* removed flag from Archive struct

Author: bsponge

txtar/archive.go

@@ -42,7 +42,6 @@ import (
 type Archive struct {
 	Comment []byte
 	Files   []File
-	UseCRLF bool
 }
 
 // A File is a single file in an archive.
@@ -55,21 +54,41 @@ type File struct {
 // It is assumed that the Archive data structure is well-formed:
 // a.Comment and all a.File[i].Data contain no file marker lines,
 // and all a.File[i].Name is non-empty. Format uses line separators
-// based on a.UseCRLF field.
+// based on the first line separator encountered in the comment section.
 func Format(a *Archive) []byte {
-	lineSeparator := lf
-	if a.UseCRLF {
-		lineSeparator = crlf
+	firstSep, ok := lineEnd(a.Comment)
+	if !ok {
+		for _, f := range a.Files {
+			firstSep, ok = lineEnd(f.Data)
+			if ok {
+				break
+			}
+		}
 	}
+
 	var buf bytes.Buffer
-	buf.Write(fixNL(a.Comment, lineSeparator))
+	buf.Write(fixNL(a.Comment, firstSep))
 	for _, f := range a.Files {
-		fmt.Fprintf(&buf, "-- %s --%s", f.Name, lineSeparator)
-		buf.Write(fixNL(f.Data, lineSeparator))
+		fmt.Fprintf(&buf, "-- %s --%s", f.Name, firstSep)
+		buf.Write(fixNL(f.Data, firstSep))
 	}
 	return buf.Bytes()
 }
 
+// lineEnd returns the line separator that was used at the end
+// of the passed byte slice and a bool flag that says if the line separator
+// was really found or it is a default value (lf).
+func lineEnd(b []byte) ([]byte, bool) {
+	switch {
+	case bytes.HasSuffix(b, crlf):
+		return crlf, true
+	case bytes.HasSuffix(b, lf):
+		return lf, true
+	default:
+		return lf, false
+	}
+}
+
 // ParseFile parses the named file as an archive.
 func ParseFile(file string) (*Archive, error) {
 	data, err := os.ReadFile(file)

txtar/archive_test.go

@@ -135,7 +135,6 @@ func TestFormat(t *testing.T) {
 					{"empty", []byte{}},
 					{"noNL", []byte("hello world")},
 				},
-				UseCRLF: false,
 			},
 			wanted: `comment1
 comment2
@@ -160,7 +159,6 @@ hello world
 					{"empty", []byte{}},
 					{"noNL", []byte("hello world")},
 				},
-				UseCRLF: true,
 			},
 			wanted: "comment1\r\n" +
 				"comment2\r\n" +
@@ -186,7 +184,6 @@ hello world
 					{"noNL", []byte("hello world\r\n")},
 					{"empty filename line", []byte("some content\r\n-- --\n")},
 				},
-				UseCRLF: true,
 			},
 			wanted: "comment1\n" +
 				"comment2\r\n" +