add method PossibleTypes and fix ms-office matchers' rules

match.go

@@ -14,6 +14,21 @@ var Matchers = matchers.Matchers
 // NewMatcher is an alias to matchers.NewMatcher
 var NewMatcher = matchers.NewMatcher
 
+// PossibleTypes returns the possible mime types of given bytes
+func PossibleTypes(b []byte) ([]types.Type, error) {
+	if len(b) == 0 {
+		return nil, ErrEmptyBuffer
+	}
+	possibleTypes := []types.Type{}
+	for _, checker := range Matchers {
+		matchedType := checker(b)
+		if matchedType != types.Unknown && matchedType.Extension != "" {
+			possibleTypes = append(possibleTypes, matchedType)
+		}
+	}
+	return possibleTypes, nil
+}
+
 // Match infers the file type of a given buffer inspecting its magic numbers signature
 func Match(buf []byte) (types.Type, error) {
 	length := len(buf)

match_test.go

@@ -185,3 +185,26 @@ func BenchmarkMatchPng(b *testing.B) {
 		Match(pngBuffer)
 	}
 }
+
+func TestPossibleTypes(t *testing.T) {
+	docBuffer, _ := ioutil.ReadFile("./fixtures/sample.doc")
+	fileBytes := [][]byte{docBuffer}
+	for _, fileByte := range fileBytes {
+		pts, err := PossibleTypes(fileByte)
+		if err != nil {
+			t.Fail()
+			t.Error(err)
+		}
+		var success bool
+		for _, typ := range pts {
+			t.Logf("possible mime-type: %s, ext: %s", typ.MIME.Value, typ.Extension)
+			if typ.Extension == "doc" {
+				success = true
+			}
+		}
+		if !success {
+			t.Fail()
+			t.Error("matched failed")
+		}
+	}
+}

matchers/document.go

@@ -1,7 +1,5 @@
 package matchers
 
-import "bytes"
-
 var (
 	TypeDoc  = newType("doc", "application/msword")
 	TypeDocx = newType("docx", "application/vnd.openxmlformats-officedocument.wordprocessingml.document")
@@ -31,8 +29,7 @@ func Doc(buf []byte) bool {
 func Docx(buf []byte) bool {
 	return len(buf) > 3 &&
 		buf[0] == 0x50 && buf[1] == 0x4B &&
-		buf[2] == 0x03 && buf[3] == 0x04 &&
-		bytes.Contains(buf[:256], []byte(TypeDocx.MIME.Value))
+		buf[2] == 0x03 && buf[3] == 0x04
 }
 
 func Xls(buf []byte) bool {
@@ -46,8 +43,7 @@ func Xls(buf []byte) bool {
 func Xlsx(buf []byte) bool {
 	return len(buf) > 3 &&
 		buf[0] == 0x50 && buf[1] == 0x4B &&
-		buf[2] == 0x03 && buf[3] == 0x04 &&
-		bytes.Contains(buf[:256], []byte(TypeXlsx.MIME.Value))
+		buf[2] == 0x03 && buf[3] == 0x04
 }
 
 func Ppt(buf []byte) bool {
@@ -61,6 +57,5 @@ func Ppt(buf []byte) bool {
 func Pptx(buf []byte) bool {
 	return len(buf) > 3 &&
 		buf[0] == 0x50 && buf[1] == 0x4B &&
-		buf[2] == 0x07 && buf[3] == 0x08 &&
-		bytes.Contains(buf[:256], []byte(TypePptx.MIME.Value))
+		buf[2] == 0x07 && buf[3] == 0x08
 }