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io: use error, add EOF, avoid os

Browse Source 
R=r, r
CC=golang-dev
https://golang.org/cl/5311068
This commit is contained in:
Russ Cox 2011-11-01 21:48:52 -04:00
parent c14f71c788
commit c06cf03f0b
6 changed files with 110 additions and 107 deletions
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102
src/pkg/io/io.go
View File

@ -8,25 +8,30 @@
// abstract the functionality, plus some other related primitives. // abstract the functionality, plus some other related primitives.
package io package io
import "os"
// Error represents an unexpected I/O behavior. // Error represents an unexpected I/O behavior.
type Error struct { type Error struct {
ErrorString string ErrorString string
} }
func (err *Error) String() string { return err.ErrorString } func (err *Error) Error() string { return err.ErrorString }
// ErrShortWrite means that a write accepted fewer bytes than requested // ErrShortWrite means that a write accepted fewer bytes than requested
// but failed to return an explicit error. // but failed to return an explicit error.
var ErrShortWrite os.Error = &Error{"short write"} var ErrShortWrite error = &Error{"short write"}
// ErrShortBuffer means that a read required a longer buffer than was provided. // ErrShortBuffer means that a read required a longer buffer than was provided.
var ErrShortBuffer os.Error = &Error{"short buffer"} var ErrShortBuffer error = &Error{"short buffer"}
// ErrUnexpectedEOF means that os.EOF was encountered in the // 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 ErrUnexpectedEOF or some other error
// giving more detail.
var EOF error = &Error{"EOF"}
// ErrUnexpectedEOF means that EOF was encountered in the
// middle of reading a fixed-size block or data structure. // middle of reading a fixed-size block or data structure.
var ErrUnexpectedEOF os.Error = &Error{"unexpected EOF"} var ErrUnexpectedEOF error = &Error{"unexpected EOF"}
// Reader is the interface that wraps the basic Read method. // Reader is the interface that wraps the basic Read method.
// //
@ -42,15 +47,15 @@ var ErrUnexpectedEOF os.Error = &Error{"unexpected EOF"}
// or return the error (and n == 0) from a subsequent call. // or return the error (and n == 0) from a subsequent call.
// An instance of this general case is that a Reader returning // An instance of this general case is that a Reader returning
// a non-zero number of bytes at the end of the input stream may // a non-zero number of bytes at the end of the input stream may
// return either err == os.EOF or err == nil. The next Read should // return either err == EOF or err == nil. The next Read should
// return 0, os.EOF regardless. // return 0, EOF regardless.
// //
// Callers should always process the n > 0 bytes returned before // Callers should always process the n > 0 bytes returned before
// considering the error err. Doing so correctly handles I/O errors // considering the error err. Doing so correctly handles I/O errors
// that happen after reading some bytes and also both of the // that happen after reading some bytes and also both of the
// allowed EOF behaviors. // allowed EOF behaviors.
type Reader interface { type Reader interface {
Read(p []byte) (n int, err os.Error) Read(p []byte) (n int, err error)
} }
// Writer is the interface that wraps the basic Write method. // Writer is the interface that wraps the basic Write method.
@ -60,12 +65,12 @@ type Reader interface {
// and any error encountered that caused the write to stop early. // and any error encountered that caused the write to stop early.
// Write must return a non-nil error if it returns n < len(p). // Write must return a non-nil error if it returns n < len(p).
type Writer interface { type Writer interface {
Write(p []byte) (n int, err os.Error) Write(p []byte) (n int, err error)
} }
// Closer is the interface that wraps the basic Close method. // Closer is the interface that wraps the basic Close method.
type Closer interface { type Closer interface {
Close() os.Error Close() error
} }
// Seeker is the interface that wraps the basic Seek method. // Seeker is the interface that wraps the basic Seek method.
@ -76,7 +81,7 @@ type Closer interface {
// relative to the end. Seek returns the new offset and an Error, if // relative to the end. Seek returns the new offset and an Error, if
// any. // any.
type Seeker interface { type Seeker interface {
Seek(offset int64, whence int) (ret int64, err os.Error) Seek(offset int64, whence int) (ret int64, err error)
} }
// ReadWriter is the interface that groups the basic Read and Write methods. // ReadWriter is the interface that groups the basic Read and Write methods.
@ -125,12 +130,12 @@ type ReadWriteSeeker interface {
// ReaderFrom is the interface that wraps the ReadFrom method. // ReaderFrom is the interface that wraps the ReadFrom method.
type ReaderFrom interface { type ReaderFrom interface {
ReadFrom(r Reader) (n int64, err os.Error) ReadFrom(r Reader) (n int64, err error)
} }
// WriterTo is the interface that wraps the WriteTo method. // WriterTo is the interface that wraps the WriteTo method.
type WriterTo interface { type WriterTo interface {
WriteTo(w Writer) (n int64, err os.Error) WriteTo(w Writer) (n int64, err error)
} }
// ReaderAt is the interface that wraps the basic ReadAt method. // ReaderAt is the interface that wraps the basic ReadAt method.
@ -149,13 +154,13 @@ type WriterTo interface {
// In this respect ReadAt is different from Read. // In this respect ReadAt is different from Read.
// //
// If the n = len(p) bytes returned by ReadAt are at the end of the // If the n = len(p) bytes returned by ReadAt are at the end of the
// input source, ReadAt may return either err == os.EOF or err == nil. // input source, ReadAt may return either err == EOF or err == nil.
// //
// If ReadAt is reading from an input source with a seek offset, // If ReadAt is reading from an input source with a seek offset,
// ReadAt should not affect nor be affected by the underlying // ReadAt should not affect nor be affected by the underlying
// seek offset. // seek offset.
type ReaderAt interface { type ReaderAt interface {
ReadAt(p []byte, off int64) (n int, err os.Error) ReadAt(p []byte, off int64) (n int, err error)
} }
// WriterAt is the interface that wraps the basic WriteAt method. // WriterAt is the interface that wraps the basic WriteAt method.
@ -165,7 +170,7 @@ type ReaderAt interface {
// and any error encountered that caused the write to stop early. // and any error encountered that caused the write to stop early.
// WriteAt must return a non-nil error if it returns n < len(p). // WriteAt must return a non-nil error if it returns n < len(p).
type WriterAt interface { type WriterAt interface {
WriteAt(p []byte, off int64) (n int, err os.Error) WriteAt(p []byte, off int64) (n int, err error)
} }
// ByteReader is the interface that wraps the ReadByte method. // ByteReader is the interface that wraps the ReadByte method.
@ -173,7 +178,7 @@ type WriterAt interface {
// ReadByte reads and returns the next byte from the input. // ReadByte reads and returns the next byte from the input.
// If no byte is available, err will be set. // If no byte is available, err will be set.
type ByteReader interface { type ByteReader interface {
ReadByte() (c byte, err os.Error) ReadByte() (c byte, err error)
} }
// ByteScanner is the interface that adds the UnreadByte method to the // ByteScanner is the interface that adds the UnreadByte method to the
@ -185,7 +190,7 @@ type ByteReader interface {
// call to ReadByte. // call to ReadByte.
type ByteScanner interface { type ByteScanner interface {
ByteReader ByteReader
UnreadByte() os.Error UnreadByte() error
} }
// RuneReader is the interface that wraps the ReadRune method. // RuneReader is the interface that wraps the ReadRune method.
@ -194,7 +199,7 @@ type ByteScanner interface {
// and returns the rune and its size in bytes. If no character is // and returns the rune and its size in bytes. If no character is
// available, err will be set. // available, err will be set.
type RuneReader interface { type RuneReader interface {
ReadRune() (r rune, size int, err os.Error) ReadRune() (r rune, size int, err error)
} }
// RuneScanner is the interface that adds the UnreadRune method to the // RuneScanner is the interface that adds the UnreadRune method to the
@ -206,16 +211,16 @@ type RuneReader interface {
// call to ReadRune. // call to ReadRune.
type RuneScanner interface { type RuneScanner interface {
RuneReader RuneReader
UnreadRune() os.Error UnreadRune() error
} }
// stringWriter is the interface that wraps the WriteString method. // stringWriter is the interface that wraps the WriteString method.
type stringWriter interface { type stringWriter interface {
WriteString(s string) (n int, err os.Error) WriteString(s string) (n int, err error)
} }
// WriteString writes the contents of the string s to w, which accepts an array of bytes. // WriteString writes the contents of the string s to w, which accepts an array of bytes.
func WriteString(w Writer, s string) (n int, err os.Error) { func WriteString(w Writer, s string) (n int, err error) {
if sw, ok := w.(stringWriter); ok { if sw, ok := w.(stringWriter); ok {
return sw.WriteString(s) return sw.WriteString(s)
} }
@ -224,11 +229,11 @@ func WriteString(w Writer, s string) (n int, err os.Error) {
// ReadAtLeast reads from r into buf until it has read at least min bytes. // ReadAtLeast reads from r into buf until it has read at least min bytes.
// It returns the number of bytes copied and an error if fewer bytes were read. // It returns the number of bytes copied and an error if fewer bytes were read.
// The error is os.EOF only if no bytes were read. // The error is EOF only if no bytes were read.
// If an EOF happens after reading fewer than min bytes, // If an EOF happens after reading fewer than min bytes,
// ReadAtLeast returns ErrUnexpectedEOF. // ReadAtLeast returns ErrUnexpectedEOF.
// If min is greater than the length of buf, ReadAtLeast returns ErrShortBuffer. // If min is greater than the length of buf, ReadAtLeast returns ErrShortBuffer.
func ReadAtLeast(r Reader, buf []byte, min int) (n int, err os.Error) { func ReadAtLeast(r Reader, buf []byte, min int) (n int, err error) {
if len(buf) < min { if len(buf) < min {
return 0, ErrShortBuffer return 0, ErrShortBuffer
} }
@ -237,7 +242,7 @@ func ReadAtLeast(r Reader, buf []byte, min int) (n int, err os.Error) {
nn, err = r.Read(buf[n:]) nn, err = r.Read(buf[n:])
n += nn n += nn
} }
if err == os.EOF { if err == EOF {
if n >= min { if n >= min {
err = nil err = nil
} else if n > 0 { } else if n > 0 {
@ -249,10 +254,10 @@ func ReadAtLeast(r Reader, buf []byte, min int) (n int, err os.Error) {
// ReadFull reads exactly len(buf) bytes from r into buf. // ReadFull reads exactly len(buf) bytes from r into buf.
// It returns the number of bytes copied and an error if fewer bytes were read. // It returns the number of bytes copied and an error if fewer bytes were read.
// The error is os.EOF only if no bytes were read. // The error is EOF only if no bytes were read.
// If an EOF happens after reading some but not all the bytes, // If an EOF happens after reading some but not all the bytes,
// ReadFull returns ErrUnexpectedEOF. // ReadFull returns ErrUnexpectedEOF.
func ReadFull(r Reader, buf []byte) (n int, err os.Error) { func ReadFull(r Reader, buf []byte) (n int, err error) {
return ReadAtLeast(r, buf, len(buf)) return ReadAtLeast(r, buf, len(buf))
} }
@ -260,18 +265,18 @@ func ReadFull(r Reader, buf []byte) (n int, err os.Error) {
// It returns the number of bytes copied and the earliest // It returns the number of bytes copied and the earliest
// error encountered while copying. Because Read can // error encountered while copying. Because Read can
// return the full amount requested as well as an error // return the full amount requested as well as an error
// (including os.EOF), so can CopyN. // (including EOF), so can CopyN.
// //
// If dst implements the ReaderFrom interface, // If dst implements the ReaderFrom interface,
// the copy is implemented by calling dst.ReadFrom(src). // the copy is implemented by calling dst.ReadFrom(src).
func CopyN(dst Writer, src Reader, n int64) (written int64, err os.Error) { func CopyN(dst Writer, src Reader, n int64) (written int64, err error) {
// If the writer has a ReadFrom method, use it to do the copy. // If the writer has a ReadFrom method, use it to do the copy.
// Avoids a buffer allocation and a copy. // Avoids a buffer allocation and a copy.
if rt, ok := dst.(ReaderFrom); ok { if rt, ok := dst.(ReaderFrom); ok {
written, err = rt.ReadFrom(LimitReader(src, n)) written, err = rt.ReadFrom(LimitReader(src, n))
if written < n && err == nil { if written < n && err == nil {
// rt stopped early; must have been EOF. // rt stopped early; must have been EOF.
err = os.EOF err = EOF
} }
return return
} }
@ -308,7 +313,7 @@ func CopyN(dst Writer, src Reader, n int64) (written int64, err os.Error) {
// on src or an error occurs. It returns the number of bytes // on src or an error occurs. It returns the number of bytes
// copied and the first error encountered while copying, if any. // copied and the first error encountered while copying, if any.
// //
// A successful Copy returns err == nil, not err == os.EOF. // A successful Copy returns err == nil, not err == EOF.
// Because Copy is defined to read from src until EOF, it does // Because Copy is defined to read from src until EOF, it does
// not treat an EOF from Read as an error to be reported. // not treat an EOF from Read as an error to be reported.
// //
@ -316,7 +321,7 @@ func CopyN(dst Writer, src Reader, n int64) (written int64, err os.Error) {
// the copy is implemented by calling dst.ReadFrom(src). // the copy is implemented by calling dst.ReadFrom(src).
// Otherwise, if src implements the WriterTo interface, // Otherwise, if src implements the WriterTo interface,
// the copy is implemented by calling src.WriteTo(dst). // the copy is implemented by calling src.WriteTo(dst).
func Copy(dst Writer, src Reader) (written int64, err os.Error) { func Copy(dst Writer, src Reader) (written int64, err error) {
// If the writer has a ReadFrom method, use it to do the copy. // If the writer has a ReadFrom method, use it to do the copy.
// Avoids an allocation and a copy. // Avoids an allocation and a copy.
if rt, ok := dst.(ReaderFrom); ok { if rt, ok := dst.(ReaderFrom); ok {
@ -343,7 +348,7 @@ func Copy(dst Writer, src Reader) (written int64, err os.Error) {
break break
} }
} }
if er == os.EOF { if er == EOF {
break break
} }
if er != nil { if er != nil {
@ -355,7 +360,7 @@ func Copy(dst Writer, src Reader) (written int64, err os.Error) {
} }
// LimitReader returns a Reader that reads from r // LimitReader returns a Reader that reads from r
// but stops with os.EOF after n bytes. // but stops with EOF after n bytes.
// The underlying implementation is a *LimitedReader. // The underlying implementation is a *LimitedReader.
func LimitReader(r Reader, n int64) Reader { return &LimitedReader{r, n} } func LimitReader(r Reader, n int64) Reader { return &LimitedReader{r, n} }
@ -367,9 +372,9 @@ type LimitedReader struct {
N int64 // max bytes remaining N int64 // max bytes remaining
} }
func (l *LimitedReader) Read(p []byte) (n int, err os.Error) { func (l *LimitedReader) Read(p []byte) (n int, err error) {
if l.N <= 0 { if l.N <= 0 {
return 0, os.EOF return 0, EOF
} }
if int64(len(p)) > l.N { if int64(len(p)) > l.N {
p = p[0:l.N] p = p[0:l.N]
@ -380,7 +385,7 @@ func (l *LimitedReader) Read(p []byte) (n int, err os.Error) {
} }
// NewSectionReader returns a SectionReader that reads from r // NewSectionReader returns a SectionReader that reads from r
// starting at offset off and stops with os.EOF after n bytes. // starting at offset off and stops with EOF after n bytes.
func NewSectionReader(r ReaderAt, off int64, n int64) *SectionReader { func NewSectionReader(r ReaderAt, off int64, n int64) *SectionReader {
return &SectionReader{r, off, off, off + n} return &SectionReader{r, off, off, off + n}
} }
@ -394,9 +399,9 @@ type SectionReader struct {
limit int64 limit int64
} }
func (s *SectionReader) Read(p []byte) (n int, err os.Error) { func (s *SectionReader) Read(p []byte) (n int, err error) {
if s.off >= s.limit { if s.off >= s.limit {
return 0, os.EOF return 0, EOF
} }
if max := s.limit - s.off; int64(len(p)) > max { if max := s.limit - s.off; int64(len(p)) > max {
p = p[0:max] p = p[0:max]
@ -406,10 +411,13 @@ func (s *SectionReader) Read(p []byte) (n int, err os.Error) {
return return
} }
func (s *SectionReader) Seek(offset int64, whence int) (ret int64, err os.Error) { var errWhence = &Error{"Seek: invalid whence"}
var errOffset = &Error{"Seek: invalid offset"}
func (s *SectionReader) Seek(offset int64, whence int) (ret int64, err error) {
switch whence { switch whence {
default: default:
return 0, os.EINVAL return 0, errWhence
case 0: case 0:
offset += s.base offset += s.base
case 1: case 1:
@ -418,15 +426,15 @@ func (s *SectionReader) Seek(offset int64, whence int) (ret int64, err os.Error)
offset += s.limit offset += s.limit
} }
if offset < s.base || offset > s.limit { if offset < s.base || offset > s.limit {
return 0, os.EINVAL return 0, errOffset
} }
s.off = offset s.off = offset
return offset - s.base, nil return offset - s.base, nil
} }
func (s *SectionReader) ReadAt(p []byte, off int64) (n int, err os.Error) { func (s *SectionReader) ReadAt(p []byte, off int64) (n int, err error) {
if off < 0 || off >= s.limit-s.base { if off < 0 || off >= s.limit-s.base {
return 0, os.EOF return 0, EOF
} }
off += s.base off += s.base
if max := s.limit - off; int64(len(p)) > max { if max := s.limit - off; int64(len(p)) > max {
@ -452,7 +460,7 @@ type teeReader struct {
w Writer w Writer
} }
func (t *teeReader) Read(p []byte) (n int, err os.Error) { func (t *teeReader) Read(p []byte) (n int, err error) {
n, err = t.r.Read(p) n, err = t.r.Read(p)
if n > 0 { if n > 0 {
if n, err := t.w.Write(p[:n]); err != nil { if n, err := t.w.Write(p[:n]); err != nil {

19
src/pkg/io/io_test.go
View File

@ -7,7 +7,6 @@ package io_test
import ( import (
"bytes" "bytes"
. "io" . "io"
"os"
"strings" "strings"
"testing" "testing"
) )
@ -85,7 +84,7 @@ type noReadFrom struct {
w Writer w Writer
} }
func (w *noReadFrom) Write(p []byte) (n int, err os.Error) { func (w *noReadFrom) Write(p []byte) (n int, err error) {
return w.w.Write(p) return w.w.Write(p)
} }
@ -101,7 +100,7 @@ func TestCopyNEOF(t *testing.T) {
} }
n, err = CopyN(&noReadFrom{b}, strings.NewReader("foo"), 4) n, err = CopyN(&noReadFrom{b}, strings.NewReader("foo"), 4)
if n != 3 || err != os.EOF { if n != 3 || err != EOF {
t.Errorf("CopyN(noReadFrom, foo, 4) = %d, %v; want 3, EOF", n, err) t.Errorf("CopyN(noReadFrom, foo, 4) = %d, %v; want 3, EOF", n, err)
} }
@ -111,7 +110,7 @@ func TestCopyNEOF(t *testing.T) {
} }
n, err = CopyN(b, strings.NewReader("foo"), 4) // b has read from n, err = CopyN(b, strings.NewReader("foo"), 4) // b has read from
if n != 3 || err != os.EOF { if n != 3 || err != EOF {
t.Errorf("CopyN(bytes.Buffer, foo, 4) = %d, %v; want 3, EOF", n, err) t.Errorf("CopyN(bytes.Buffer, foo, 4) = %d, %v; want 3, EOF", n, err)
} }
} }
@ -121,16 +120,16 @@ func TestReadAtLeast(t *testing.T) {
testReadAtLeast(t, &rb) testReadAtLeast(t, &rb)
} }
// A version of bytes.Buffer that returns n > 0, os.EOF on Read // A version of bytes.Buffer that returns n > 0, EOF on Read
// when the input is exhausted. // when the input is exhausted.
type dataAndEOFBuffer struct { type dataAndEOFBuffer struct {
bytes.Buffer bytes.Buffer
} }
func (r *dataAndEOFBuffer) Read(p []byte) (n int, err os.Error) { func (r *dataAndEOFBuffer) Read(p []byte) (n int, err error) {
n, err = r.Buffer.Read(p) n, err = r.Buffer.Read(p)
if n > 0 && r.Buffer.Len() == 0 && err == nil { if n > 0 && r.Buffer.Len() == 0 && err == nil {
err = os.EOF err = EOF
} }
return return
} }
@ -162,7 +161,7 @@ func testReadAtLeast(t *testing.T, rb ReadWriter) {
t.Errorf("expected to have read 2 bytes, got %v", n) t.Errorf("expected to have read 2 bytes, got %v", n)
} }
n, err = ReadAtLeast(rb, buf, 2) n, err = ReadAtLeast(rb, buf, 2)
if err != os.EOF { if err != EOF {
t.Errorf("expected EOF, got %v", err) t.Errorf("expected EOF, got %v", err)
} }
if n != 0 { if n != 0 {
@ -193,14 +192,14 @@ func TestTeeReader(t *testing.T) {
if !bytes.Equal(wb.Bytes(), src) { if !bytes.Equal(wb.Bytes(), src) {
t.Errorf("bytes written = %q want %q", wb.Bytes(), src) t.Errorf("bytes written = %q want %q", wb.Bytes(), src)
} }
if n, err := r.Read(dst); n != 0 || err != os.EOF { if n, err := r.Read(dst); n != 0 || err != EOF {
t.Errorf("r.Read at EOF = %d, %v want 0, EOF", n, err) t.Errorf("r.Read at EOF = %d, %v want 0, EOF", n, err)
} }
rb = bytes.NewBuffer(src) rb = bytes.NewBuffer(src)
pr, pw := Pipe() pr, pw := Pipe()
pr.Close() pr.Close()
r = TeeReader(rb, pw) r = TeeReader(rb, pw)
if n, err := ReadFull(r, dst); n != 0 || err != os.EPIPE { if n, err := ReadFull(r, dst); n != 0 || err != ErrClosedPipe {
t.Errorf("closed tee: ReadFull(r, dst) = %d, %v; want 0, EPIPE", n, err) t.Errorf("closed tee: ReadFull(r, dst) = %d, %v; want 0, EPIPE", n, err)
} }
} }

14
src/pkg/io/multi.go
View File

@ -4,17 +4,15 @@
package io package io
import "os"
type multiReader struct { type multiReader struct {
readers []Reader readers []Reader
} }
func (mr *multiReader) Read(p []byte) (n int, err os.Error) { func (mr *multiReader) Read(p []byte) (n int, err error) {
for len(mr.readers) > 0 { for len(mr.readers) > 0 {
n, err = mr.readers[0].Read(p) n, err = mr.readers[0].Read(p)
if n > 0 || err != os.EOF { if n > 0 || err != EOF {
if err == os.EOF { if err == EOF {
// Don't return EOF yet. There may be more bytes // Don't return EOF yet. There may be more bytes
// in the remaining readers. // in the remaining readers.
err = nil err = nil
@ -23,12 +21,12 @@ func (mr *multiReader) Read(p []byte) (n int, err os.Error) {
} }
mr.readers = mr.readers[1:] mr.readers = mr.readers[1:]
} }
return 0, os.EOF return 0, EOF
} }
// MultiReader returns a Reader that's the logical concatenation of // MultiReader returns a Reader that's the logical concatenation of
// the provided input readers. They're read sequentially. Once all // the provided input readers. They're read sequentially. Once all
// inputs are drained, Read will return os.EOF. // inputs are drained, Read will return EOF.
func MultiReader(readers ...Reader) Reader { func MultiReader(readers ...Reader) Reader {
return &multiReader{readers} return &multiReader{readers}
} }
@ -37,7 +35,7 @@ type multiWriter struct {
writers []Writer writers []Writer
} }
func (t *multiWriter) Write(p []byte) (n int, err os.Error) { func (t *multiWriter) Write(p []byte) (n int, err error) {
for _, w := range t.writers { for _, w := range t.writers {
n, err = w.Write(p) n, err = w.Write(p)
if err != nil { if err != nil {

7
src/pkg/io/multi_test.go
View File

@ -9,7 +9,6 @@ import (
"bytes" "bytes"
"crypto/sha1" "crypto/sha1"
"fmt" "fmt"
"os"
"strings" "strings"
"testing" "testing"
) )
@ -26,7 +25,7 @@ func TestMultiReader(t *testing.T) {
buf = make([]byte, 20) buf = make([]byte, 20)
tests() tests()
} }
expectRead := func(size int, expected string, eerr os.Error) { expectRead := func(size int, expected string, eerr error) {
nread++ nread++
n, gerr := mr.Read(buf[0:size]) n, gerr := mr.Read(buf[0:size])
if n != len(expected) { if n != len(expected) {
@ -48,13 +47,13 @@ func TestMultiReader(t *testing.T) {
expectRead(2, "fo", nil) expectRead(2, "fo", nil)
expectRead(5, "o ", nil) expectRead(5, "o ", nil)
expectRead(5, "bar", nil) expectRead(5, "bar", nil)
expectRead(5, "", os.EOF) expectRead(5, "", EOF)
}) })
withFooBar(func() { withFooBar(func() {
expectRead(4, "foo ", nil) expectRead(4, "foo ", nil)
expectRead(1, "b", nil) expectRead(1, "b", nil)
expectRead(3, "ar", nil) expectRead(3, "ar", nil)
expectRead(1, "", os.EOF) expectRead(1, "", EOF)
}) })
withFooBar(func() { withFooBar(func() {
expectRead(5, "foo ", nil) expectRead(5, "foo ", nil)

50
src/pkg/io/pipe.go
View File

@ -7,14 +7,14 @@
package io package io
import ( import "sync"
"os"
"sync" // ErrClosedPipe is the error used for read or write operations on a closed pipe.
) var ErrClosedPipe = &Error{"io: read/write on closed pipe"}
type pipeResult struct { type pipeResult struct {
n int n int
err os.Error err error
} }
// A pipe is the shared pipe structure underlying PipeReader and PipeWriter. // A pipe is the shared pipe structure underlying PipeReader and PipeWriter.
@ -25,11 +25,11 @@ type pipe struct {
data []byte // data remaining in pending write data []byte // data remaining in pending write
rwait sync.Cond // waiting reader rwait sync.Cond // waiting reader
wwait sync.Cond // waiting writer wwait sync.Cond // waiting writer
rerr os.Error // if reader closed, error to give writes rerr error // if reader closed, error to give writes
werr os.Error // if writer closed, error to give reads werr error // if writer closed, error to give reads
} }
func (p *pipe) read(b []byte) (n int, err os.Error) { func (p *pipe) read(b []byte) (n int, err error) {
// One reader at a time. // One reader at a time.
p.rl.Lock() p.rl.Lock()
defer p.rl.Unlock() defer p.rl.Unlock()
@ -38,7 +38,7 @@ func (p *pipe) read(b []byte) (n int, err os.Error) {
defer p.l.Unlock() defer p.l.Unlock()
for { for {
if p.rerr != nil { if p.rerr != nil {
return 0, os.EINVAL return 0, ErrClosedPipe
} }
if p.data != nil { if p.data != nil {
break break
@ -59,7 +59,7 @@ func (p *pipe) read(b []byte) (n int, err os.Error) {
var zero [0]byte var zero [0]byte
func (p *pipe) write(b []byte) (n int, err os.Error) { func (p *pipe) write(b []byte) (n int, err error) {
// pipe uses nil to mean not available // pipe uses nil to mean not available
if b == nil { if b == nil {
b = zero[:] b = zero[:]
@ -82,7 +82,7 @@ func (p *pipe) write(b []byte) (n int, err os.Error) {
break break
} }
if p.werr != nil { if p.werr != nil {
err = os.EINVAL err = ErrClosedPipe
} }
p.wwait.Wait() p.wwait.Wait()
} }
@ -91,9 +91,9 @@ func (p *pipe) write(b []byte) (n int, err os.Error) {
return return
} }
func (p *pipe) rclose(err os.Error) { func (p *pipe) rclose(err error) {
if err == nil { if err == nil {
err = os.EPIPE err = ErrClosedPipe
} }
p.l.Lock() p.l.Lock()
defer p.l.Unlock() defer p.l.Unlock()
@ -102,9 +102,9 @@ func (p *pipe) rclose(err os.Error) {
p.wwait.Signal() p.wwait.Signal()
} }
func (p *pipe) wclose(err os.Error) { func (p *pipe) wclose(err error) {
if err == nil { if err == nil {
err = os.EOF err = EOF
} }
p.l.Lock() p.l.Lock()
defer p.l.Unlock() defer p.l.Unlock()
@ -122,20 +122,20 @@ type PipeReader struct {
// it reads data from the pipe, blocking until a writer // it reads data from the pipe, blocking until a writer
// arrives or the write end is closed. // arrives or the write end is closed.
// If the write end is closed with an error, that error is // If the write end is closed with an error, that error is
// returned as err; otherwise err is os.EOF. // returned as err; otherwise err is EOF.
func (r *PipeReader) Read(data []byte) (n int, err os.Error) { func (r *PipeReader) Read(data []byte) (n int, err error) {
return r.p.read(data) return r.p.read(data)
} }
// Close closes the reader; subsequent writes to the // Close closes the reader; subsequent writes to the
// write half of the pipe will return the error os.EPIPE. // write half of the pipe will return the error ErrClosedPipe.
func (r *PipeReader) Close() os.Error { func (r *PipeReader) Close() error {
return r.CloseWithError(nil) return r.CloseWithError(nil)
} }
// CloseWithError closes the reader; subsequent writes // CloseWithError closes the reader; subsequent writes
// to the write half of the pipe will return the error err. // to the write half of the pipe will return the error err.
func (r *PipeReader) CloseWithError(err os.Error) os.Error { func (r *PipeReader) CloseWithError(err error) error {
r.p.rclose(err) r.p.rclose(err)
return nil return nil
} }
@ -149,20 +149,20 @@ type PipeWriter struct {
// it writes data to the pipe, blocking until readers // it writes data to the pipe, blocking until readers
// have consumed all the data or the read end is closed. // have consumed all the data or the read end is closed.
// If the read end is closed with an error, that err is // If the read end is closed with an error, that err is
// returned as err; otherwise err is os.EPIPE. // returned as err; otherwise err is ErrClosedPipe.
func (w *PipeWriter) Write(data []byte) (n int, err os.Error) { func (w *PipeWriter) Write(data []byte) (n int, err error) {
return w.p.write(data) return w.p.write(data)
} }
// Close closes the writer; subsequent reads from the // Close closes the writer; subsequent reads from the
// read half of the pipe will return no bytes and os.EOF. // read half of the pipe will return no bytes and EOF.
func (w *PipeWriter) Close() os.Error { func (w *PipeWriter) Close() error {
return w.CloseWithError(nil) return w.CloseWithError(nil)
} }
// CloseWithError closes the writer; subsequent reads from the // CloseWithError closes the writer; subsequent reads from the
// read half of the pipe will return no bytes and the error err. // read half of the pipe will return no bytes and the error err.
func (w *PipeWriter) CloseWithError(err os.Error) os.Error { func (w *PipeWriter) CloseWithError(err error) error {
w.p.wclose(err) w.p.wclose(err)
return nil return nil
} }

25
src/pkg/io/pipe_test.go
View File

@ -7,7 +7,6 @@ package io_test
import ( import (
"fmt" "fmt"
. "io" . "io"
"os"
"testing" "testing"
"time" "time"
) )
@ -44,7 +43,7 @@ func reader(t *testing.T, r Reader, c chan int) {
var buf = make([]byte, 64) var buf = make([]byte, 64)
for { for {
n, err := r.Read(buf) n, err := r.Read(buf)
if err == os.EOF { if err == EOF {
c <- 0 c <- 0
break break
} }
@ -84,7 +83,7 @@ func TestPipe2(t *testing.T) {
type pipeReturn struct { type pipeReturn struct {
n int n int
err os.Error err error
} }
// Test a large write that requires multiple reads to satisfy. // Test a large write that requires multiple reads to satisfy.
@ -106,7 +105,7 @@ func TestPipe3(t *testing.T) {
tot := 0 tot := 0
for n := 1; n <= 256; n *= 2 { for n := 1; n <= 256; n *= 2 {
nn, err := r.Read(rdat[tot : tot+n]) nn, err := r.Read(rdat[tot : tot+n])
if err != nil && err != os.EOF { if err != nil && err != EOF {
t.Fatalf("read: %v", err) t.Fatalf("read: %v", err)
} }
@ -116,7 +115,7 @@ func TestPipe3(t *testing.T) {
expect = 1 expect = 1
} else if n == 256 { } else if n == 256 {
expect = 0 expect = 0
if err != os.EOF { if err != EOF {
t.Fatalf("read at end: %v", err) t.Fatalf("read at end: %v", err)
} }
} }
@ -142,13 +141,13 @@ func TestPipe3(t *testing.T) {
// Test read after/before writer close. // Test read after/before writer close.
type closer interface { type closer interface {
CloseWithError(os.Error) os.Error CloseWithError(error) error
Close() os.Error Close() error
} }
type pipeTest struct { type pipeTest struct {
async bool async bool
err os.Error err error
closeWithError bool closeWithError bool
} }
@ -167,7 +166,7 @@ var pipeTests = []pipeTest{
func delayClose(t *testing.T, cl closer, ch chan int, tt pipeTest) { func delayClose(t *testing.T, cl closer, ch chan int, tt pipeTest) {
time.Sleep(1e6) // 1 ms time.Sleep(1e6) // 1 ms
var err os.Error var err error
if tt.closeWithError { if tt.closeWithError {
err = cl.CloseWithError(tt.err) err = cl.CloseWithError(tt.err)
} else { } else {
@ -193,7 +192,7 @@ func TestPipeReadClose(t *testing.T) {
<-c <-c
want := tt.err want := tt.err
if want == nil { if want == nil {
want = os.EOF want = EOF
} }
if err != want { if err != want {
t.Errorf("read from closed pipe: %v want %v", err, want) t.Errorf("read from closed pipe: %v want %v", err, want)
@ -214,8 +213,8 @@ func TestPipeReadClose2(t *testing.T) {
go delayClose(t, r, c, pipeTest{}) go delayClose(t, r, c, pipeTest{})
n, err := r.Read(make([]byte, 64)) n, err := r.Read(make([]byte, 64))
<-c <-c
if n != 0 || err != os.EINVAL { if n != 0 || err != ErrClosedPipe {
t.Errorf("read from closed pipe: %v, %v want %v, %v", n, err, 0, os.EINVAL) t.Errorf("read from closed pipe: %v, %v want %v, %v", n, err, 0, ErrClosedPipe)
} }
} }
@ -234,7 +233,7 @@ func TestPipeWriteClose(t *testing.T) {
<-c <-c
expect := tt.err expect := tt.err
if expect == nil { if expect == nil {
expect = os.EPIPE expect = ErrClosedPipe
} }
if err != expect { if err != expect {
t.Errorf("write on closed pipe: %v want %v", err, expect) t.Errorf("write on closed pipe: %v want %v", err, expect)