fix size-0 chunker bug

parse.go

@@ -8,7 +8,10 @@ import (
 	"strings"
 )
 
-var ErrRabinMin = errors.New("rabin min must be greater than 16")
+var (
+	ErrRabinMin = errors.New("rabin min must be greater than 16")
+	ErrSize     = errors.New("chunker size muster greater than 0")
+)
 
 // FromString returns a Splitter depending on the given string:
 // it supports "default" (""), "size-{size}", "rabin", "rabin-{blocksize}" and
@@ -23,6 +26,8 @@ func FromString(r io.Reader, chunker string) (Splitter, error) {
 		size, err := strconv.Atoi(sizeStr)
 		if err != nil {
 			return nil, err
+		} else if size <= 0 {
+			return nil, ErrSize
 		}
 		return NewSizeSplitter(r, int64(size)), nil
 

parse_test.go

@@ -5,7 +5,7 @@ import (
 	"testing"
 )
 
-func TestParse(t *testing.T) {
+func TestParseRabin(t *testing.T) {
 	max := 1000
 	r := bytes.NewReader(randBuf(t, max))
 	chk1 := "rabin-18-25-32"
@@ -19,3 +19,18 @@ func TestParse(t *testing.T) {
 		t.Log("it should be ErrRabinMin here.")
 	}
 }
+
+func TestParseSize(t *testing.T) {
+	max := 1000
+	r := bytes.NewReader(randBuf(t, max))
+	size1 := "size-0"
+	size2 := "size-32"
+	_, err := FromString(r, size1)
+	if err == ErrSize {
+		t.Log("it should be ErrSize here.")
+	}
+	_, err = FromString(r, size2)
+	if err == ErrSize {
+		t.Fatal(err)
+	}
+}