os: use error, io.EOF

R=r
CC=golang-dev
https://golang.org/cl/5298073

src/pkg/os/dir_plan9.go

@@ -5,6 +5,7 @@
 package os
 
 import (
+	"io"
 	"syscall"
 )
 
@@ -15,7 +16,7 @@ import (
 //
 // If n > 0, Readdir returns at most n FileInfo structures. In this case, if
 // Readdirnames returns an empty slice, it will return a non-nil error
-// explaining why. At the end of a directory, the error is os.EOF.
+// explaining why. At the end of a directory, the error is io.EOF.
 //
 // If n <= 0, Readdir returns all the FileInfo from the directory in
 // a single slice. In this case, if Readdir succeeds (reads all
@@ -23,7 +24,7 @@ import (
 // nil os.Error. If it encounters an error before the end of the
 // directory, Readdir returns the FileInfo read until that point
 // and a non-nil error.
-func (file *File) Readdir(n int) (fi []FileInfo, err Error) {
+func (file *File) Readdir(n int) (fi []FileInfo, err error) {
 	// If this file has no dirinfo, create one.
 	if file.dirinfo == nil {
 		file.dirinfo = new(dirInfo)
@@ -39,12 +40,12 @@ func (file *File) Readdir(n int) (fi []FileInfo, err Error) {
 		// Refill the buffer if necessary
 		if d.bufp >= d.nbuf {
 			d.bufp = 0
-			var e Error
+			var e error
 			d.nbuf, e = file.Read(d.buf[:])
-			if e != nil && e != EOF {
+			if e != nil && e != io.EOF {
 				return result, &PathError{"readdir", file.name, e}
 			}
-			if e == EOF {
+			if e == io.EOF {
 				break
 			}
 			if d.nbuf < syscall.STATFIXLEN {
@@ -71,7 +72,7 @@ func (file *File) Readdir(n int) (fi []FileInfo, err Error) {
 	}
 
 	if n >= 0 && len(result) == 0 {
-		return result, EOF
+		return result, io.EOF
 	}
 	return result, nil
 }
@@ -80,7 +81,7 @@ func (file *File) Readdir(n int) (fi []FileInfo, err Error) {
 //
 // If n > 0, Readdirnames returns at most n names. In this case, if
 // Readdirnames returns an empty slice, it will return a non-nil error
-// explaining why. At the end of a directory, the error is os.EOF.
+// explaining why. At the end of a directory, the error is io.EOF.
 //
 // If n <= 0, Readdirnames returns all the names from the directory in
 // a single slice. In this case, if Readdirnames succeeds (reads all
@@ -88,7 +89,7 @@ func (file *File) Readdir(n int) (fi []FileInfo, err Error) {
 // nil os.Error. If it encounters an error before the end of the
 // directory, Readdirnames returns the names read until that point and
 // a non-nil error.
-func (file *File) Readdirnames(n int) (names []string, err Error) {
+func (file *File) Readdirnames(n int) (names []string, err error) {
 	fi, err := file.Readdir(n)
 	names = make([]string, len(fi))
 	for i := range fi {
@@ -160,7 +161,7 @@ func pdir(b []byte, d *Dir) []byte {
 
 // UnmarshalDir reads a 9P Stat message from a 9P protocol message stored in b,
 // returning the corresponding Dir struct.
-func UnmarshalDir(b []byte) (d *Dir, err Error) {
+func UnmarshalDir(b []byte) (d *Dir, err error) {
 	n := uint16(0)
 	n, b = gbit16(b)
 

src/pkg/os/dir_unix.go

@@ -7,6 +7,7 @@
 package os
 
 import (
+	"io"
 	"syscall"
 )
 
@@ -26,7 +27,7 @@ const (
 // nil os.Error. If it encounters an error before the end of the
 // directory, Readdirnames returns the names read until that point and
 // a non-nil error.
-func (f *File) Readdirnames(n int) (names []string, err Error) {
+func (f *File) Readdirnames(n int) (names []string, err error) {
 	// If this file has no dirinfo, create one.
 	if f.dirinfo == nil {
 		f.dirinfo = new(dirInfo)
@@ -63,7 +64,7 @@ func (f *File) Readdirnames(n int) (names []string, err Error) {
 		n -= nc
 	}
 	if n >= 0 && len(names) == 0 {
-		return names, EOF
+		return names, io.EOF
 	}
 	return names, nil
 }

src/pkg/os/dir_windows.go

@@ -4,7 +4,7 @@
 
 package os
 
-func (file *File) Readdirnames(n int) (names []string, err Error) {
+func (file *File) Readdirnames(n int) (names []string, err error) {
 	fis, err := file.Readdir(n)
 	names = make([]string, len(fis))
 	for i, fi := range fis {

src/pkg/os/env_plan9.go

@@ -8,12 +8,12 @@ package os
 
 import "syscall"
 
-// ENOENV is the Error indicating that an environment variable does not exist.
+// 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) {
+func Getenverror(key string) (value string, err error) {
 	if len(key) == 0 {
 		return "", EINVAL
 	}
@@ -45,8 +45,8 @@ func Getenv(key string) string {
 }
 
 // Setenv sets the value of the environment variable named by the key.
-// It returns an Error, if any.
-func Setenv(key, value string) Error {
+// It returns an error, if any.
+func Setenv(key, value string) error {
 	if len(key) == 0 {
 		return EINVAL
 	}

src/pkg/os/env_unix.go

@@ -9,11 +9,12 @@
 package os
 
 import (
+	"errors"
 	"sync"
 )
 
-// ENOENV is the Error indicating that an environment variable does not exist.
-var ENOENV = NewError("no such environment variable")
+// ENOENV is the error indicating that an environment variable does not exist.
+var ENOENV = errors.New("no such environment variable")
 
 var env map[string]string
 var once sync.Once
@@ -34,7 +35,7 @@ var envLock sync.RWMutex
 
 // 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) {
+func Getenverror(key string) (value string, err error) {
 	once.Do(copyenv)
 
 	if len(key) == 0 {
@@ -59,8 +60,8 @@ func Getenv(key string) string {
 }
 
 // Setenv sets the value of the environment variable named by the key.
-// It returns an Error, if any.
-func Setenv(key, value string) Error {
+// It returns an error, if any.
+func Setenv(key, value string) error {
 	once.Do(copyenv)
 	if len(key) == 0 {
 		return EINVAL

src/pkg/os/env_windows.go

@@ -12,12 +12,12 @@ import (
 	"unsafe"
 )
 
-// ENOENV is the Error indicating that an environment variable does not exist.
+// 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) {
+func Getenverror(key string) (value string, err error) {
 	b := make([]uint16, 100)
 	n, e := syscall.GetEnvironmentVariable(syscall.StringToUTF16Ptr(key), &b[0], uint32(len(b)))
 	if n == 0 && e == syscall.ERROR_ENVVAR_NOT_FOUND {
@@ -44,8 +44,8 @@ func Getenv(key string) string {
 }
 
 // Setenv sets the value of the environment variable named by the key.
-// It returns an Error, if any.
-func Setenv(key, value string) Error {
+// It returns an error, if any.
+func Setenv(key, value string) error {
 	var v *uint16
 	if len(value) > 0 {
 		v = syscall.StringToUTF16Ptr(value)

src/pkg/os/error.go

@@ -4,28 +4,11 @@
 
 package os
 
-// An Error can represent any printable error condition.
-type Error interface {
-	String() string
-}
-
-// // errorString is a helper type used by NewError.
-type errorString string
-
-func (e errorString) String() string { return string(e) }
-
-// Note: If the name of the function NewError changes,
-// pkg/go/doc/doc.go should be adjusted since it hardwires
-// this name in a heuristic.
-
-// // NewError returns a new error with error.String() == s.
-func NewError(s string) Error { return errorString(s) }
-
 // PathError records an error and the operation and file path that caused it.
 type PathError struct {
-	Op    string
-	Path  string
-	Error Error
+	Op   string
+	Path string
+	Err  error
 }
 
-func (e *PathError) String() string { return e.Op + " " + e.Path + ": " + e.Error.String() }
+func (e *PathError) Error() string { return e.Op + " " + e.Path + ": " + e.Err.Error() }

src/pkg/os/error_plan9.go

@@ -12,16 +12,16 @@ type SyscallError struct {
 	Err     string
 }
 
-func (e *SyscallError) String() string { return e.Syscall + ": " + e.Err }
+func (e *SyscallError) Error() 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
+// 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 {
+func NewSyscallError(syscall string, err syscall.Error) error {
 	if err == nil {
 		return nil
 	}

src/pkg/os/error_posix.go

@@ -9,10 +9,10 @@ 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.
+// 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) Error() string { return syscall.Errstr(int(e)) }
 
 func (e Errno) Temporary() bool {
 	return e == Errno(syscall.EINTR) || e == Errno(syscall.EMFILE) || e.Timeout()
@@ -24,45 +24,45 @@ func (e Errno) Timeout() bool {
 
 // 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)
+	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.
@@ -71,16 +71,16 @@ type SyscallError struct {
 	Errno   Errno
 }
 
-func (e *SyscallError) String() string { return e.Syscall + ": " + e.Errno.String() }
+func (e *SyscallError) Error() string { return e.Syscall + ": " + e.Errno.Error() }
 
 // 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
+// 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 {
+func NewSyscallError(syscall string, errno int) error {
 	if errno == 0 {
 		return nil
 	}

src/pkg/os/exec_plan9.go

@@ -11,7 +11,7 @@ import (
 
 // 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) {
+func StartProcess(name string, argv []string, attr *ProcAttr) (p *Process, err error) {
 	sysattr := &syscall.ProcAttr{
 		Dir: attr.Dir,
 		Env: attr.Env,
@@ -45,7 +45,7 @@ func (note Plan9Note) String() string {
 	return string(note)
 }
 
-func (p *Process) Signal(sig Signal) Error {
+func (p *Process) Signal(sig Signal) error {
 	if p.done {
 		return NewError("os: process already finished")
 	}
@@ -60,7 +60,7 @@ func (p *Process) Signal(sig Signal) Error {
 }
 
 // Kill causes the Process to exit immediately.
-func (p *Process) Kill() Error {
+func (p *Process) Kill() error {
 	f, e := OpenFile("/proc/"+itoa(p.Pid)+"/ctl", O_WRONLY, 0)
 	if iserror(e) {
 		return NewSyscallError("kill", e)
@@ -72,9 +72,9 @@ func (p *Process) Kill() Error {
 
 // 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.
+// 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 {
+func Exec(name string, argv []string, envv []string) error {
 	e := syscall.Exec(name, argv, envv)
 	if iserror(e) {
 		return &PathError{"exec", name, e}
@@ -89,9 +89,9 @@ type Waitmsg struct {
 }
 
 // Wait waits for the Process to exit or stop, and then returns a
-// Waitmsg describing its status and an Error, if any. The options
+// 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) {
+func (p *Process) Wait(options int) (w *Waitmsg, err error) {
 	var waitmsg syscall.Waitmsg
 
 	if p.Pid == -1 {
@@ -115,11 +115,11 @@ func (p *Process) Wait(options int) (w *Waitmsg, err Error) {
 }
 
 // Wait waits for process pid to exit or stop, and then returns a
-// Waitmsg describing its status and an Error, if any. The options
+// 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) {
+func Wait(pid int, options int) (w *Waitmsg, err error) {
 	p, e := FindProcess(pid)
 	if e != nil {
 		return nil, e
@@ -129,7 +129,7 @@ func Wait(pid int, options int) (w *Waitmsg, err Error) {
 }
 
 // Release releases any resources associated with the Process.
-func (p *Process) Release() Error {
+func (p *Process) Release() error {
 	// NOOP for Plan 9.
 	p.Pid = -1
 	// no need for a finalizer anymore
@@ -140,7 +140,7 @@ func (p *Process) Release() Error {
 // 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) {
+func FindProcess(pid int) (p *Process, err error) {
 	// NOOP for Plan 9.
 	return newProcess(pid, 0), nil
 }

src/pkg/os/exec_posix.go

@@ -26,7 +26,7 @@ func (sig UnixSignal) String() string {
 //
 // StartProcess is a low-level interface. The exec package provides
 // higher-level interfaces.
-func StartProcess(name string, argv []string, attr *ProcAttr) (p *Process, err Error) {
+func StartProcess(name string, argv []string, attr *ProcAttr) (p *Process, err error) {
 	sysattr := &syscall.ProcAttr{
 		Dir: attr.Dir,
 		Env: attr.Env,
@@ -47,17 +47,17 @@ func StartProcess(name string, argv []string, attr *ProcAttr) (p *Process, err E
 }
 
 // Kill causes the Process to exit immediately.
-func (p *Process) Kill() Error {
+func (p *Process) Kill() error {
 	return p.Signal(SIGKILL)
 }
 
 // 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.
+// If successful, Exec never returns.  If it fails, it returns an error.
 //
 // To run a child process, see StartProcess (for a low-level interface)
 // or the exec package (for higher-level interfaces).
-func Exec(name string, argv []string, envv []string) Error {
+func Exec(name string, argv []string, envv []string) error {
 	if envv == nil {
 		envv = Environ()
 	}
@@ -83,11 +83,11 @@ type Waitmsg struct {
 }
 
 // Wait waits for process pid to exit or stop, and then returns a
-// Waitmsg describing its status and an Error, if any. The options
+// 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) {
+func Wait(pid int, options int) (w *Waitmsg, err error) {
 	p, e := FindProcess(pid)
 	if e != nil {
 		return nil, e

src/pkg/os/exec_unix.go

@@ -7,6 +7,7 @@
 package os
 
 import (
+	"errors"
 	"runtime"
 	"syscall"
 )
@@ -24,9 +25,9 @@ const (
 // 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
+// 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) {
+func (p *Process) Wait(options int) (w *Waitmsg, err error) {
 	if p.Pid == -1 {
 		return nil, EINVAL
 	}
@@ -52,9 +53,9 @@ func (p *Process) Wait(options int) (w *Waitmsg, err Error) {
 }
 
 // Signal sends a signal to the Process.
-func (p *Process) Signal(sig Signal) Error {
+func (p *Process) Signal(sig Signal) error {
 	if p.done {
-		return NewError("os: process already finished")
+		return errors.New("os: process already finished")
 	}
 	if e := syscall.Kill(p.Pid, int(sig.(UnixSignal))); e != 0 {
 		return Errno(e)
@@ -63,7 +64,7 @@ func (p *Process) Signal(sig Signal) Error {
 }
 
 // Release releases any resources associated with the Process.
-func (p *Process) Release() Error {
+func (p *Process) Release() error {
 	// NOOP for unix.
 	p.Pid = -1
 	// no need for a finalizer anymore
@@ -74,7 +75,7 @@ func (p *Process) Release() Error {
 // 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) {
+func FindProcess(pid int) (p *Process, err error) {
 	// NOOP for unix.
 	return newProcess(pid, 0), nil
 }

src/pkg/os/exec_windows.go

@@ -9,7 +9,7 @@ import (
 	"syscall"
 )
 
-func (p *Process) Wait(options int) (w *Waitmsg, err Error) {
+func (p *Process) Wait(options int) (w *Waitmsg, err error) {
 	s, e := syscall.WaitForSingleObject(syscall.Handle(p.handle), syscall.INFINITE)
 	switch s {
 	case syscall.WAIT_OBJECT_0:
@@ -29,7 +29,7 @@ func (p *Process) Wait(options int) (w *Waitmsg, err Error) {
 }
 
 // Signal sends a signal to the Process.
-func (p *Process) Signal(sig Signal) Error {
+func (p *Process) Signal(sig Signal) error {
 	if p.done {
 		return NewError("os: process already finished")
 	}
@@ -41,7 +41,7 @@ func (p *Process) Signal(sig Signal) Error {
 	return Errno(syscall.EWINDOWS)
 }
 
-func (p *Process) Release() Error {
+func (p *Process) Release() error {
 	if p.handle == -1 {
 		return EINVAL
 	}
@@ -55,7 +55,7 @@ func (p *Process) Release() Error {
 	return nil
 }
 
-func FindProcess(pid int) (p *Process, err Error) {
+func FindProcess(pid int) (p *Process, err error) {
 	const da = syscall.STANDARD_RIGHTS_READ |
 		syscall.PROCESS_QUERY_INFORMATION | syscall.SYNCHRONIZE
 	h, e := syscall.OpenProcess(da, false, uint32(pid))

src/pkg/os/file.go

@@ -9,6 +9,7 @@
 package os
 
 import (
+	"io"
 	"syscall"
 )
 
@@ -47,21 +48,10 @@ const (
 	SEEK_END int = 2 // seek relative to the end
 )
 
-type eofError int
-
-func (eofError) String() string { return "EOF" }
-
-// EOF is the Error returned by Read when no more input is available.
-// Functions should return EOF only to signal a graceful end of input.
-// If the EOF occurs unexpectedly in a structured data stream,
-// the appropriate error is either io.ErrUnexpectedEOF or some other error
-// giving more detail.
-var EOF Error = eofError(0)
-
 // Read reads up to len(b) bytes from the File.
-// It returns the number of bytes read and an Error, if any.
-// EOF is signaled by a zero count with err set to EOF.
-func (file *File) Read(b []byte) (n int, err Error) {
+// It returns the number of bytes read and an error, if any.
+// EOF is signaled by a zero count with err set to io.EOF.
+func (file *File) Read(b []byte) (n int, err error) {
 	if file == nil {
 		return 0, EINVAL
 	}
@@ -70,7 +60,7 @@ func (file *File) Read(b []byte) (n int, err Error) {
 		n = 0
 	}
 	if n == 0 && len(b) > 0 && !iserror(e) {
-		return 0, EOF
+		return 0, io.EOF
 	}
 	if iserror(e) {
 		err = &PathError{"read", file.name, Errno(e)}
@@ -79,17 +69,17 @@ func (file *File) Read(b []byte) (n int, err Error) {
 }
 
 // ReadAt reads len(b) bytes from the File starting at byte offset off.
-// It returns the number of bytes read and the Error, if any.
-// EOF is signaled by a zero count with err set to EOF.
-// ReadAt always returns a non-nil Error when n != len(b).
-func (file *File) ReadAt(b []byte, off int64) (n int, err Error) {
+// It returns the number of bytes read and the error, if any.
+// EOF is signaled by a zero count with err set to io.EOF.
+// ReadAt always returns a non-nil error when n != len(b).
+func (file *File) ReadAt(b []byte, off int64) (n int, err error) {
 	if file == nil {
 		return 0, EINVAL
 	}
 	for len(b) > 0 {
 		m, e := file.pread(b, off)
 		if m == 0 && !iserror(e) {
-			return n, EOF
+			return n, io.EOF
 		}
 		if iserror(e) {
 			err = &PathError{"read", file.name, Errno(e)}
@@ -103,9 +93,9 @@ func (file *File) ReadAt(b []byte, off int64) (n int, err Error) {
 }
 
 // Write writes len(b) bytes to the File.
-// It returns the number of bytes written and an Error, if any.
-// Write returns a non-nil Error when n != len(b).
-func (file *File) Write(b []byte) (n int, err Error) {
+// It returns the number of bytes written and an error, if any.
+// Write returns a non-nil error when n != len(b).
+func (file *File) Write(b []byte) (n int, err error) {
 	if file == nil {
 		return 0, EINVAL
 	}
@@ -123,9 +113,9 @@ func (file *File) Write(b []byte) (n int, err Error) {
 }
 
 // WriteAt writes len(b) bytes to the File starting at byte offset off.
-// It returns the number of bytes written and an Error, if any.
-// WriteAt returns a non-nil Error when n != len(b).
-func (file *File) WriteAt(b []byte, off int64) (n int, err Error) {
+// It returns the number of bytes written and an error, if any.
+// WriteAt returns a non-nil error when n != len(b).
+func (file *File) WriteAt(b []byte, off int64) (n int, err error) {
 	if file == nil {
 		return 0, EINVAL
 	}
@@ -145,8 +135,8 @@ func (file *File) WriteAt(b []byte, off int64) (n int, err Error) {
 // Seek sets the offset for the next Read or Write on file to offset, interpreted
 // according to whence: 0 means relative to the origin of the file, 1 means
 // relative to the current offset, and 2 means relative to the end.
-// It returns the new offset and an Error, if any.
-func (file *File) Seek(offset int64, whence int) (ret int64, 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 := file.seek(offset, whence)
 	if !iserror(e) && file.dirinfo != nil && r != 0 {
 		e = syscall.EISDIR
@@ -159,7 +149,7 @@ func (file *File) Seek(offset int64, whence int) (ret int64, err Error) {
 
 // WriteString is like Write, but writes the contents of string s rather than
 // an array of bytes.
-func (file *File) WriteString(s string) (ret int, err Error) {
+func (file *File) WriteString(s string) (ret int, err error) {
 	if file == nil {
 		return 0, EINVAL
 	}
@@ -168,7 +158,7 @@ func (file *File) WriteString(s string) (ret int, err Error) {
 
 // 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 {
+func Mkdir(name string, perm uint32) error {
 	e := syscall.Mkdir(name, perm)
 	if iserror(e) {
 		return &PathError{"mkdir", name, Errno(e)}
@@ -177,7 +167,7 @@ func Mkdir(name string, perm uint32) Error {
 }
 
 // Chdir changes the current working directory to the named directory.
-func Chdir(dir string) Error {
+func Chdir(dir string) error {
 	if e := syscall.Chdir(dir); iserror(e) {
 		return &PathError{"chdir", dir, Errno(e)}
 	}
@@ -186,7 +176,7 @@ func Chdir(dir string) Error {
 
 // Chdir changes the current working directory to the file,
 // which must be a directory.
-func (f *File) Chdir() Error {
+func (f *File) Chdir() error {
 	if e := syscall.Fchdir(f.fd); iserror(e) {
 		return &PathError{"chdir", f.name, Errno(e)}
 	}
@@ -196,8 +186,8 @@ func (f *File) Chdir() Error {
 // Open opens the named file for reading.  If successful, methods on
 // the returned file can be used for reading; the associated file
 // descriptor has mode O_RDONLY.
-// It returns the File and an Error, if any.
-func Open(name string) (file *File, err Error) {
+// It returns the File and an error, if any.
+func Open(name string) (file *File, err error) {
 	return OpenFile(name, O_RDONLY, 0)
 }
 
@@ -205,7 +195,7 @@ func Open(name string) (file *File, err Error) {
 // it if it already exists.  If successful, methods on the returned
 // File can be used for I/O; the associated file descriptor has mode
 // O_RDWR.
-// It returns the File and an Error, if any.
-func Create(name string) (file *File, err Error) {
+// It returns the File and an error, if any.
+func Create(name string) (file *File, err error) {
 	return OpenFile(name, O_RDWR|O_CREATE|O_TRUNC, 0666)
 }

src/pkg/os/file_plan9.go

@@ -52,8 +52,8 @@ const DevNull = "/dev/null"
 // or Create instead.  It opens the named file with specified flag
 // (O_RDONLY etc.) and perm, (0666 etc.) if applicable.  If successful,
 // methods on the returned File can be used for I/O.
-// It returns the File and an Error, if any.
-func OpenFile(name string, flag int, perm uint32) (file *File, err Error) {
+// It returns the File and an error, if any.
+func OpenFile(name string, flag int, perm uint32) (file *File, err error) {
 	var (
 		fd     int
 		e      syscall.Error
@@ -108,12 +108,12 @@ func OpenFile(name string, flag int, perm uint32) (file *File, err Error) {
 }
 
 // Close closes the File, rendering it unusable for I/O.
-// It returns an Error, if any.
-func (file *File) Close() Error {
+// It returns an error, if any.
+func (file *File) Close() error {
 	if file == nil || file.fd < 0 {
 		return Ebadfd
 	}
-	var err Error
+	var err error
 	syscall.ForkLock.RLock()
 	if e := syscall.Close(file.fd); e != nil {
 		err = &PathError{"close", file.name, e}
@@ -128,7 +128,7 @@ func (file *File) Close() Error {
 
 // Stat returns the FileInfo structure describing file.
 // It returns the FileInfo and an error, if any.
-func (f *File) Stat() (fi *FileInfo, err Error) {
+func (f *File) Stat() (fi *FileInfo, err error) {
 	d, err := dirstat(f)
 	if iserror(err) {
 		return nil, err
@@ -138,7 +138,7 @@ func (f *File) Stat() (fi *FileInfo, err Error) {
 
 // Truncate changes the size of the file.
 // It does not change the I/O offset.
-func (f *File) Truncate(size int64) Error {
+func (f *File) Truncate(size int64) error {
 	var d Dir
 	d.Null()
 
@@ -151,7 +151,7 @@ func (f *File) Truncate(size int64) Error {
 }
 
 // Chmod changes the mode of the file to mode.
-func (f *File) Chmod(mode uint32) Error {
+func (f *File) Chmod(mode uint32) error {
 	var d Dir
 	var mask = ^uint32(0777)
 
@@ -171,7 +171,7 @@ func (f *File) Chmod(mode uint32) Error {
 // 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) {
+func (f *File) Sync() (err error) {
 	if f == nil {
 		return EINVAL
 	}
@@ -220,7 +220,7 @@ func (f *File) seek(offset int64, whence int) (ret int64, err syscall.Error) {
 
 // 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 {
+func Truncate(name string, size int64) error {
 	var d Dir
 	d.Null()
 
@@ -233,7 +233,7 @@ func Truncate(name string, size int64) Error {
 }
 
 // Remove removes the named file or directory.
-func Remove(name string) Error {
+func Remove(name string) error {
 	if e := syscall.Remove(name); iserror(e) {
 		return &PathError{"remove", name, e}
 	}
@@ -241,7 +241,7 @@ func Remove(name string) Error {
 }
 
 // Rename renames a file.
-func Rename(oldname, newname string) Error {
+func Rename(oldname, newname string) error {
 	var d Dir
 	d.Null()
 
@@ -254,7 +254,7 @@ func Rename(oldname, newname string) Error {
 }
 
 // Chmod changes the mode of the named file to mode.
-func Chmod(name string, mode uint32) Error {
+func Chmod(name string, mode uint32) error {
 	var d Dir
 	var mask = ^uint32(0777)
 
@@ -277,7 +277,7 @@ func Chmod(name string, mode uint32) Error {
 // 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 {
+func Chtimes(name string, atimeNs int64, mtimeNs int64) error {
 	var d Dir
 	d.Null()
 
@@ -290,7 +290,7 @@ func Chtimes(name string, atimeNs int64, mtimeNs int64) Error {
 	return nil
 }
 
-func Pipe() (r *File, w *File, err Error) {
+func Pipe() (r *File, w *File, err error) {
 	var p [2]int
 
 	syscall.ForkLock.RLock()
@@ -306,26 +306,26 @@ func Pipe() (r *File, w *File, err Error) {
 // not supported on Plan 9
 
 // Link creates a hard link.
-func Link(oldname, newname string) Error {
+func Link(oldname, newname string) error {
 	return EPLAN9
 }
 
-func Symlink(oldname, newname string) Error {
+func Symlink(oldname, newname string) error {
 	return EPLAN9
 }
 
-func Readlink(name string) (string, Error) {
+func Readlink(name string) (string, error) {
 	return "", EPLAN9
 }
 
-func Chown(name string, uid, gid int) Error {
+func Chown(name string, uid, gid int) error {
 	return EPLAN9
 }
 
-func Lchown(name string, uid, gid int) Error {
+func Lchown(name string, uid, gid int) error {
 	return EPLAN9
 }
 
-func (f *File) Chown(uid, gid int) Error {
+func (f *File) Chown(uid, gid int) error {
 	return EPLAN9
 }

src/pkg/os/file_posix.go

@@ -24,7 +24,7 @@ func epipecheck(file *File, e int) {
 }
 
 // Remove removes the named file or directory.
-func Remove(name string) Error {
+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
@@ -59,18 +59,18 @@ func Remove(name string) Error {
 // 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
+	Op  string
+	Old string
+	New string
+	Err error
 }
 
-func (e *LinkError) String() string {
-	return e.Op + " " + e.Old + " " + e.New + ": " + e.Error.String()
+func (e *LinkError) Error() string {
+	return e.Op + " " + e.Old + " " + e.New + ": " + e.Err.Error()
 }
 
 // Link creates a hard link.
-func Link(oldname, newname string) Error {
+func Link(oldname, newname string) error {
 	e := syscall.Link(oldname, newname)
 	if iserror(e) {
 		return &LinkError{"link", oldname, newname, Errno(e)}
@@ -79,7 +79,7 @@ func Link(oldname, newname string) Error {
 }
 
 // Symlink creates a symbolic link.
-func Symlink(oldname, newname string) Error {
+func Symlink(oldname, newname string) error {
 	e := syscall.Symlink(oldname, newname)
 	if iserror(e) {
 		return &LinkError{"symlink", oldname, newname, Errno(e)}
@@ -88,8 +88,8 @@ func Symlink(oldname, newname string) Error {
 }
 
 // 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) {
+// 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)
@@ -105,7 +105,7 @@ func Readlink(name string) (string, Error) {
 }
 
 // Rename renames a file.
-func Rename(oldname, newname string) Error {
+func Rename(oldname, newname string) error {
 	e := syscall.Rename(oldname, newname)
 	if iserror(e) {
 		return &LinkError{"rename", oldname, newname, Errno(e)}
@@ -115,7 +115,7 @@ func Rename(oldname, newname string) Error {
 
 // 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 {
+func Chmod(name string, mode uint32) error {
 	if e := syscall.Chmod(name, mode); iserror(e) {
 		return &PathError{"chmod", name, Errno(e)}
 	}
@@ -123,7 +123,7 @@ func Chmod(name string, mode uint32) Error {
 }
 
 // Chmod changes the mode of the file to mode.
-func (f *File) Chmod(mode uint32) Error {
+func (f *File) Chmod(mode uint32) error {
 	if e := syscall.Fchmod(f.fd, mode); iserror(e) {
 		return &PathError{"chmod", f.name, Errno(e)}
 	}
@@ -132,7 +132,7 @@ func (f *File) Chmod(mode uint32) Error {
 
 // 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 {
+func Chown(name string, uid, gid int) error {
 	if e := syscall.Chown(name, uid, gid); iserror(e) {
 		return &PathError{"chown", name, Errno(e)}
 	}
@@ -141,7 +141,7 @@ func Chown(name string, uid, gid int) Error {
 
 // 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 {
+func Lchown(name string, uid, gid int) error {
 	if e := syscall.Lchown(name, uid, gid); iserror(e) {
 		return &PathError{"lchown", name, Errno(e)}
 	}
@@ -149,7 +149,7 @@ func Lchown(name string, uid, gid int) Error {
 }
 
 // Chown changes the numeric uid and gid of the named file.
-func (f *File) Chown(uid, gid int) Error {
+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)}
 	}
@@ -158,7 +158,7 @@ func (f *File) Chown(uid, gid int) Error {
 
 // Truncate changes the size of the file.
 // It does not change the I/O offset.
-func (f *File) Truncate(size int64) Error {
+func (f *File) Truncate(size int64) error {
 	if e := syscall.Ftruncate(f.fd, size); iserror(e) {
 		return &PathError{"truncate", f.name, Errno(e)}
 	}
@@ -168,7 +168,7 @@ func (f *File) Truncate(size int64) Error {
 // 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) {
+func (file *File) Sync() (err error) {
 	if file == nil {
 		return EINVAL
 	}
@@ -184,7 +184,7 @@ func (file *File) Sync() (err Error) {
 // 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 {
+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)

src/pkg/os/file_unix.go

@@ -52,8 +52,8 @@ const DevNull = "/dev/null"
 // or Create instead.  It opens the named file with specified flag
 // (O_RDONLY etc.) and perm, (0666 etc.) if applicable.  If successful,
 // methods on the returned File can be used for I/O.
-// It returns the File and an Error, if any.
-func OpenFile(name string, flag int, perm uint32) (file *File, err Error) {
+// It returns the File and an error, if any.
+func OpenFile(name string, flag int, perm uint32) (file *File, err error) {
 	r, e := syscall.Open(name, flag|syscall.O_CLOEXEC, perm)
 	if e != 0 {
 		return nil, &PathError{"open", name, Errno(e)}
@@ -69,12 +69,12 @@ func OpenFile(name string, flag int, perm uint32) (file *File, err Error) {
 }
 
 // Close closes the File, rendering it unusable for I/O.
-// It returns an Error, if any.
-func (file *File) Close() Error {
+// It returns an error, if any.
+func (file *File) Close() error {
 	if file == nil || file.fd < 0 {
 		return EINVAL
 	}
-	var err Error
+	var err error
 	if e := syscall.Close(file.fd); e != 0 {
 		err = &PathError{"close", file.name, Errno(e)}
 	}
@@ -87,7 +87,7 @@ func (file *File) Close() Error {
 
 // Stat returns the FileInfo structure describing file.
 // It returns the FileInfo and an error, if any.
-func (file *File) Stat() (fi *FileInfo, err Error) {
+func (file *File) Stat() (fi *FileInfo, err error) {
 	var stat syscall.Stat_t
 	e := syscall.Fstat(file.fd, &stat)
 	if e != 0 {
@@ -101,7 +101,7 @@ func (file *File) Stat() (fi *FileInfo, err Error) {
 // 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) {
+func Stat(name string) (fi *FileInfo, err error) {
 	var lstat, stat syscall.Stat_t
 	e := syscall.Lstat(name, &lstat)
 	if iserror(e) {
@@ -120,7 +120,7 @@ func Stat(name string) (fi *FileInfo, err Error) {
 // 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) {
+func Lstat(name string) (fi *FileInfo, err error) {
 	var stat syscall.Stat_t
 	e := syscall.Lstat(name, &stat)
 	if iserror(e) {
@@ -144,7 +144,7 @@ func Lstat(name string) (fi *FileInfo, err Error) {
 // nil os.Error. If it encounters an error before the end of the
 // directory, Readdir returns the FileInfo read until that point
 // and a non-nil error.
-func (file *File) Readdir(n int) (fi []FileInfo, err Error) {
+func (file *File) Readdir(n int) (fi []FileInfo, err error) {
 	dirname := file.name
 	if dirname == "" {
 		dirname = "."
@@ -198,7 +198,7 @@ func (f *File) seek(offset int64, whence int) (ret int64, err int) {
 
 // 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 {
+func Truncate(name string, size int64) error {
 	if e := syscall.Truncate(name, size); e != 0 {
 		return &PathError{"truncate", name, Errno(e)}
 	}
@@ -224,8 +224,8 @@ func basename(name string) string {
 }
 
 // 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) {
+// 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.

src/pkg/os/file_windows.go

@@ -5,6 +5,7 @@
 package os
 
 import (
+	"io"
 	"runtime"
 	"sync"
 	"syscall"
@@ -47,7 +48,7 @@ const DevNull = "NUL"
 
 func (file *File) isdir() bool { return file != nil && file.dirinfo != nil }
 
-func openFile(name string, flag int, perm uint32) (file *File, err Error) {
+func openFile(name string, flag int, perm uint32) (file *File, err error) {
 	r, e := syscall.Open(name, flag|syscall.O_CLOEXEC, perm)
 	if e != 0 {
 		return nil, &PathError{"open", name, Errno(e)}
@@ -62,7 +63,7 @@ func openFile(name string, flag int, perm uint32) (file *File, err Error) {
 	return NewFile(r, name), nil
 }
 
-func openDir(name string) (file *File, err Error) {
+func openDir(name string) (file *File, err error) {
 	d := new(dirInfo)
 	r, e := syscall.FindFirstFile(syscall.StringToUTF16Ptr(name+`\*`), &d.data)
 	if e != 0 {
@@ -77,8 +78,8 @@ func openDir(name string) (file *File, err Error) {
 // or Create instead.  It opens the named file with specified flag
 // (O_RDONLY etc.) and perm, (0666 etc.) if applicable.  If successful,
 // methods on the returned File can be used for I/O.
-// It returns the File and an Error, if any.
-func OpenFile(name string, flag int, perm uint32) (file *File, err Error) {
+// It returns the File and an error, if any.
+func OpenFile(name string, flag int, perm uint32) (file *File, err error) {
 	// TODO(brainman): not sure about my logic of assuming it is dir first, then fall back to file
 	r, e := openDir(name)
 	if e == nil {
@@ -96,8 +97,8 @@ func OpenFile(name string, flag int, perm uint32) (file *File, err Error) {
 }
 
 // Close closes the File, rendering it unusable for I/O.
-// It returns an Error, if any.
-func (file *File) Close() Error {
+// It returns an error, if any.
+func (file *File) Close() error {
 	if file == nil || file.fd < 0 {
 		return EINVAL
 	}
@@ -107,7 +108,7 @@ func (file *File) Close() Error {
 	} else {
 		e = syscall.CloseHandle(syscall.Handle(file.fd))
 	}
-	var err Error
+	var err error
 	if e != 0 {
 		err = &PathError{"close", file.name, Errno(e)}
 	}
@@ -133,7 +134,7 @@ func (file *File) Close() Error {
 // nil os.Error. If it encounters an error before the end of the
 // directory, Readdir returns the FileInfo read until that point
 // and a non-nil error.
-func (file *File) Readdir(n int) (fi []FileInfo, err Error) {
+func (file *File) Readdir(n int) (fi []FileInfo, err error) {
 	if file == nil || file.fd < 0 {
 		return nil, EINVAL
 	}
@@ -173,7 +174,7 @@ func (file *File) Readdir(n int) (fi []FileInfo, err Error) {
 		fi = append(fi, f)
 	}
 	if !wantAll && len(fi) == 0 {
-		return fi, EOF
+		return fi, io.EOF
 	}
 	return fi, nil
 }
@@ -251,7 +252,7 @@ func (f *File) seek(offset int64, whence int) (ret int64, err int) {
 
 // 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 {
+func Truncate(name string, size int64) error {
 	f, e := OpenFile(name, O_WRONLY|O_CREATE, 0666)
 	if e != nil {
 		return e
@@ -265,8 +266,8 @@ func Truncate(name string, size int64) Error {
 }
 
 // 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) {
+// It returns the files and an error, if any.
+func Pipe() (r *File, w *File, err error) {
 	var p [2]syscall.Handle
 
 	// See ../syscall/exec.go for description of lock.

src/pkg/os/getwd.go

@@ -12,7 +12,7 @@ import (
 // current directory.  If the current directory can be
 // reached via multiple paths (due to symbolic links),
 // Getwd may return any one of them.
-func Getwd() (string, Error) {
+func Getwd() (string, error) {
 	// If the operating system provides a Getwd call, use it.
 	if syscall.ImplementsGetwd {
 		s, e := syscall.Getwd()

src/pkg/os/os_test.go

@@ -77,7 +77,7 @@ func size(name string, t *testing.T) int64 {
 	for {
 		n, e := file.Read(buf[0:])
 		len += n
-		if e == EOF {
+		if e == io.EOF {
 			break
 		}
 		if e != nil {
@@ -257,7 +257,7 @@ func smallReaddirnames(file *File, length int, t *testing.T) []string {
 	count := 0
 	for {
 		d, err := file.Readdirnames(1)
-		if err == EOF {
+		if err == io.EOF {
 			break
 		}
 		if err != nil {
@@ -328,14 +328,14 @@ func TestReaddirNValues(t *testing.T) {
 
 	var d *File
 	openDir := func() {
-		var err Error
+		var err error
 		d, err = Open(dir)
 		if err != nil {
 			t.Fatalf("Open directory: %v", err)
 		}
 	}
 
-	readDirExpect := func(n, want int, wantErr Error) {
+	readDirExpect := func(n, want int, wantErr error) {
 		fi, err := d.Readdir(n)
 		if err != wantErr {
 			t.Fatalf("Readdir of %d got error %v, want %v", n, err, wantErr)
@@ -345,7 +345,7 @@ func TestReaddirNValues(t *testing.T) {
 		}
 	}
 
-	readDirNamesExpect := func(n, want int, wantErr Error) {
+	readDirNamesExpect := func(n, want int, wantErr error) {
 		fi, err := d.Readdirnames(n)
 		if err != wantErr {
 			t.Fatalf("Readdirnames of %d got error %v, want %v", n, err, wantErr)
@@ -355,7 +355,7 @@ func TestReaddirNValues(t *testing.T) {
 		}
 	}
 
-	for _, fn := range []func(int, int, Error){readDirExpect, readDirNamesExpect} {
+	for _, fn := range []func(int, int, error){readDirExpect, readDirNamesExpect} {
 		// Test the slurp case
 		openDir()
 		fn(0, 105, nil)
@@ -374,7 +374,7 @@ func TestReaddirNValues(t *testing.T) {
 		fn(1, 1, nil)
 		fn(2, 2, nil)
 		fn(105, 102, nil) // and tests buffer >100 case
-		fn(3, 0, EOF)
+		fn(3, 0, io.EOF)
 		d.Close()
 	}
 }
@@ -841,7 +841,7 @@ func TestSeek(t *testing.T) {
 	for i, tt := range tests {
 		off, err := f.Seek(tt.in, tt.whence)
 		if off != tt.out || err != nil {
-			if e, ok := err.(*PathError); ok && e.Error == EINVAL && tt.out > 1<<32 {
+			if e, ok := err.(*PathError); ok && e.Err == EINVAL && tt.out > 1<<32 {
 				// Reiserfs rejects the big seeks.
 				// http://code.google.com/p/go/issues/detail?id=91
 				break
@@ -854,7 +854,7 @@ func TestSeek(t *testing.T) {
 type openErrorTest struct {
 	path  string
 	mode  int
-	error Error
+	error error
 }
 
 var openErrorTests = []openErrorTest{
@@ -887,15 +887,15 @@ func TestOpenError(t *testing.T) {
 		if !ok {
 			t.Errorf("Open(%q, %d) returns error of %T type; want *os.PathError", tt.path, tt.mode, err)
 		}
-		if perr.Error != tt.error {
+		if perr.Err != tt.error {
 			if syscall.OS == "plan9" {
-				syscallErrStr := perr.Error.String()
-				expectedErrStr := strings.Replace(tt.error.String(), "file ", "", 1)
+				syscallErrStr := perr.Err.Error()
+				expectedErrStr := strings.Replace(tt.error.Error(), "file ", "", 1)
 				if !strings.HasSuffix(syscallErrStr, expectedErrStr) {
 					t.Errorf("Open(%q, %d) = _, %q; want suffix %q", tt.path, tt.mode, syscallErrStr, expectedErrStr)
 				}
 			} else {
-				t.Errorf("Open(%q, %d) = _, %q; want %q", tt.path, tt.mode, perr.Error.String(), tt.error.String())
+				t.Errorf("Open(%q, %d) = _, %q; want %q", tt.path, tt.mode, perr.Err.Error(), tt.error.Error())
 			}
 		}
 	}

src/pkg/os/path.go

@@ -4,6 +4,8 @@
 
 package os
 
+import "io"
+
 // MkdirAll creates a directory named path,
 // along with any necessary parents, and returns nil,
 // or else returns an error.
@@ -11,7 +13,7 @@ package os
 // directories that MkdirAll creates.
 // If path is already a directory, MkdirAll does nothing
 // and returns nil.
-func MkdirAll(path string, perm uint32) Error {
+func MkdirAll(path string, perm uint32) error {
 	// If path exists, stop with success or error.
 	dir, err := Stat(path)
 	if err == nil {
@@ -58,7 +60,7 @@ func MkdirAll(path string, perm uint32) Error {
 // It removes everything it can but returns the first error
 // it encounters.  If the path does not exist, RemoveAll
 // returns nil (no error).
-func RemoveAll(path string) Error {
+func RemoveAll(path string) error {
 	// Simple case: if Remove works, we're done.
 	err := Remove(path)
 	if err == nil {
@@ -68,7 +70,7 @@ func RemoveAll(path string) Error {
 	// Otherwise, is this a directory we need to recurse into?
 	dir, serr := Lstat(path)
 	if serr != nil {
-		if serr, ok := serr.(*PathError); ok && (serr.Error == ENOENT || serr.Error == ENOTDIR) {
+		if serr, ok := serr.(*PathError); ok && (serr.Err == ENOENT || serr.Err == ENOTDIR) {
 			return nil
 		}
 		return serr
@@ -94,7 +96,7 @@ func RemoveAll(path string) Error {
 				err = err1
 			}
 		}
-		if err1 == EOF {
+		if err1 == io.EOF {
 			break
 		}
 		// If Readdirnames returned an error, use it.

src/pkg/os/path_test.go

@@ -199,7 +199,7 @@ func TestMkdirAllAtSlash(t *testing.T) {
 	if err != nil {
 		pathErr, ok := err.(*PathError)
 		// common for users not to be able to write to /
-		if ok && pathErr.Error == EACCES {
+		if ok && pathErr.Err == EACCES {
 			return
 		}
 		t.Fatalf(`MkdirAll "/_go_os_test/dir": %v`, err)

src/pkg/os/proc.go

@@ -24,7 +24,7 @@ func Getgid() int { return syscall.Getgid() }
 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) {
+func Getgroups() ([]int, error) {
 	gids, e := syscall.Getgroups()
 	return gids, NewSyscallError("getgroups", e)
 }

src/pkg/os/stat_plan9.go

@@ -26,7 +26,7 @@ func fileInfoFromStat(fi *FileInfo, d *Dir) *FileInfo {
 }
 
 // arg is an open *File or a path string. 
-func dirstat(arg interface{}) (d *Dir, err Error) {
+func dirstat(arg interface{}) (d *Dir, err error) {
 	var name string
 	nd := syscall.STATFIXLEN + 16*4
 
@@ -70,7 +70,7 @@ func dirstat(arg interface{}) (d *Dir, err Error) {
 }
 
 // Stat returns a FileInfo structure describing the named file and an error, if any.
-func Stat(name string) (fi *FileInfo, err Error) {
+func Stat(name string) (fi *FileInfo, err error) {
 	d, err := dirstat(name)
 	if iserror(err) {
 		return nil, err
@@ -81,7 +81,7 @@ func Stat(name string) (fi *FileInfo, err Error) {
 // 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) {
+func Lstat(name string) (fi *FileInfo, err error) {
 	d, err := dirstat(name)
 	if iserror(err) {
 		return nil, err

src/pkg/os/stat_windows.go

@@ -11,7 +11,7 @@ import (
 
 // Stat returns the FileInfo structure describing file.
 // It returns the FileInfo and an error, if any.
-func (file *File) Stat() (fi *FileInfo, err Error) {
+func (file *File) Stat() (fi *FileInfo, err error) {
 	if file == nil || file.fd < 0 {
 		return nil, EINVAL
 	}
@@ -32,7 +32,7 @@ func (file *File) Stat() (fi *FileInfo, err Error) {
 // 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) {
+func Stat(name string) (fi *FileInfo, err error) {
 	if len(name) == 0 {
 		return nil, &PathError{"Stat", name, Errno(syscall.ERROR_PATH_NOT_FOUND)}
 	}
@@ -47,7 +47,7 @@ func Stat(name string) (fi *FileInfo, err Error) {
 // 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) {
+func Lstat(name string) (fi *FileInfo, err error) {
 	// No links on Windows
 	return Stat(name)
 }

src/pkg/os/sys_bsd.go

@@ -11,7 +11,7 @@ package os
 
 import "syscall"
 
-func Hostname() (name string, err Error) {
+func Hostname() (name string, err error) {
 	var errno int
 	name, errno = syscall.Sysctl("kern.hostname")
 	if errno != 0 {

src/pkg/os/sys_linux.go

@@ -7,7 +7,7 @@
 package os
 
 // Hostname returns the host name reported by the kernel.
-func Hostname() (name string, err Error) {
+func Hostname() (name string, err error) {
 	f, err := Open("/proc/sys/kernel/hostname")
 	if err != nil {
 		return "", err

src/pkg/os/sys_plan9.go

@@ -6,7 +6,7 @@
 
 package os
 
-func Hostname() (name string, err Error) {
+func Hostname() (name string, err error) {
 	f, err := Open("#c/sysname")
 	if err != nil {
 		return "", err

src/pkg/os/sys_windows.go

@@ -6,7 +6,7 @@ package os
 
 import "syscall"
 
-func Hostname() (name string, err Error) {
+func Hostname() (name string, err error) {
 	s, e := syscall.ComputerName()
 	if e != 0 {
 		return "", NewSyscallError("ComputerName", e)

src/pkg/os/time.go

@@ -7,10 +7,10 @@ package os
 import "syscall"
 
 // Time returns the current time, in whole seconds and
-// fractional nanoseconds, plus an Error if any. The current
+// fractional nanoseconds, plus an error if any. The current
 // time is thus 1e9*sec+nsec, in nanoseconds.  The zero of
 // time is the Unix epoch.
-func Time() (sec int64, nsec int64, err Error) {
+func Time() (sec int64, nsec int64, err error) {
 	var tv syscall.Timeval
 	if e := syscall.Gettimeofday(&tv); iserror(e) {
 		return 0, 0, NewSyscallError("gettimeofday", e)