From da386ea282bd9ed28f62e4d2a3e1172a9bbf5b2b Mon Sep 17 00:00:00 2001
From: Mattias Wadman <mattias.wadman@gmail.com>
Date: Tue, 7 Sep 2021 11:51:18 +0200
Subject: [PATCH] mp3: Be more relaxed with zero padding, just warn

---
 format/id3/id3v2.go          |  7 +++----
 pkg/decode/decode_readers.go | 13 +++++++++++--
 2 files changed, 14 insertions(+), 6 deletions(-)

diff --git a/format/id3/id3v2.go b/format/id3/id3v2.go
index 10635479..2944ce7d 100644
--- a/format/id3/id3v2.go
+++ b/format/id3/id3v2.go
@@ -368,7 +368,7 @@ func decodeFrame(d *decode.D, version int) uint64 {
 			d.FieldU5("unused0")
 
 			d.FieldBool("compression")
-			// TODO: read encruption byte, skip decode of frame data?
+			// TODO: read encryption byte, skip decode of frame data?
 			d.FieldBool("encryption")
 			d.FieldBool("grouping_identity")
 
@@ -399,7 +399,7 @@ func decodeFrame(d *decode.D, version int) uint64 {
 			d.FieldU2("unused2")
 
 			d.FieldBool("compression")
-			// TODO: read encruption byte, skip decode of frame data?
+			// TODO: read encryption byte, skip decode of frame data?
 			d.FieldBool("encryption")
 			unsyncFlag = d.FieldBool("unsync")
 			dataLenFlag = d.FieldBool("data_length_indicator")
@@ -577,11 +577,10 @@ func decodeFrames(d *decode.D, version int, size uint64) {
 				size -= decodeFrame(d, version)
 			})
 		}
-
 	})
 
 	if size > 0 {
-		d.FieldValidateZeroPadding("padding", int(size)*8)
+		d.FieldZeroPadding("padding", int(size)*8)
 	}
 }
 
diff --git a/pkg/decode/decode_readers.go b/pkg/decode/decode_readers.go
index 0b5aca3d..dc34f498 100644
--- a/pkg/decode/decode_readers.go
+++ b/pkg/decode/decode_readers.go
@@ -175,7 +175,7 @@ func (d *D) FieldOptionalZeroBytes(name string) int64 {
 	})
 }
 
-func (d *D) FieldValidateZeroPadding(name string, nBits int) {
+func (d *D) fieldZeroPadding(name string, nBits int, panicOnNonZero bool) {
 	pos := d.Pos()
 	var isZero bool
 	d.FieldFn(name, func() *Value {
@@ -184,13 +184,22 @@ func (d *D) FieldValidateZeroPadding(name string, nBits int) {
 		if !isZero {
 			s = "Incorrect"
 		}
+		// TODO: proper warnings
 		return &Value{Symbol: s, Description: "zero padding"}
 	})
-	if !isZero {
+	if panicOnNonZero && !isZero {
 		panic(ValidateError{Reason: "expected zero padding", Pos: pos})
 	}
 }
 
+func (d *D) FieldValidateZeroPadding(name string, nBits int) {
+	d.fieldZeroPadding(name, nBits, true)
+}
+
+func (d *D) FieldZeroPadding(name string, nBits int) {
+	d.fieldZeroPadding(name, nBits, false)
+}
+
 // Bool reads one bit as a boolean
 func (d *D) TryBool() (bool, error) {
 	n, err := d.TryU(1)