io: use error, add EOF, avoid os

R=r, r
CC=golang-dev
https://golang.org/cl/5311068

src/pkg/io/io_test.go

@@ -7,7 +7,6 @@ package io_test
 import (
 	"bytes"
 	. "io"
-	"os"
 	"strings"
 	"testing"
 )
@@ -85,7 +84,7 @@ type noReadFrom struct {
 	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)
 }
 
@@ -101,7 +100,7 @@ func TestCopyNEOF(t *testing.T) {
 	}
 
 	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)
 	}
 
@@ -111,7 +110,7 @@ func TestCopyNEOF(t *testing.T) {
 	}
 
 	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)
 	}
 }
@@ -121,16 +120,16 @@ func TestReadAtLeast(t *testing.T) {
 	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.
 type dataAndEOFBuffer struct {
 	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)
 	if n > 0 && r.Buffer.Len() == 0 && err == nil {
-		err = os.EOF
+		err = EOF
 	}
 	return
 }
@@ -162,7 +161,7 @@ func testReadAtLeast(t *testing.T, rb ReadWriter) {
 		t.Errorf("expected to have read 2 bytes, got %v", n)
 	}
 	n, err = ReadAtLeast(rb, buf, 2)
-	if err != os.EOF {
+	if err != EOF {
 		t.Errorf("expected EOF, got %v", err)
 	}
 	if n != 0 {
@@ -193,14 +192,14 @@ func TestTeeReader(t *testing.T) {
 	if !bytes.Equal(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)
 	}
 	rb = bytes.NewBuffer(src)
 	pr, pw := Pipe()
 	pr.Close()
 	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)
 	}
 }

src/pkg/io/multi.go

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

src/pkg/io/multi_test.go

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

src/pkg/io/pipe.go

@@ -7,14 +7,14 @@
 
 package io
 
-import (
-	"os"
-	"sync"
-)
+import "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 {
 	n   int
-	err os.Error
+	err error
 }
 
 // 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
 	rwait sync.Cond  // waiting reader
 	wwait sync.Cond  // waiting writer
-	rerr  os.Error   // if reader closed, error to give writes
-	werr  os.Error   // if writer closed, error to give reads
+	rerr  error      // if reader closed, error to give writes
+	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.
 	p.rl.Lock()
 	defer p.rl.Unlock()
@@ -38,7 +38,7 @@ func (p *pipe) read(b []byte) (n int, err os.Error) {
 	defer p.l.Unlock()
 	for {
 		if p.rerr != nil {
-			return 0, os.EINVAL
+			return 0, ErrClosedPipe
 		}
 		if p.data != nil {
 			break
@@ -59,7 +59,7 @@ func (p *pipe) read(b []byte) (n int, err os.Error) {
 
 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
 	if b == nil {
 		b = zero[:]
@@ -82,7 +82,7 @@ func (p *pipe) write(b []byte) (n int, err os.Error) {
 			break
 		}
 		if p.werr != nil {
-			err = os.EINVAL
+			err = ErrClosedPipe
 		}
 		p.wwait.Wait()
 	}
@@ -91,9 +91,9 @@ func (p *pipe) write(b []byte) (n int, err os.Error) {
 	return
 }
 
-func (p *pipe) rclose(err os.Error) {
+func (p *pipe) rclose(err error) {
 	if err == nil {
-		err = os.EPIPE
+		err = ErrClosedPipe
 	}
 	p.l.Lock()
 	defer p.l.Unlock()
@@ -102,9 +102,9 @@ func (p *pipe) rclose(err os.Error) {
 	p.wwait.Signal()
 }
 
-func (p *pipe) wclose(err os.Error) {
+func (p *pipe) wclose(err error) {
 	if err == nil {
-		err = os.EOF
+		err = EOF
 	}
 	p.l.Lock()
 	defer p.l.Unlock()
@@ -122,20 +122,20 @@ type PipeReader struct {
 // it reads data from the pipe, blocking until a writer
 // arrives or the write end is closed.
 // If the write end is closed with an error, that error is
-// returned as err; otherwise err is os.EOF.
-func (r *PipeReader) Read(data []byte) (n int, err os.Error) {
+// returned as err; otherwise err is EOF.
+func (r *PipeReader) Read(data []byte) (n int, err error) {
 	return r.p.read(data)
 }
 
 // Close closes the reader; subsequent writes to the
-// write half of the pipe will return the error os.EPIPE.
-func (r *PipeReader) Close() os.Error {
+// write half of the pipe will return the error ErrClosedPipe.
+func (r *PipeReader) Close() error {
 	return r.CloseWithError(nil)
 }
 
 // CloseWithError closes the reader; subsequent writes
 // 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)
 	return nil
 }
@@ -149,20 +149,20 @@ type PipeWriter struct {
 // it writes data to the pipe, blocking until readers
 // have consumed all the data or the read end is closed.
 // If the read end is closed with an error, that err is
-// returned as err; otherwise err is os.EPIPE.
-func (w *PipeWriter) Write(data []byte) (n int, err os.Error) {
+// returned as err; otherwise err is ErrClosedPipe.
+func (w *PipeWriter) Write(data []byte) (n int, err error) {
 	return w.p.write(data)
 }
 
 // Close closes the writer; subsequent reads from the
-// read half of the pipe will return no bytes and os.EOF.
-func (w *PipeWriter) Close() os.Error {
+// read half of the pipe will return no bytes and EOF.
+func (w *PipeWriter) Close() error {
 	return w.CloseWithError(nil)
 }
 
 // CloseWithError closes the writer; subsequent reads from the
 // 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)
 	return nil
 }

src/pkg/io/pipe_test.go

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