MultiFileDiffReader returns trailing content

Along with EOF. This is useful for handling mixed diff and non-diff
output. Note that "stray" content between diff files was already
included in the extended headers for the next diff. All this commit does
is return a partial FileDiff, with only extended headers and no actual
diff content, along with an EOF.

Author: craigfurman

cmd/go-diff/go-diff.go

@@ -46,6 +46,13 @@ func main() {
 			label = fmt.Sprintf("orig(%s) new(%s)", fdiff.OrigName, fdiff.NewName)
 		}
 		if err == io.EOF {
+			// Any trailing content is found in extended headers for the "next" diff,
+			// that was never found.
+			if fdiff != nil {
+				for _, extended := range fdiff.Extended {
+					fmt.Println(extended)
+				}
+			}
 			break
 		}
 		if err != nil {

diff/parse.go

@@ -59,7 +59,7 @@ func (r *MultiFileDiffReader) ReadFile() (*FileDiff, error) {
 		switch e := err.(type) {
 		case *ParseError:
 			if e.Err == ErrNoFileHeader || e.Err == ErrExtendedHeadersEOF {
-				return nil, io.EOF
+				return fd, io.EOF
 			}
 			return nil, err