Better text detection

display.go

@@ -77,7 +77,7 @@ func fileDisplayHandler(c web.C, w http.ResponseWriter, r *http.Request) {
 	} else if metadata.Mimetype == "application/pdf" {
 		tpl = Templates["display/pdf.html"]
 
-	} else if supportedBinExtension(extension) {
+	} else if metadata.Mimetype == "text/plain" || supportedBinExtension(extension) {
 		if metadata.Size < maxDisplayFileSizeBytes {
 			bytes, err := ioutil.ReadFile(filePath)
 			if err == nil {

meta.go

@@ -15,6 +15,7 @@ import (
 	"path"
 	"sort"
 	"time"
+	"unicode/utf8"
 
 	"bitbucket.org/taruti/mimemagic"
 	"github.com/dchest/uniuri"
@@ -64,6 +65,15 @@ func generateMetadata(fName string, exp time.Time, delKey string) (m Metadata, e
 
 	m.Mimetype = mimemagic.Match("", header)
 
+	if m.Mimetype == "" {
+		// Check if the file seems anything like text
+		if utf8.Valid(header) {
+			m.Mimetype = "text/plain"
+		} else {
+			m.Mimetype = "application/octet-stream"
+		}
+	}
+
 	// Compute the sha256sum
 	hasher := sha256.New()
 	file.Seek(0, 0)