bytes, strings: allow Reader.Seek past 1<<31
Fixes #7654
LGTM=rsc
R=rsc, dan.kortschak
CC=golang-codereviews
https://golang.org/cl/81530043
diff --git a/src/pkg/bytes/reader.go b/src/pkg/bytes/reader.go
index 1151ffc..cdc3233 100644
--- a/src/pkg/bytes/reader.go
+++ b/src/pkg/bytes/reader.go
@@ -16,17 +16,17 @@
// Unlike a Buffer, a Reader is read-only and supports seeking.
type Reader struct {
s []byte
- i int // current reading index
- prevRune int // index of previous rune; or < 0
+ i int64 // current reading index
+ prevRune int // index of previous rune; or < 0
}
// Len returns the number of bytes of the unread portion of the
// slice.
func (r *Reader) Len() int {
- if r.i >= len(r.s) {
+ if r.i >= int64(len(r.s)) {
return 0
}
- return len(r.s) - r.i
+ return int(int64(len(r.s)) - r.i)
}
func (r *Reader) Read(b []byte) (n int, err error) {
@@ -34,11 +34,11 @@
if len(b) == 0 {
return 0, nil
}
- if r.i >= len(r.s) {
+ if r.i >= int64(len(r.s)) {
return 0, io.EOF
}
n = copy(b, r.s[r.i:])
- r.i += n
+ r.i += int64(n)
return
}
@@ -49,7 +49,7 @@
if off >= int64(len(r.s)) {
return 0, io.EOF
}
- n = copy(b, r.s[int(off):])
+ n = copy(b, r.s[off:])
if n < len(b) {
err = io.EOF
}
@@ -58,7 +58,7 @@
func (r *Reader) ReadByte() (b byte, err error) {
r.prevRune = -1
- if r.i >= len(r.s) {
+ if r.i >= int64(len(r.s)) {
return 0, io.EOF
}
b = r.s[r.i]
@@ -76,17 +76,17 @@
}
func (r *Reader) ReadRune() (ch rune, size int, err error) {
- if r.i >= len(r.s) {
+ if r.i >= int64(len(r.s)) {
r.prevRune = -1
return 0, 0, io.EOF
}
- r.prevRune = r.i
+ r.prevRune = int(r.i)
if c := r.s[r.i]; c < utf8.RuneSelf {
r.i++
return rune(c), 1, nil
}
ch, size = utf8.DecodeRune(r.s[r.i:])
- r.i += size
+ r.i += int64(size)
return
}
@@ -94,7 +94,7 @@
if r.prevRune < 0 {
return errors.New("bytes.Reader: previous operation was not ReadRune")
}
- r.i = r.prevRune
+ r.i = int64(r.prevRune)
r.prevRune = -1
return nil
}
@@ -116,17 +116,14 @@
if abs < 0 {
return 0, errors.New("bytes: negative position")
}
- if abs >= 1<<31 {
- return 0, errors.New("bytes: position out of range")
- }
- r.i = int(abs)
+ r.i = abs
return abs, nil
}
// WriteTo implements the io.WriterTo interface.
func (r *Reader) WriteTo(w io.Writer) (n int64, err error) {
r.prevRune = -1
- if r.i >= len(r.s) {
+ if r.i >= int64(len(r.s)) {
return 0, nil
}
b := r.s[r.i:]
@@ -134,7 +131,7 @@
if m > len(b) {
panic("bytes.Reader.WriteTo: invalid Write count")
}
- r.i += m
+ r.i += int64(m)
n = int64(m)
if m != len(b) && err == nil {
err = io.ErrShortWrite
diff --git a/src/pkg/bytes/reader_test.go b/src/pkg/bytes/reader_test.go
index fc502d7..a25f8ff 100644
--- a/src/pkg/bytes/reader_test.go
+++ b/src/pkg/bytes/reader_test.go
@@ -27,8 +27,8 @@
{seek: os.SEEK_SET, off: 1, n: 1, want: "1"},
{seek: os.SEEK_CUR, off: 1, wantpos: 3, n: 2, want: "34"},
{seek: os.SEEK_SET, off: -1, seekerr: "bytes: negative position"},
- {seek: os.SEEK_SET, off: 1<<31 - 1},
- {seek: os.SEEK_CUR, off: 1, seekerr: "bytes: position out of range"},
+ {seek: os.SEEK_SET, off: 1 << 33, wantpos: 1 << 33},
+ {seek: os.SEEK_CUR, off: 1, wantpos: 1<<33 + 1},
{seek: os.SEEK_SET, n: 5, want: "01234"},
{seek: os.SEEK_CUR, n: 5, want: "56789"},
{seek: os.SEEK_END, off: -1, n: 1, wantpos: 9, want: "9"},
@@ -60,6 +60,16 @@
}
}
+func TestReadAfterBigSeek(t *testing.T) {
+ r := NewReader([]byte("0123456789"))
+ if _, err := r.Seek(1<<31+5, os.SEEK_SET); err != nil {
+ t.Fatal(err)
+ }
+ if n, err := r.Read(make([]byte, 10)); n != 0 || err != io.EOF {
+ t.Errorf("Read = %d, %v; want 0, EOF", n, err)
+ }
+}
+
func TestReaderAt(t *testing.T) {
r := NewReader([]byte("0123456789"))
tests := []struct {
diff --git a/src/pkg/strings/reader.go b/src/pkg/strings/reader.go
index 75bf07b..93ff804 100644
--- a/src/pkg/strings/reader.go
+++ b/src/pkg/strings/reader.go
@@ -15,17 +15,17 @@
// from a string.
type Reader struct {
s string
- i int // current reading index
- prevRune int // index of previous rune; or < 0
+ i int64 // current reading index
+ prevRune int // index of previous rune; or < 0
}
// Len returns the number of bytes of the unread portion of the
// string.
func (r *Reader) Len() int {
- if r.i >= len(r.s) {
+ if r.i >= int64(len(r.s)) {
return 0
}
- return len(r.s) - r.i
+ return int(int64(len(r.s)) - r.i)
}
func (r *Reader) Read(b []byte) (n int, err error) {
@@ -33,11 +33,11 @@
if len(b) == 0 {
return 0, nil
}
- if r.i >= len(r.s) {
+ if r.i >= int64(len(r.s)) {
return 0, io.EOF
}
n = copy(b, r.s[r.i:])
- r.i += n
+ r.i += int64(n)
return
}
@@ -48,7 +48,7 @@
if off >= int64(len(r.s)) {
return 0, io.EOF
}
- n = copy(b, r.s[int(off):])
+ n = copy(b, r.s[off:])
if n < len(b) {
err = io.EOF
}
@@ -57,7 +57,7 @@
func (r *Reader) ReadByte() (b byte, err error) {
r.prevRune = -1
- if r.i >= len(r.s) {
+ if r.i >= int64(len(r.s)) {
return 0, io.EOF
}
b = r.s[r.i]
@@ -75,17 +75,17 @@
}
func (r *Reader) ReadRune() (ch rune, size int, err error) {
- if r.i >= len(r.s) {
+ if r.i >= int64(len(r.s)) {
r.prevRune = -1
return 0, 0, io.EOF
}
- r.prevRune = r.i
+ r.prevRune = int(r.i)
if c := r.s[r.i]; c < utf8.RuneSelf {
r.i++
return rune(c), 1, nil
}
ch, size = utf8.DecodeRuneInString(r.s[r.i:])
- r.i += size
+ r.i += int64(size)
return
}
@@ -93,7 +93,7 @@
if r.prevRune < 0 {
return errors.New("strings.Reader: previous operation was not ReadRune")
}
- r.i = r.prevRune
+ r.i = int64(r.prevRune)
r.prevRune = -1
return nil
}
@@ -115,17 +115,14 @@
if abs < 0 {
return 0, errors.New("strings: negative position")
}
- if abs >= 1<<31 {
- return 0, errors.New("strings: position out of range")
- }
- r.i = int(abs)
+ r.i = abs
return abs, nil
}
// WriteTo implements the io.WriterTo interface.
func (r *Reader) WriteTo(w io.Writer) (n int64, err error) {
r.prevRune = -1
- if r.i >= len(r.s) {
+ if r.i >= int64(len(r.s)) {
return 0, nil
}
s := r.s[r.i:]
@@ -133,7 +130,7 @@
if m > len(s) {
panic("strings.Reader.WriteTo: invalid WriteString count")
}
- r.i += m
+ r.i += int64(m)
n = int64(m)
if m != len(s) && err == nil {
err = io.ErrShortWrite
diff --git a/src/pkg/strings/reader_test.go b/src/pkg/strings/reader_test.go
index 4fdddcd..c7a3412 100644
--- a/src/pkg/strings/reader_test.go
+++ b/src/pkg/strings/reader_test.go
@@ -27,8 +27,8 @@
{seek: os.SEEK_SET, off: 1, n: 1, want: "1"},
{seek: os.SEEK_CUR, off: 1, wantpos: 3, n: 2, want: "34"},
{seek: os.SEEK_SET, off: -1, seekerr: "strings: negative position"},
- {seek: os.SEEK_SET, off: 1<<31 - 1},
- {seek: os.SEEK_CUR, off: 1, seekerr: "strings: position out of range"},
+ {seek: os.SEEK_SET, off: 1 << 33, wantpos: 1 << 33},
+ {seek: os.SEEK_CUR, off: 1, wantpos: 1<<33 + 1},
{seek: os.SEEK_SET, n: 5, want: "01234"},
{seek: os.SEEK_CUR, n: 5, want: "56789"},
{seek: os.SEEK_END, off: -1, n: 1, wantpos: 9, want: "9"},
@@ -60,6 +60,16 @@
}
}
+func TestReadAfterBigSeek(t *testing.T) {
+ r := strings.NewReader("0123456789")
+ if _, err := r.Seek(1<<31+5, os.SEEK_SET); err != nil {
+ t.Fatal(err)
+ }
+ if n, err := r.Read(make([]byte, 10)); n != 0 || err != io.EOF {
+ t.Errorf("Read = %d, %v; want 0, EOF", n, err)
+ }
+}
+
func TestReaderAt(t *testing.T) {
r := strings.NewReader("0123456789")
tests := []struct {
