Add binary file detection

go.mod

@@ -4,6 +4,7 @@ go 1.12
 
 require (
 	github.com/dustin/go-humanize v1.0.0
+	github.com/gabriel-vasile/mimetype v1.0.2
 	github.com/jessevdk/go-flags v1.4.0
 	github.com/manifoldco/promptui v0.7.0
 	github.com/mattn/go-colorable v0.1.4 // indirect

go.sum

@@ -6,6 +6,8 @@ github.com/chzyer/test v0.0.0-20180213035817-a1ea475d72b1 h1:q763qf9huN11kDQavWs
 github.com/chzyer/test v0.0.0-20180213035817-a1ea475d72b1/go.mod h1:Q3SI9o4m/ZMnBNeIyt5eFwwo7qiLfzFZmjNmxjkiQlU=
 github.com/dustin/go-humanize v1.0.0 h1:VSnTsYCnlFHaM2/igO1h6X3HA71jcobQuxemgkq4zYo=
 github.com/dustin/go-humanize v1.0.0/go.mod h1:HtrtbFcZ19U5GC7JDqmcUSB87Iq5E25KnS6fMYU6eOk=
+github.com/gabriel-vasile/mimetype v1.0.2 h1:GKCo1TUCg0pV0R4atTcaLv/9SI2W9xPgMySZxUxcJOE=
+github.com/gabriel-vasile/mimetype v1.0.2/go.mod h1:6CDPel/o/3/s4+bp6kIbsWATq8pmgOisOPG40CJa6To=
 github.com/jessevdk/go-flags v1.4.0 h1:4IU2WS7AumrZ/40jfhf4QVDMsQwqA7VEHozFRrGARJA=
 github.com/jessevdk/go-flags v1.4.0/go.mod h1:4FA24M0QyGHXBuZZK/XkWh8h0e1EYbRYJSGM75WSRxI=
 github.com/juju/ansiterm v0.0.0-20180109212912-720a0952cc2a h1:FaWFmfWdAUKbSCtOU2QjDaorUexogfaMgbipgYATUMU=

main.go

@@ -13,6 +13,7 @@ import (
 	"time"
 
 	"github.com/dustin/go-humanize"
+	"github.com/gabriel-vasile/mimetype"
 	"github.com/jessevdk/go-flags"
 	"github.com/manifoldco/promptui"
 	"github.com/rs/xid"
@@ -128,6 +129,20 @@ func makeFile(groupID string, arg string) (File, error) {
 	}, nil
 }
 
+func isBinary(path string) bool {
+	detectedMIME, err := mimetype.DetectFile(path)
+	if err != nil {
+		return true
+	}
+	isBinary := true
+	for mime := detectedMIME; mime != nil; mime = mime.Parent() {
+		if mime.Is("text/plain") {
+			isBinary = false
+		}
+	}
+	return isBinary
+}
+
 func head(path string) string {
 	max := 5
 	wrap := func(line string) string {
@@ -171,6 +186,9 @@ func head(path string) string {
 			lines = append(lines, fmt.Sprintf("%s\t%s", dir.Mode().String(), dir.Name()))
 		}
 	default:
+		if isBinary(path) {
+			return "(binary file)"
+		}
 		lines = []string{""}
 		fp, _ := os.Open(path)
 		defer fp.Close()