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// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package io_test
import (
"bytes"
"errors"
"fmt"
. "io"
"os"
"strings"
"sync"
"sync/atomic"
"testing"
)
// A version of bytes.Buffer without ReadFrom and WriteTo
type Buffer struct {
bytes.Buffer
ReaderFrom // conflicts with and hides bytes.Buffer's ReaderFrom.
WriterTo // conflicts with and hides bytes.Buffer's WriterTo.
}
// Simple tests, primarily to verify the ReadFrom and WriteTo callouts inside Copy, CopyBuffer and CopyN.
func TestCopy(t *testing.T) {
rb := new(Buffer)
wb := new(Buffer)
rb.WriteString("hello, world.")
Copy(wb, rb)
if wb.String() != "hello, world." {
t.Errorf("Copy did not work properly")
}
}
func TestCopyNegative(t *testing.T) {
rb := new(Buffer)
wb := new(Buffer)
rb.WriteString("hello")
Copy(wb, &LimitedReader{R: rb, N: -1})
if wb.String() != "" {
t.Errorf("Copy on LimitedReader with N<0 copied data")
}
CopyN(wb, rb, -1)
if wb.String() != "" {
t.Errorf("CopyN with N<0 copied data")
}
}
func TestCopyBuffer(t *testing.T) {
rb := new(Buffer)
wb := new(Buffer)
rb.WriteString("hello, world.")
CopyBuffer(wb, rb, make([]byte, 1)) // Tiny buffer to keep it honest.
if wb.String() != "hello, world." {
t.Errorf("CopyBuffer did not work properly")
}
}
func TestCopyBufferNil(t *testing.T) {
rb := new(Buffer)
wb := new(Buffer)
rb.WriteString("hello, world.")
CopyBuffer(wb, rb, nil) // Should allocate a buffer.
if wb.String() != "hello, world." {
t.Errorf("CopyBuffer did not work properly")
}
}
func TestCopyReadFrom(t *testing.T) {
rb := new(Buffer)
wb := new(bytes.Buffer) // implements ReadFrom.
rb.WriteString("hello, world.")
Copy(wb, rb)
if wb.String() != "hello, world." {
t.Errorf("Copy did not work properly")
}
}
func TestCopyWriteTo(t *testing.T) {
rb := new(bytes.Buffer) // implements WriteTo.
wb := new(Buffer)
rb.WriteString("hello, world.")
Copy(wb, rb)
if wb.String() != "hello, world." {
t.Errorf("Copy did not work properly")
}
}
// Version of bytes.Buffer that checks whether WriteTo was called or not
type writeToChecker struct {
bytes.Buffer
writeToCalled bool
}
func (wt *writeToChecker) WriteTo(w Writer) (int64, error) {
wt.writeToCalled = true
return wt.Buffer.WriteTo(w)
}
// It's preferable to choose WriterTo over ReaderFrom, since a WriterTo can issue one large write,
// while the ReaderFrom must read until EOF, potentially allocating when running out of buffer.
// Make sure that we choose WriterTo when both are implemented.
func TestCopyPriority(t *testing.T) {
rb := new(writeToChecker)
wb := new(bytes.Buffer)
rb.WriteString("hello, world.")
Copy(wb, rb)
if wb.String() != "hello, world." {
t.Errorf("Copy did not work properly")
} else if !rb.writeToCalled {
t.Errorf("WriteTo was not prioritized over ReadFrom")
}
}
type zeroErrReader struct {
err error
}
func (r zeroErrReader) Read(p []byte) (int, error) {
return copy(p, []byte{0}), r.err
}
type errWriter struct {
err error
}
func (w errWriter) Write([]byte) (int, error) {
return 0, w.err
}
// In case a Read results in an error with non-zero bytes read, and
// the subsequent Write also results in an error, the error from Write
// is returned, as it is the one that prevented progressing further.
func TestCopyReadErrWriteErr(t *testing.T) {
er, ew := errors.New("readError"), errors.New("writeError")
r, w := zeroErrReader{err: er}, errWriter{err: ew}
n, err := Copy(w, r)
if n != 0 || err != ew {
t.Errorf("Copy(zeroErrReader, errWriter) = %d, %v; want 0, writeError", n, err)
}
}
func TestCopyN(t *testing.T) {
rb := new(Buffer)
wb := new(Buffer)
rb.WriteString("hello, world.")
CopyN(wb, rb, 5)
if wb.String() != "hello" {
t.Errorf("CopyN did not work properly")
}
}
func TestCopyNReadFrom(t *testing.T) {
rb := new(Buffer)
wb := new(bytes.Buffer) // implements ReadFrom.
rb.WriteString("hello")
CopyN(wb, rb, 5)
if wb.String() != "hello" {
t.Errorf("CopyN did not work properly")
}
}
func TestCopyNWriteTo(t *testing.T) {
rb := new(bytes.Buffer) // implements WriteTo.
wb := new(Buffer)
rb.WriteString("hello, world.")
CopyN(wb, rb, 5)
if wb.String() != "hello" {
t.Errorf("CopyN did not work properly")
}
}
func BenchmarkCopyNSmall(b *testing.B) {
bs := bytes.Repeat([]byte{0}, 512+1)
rd := bytes.NewReader(bs)
buf := new(Buffer)
b.ResetTimer()
for i := 0; i < b.N; i++ {
CopyN(buf, rd, 512)
rd.Reset(bs)
}
}
func BenchmarkCopyNLarge(b *testing.B) {
bs := bytes.Repeat([]byte{0}, (32*1024)+1)
rd := bytes.NewReader(bs)
buf := new(Buffer)
b.ResetTimer()
for i := 0; i < b.N; i++ {
CopyN(buf, rd, 32*1024)
rd.Reset(bs)
}
}
type noReadFrom struct {
w Writer
}
func (w *noReadFrom) Write(p []byte) (n int, err error) {
return w.w.Write(p)
}
type wantedAndErrReader struct{}
func (wantedAndErrReader) Read(p []byte) (int, error) {
return len(p), errors.New("wantedAndErrReader error")
}
func TestCopyNEOF(t *testing.T) {
// Test that EOF behavior is the same regardless of whether
// argument to CopyN has ReadFrom.
b := new(bytes.Buffer)
n, err := CopyN(&noReadFrom{b}, strings.NewReader("foo"), 3)
if n != 3 || err != nil {
t.Errorf("CopyN(noReadFrom, foo, 3) = %d, %v; want 3, nil", n, err)
}
n, err = CopyN(&noReadFrom{b}, strings.NewReader("foo"), 4)
if n != 3 || err != EOF {
t.Errorf("CopyN(noReadFrom, foo, 4) = %d, %v; want 3, EOF", n, err)
}
n, err = CopyN(b, strings.NewReader("foo"), 3) // b has read from
if n != 3 || err != nil {
t.Errorf("CopyN(bytes.Buffer, foo, 3) = %d, %v; want 3, nil", n, err)
}
n, err = CopyN(b, strings.NewReader("foo"), 4) // b has read from
if n != 3 || err != EOF {
t.Errorf("CopyN(bytes.Buffer, foo, 4) = %d, %v; want 3, EOF", n, err)
}
n, err = CopyN(b, wantedAndErrReader{}, 5)
if n != 5 || err != nil {
t.Errorf("CopyN(bytes.Buffer, wantedAndErrReader, 5) = %d, %v; want 5, nil", n, err)
}
n, err = CopyN(&noReadFrom{b}, wantedAndErrReader{}, 5)
if n != 5 || err != nil {
t.Errorf("CopyN(noReadFrom, wantedAndErrReader, 5) = %d, %v; want 5, nil", n, err)
}
}
func TestReadAtLeast(t *testing.T) {
var rb bytes.Buffer
testReadAtLeast(t, &rb)
}
// A version of bytes.Buffer that returns n > 0, err on Read
// when the input is exhausted.
type dataAndErrorBuffer struct {
err error
bytes.Buffer
}
func (r *dataAndErrorBuffer) Read(p []byte) (n int, err error) {
n, err = r.Buffer.Read(p)
if n > 0 && r.Buffer.Len() == 0 && err == nil {
err = r.err
}
return
}
func TestReadAtLeastWithDataAndEOF(t *testing.T) {
var rb dataAndErrorBuffer
rb.err = EOF
testReadAtLeast(t, &rb)
}
func TestReadAtLeastWithDataAndError(t *testing.T) {
var rb dataAndErrorBuffer
rb.err = fmt.Errorf("fake error")
testReadAtLeast(t, &rb)
}
func testReadAtLeast(t *testing.T, rb ReadWriter) {
rb.Write([]byte("0123"))
buf := make([]byte, 2)
n, err := ReadAtLeast(rb, buf, 2)
if err != nil {
t.Error(err)
}
if n != 2 {
t.Errorf("expected to have read 2 bytes, got %v", n)
}
n, err = ReadAtLeast(rb, buf, 4)
if err != ErrShortBuffer {
t.Errorf("expected ErrShortBuffer got %v", err)
}
if n != 0 {
t.Errorf("expected to have read 0 bytes, got %v", n)
}
n, err = ReadAtLeast(rb, buf, 1)
if err != nil {
t.Error(err)
}
if n != 2 {
t.Errorf("expected to have read 2 bytes, got %v", n)
}
n, err = ReadAtLeast(rb, buf, 2)
if err != EOF {
t.Errorf("expected EOF, got %v", err)
}
if n != 0 {
t.Errorf("expected to have read 0 bytes, got %v", n)
}
rb.Write([]byte("4"))
n, err = ReadAtLeast(rb, buf, 2)
want := ErrUnexpectedEOF
if rb, ok := rb.(*dataAndErrorBuffer); ok && rb.err != EOF {
want = rb.err
}
if err != want {
t.Errorf("expected %v, got %v", want, err)
}
if n != 1 {
t.Errorf("expected to have read 1 bytes, got %v", n)
}
}
func TestTeeReader(t *testing.T) {
src := []byte("hello, world")
dst := make([]byte, len(src))
rb := bytes.NewBuffer(src)
wb := new(bytes.Buffer)
r := TeeReader(rb, wb)
if n, err := ReadFull(r, dst); err != nil || n != len(src) {
t.Fatalf("ReadFull(r, dst) = %d, %v; want %d, nil", n, err, len(src))
}
if !bytes.Equal(dst, src) {
t.Errorf("bytes read = %q want %q", dst, src)
}
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 != 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 != ErrClosedPipe {
t.Errorf("closed tee: ReadFull(r, dst) = %d, %v; want 0, EPIPE", n, err)
}
}
func TestSectionReader_ReadAt(t *testing.T) {
dat := "a long sample data, 1234567890"
tests := []struct {
data string
off int
n int
bufLen int
at int
exp string
err error
}{
{data: "", off: 0, n: 10, bufLen: 2, at: 0, exp: "", err: EOF},
{data: dat, off: 0, n: len(dat), bufLen: 0, at: 0, exp: "", err: nil},
{data: dat, off: len(dat), n: 1, bufLen: 1, at: 0, exp: "", err: EOF},
{data: dat, off: 0, n: len(dat) + 2, bufLen: len(dat), at: 0, exp: dat, err: nil},
{data: dat, off: 0, n: len(dat), bufLen: len(dat) / 2, at: 0, exp: dat[:len(dat)/2], err: nil},
{data: dat, off: 0, n: len(dat), bufLen: len(dat), at: 0, exp: dat, err: nil},
{data: dat, off: 0, n: len(dat), bufLen: len(dat) / 2, at: 2, exp: dat[2 : 2+len(dat)/2], err: nil},
{data: dat, off: 3, n: len(dat), bufLen: len(dat) / 2, at: 2, exp: dat[5 : 5+len(dat)/2], err: nil},
{data: dat, off: 3, n: len(dat) / 2, bufLen: len(dat)/2 - 2, at: 2, exp: dat[5 : 5+len(dat)/2-2], err: nil},
{data: dat, off: 3, n: len(dat) / 2, bufLen: len(dat)/2 + 2, at: 2, exp: dat[5 : 5+len(dat)/2-2], err: EOF},
{data: dat, off: 0, n: 0, bufLen: 0, at: -1, exp: "", err: EOF},
{data: dat, off: 0, n: 0, bufLen: 0, at: 1, exp: "", err: EOF},
}
for i, tt := range tests {
r := strings.NewReader(tt.data)
s := NewSectionReader(r, int64(tt.off), int64(tt.n))
buf := make([]byte, tt.bufLen)
if n, err := s.ReadAt(buf, int64(tt.at)); n != len(tt.exp) || string(buf[:n]) != tt.exp || err != tt.err {
t.Fatalf("%d: ReadAt(%d) = %q, %v; expected %q, %v", i, tt.at, buf[:n], err, tt.exp, tt.err)
}
}
}
func TestSectionReader_Seek(t *testing.T) {
// Verifies that NewSectionReader's Seeker behaves like bytes.NewReader (which is like strings.NewReader)
br := bytes.NewReader([]byte("foo"))
sr := NewSectionReader(br, 0, int64(len("foo")))
for _, whence := range []int{SeekStart, SeekCurrent, SeekEnd} {
for offset := int64(-3); offset <= 4; offset++ {
brOff, brErr := br.Seek(offset, whence)
srOff, srErr := sr.Seek(offset, whence)
if (brErr != nil) != (srErr != nil) || brOff != srOff {
t.Errorf("For whence %d, offset %d: bytes.Reader.Seek = (%v, %v) != SectionReader.Seek = (%v, %v)",
whence, offset, brOff, brErr, srErr, srOff)
}
}
}
// And verify we can just seek past the end and get an EOF
got, err := sr.Seek(100, SeekStart)
if err != nil || got != 100 {
t.Errorf("Seek = %v, %v; want 100, nil", got, err)
}
n, err := sr.Read(make([]byte, 10))
if n != 0 || err != EOF {
t.Errorf("Read = %v, %v; want 0, EOF", n, err)
}
}
func TestSectionReader_Size(t *testing.T) {
tests := []struct {
data string
want int64
}{
{"a long sample data, 1234567890", 30},
{"", 0},
}
for _, tt := range tests {
r := strings.NewReader(tt.data)
sr := NewSectionReader(r, 0, int64(len(tt.data)))
if got := sr.Size(); got != tt.want {
t.Errorf("Size = %v; want %v", got, tt.want)
}
}
}
func TestSectionReader_Max(t *testing.T) {
r := strings.NewReader("abcdef")
const maxint64 = 1<<63 - 1
sr := NewSectionReader(r, 3, maxint64)
n, err := sr.Read(make([]byte, 3))
if n != 3 || err != nil {
t.Errorf("Read = %v %v, want 3, nil", n, err)
}
n, err = sr.Read(make([]byte, 3))
if n != 0 || err != EOF {
t.Errorf("Read = %v, %v, want 0, EOF", n, err)
}
}
// largeWriter returns an invalid count that is larger than the number
// of bytes provided (issue 39978).
type largeWriter struct {
err error
}
func (w largeWriter) Write(p []byte) (int, error) {
return len(p) + 1, w.err
}
func TestCopyLargeWriter(t *testing.T) {
want := ErrInvalidWrite
rb := new(Buffer)
wb := largeWriter{}
rb.WriteString("hello, world.")
if _, err := Copy(wb, rb); err != want {
t.Errorf("Copy error: got %v, want %v", err, want)
}
want = errors.New("largeWriterError")
rb = new(Buffer)
wb = largeWriter{err: want}
rb.WriteString("hello, world.")
if _, err := Copy(wb, rb); err != want {
t.Errorf("Copy error: got %v, want %v", err, want)
}
}
func TestNopCloserWriterToForwarding(t *testing.T) {
for _, tc := range [...]struct {
Name string
r Reader
}{
{"not a WriterTo", Reader(nil)},
{"a WriterTo", struct {
Reader
WriterTo
}{}},
} {
nc := NopCloser(tc.r)
_, expected := tc.r.(WriterTo)
_, got := nc.(WriterTo)
if expected != got {
t.Errorf("NopCloser incorrectly forwards WriterTo for %s, got %t want %t", tc.Name, got, expected)
}
}
}
func TestOffsetWriter_Seek(t *testing.T) {
tmpfilename := "TestOffsetWriter_Seek"
tmpfile, err := os.CreateTemp(t.TempDir(), tmpfilename)
if err != nil || tmpfile == nil {
t.Fatalf("CreateTemp(%s) failed: %v", tmpfilename, err)
}
defer tmpfile.Close()
w := NewOffsetWriter(tmpfile, 0)
// Should throw error errWhence if whence is not valid
t.Run("errWhence", func(t *testing.T) {
for _, whence := range []int{-3, -2, -1, 3, 4, 5} {
var offset int64 = 0
gotOff, gotErr := w.Seek(offset, whence)
if gotOff != 0 || gotErr != ErrWhence {
t.Errorf("For whence %d, offset %d, OffsetWriter.Seek got: (%d, %v), want: (%d, %v)",
whence, offset, gotOff, gotErr, 0, ErrWhence)
}
}
})
// Should throw error errOffset if offset is negative
t.Run("errOffset", func(t *testing.T) {
for _, whence := range []int{SeekStart, SeekCurrent} {
for offset := int64(-3); offset < 0; offset++ {
gotOff, gotErr := w.Seek(offset, whence)
if gotOff != 0 || gotErr != ErrOffset {
t.Errorf("For whence %d, offset %d, OffsetWriter.Seek got: (%d, %v), want: (%d, %v)",
whence, offset, gotOff, gotErr, 0, ErrOffset)
}
}
}
})
// Normal tests
t.Run("normal", func(t *testing.T) {
tests := []struct {
offset int64
whence int
returnOff int64
}{
// keep in order
{whence: SeekStart, offset: 1, returnOff: 1},
{whence: SeekStart, offset: 2, returnOff: 2},
{whence: SeekStart, offset: 3, returnOff: 3},
{whence: SeekCurrent, offset: 1, returnOff: 4},
{whence: SeekCurrent, offset: 2, returnOff: 6},
{whence: SeekCurrent, offset: 3, returnOff: 9},
}
for idx, tt := range tests {
gotOff, gotErr := w.Seek(tt.offset, tt.whence)
if gotOff != tt.returnOff || gotErr != nil {
t.Errorf("%d:: For whence %d, offset %d, OffsetWriter.Seek got: (%d, %v), want: (%d, <nil>)",
idx+1, tt.whence, tt.offset, gotOff, gotErr, tt.returnOff)
}
}
})
}
func TestOffsetWriter_WriteAt(t *testing.T) {
const content = "0123456789ABCDEF"
contentSize := int64(len(content))
tmpdir, err := os.MkdirTemp(t.TempDir(), "TestOffsetWriter_WriteAt")
if err != nil {
t.Fatal(err)
}
work := func(off, at int64) {
position := fmt.Sprintf("off_%d_at_%d", off, at)
tmpfile, err := os.CreateTemp(tmpdir, position)
if err != nil || tmpfile == nil {
t.Fatalf("CreateTemp(%s) failed: %v", position, err)
}
defer tmpfile.Close()
var writeN int64
var wg sync.WaitGroup
// Concurrent writes, one byte at a time
for step, value := range []byte(content) {
wg.Add(1)
go func(wg *sync.WaitGroup, tmpfile *os.File, value byte, off, at int64, step int) {
defer wg.Done()
w := NewOffsetWriter(tmpfile, off)
n, e := w.WriteAt([]byte{value}, at+int64(step))
if e != nil {
t.Errorf("WriteAt failed. off: %d, at: %d, step: %d\n error: %v", off, at, step, e)
}
atomic.AddInt64(&writeN, int64(n))
}(&wg, tmpfile, value, off, at, step)
}
wg.Wait()
// Read one more byte to reach EOF
buf := make([]byte, contentSize+1)
readN, err := tmpfile.ReadAt(buf, off+at)
if err != EOF {
t.Fatalf("ReadAt failed: %v", err)
}
readContent := string(buf[:contentSize])
if writeN != int64(readN) || writeN != contentSize || readContent != content {
t.Fatalf("%s:: WriteAt(%s, %d) error. \ngot n: %v, content: %s \nexpected n: %v, content: %v",
position, content, at, readN, readContent, contentSize, content)
}
}
for off := int64(0); off < 2; off++ {
for at := int64(0); at < 2; at++ {
work(off, at)
}
}
}
func TestOffsetWriter_Write(t *testing.T) {
const content = "0123456789ABCDEF"
contentSize := len(content)
tmpdir := t.TempDir()
makeOffsetWriter := func(name string) (*OffsetWriter, *os.File) {
tmpfilename := "TestOffsetWriter_Write_" + name
tmpfile, err := os.CreateTemp(tmpdir, tmpfilename)
if err != nil || tmpfile == nil {
t.Fatalf("CreateTemp(%s) failed: %v", tmpfilename, err)
}
return NewOffsetWriter(tmpfile, 0), tmpfile
}
checkContent := func(name string, f *os.File) {
// Read one more byte to reach EOF
buf := make([]byte, contentSize+1)
readN, err := f.ReadAt(buf, 0)
if err != EOF {
t.Fatalf("ReadAt failed, err: %v", err)
}
readContent := string(buf[:contentSize])
if readN != contentSize || readContent != content {
t.Fatalf("%s error. \ngot n: %v, content: %s \nexpected n: %v, content: %v",
name, readN, readContent, contentSize, content)
}
}
var name string
name = "Write"
t.Run(name, func(t *testing.T) {
// Write directly (off: 0, at: 0)
// Write content to file
w, f := makeOffsetWriter(name)
defer f.Close()
for _, value := range []byte(content) {
n, err := w.Write([]byte{value})
if err != nil {
t.Fatalf("Write failed, n: %d, err: %v", n, err)
}
}
checkContent(name, f)
// Copy -> Write
// Copy file f to file f2
name = "Copy"
w2, f2 := makeOffsetWriter(name)
defer f2.Close()
Copy(w2, f)
checkContent(name, f2)
})
// Copy -> WriteTo -> Write
// Note: strings.Reader implements the io.WriterTo interface.
name = "Write_Of_Copy_WriteTo"
t.Run(name, func(t *testing.T) {
w, f := makeOffsetWriter(name)
defer f.Close()
Copy(w, strings.NewReader(content))
checkContent(name, f)
})
}