src/pkg/[a-m]*: gofix -r error -force=error

R=golang-dev, iant
CC=golang-dev
https://golang.org/cl/5322051
diff --git a/src/pkg/bufio/bufio.go b/src/pkg/bufio/bufio.go
index 3a4e0ed..f4ed91b 100644
--- a/src/pkg/bufio/bufio.go
+++ b/src/pkg/bufio/bufio.go
@@ -10,7 +10,6 @@
 import (
 	"bytes"
 	"io"
-	"os"
 	"strconv"
 	"utf8"
 )
@@ -24,20 +23,20 @@
 	ErrorString string
 }
 
-func (err *Error) String() string { return err.ErrorString }
+func (err *Error) Error() string { return err.ErrorString }
 
 var (
-	ErrInvalidUnreadByte os.Error = &Error{"bufio: invalid use of UnreadByte"}
-	ErrInvalidUnreadRune os.Error = &Error{"bufio: invalid use of UnreadRune"}
-	ErrBufferFull        os.Error = &Error{"bufio: buffer full"}
-	ErrNegativeCount     os.Error = &Error{"bufio: negative count"}
-	errInternal          os.Error = &Error{"bufio: internal error"}
+	ErrInvalidUnreadByte error = &Error{"bufio: invalid use of UnreadByte"}
+	ErrInvalidUnreadRune error = &Error{"bufio: invalid use of UnreadRune"}
+	ErrBufferFull        error = &Error{"bufio: buffer full"}
+	ErrNegativeCount     error = &Error{"bufio: negative count"}
+	errInternal          error = &Error{"bufio: internal error"}
 )
 
 // BufSizeError is the error representing an invalid buffer size.
 type BufSizeError int
 
-func (b BufSizeError) String() string {
+func (b BufSizeError) Error() string {
 	return "bufio: bad buffer size " + strconv.Itoa(int(b))
 }
 
@@ -48,7 +47,7 @@
 	buf          []byte
 	rd           io.Reader
 	r, w         int
-	err          os.Error
+	err          error
 	lastByte     int
 	lastRuneSize int
 }
@@ -57,7 +56,7 @@
 // which must be greater than one.  If the argument io.Reader is already a
 // Reader with large enough size, it returns the underlying Reader.
 // It returns the Reader and any error.
-func NewReaderSize(rd io.Reader, size int) (*Reader, os.Error) {
+func NewReaderSize(rd io.Reader, size int) (*Reader, error) {
 	if size <= 1 {
 		return nil, BufSizeError(size)
 	}
@@ -101,7 +100,7 @@
 	}
 }
 
-func (b *Reader) readErr() os.Error {
+func (b *Reader) readErr() error {
 	err := b.err
 	b.err = nil
 	return err
@@ -111,7 +110,7 @@
 // being valid at the next read call. If Peek returns fewer than n bytes, it
 // also returns an error explaining why the read is short. The error is
 // ErrBufferFull if n is larger than b's buffer size.
-func (b *Reader) Peek(n int) ([]byte, os.Error) {
+func (b *Reader) Peek(n int) ([]byte, error) {
 	if n < 0 {
 		return nil, ErrNegativeCount
 	}
@@ -137,7 +136,7 @@
 // It calls Read at most once on the underlying Reader,
 // hence n may be less than len(p).
 // At EOF, the count will be zero and err will be os.EOF.
-func (b *Reader) Read(p []byte) (n int, err os.Error) {
+func (b *Reader) Read(p []byte) (n int, err error) {
 	n = len(p)
 	if n == 0 {
 		return 0, b.readErr()
@@ -174,7 +173,7 @@
 
 // ReadByte reads and returns a single byte.
 // If no byte is available, returns an error.
-func (b *Reader) ReadByte() (c byte, err os.Error) {
+func (b *Reader) ReadByte() (c byte, err error) {
 	b.lastRuneSize = -1
 	for b.w == b.r {
 		if b.err != nil {
@@ -189,7 +188,7 @@
 }
 
 // UnreadByte unreads the last byte.  Only the most recently read byte can be unread.
-func (b *Reader) UnreadByte() os.Error {
+func (b *Reader) UnreadByte() error {
 	b.lastRuneSize = -1
 	if b.r == b.w && b.lastByte >= 0 {
 		b.w = 1
@@ -208,7 +207,7 @@
 
 // ReadRune reads a single UTF-8 encoded Unicode character and returns the
 // rune and its size in bytes.
-func (b *Reader) ReadRune() (r rune, size int, err os.Error) {
+func (b *Reader) ReadRune() (r rune, size int, err error) {
 	for b.r+utf8.UTFMax > b.w && !utf8.FullRune(b.buf[b.r:b.w]) && b.err == nil {
 		b.fill()
 	}
@@ -230,7 +229,7 @@
 // the buffer was not a ReadRune, UnreadRune returns an error.  (In this
 // regard it is stricter than UnreadByte, which will unread the last byte
 // from any read operation.)
-func (b *Reader) UnreadRune() os.Error {
+func (b *Reader) UnreadRune() error {
 	if b.lastRuneSize < 0 || b.r == 0 {
 		return ErrInvalidUnreadRune
 	}
@@ -253,7 +252,7 @@
 // by the next I/O operation, most clients should use
 // ReadBytes or ReadString instead.
 // ReadSlice returns err != nil if and only if line does not end in delim.
-func (b *Reader) ReadSlice(delim byte) (line []byte, err os.Error) {
+func (b *Reader) ReadSlice(delim byte) (line []byte, err error) {
 	// Look in buffer.
 	if i := bytes.IndexByte(b.buf[b.r:b.w], delim); i >= 0 {
 		line1 := b.buf[b.r : b.r+i+1]
@@ -295,7 +294,7 @@
 // of the line. The returned buffer is only valid until the next call to
 // ReadLine. ReadLine either returns a non-nil line or it returns an error,
 // never both.
-func (b *Reader) ReadLine() (line []byte, isPrefix bool, err os.Error) {
+func (b *Reader) ReadLine() (line []byte, isPrefix bool, err error) {
 	line, err = b.ReadSlice('\n')
 	if err == ErrBufferFull {
 		// Handle the case where "\r\n" straddles the buffer.
@@ -333,7 +332,7 @@
 // it returns the data read before the error and the error itself (often os.EOF).
 // ReadBytes returns err != nil if and only if the returned data does not end in
 // delim.
-func (b *Reader) ReadBytes(delim byte) (line []byte, err os.Error) {
+func (b *Reader) ReadBytes(delim byte) (line []byte, err error) {
 	// Use ReadSlice to look for array,
 	// accumulating full buffers.
 	var frag []byte
@@ -341,7 +340,7 @@
 	err = nil
 
 	for {
-		var e os.Error
+		var e error
 		frag, e = b.ReadSlice(delim)
 		if e == nil { // got final fragment
 			break
@@ -380,7 +379,7 @@
 // it returns the data read before the error and the error itself (often os.EOF).
 // ReadString returns err != nil if and only if the returned data does not end in
 // delim.
-func (b *Reader) ReadString(delim byte) (line string, err os.Error) {
+func (b *Reader) ReadString(delim byte) (line string, err error) {
 	bytes, e := b.ReadBytes(delim)
 	return string(bytes), e
 }
@@ -389,7 +388,7 @@
 
 // Writer implements buffering for an io.Writer object.
 type Writer struct {
-	err os.Error
+	err error
 	buf []byte
 	n   int
 	wr  io.Writer
@@ -399,7 +398,7 @@
 // which must be greater than zero. If the argument io.Writer is already a
 // Writer with large enough size, it returns the underlying Writer.
 // It returns the Writer and any error.
-func NewWriterSize(wr io.Writer, size int) (*Writer, os.Error) {
+func NewWriterSize(wr io.Writer, size int) (*Writer, error) {
 	if size <= 0 {
 		return nil, BufSizeError(size)
 	}
@@ -425,7 +424,7 @@
 }
 
 // Flush writes any buffered data to the underlying io.Writer.
-func (b *Writer) Flush() os.Error {
+func (b *Writer) Flush() error {
 	if b.err != nil {
 		return b.err
 	}
@@ -458,7 +457,7 @@
 // It returns the number of bytes written.
 // If nn < len(p), it also returns an error explaining
 // why the write is short.
-func (b *Writer) Write(p []byte) (nn int, err os.Error) {
+func (b *Writer) Write(p []byte) (nn int, err error) {
 	for len(p) > b.Available() && b.err == nil {
 		var n int
 		if b.Buffered() == 0 {
@@ -483,7 +482,7 @@
 }
 
 // WriteByte writes a single byte.
-func (b *Writer) WriteByte(c byte) os.Error {
+func (b *Writer) WriteByte(c byte) error {
 	if b.err != nil {
 		return b.err
 	}
@@ -497,7 +496,7 @@
 
 // WriteRune writes a single Unicode code point, returning
 // the number of bytes written and any error.
-func (b *Writer) WriteRune(r rune) (size int, err os.Error) {
+func (b *Writer) WriteRune(r rune) (size int, err error) {
 	if r < utf8.RuneSelf {
 		err = b.WriteByte(byte(r))
 		if err != nil {
@@ -528,7 +527,7 @@
 // It returns the number of bytes written.
 // If the count is less than len(s), it also returns an error explaining
 // why the write is short.
-func (b *Writer) WriteString(s string) (int, os.Error) {
+func (b *Writer) WriteString(s string) (int, error) {
 	nn := 0
 	for len(s) > b.Available() && b.err == nil {
 		n := copy(b.buf[b.n:], s)