fix panic: runtime error: slice bounds out of range

Author: iambus

diffmatchpatch/diff.go

@@ -34,8 +34,6 @@ const (
 	DiffInsert Operation = 1
 	// DiffEqual item represents an equal diff.
 	DiffEqual Operation = 0
-	//IndexSeparator is used to seperate the array indexes in an index string
-	IndexSeparator = ","
 )
 
 // Diff represents one diff operation
@@ -406,17 +404,11 @@ func (dmp *DiffMatchPatch) DiffLinesToRunes(text1, text2 string) ([]rune, []rune
 func (dmp *DiffMatchPatch) DiffCharsToLines(diffs []Diff, lineArray []string) []Diff {
 	hydrated := make([]Diff, 0, len(diffs))
 	for _, aDiff := range diffs {
-		chars := strings.Split(aDiff.Text, IndexSeparator)
-		text := make([]string, len(chars))
-
-		for i, r := range chars {
-			i1, err := strconv.Atoi(r)
-			if err == nil {
-				text[i] = lineArray[i1]
-			}
+		var sb strings.Builder
+		for _, i := range []rune(aDiff.Text) {
+			sb.WriteString(lineArray[i])
 		}
-
-		aDiff.Text = strings.Join(text, "")
+		aDiff.Text = sb.String()
 		hydrated = append(hydrated, aDiff)
 	}
 	return hydrated

diffmatchpatch/patch_test.go

@@ -337,3 +337,28 @@ func TestPatchApply(t *testing.T) {
 		assert.Equal(t, tc.ExpectedApplies, actualApplies, fmt.Sprintf("Test case #%d, %s", i, tc.Name))
 	}
 }
+
+func TestPatchMakeOutOfRangePanic(t *testing.T) {
+	text1 := `
+  1111111111111 000000
+  ------------- ------
+  xxxxxxxxxxxxx ------
+  xxxxxxxxxxxxx ------
+  xxxxxxxxxxxxx xxxxxx
+  xxxxxxxxxxxxx ......
+  xxxxxxxxxxxxx 111111
+  xxxxxxxxxxxxx ??????
+  xxxxxxxxxxxxx 333333
+  xxxxxxxxxxxxx 555555
+  xxxxxxxxxx xxxxx
+  xxxxxxxxxx xxxxx
+  xxxxxxxxxx xxxxx
+  xxxxxxxxxx xxxxx
+`
+	text2 := `
+  2222222222222 000000
+  xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx`
+	dmp := New()
+	patches := dmp.PatchMake(text1, text2)
+	assert.Equal(t, 6, len(patches), "TestPatchMakeOutOfRangePanic")
+}

diffmatchpatch/stringutil.go

@@ -9,7 +9,6 @@
 package diffmatchpatch
 
 import (
-	"strconv"
 	"strings"
 	"unicode/utf8"
 )
@@ -89,18 +88,9 @@ func runesIndex(r1, r2 []rune) int {
 }
 
 func intArrayToString(ns []uint32) string {
-	if len(ns) == 0 {
-		return ""
+	runes := make([]rune, len(ns))
+	for i := 0; i < len(ns); i++ {
+		runes[i] = rune(ns[i])
 	}
-
-	indexSeparator := IndexSeparator[0]
-
-	// Appr. 3 chars per num plus the comma.
-	b := []byte{}
-	for _, n := range ns {
-		b = strconv.AppendInt(b, int64(n), 10)
-		b = append(b, indexSeparator)
-	}
-	b = b[:len(b)-1]
-	return string(b)
+	return string(runes)
 }