Correctly handle empty files

Former-commit-id: d166aa352ce4bf32739ddc2f7d1c9967918822fd

pkg/obiformats/genbank_read.go

@@ -4,14 +4,11 @@ import (
 	"bufio"
 	"bytes"
 	"io"
-	"os"
 	"path"
 	"regexp"
 	"strconv"
 	"strings"
 
-	gzip "github.com/klauspost/pgzip"
-
 	log "github.com/sirupsen/logrus"
 
 	"git.metabarcoding.org/lecasofts/go/obitools/pkg/obiiter"
@@ -173,23 +170,21 @@ func ReadGenbank(reader io.Reader, options ...WithOption) obiiter.IBioSequence {
 
 func ReadGenbankFromFile(filename string, options ...WithOption) (obiiter.IBioSequence, error) {
 	var reader io.Reader
-	var greader io.Reader
 	var err error
 
 	options = append(options, OptionsSource(obiutils.RemoveAllExt((path.Base(filename)))))
 
-	reader, err = os.Open(filename)
+	reader, err = Ropen(filename)
+
+	if err == ErrNoContent {
+		log.Infof("file %s is empty", filename)
+		return ReadEmptyFile(options...)
+	}
+
 	if err != nil {
 		log.Printf("open file error: %+v", err)
 		return obiiter.NilIBioSequence, err
 	}
 
-	// Test if the flux is compressed by gzip
-	//greader, err = gzip.NewReader(reader)
-	greader, err = gzip.NewReaderN(reader, 1<<24, 2)
-	if err == nil {
-		reader = greader
-	}
-
 	return ReadGenbank(reader, options...), nil
 }