From f64c986efc1096ca08515fab6a29ec2ade46dfca Mon Sep 17 00:00:00 2001
From: Saxon <saxon@ausocean.org>
Date: Mon, 20 Jan 2020 15:03:49 +1030
Subject: [PATCH] codec: corrected error handling in lexers

---
 codec/h264/lex.go  | 21 +++++++++++++++++----
 codec/h265/lex.go  | 10 ++++++++--
 codec/mjpeg/lex.go |  9 ++++++---
 3 files changed, 31 insertions(+), 9 deletions(-)

diff --git a/codec/h264/lex.go b/codec/h264/lex.go
index 1f169afe..3d9fb8a4 100644
--- a/codec/h264/lex.go
+++ b/codec/h264/lex.go
@@ -31,7 +31,6 @@ LICENSE
 package h264
 
 import (
-	"fmt"
 	"io"
 	"time"
 
@@ -68,18 +67,25 @@ func Lex(dst io.Writer, src io.Reader, delay time.Duration) error {
 	copy(buf, h264Prefix[:])
 	writeOut := false
 
+outer:
 	for {
 		var b byte
 		var err error
 		buf, b, err = c.ScanUntil(buf, 0x00)
 		if err != nil {
-			return fmt.Errorf("can't scan until: %w", err)
+			if err != io.EOF {
+				return err
+			}
+			break
 		}
 
 		for n := 1; b == 0x0 && n < 4; n++ {
 			b, err = c.ReadByte()
 			if err != nil {
-				return fmt.Errorf("can't read byte: %w", err)
+				if err != io.EOF {
+					return err
+				}
+				break outer
 			}
 			buf = append(buf, b)
 
@@ -101,7 +107,10 @@ func Lex(dst io.Writer, src io.Reader, delay time.Duration) error {
 
 			b, err = c.ReadByte()
 			if err != nil {
-				return fmt.Errorf("can't read byte: %w", err)
+				if err != io.EOF {
+					return err
+				}
+				break outer
 			}
 			buf = append(buf, b)
 
@@ -119,4 +128,8 @@ func Lex(dst io.Writer, src io.Reader, delay time.Duration) error {
 			}
 		}
 	}
+	if len(buf) == len(h264Prefix) {
+		return io.EOF
+	}
+	return io.ErrUnexpectedEOF
 }
diff --git a/codec/h265/lex.go b/codec/h265/lex.go
index 6534e571..2fb41a9d 100644
--- a/codec/h265/lex.go
+++ b/codec/h265/lex.go
@@ -77,7 +77,13 @@ func (l *Lexer) Lex(dst io.Writer, src io.Reader, delay time.Duration) error {
 		switch err {
 		case nil: // Do nothing.
 		default:
-			return fmt.Errorf("source read error: %w\n", err)
+			if err == io.EOF {
+				if l.buf.Len() == 0 {
+					return io.EOF
+				}
+				return io.ErrUnexpectedEOF
+			}
+			return err
 		}
 
 		// Get payload from RTP packet.
@@ -179,7 +185,7 @@ func (l *Lexer) handleFragmentation(d []byte) {
 	}
 }
 
-// handlePACI will handl PACI packets
+// handlePACI will handle PACI packets
 //
 // TODO: complete this
 func (l *Lexer) handlePACI(d []byte) {
diff --git a/codec/mjpeg/lex.go b/codec/mjpeg/lex.go
index d8b671b2..aea4ce9f 100644
--- a/codec/mjpeg/lex.go
+++ b/codec/mjpeg/lex.go
@@ -60,10 +60,10 @@ func Lex(dst io.Writer, src io.Reader, delay time.Duration) error {
 		buf := make([]byte, 2, 4<<10)
 		n, err := r.Read(buf)
 		if n < 2 {
-			return nil
+			return io.ErrUnexpectedEOF
 		}
 		if err != nil {
-			return fmt.Errorf("can't read source: %w", err)
+			return err
 		}
 		if !bytes.Equal(buf, []byte{0xff, 0xd8}) {
 			return fmt.Errorf("parser: not MJPEG frame start: %#v", buf)
@@ -72,7 +72,10 @@ func Lex(dst io.Writer, src io.Reader, delay time.Duration) error {
 		for {
 			b, err := r.ReadByte()
 			if err != nil {
-				return fmt.Errorf("can't read byte: %w", err)
+				if err == io.EOF {
+					return io.ErrUnexpectedEOF
+				}
+				return err
 			}
 			buf = append(buf, b)
 			if last == 0xff && b == 0xd9 {