtime"
+	"syscall"
+)
+
+func epipecheck(file *File, e syscall.Error) {
+}
+
+
+// DevNull is the name of the operating system's ``null device.''
+// On Unix-like systems, it is "/dev/null"; on Windows, "NUL".
+const DevNull = "/dev/null"
+
+// Open opens the named file with specified flag (O_RDONLY etc.) and perm.
+// If successful, methods on the returned File can be used for I/O.
+// It returns the File and an Error, if any.
+func Open(name string, flag int, perm uint32) (file *File, err Error) {
+	var fd int
+	var e syscall.Error
+
+	syscall.ForkLock.RLock()
+	if flag&O_CREAT == O_CREAT {
+		fd, e = syscall.Create(name, flag & ^O_CREAT, perm)
+	} else {
+		fd, e = syscall.Open(name, flag)
+	}
+	syscall.ForkLock.RUnlock()
+
+	if e != nil {
+		return nil, &PathError{"open", name, e}
+	}
+
+	return NewFile(fd, name), nil
+}
+
+// Close closes the File, rendering it unusable for I/O.
+// It returns an Error, if any.
+func (file *File) Close() Error {
+	if file == nil || file.fd < 0 {
+		return Ebadfd
+	}
+	var err Error
+	syscall.ForkLock.RLock()
+	if e := syscall.Close(file.fd); e != nil {
+		err = &PathError{"close", file.name, e}
+	}
+	syscall.ForkLock.RUnlock()
+	file.fd = -1 // so it can't be closed again
+
+	// no need for a finalizer anymore
+	runtime.SetFinalizer(file, nil)
+	return err
+}
+
+// Stat returns the FileInfo structure describing file.
+// It returns the FileInfo and an error, if any.
+func (file *File) Stat() (fi *FileInfo, err Error) {
+	return dirstat(file)
+}
+
+// Truncate changes the size of the file.
+// It does not change the I/O offset.
+func (f *File) Truncate(size int64) Error {
+	var d Dir
+	d.Null()
+
+	d.Length = uint64(size)
+
+	if e := syscall.Fwstat(f.fd, pdir(nil, &d)); iserror(e) {
+		return &PathError{"truncate", f.name, e}
+	}
+	return nil
+}
+
+// Chmod changes the mode of the file to mode.
+func (f *File) Chmod(mode uint32) Error {
+	var d Dir
+	d.Null()
+
+	d.Mode = mode & 0777
+
+	if e := syscall.Fwstat(f.fd, pdir(nil, &d)); iserror(e) {
+		return &PathError{"chmod", f.name, e}
+	}
+	return nil
+}
+
+// Sync commits the current contents of the file to stable storage.
+// Typically, this means flushing the file system's in-memory copy
+// of recently written data to disk.
+func (f *File) Sync() (err Error) {
+	if f == nil {
+		return EINVAL
+	}
+
+	var d Dir
+	d.Null()
+
+	if e := syscall.Fwstat(f.fd, pdir(nil, &d)); iserror(e) {
+		return NewSyscallError("fsync", e)
+	}
+	return nil
+}
+
+// Truncate changes the size of the named file.
+// If the file is a symbolic link, it changes the size of the link's target.
+func Truncate(name string, size int64) Error {
+	var d Dir
+	d.Null()
+
+	d.Length = uint64(size)
+
+	if e := syscall.Wstat(name, pdir(nil, &d)); iserror(e) {
+		return &PathError{"truncate", name, e}
+	}
+	return nil
+}
+
+// Remove removes the named file or directory.
+func Remove(name string) Error {
+	if e := syscall.Remove(name); iserror(e) {
+		return &PathError{"remove", name, e}
+	}
+	return nil
+}
+
+// Rename renames a file.
+func Rename(oldname, newname string) Error {
+	var d Dir
+	d.Null()
+
+	d.Name = newname
+
+	if e := syscall.Wstat(oldname, pdir(nil, &d)); iserror(e) {
+		return &PathError{"rename", oldname, e}
+	}
+	return nil
+}
+
+// Chmod changes the mode of the named file to mode.
+func Chmod(name string, mode uint32) Error {
+	var d Dir
+	d.Null()
+
+	d.Mode = mode & 0777
+
+	if e := syscall.Wstat(name, pdir(nil, &d)); iserror(e) {
+		return &PathError{"chmod", name, e}
+	}
+	return nil
+}
+
+// ChownPlan9 changes the uid and gid strings of the named file.
+func ChownPlan9(name, uid, gid string) Error {
+	var d Dir
+	d.Null()
+
+	d.Uid = uid
+	d.Gid = gid
+
+	if e := syscall.Wstat(name, pdir(nil, &d)); iserror(e) {
+		return &PathError{"chown_plan9", name, e}
+	}
+	return nil
+}
+
+// Chtimes changes the access and modification times of the named
+// file, similar to the Unix utime() or utimes() functions.
+//
+// The argument times are in nanoseconds, although the underlying
+// filesystem may truncate or round the values to a more
+// coarse time unit.
+func Chtimes(name string, atimeNs int64, mtimeNs int64) Error {
+	var d Dir
+	d.Null()
+
+	d.Atime = uint32(atimeNs / 1e9)
+	d.Mtime = uint32(mtimeNs / 1e9)
+
+	if e := syscall.Wstat(name, pdir(nil, &d)); iserror(e) {
+		return &PathError{"chtimes", name, e}
+	}
+	return nil
+}
+
+func Pipe() (r *File, w *File, err Error) {
+	var p [2]int
+
+	syscall.ForkLock.RLock()
+	if e := syscall.Pipe(p[0:]); iserror(e) {
+		syscall.ForkLock.RUnlock()
+		return nil, nil, NewSyscallError("pipe", e)
+	}
+	syscall.ForkLock.RUnlock()
+
+	return NewFile(p[0], "|0"), NewFile(p[1], "|1"), nil
+}
+
+
+// not supported on Plan 9
+
+// Link creates a hard link.
+func Link(oldname, newname string) Error {
+	return EPLAN9
+}
+
+func Symlink(oldname, newname string) Error {
+	return EPLAN9
+}
+
+func Readlink(name string) (string, Error) {
+	return "", EPLAN9
+}
+
+func Chown(name string, uid, gid int) Error {
+	return EPLAN9
+}
+
+func Lchown(name string, uid, gid int) Error {
+	return EPLAN9
+}
+
+func (f *File) Chown(uid, gid int) Error {
+	return EPLAN9
+}
diff --git a/src/pkg/os/file_posix.go b/src/pkg/os/file_posix.go
new file mode 100644
index 0000000000..5151df4987
--- /dev/null
+++ b/src/pkg/os/file_posix.go
@@ -0,0 +1,246 @@
+// 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.
+
+// The os package provides a platform-independent interface to operating
+// system functionality.  The design is Unix-like.
+package os
+
+import (
+	"syscall"
+)
+
+func epipecheck(file *File, e int) {
+	if e == syscall.EPIPE {
+		file.nepipe++
+		if file.nepipe >= 10 {
+			Exit(syscall.EPIPE)
+		}
+	} else {
+		file.nepipe = 0
+	}
+}
+
+
+// Pipe returns a connected pair of Files; reads from r return bytes written to w.
+// It returns the files and an Error, if any.
+func Pipe() (r *File, w *File, err Error) {
+	var p [2]int
+
+	// See ../syscall/exec.go for description of lock.
+	syscall.ForkLock.RLock()
+	e := syscall.Pipe(p[0:])
+	if iserror(e) {
+		syscall.ForkLock.RUnlock()
+		return nil, nil, NewSyscallError("pipe", e)
+	}
+	syscall.CloseOnExec(p[0])
+	syscall.CloseOnExec(p[1])
+	syscall.ForkLock.RUnlock()
+
+	return NewFile(p[0], "|0"), NewFile(p[1], "|1"), nil
+}
+
+// Stat returns a FileInfo structure describing the named file and an error, if any.
+// If name names a valid symbolic link, the returned FileInfo describes
+// the file pointed at by the link and has fi.FollowedSymlink set to true.
+// If name names an invalid symbolic link, the returned FileInfo describes
+// the link itself and has fi.FollowedSymlink set to false.
+func Stat(name string) (fi *FileInfo, err Error) {
+	var lstat, stat syscall.Stat_t
+	e := syscall.Lstat(name, &lstat)
+	if iserror(e) {
+		return nil, &PathError{"stat", name, Errno(e)}
+	}
+	statp := &lstat
+	if lstat.Mode&syscall.S_IFMT == syscall.S_IFLNK {
+		e := syscall.Stat(name, &stat)
+		if !iserror(e) {
+			statp = &stat
+		}
+	}
+	return fileInfoFromStat(name, new(FileInfo), &lstat, statp), nil
+}
+
+// Lstat returns the FileInfo structure describing the named file and an
+// error, if any.  If the file is a symbolic link, the returned FileInfo
+// describes the symbolic link.  Lstat makes no attempt to follow the link.
+func Lstat(name string) (fi *FileInfo, err Error) {
+	var stat syscall.Stat_t
+	e := syscall.Lstat(name, &stat)
+	if iserror(e) {
+		return nil, &PathError{"lstat", name, Errno(e)}
+	}
+	return fileInfoFromStat(name, new(FileInfo), &stat, &stat), nil
+}
+
+// Remove removes the named file or directory.
+func Remove(name string) Error {
+	// System call interface forces us to know
+	// whether name is a file or directory.
+	// Try both: it is cheaper on average than
+	// doing a Stat plus the right one.
+	e := syscall.Unlink(name)
+	if !iserror(e) {
+		return nil
+	}
+	e1 := syscall.Rmdir(name)
+	if !iserror(e1) {
+		return nil
+	}
+
+	// Both failed: figure out which error to return.
+	// OS X and Linux differ on whether unlink(dir)
+	// returns EISDIR, so can't use that.  However,
+	// both agree that rmdir(file) returns ENOTDIR,
+	// so we can use that to decide which error is real.
+	// Rmdir might also return ENOTDIR if given a bad
+	// file path, like /etc/passwd/foo, but in that case,
+	// both errors will be ENOTDIR, so it's okay to
+	// use the error from unlink.
+	// For windows syscall.ENOTDIR is set
+	// to syscall.ERROR_DIRECTORY, hopefully it should
+	// do the trick.
+	if e1 != syscall.ENOTDIR {
+		e = e1
+	}
+	return &PathError{"remove", name, Errno(e)}
+}
+
+// LinkError records an error during a link or symlink or rename
+// system call and the paths that caused it.
+type LinkError struct {
+	Op    string
+	Old   string
+	New   string
+	Error Error
+}
+
+func (e *LinkError) String() string {
+	return e.Op + " " + e.Old + " " + e.New + ": " + e.Error.String()
+}
+
+// Link creates a hard link.
+func Link(oldname, newname string) Error {
+	e := syscall.Link(oldname, newname)
+	if iserror(e) {
+		return &LinkError{"link", oldname, newname, Errno(e)}
+	}
+	return nil
+}
+
+// Symlink creates a symbolic link.
+func Symlink(oldname, newname string) Error {
+	e := syscall.Symlink(oldname, newname)
+	if iserror(e) {
+		return &LinkError{"symlink", oldname, newname, Errno(e)}
+	}
+	return nil
+}
+
+// Readlink reads the contents of a symbolic link: the destination of
+// the link.  It returns the contents and an Error, if any.
+func Readlink(name string) (string, Error) {
+	for len := 128; ; len *= 2 {
+		b := make([]byte, len)
+		n, e := syscall.Readlink(name, b)
+		if iserror(e) {
+			return "", &PathError{"readlink", name, Errno(e)}
+		}
+		if n < len {
+			return string(b[0:n]), nil
+		}
+	}
+	// Silence 6g.
+	return "", nil
+}
+
+// Rename renames a file.
+func Rename(oldname, newname string) Error {
+	e := syscall.Rename(oldname, newname)
+	if iserror(e) {
+		return &LinkError{"rename", oldname, newname, Errno(e)}
+	}
+	return nil
+}
+
+// Chmod changes the mode of the named file to mode.
+// If the file is a symbolic link, it changes the mode of the link's target.
+func Chmod(name string, mode uint32) Error {
+	if e := syscall.Chmod(name, mode); iserror(e) {
+		return &PathError{"chmod", name, Errno(e)}
+	}
+	return nil
+}
+
+// Chmod changes the mode of the file to mode.
+func (f *File) Chmod(mode uint32) Error {
+	if e := syscall.Fchmod(f.fd, mode); iserror(e) {
+		return &PathError{"chmod", f.name, Errno(e)}
+	}
+	return nil
+}
+
+// Chown changes the numeric uid and gid of the named file.
+// If the file is a symbolic link, it changes the uid and gid of the link's target.
+func Chown(name string, uid, gid int) Error {
+	if e := syscall.Chown(name, uid, gid); iserror(e) {
+		return &PathError{"chown", name, Errno(e)}
+	}
+	return nil
+}
+
+// Lchown changes the numeric uid and gid of the named file.
+// If the file is a symbolic link, it changes the uid and gid of the link itself.
+func Lchown(name string, uid, gid int) Error {
+	if e := syscall.Lchown(name, uid, gid); iserror(e) {
+		return &PathError{"lchown", name, Errno(e)}
+	}
+	return nil
+}
+
+// Chown changes the numeric uid and gid of the named file.
+func (f *File) Chown(uid, gid int) Error {
+	if e := syscall.Fchown(f.fd, uid, gid); iserror(e) {
+		return &PathError{"chown", f.name, Errno(e)}
+	}
+	return nil
+}
+
+// Truncate changes the size of the file.
+// It does not change the I/O offset.
+func (f *File) Truncate(size int64) Error {
+	if e := syscall.Ftruncate(f.fd, size); iserror(e) {
+		return &PathError{"truncate", f.name, Errno(e)}
+	}
+	return nil
+}
+
+// Sync commits the current contents of the file to stable storage.
+// Typically, this means flushing the file system's in-memory copy
+// of recently written data to disk.
+func (file *File) Sync() (err Error) {
+	if file == nil {
+		return EINVAL
+	}
+	if e := syscall.Fsync(file.fd); iserror(e) {
+		return NewSyscallError("fsync", e)
+	}
+	return nil
+}
+
+// Chtimes changes the access and modification times of the named
+// file, similar to the Unix utime() or utimes() functions.
+//
+// The argument times are in nanoseconds, although the underlying
+// filesystem may truncate or round the values to a more
+// coarse time unit.
+func Chtimes(name string, atime_ns int64, mtime_ns int64) Error {
+	var utimes [2]syscall.Timeval
+	utimes[0] = syscall.NsecToTimeval(atime_ns)
+	utimes[1] = syscall.NsecToTimeval(mtime_ns)
+	if e := syscall.Utimes(name, utimes[0:]); iserror(e) {
+		return &PathError{"chtimes", name, Errno(e)}
+	}
+	return nil
+}
diff --git a/src/pkg/os/proc.go b/src/pkg/os/proc.go
index dfddab6cb8..481ef60337 100644
--- a/src/pkg/os/proc.go
+++ b/src/pkg/os/proc.go
@@ -26,8 +26,8 @@ func Getegid() int { return syscall.Getegid() }
 
 // Getgroups returns a list of the numeric ids of groups that the caller belongs to.
 func Getgroups() ([]int, Error) {
-	gids, errno := syscall.Getgroups()
-	return gids, NewSyscallError("getgroups", errno)
+	gids, e := syscall.Getgroups()
+	return gids, NewSyscallError("getgroups", e)
 }
 
 // Exit causes the current program to exit with the given status code.
diff --git a/src/pkg/os/stat_plan9.go b/src/pkg/os/stat_plan9.go
new file mode 100644
index 0000000000..e96749d33f
--- /dev/null
+++ b/src/pkg/os/stat_plan9.go
@@ -0,0 +1,84 @@
+// 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 os
+
+import "syscall"
+
+func fileInfoFromStat(fi *FileInfo, d *Dir) *FileInfo {
+	fi.Dev = uint64(d.Qid.Vers) | uint64(d.Qid.Type<<32)
+	fi.Ino = d.Qid.Path
+
+	fi.Mode = uint32(d.Mode) & 0777
+	if (d.Mode & syscall.DMDIR) == syscall.DMDIR {
+		fi.Mode |= syscall.S_IFDIR
+	} else {
+		fi.Mode |= syscall.S_IFREG
+	}
+
+	fi.Size = int64(d.Length)
+	fi.Atime_ns = 1e9 * int64(d.Atime)
+	fi.Mtime_ns = 1e9 * int64(d.Mtime)
+	fi.Name = d.Name
+	fi.FollowedSymlink = false
+	return fi
+}
+
+// arg is an open *File or a path string. 
+func dirstat(arg interface{}) (fi *FileInfo, err Error) {
+	var name string
+	nd := syscall.STATFIXLEN + 16*4
+
+	for i := 0; i < 2; i++ { /* should work by the second try */
+		buf := make([]byte, nd)
+
+		var n int
+		var e syscall.Error
+
+		switch syscallArg := arg.(type) {
+		case *File:
+			name = syscallArg.name
+			n, e = syscall.Fstat(syscallArg.fd, buf)
+		case string:
+			name = syscallArg
+			n, e = syscall.Stat(name, buf)
+		}
+
+		if e != nil {
+			return nil, &PathError{"stat", name, e}
+		}
+
+		if n < syscall.STATFIXLEN {
+			return nil, &PathError{"stat", name, Eshortstat}
+		}
+
+		ntmp, _ := gbit16(buf)
+		nd = int(ntmp)
+
+		if nd <= n {
+			d, e := UnmarshalDir(buf[:n])
+
+			if e != nil {
+				return nil, &PathError{"stat", name, e}
+			}
+
+			return fileInfoFromStat(new(FileInfo), d), nil
+		}
+	}
+
+	return nil, &PathError{"stat", name, Ebadstat}
+}
+
+
+// Stat returns a FileInfo structure describing the named file and an error, if any.
+func Stat(name string) (fi *FileInfo, err Error) {
+	return dirstat(name)
+}
+
+// Lstat returns the FileInfo structure describing the named file and an
+// error, if any.  If the file is a symbolic link (though Plan 9 does not have symbolic links), 
+// the returned FileInfo describes the symbolic link.  Lstat makes no attempt to follow the link.
+func Lstat(name string) (fi *FileInfo, err Error) {
+	return dirstat(name)
+}
diff --git a/src/pkg/os/sys_plan9.go b/src/pkg/os/sys_plan9.go
new file mode 100644
index 0000000000..ac44445af3
--- /dev/null
+++ b/src/pkg/os/sys_plan9.go
@@ -0,0 +1,27 @@
+// 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.
+
+// Plan 9-specific
+
+package os
+
+
+func Hostname() (name string, err Error) {
+	f, err := Open("#c/sysname", O_RDONLY, 0)
+	if err != nil {
+		return "", err
+	}
+	defer f.Close()
+
+	var buf [128]byte
+	n, err := f.Read(buf[:len(buf)-1])
+
+	if err != nil {
+		return "", err
+	}
+	if n > 0 {
+		buf[n] = 0
+	}
+	return string(buf[0:n]), nil
+}
diff --git a/src/pkg/os/time.go b/src/pkg/os/time.go
index 380345f1b1..8e87a49e16 100644
--- a/src/pkg/os/time.go
+++ b/src/pkg/os/time.go
@@ -13,8 +13,8 @@ import "syscall"
 // time is the Unix epoch.
 func Time() (sec int64, nsec int64, err Error) {
 	var tv syscall.Timeval
-	if errno := syscall.Gettimeofday(&tv); errno != 0 {
-		return 0, 0, NewSyscallError("gettimeofday", errno)
+	if e := syscall.Gettimeofday(&tv); iserror(e) {
+		return 0, 0, NewSyscallError("gettimeofday", e)
 	}
 	return int64(tv.Sec), int64(tv.Usec) * 1000, err
 }