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strings, bytes: panic if Repeat overflows or if given a negative count
Panic if Repeat is given a negative count or if the value of (len(*) * count) is detected to overflow. We panic because we cannot change the signature of Repeat to return an error. Fixes #16237 Change-Id: I9f5ba031a5b8533db0582d7a672ffb715143f3fb Reviewed-on: https://go-review.googlesource.com/29954 Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
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@ -365,7 +365,20 @@ func Map(mapping func(r rune) rune, s []byte) []byte {
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}
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// Repeat returns a new byte slice consisting of count copies of b.
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//
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// It panics if count is negative or if
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// the result of (len(b) * count) overflows.
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func Repeat(b []byte, count int) []byte {
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// Since we cannot return an error on overflow,
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// we should panic if the repeat will generate
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// an overflow.
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// See Issue golang.org/issue/16237.
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if count < 0 {
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panic("bytes: negative Repeat count")
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} else if count > 0 && len(b)*count/count != len(b) {
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panic("bytes: Repeat count causes overflow")
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}
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nb := make([]byte, len(b)*count)
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bp := copy(nb, b)
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for bp < len(nb) {
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@ -903,6 +903,54 @@ func TestRepeat(t *testing.T) {
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}
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}
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func repeat(b []byte, count int) (err error) {
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defer func() {
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if r := recover(); r != nil {
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switch v := r.(type) {
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case error:
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err = v
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default:
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err = fmt.Errorf("%s", v)
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}
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}
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}()
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Repeat(b, count)
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return
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}
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// See Issue golang.org/issue/16237
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func TestRepeatCatchesOverflow(t *testing.T) {
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tests := [...]struct {
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s string
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count int
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errStr string
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}{
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0: {"--", -2147483647, "negative"},
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1: {"", int(^uint(0) >> 1), ""},
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2: {"-", 10, ""},
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3: {"gopher", 0, ""},
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4: {"-", -1, "negative"},
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5: {"--", -102, "negative"},
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6: {string(make([]byte, 255)), int((^uint(0))/255 + 1), "overflow"},
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}
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for i, tt := range tests {
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err := repeat([]byte(tt.s), tt.count)
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if tt.errStr == "" {
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if err != nil {
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t.Errorf("#%d panicked %v", i, err)
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}
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continue
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}
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if err == nil || !strings.Contains(err.Error(), tt.errStr) {
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t.Errorf("#%d expected %q got %q", i, tt.errStr, err)
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}
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}
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}
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func runesEqual(a, b []rune) bool {
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if len(a) != len(b) {
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return false
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@ -418,7 +418,20 @@ func Map(mapping func(rune) rune, s string) string {
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}
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// Repeat returns a new string consisting of count copies of the string s.
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//
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// It panics if count is negative or if
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// the result of (len(s) * count) overflows.
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func Repeat(s string, count int) string {
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// Since we cannot return an error on overflow,
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// we should panic if the repeat will generate
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// an overflow.
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// See Issue golang.org/issue/16237
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if count < 0 {
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panic("strings: negative Repeat count")
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} else if count > 0 && len(s)*count/count != len(s) {
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panic("strings: Repeat count causes overflow")
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}
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b := make([]byte, len(s)*count)
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bp := copy(b, s)
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for bp < len(b) {
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@ -6,6 +6,7 @@ package strings_test
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import (
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"bytes"
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"fmt"
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"io"
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"math/rand"
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"reflect"
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@ -892,6 +893,54 @@ func TestRepeat(t *testing.T) {
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}
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}
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func repeat(s string, count int) (err error) {
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defer func() {
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if r := recover(); r != nil {
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switch v := r.(type) {
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case error:
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err = v
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default:
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err = fmt.Errorf("%s", v)
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}
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}
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}()
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Repeat(s, count)
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return
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}
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// See Issue golang.org/issue/16237
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func TestRepeatCatchesOverflow(t *testing.T) {
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tests := [...]struct {
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s string
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count int
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errStr string
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}{
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0: {"--", -2147483647, "negative"},
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1: {"", int(^uint(0) >> 1), ""},
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2: {"-", 10, ""},
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3: {"gopher", 0, ""},
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4: {"-", -1, "negative"},
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5: {"--", -102, "negative"},
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6: {string(make([]byte, 255)), int((^uint(0))/255 + 1), "overflow"},
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}
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for i, tt := range tests {
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err := repeat(tt.s, tt.count)
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if tt.errStr == "" {
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if err != nil {
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t.Errorf("#%d panicked %v", i, err)
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}
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continue
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}
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if err == nil || !Contains(err.Error(), tt.errStr) {
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t.Errorf("#%d expected %q got %q", i, tt.errStr, err)
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}
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}
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}
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func runesEqual(a, b []rune) bool {
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if len(a) != len(b) {
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return false
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