From b2d7bff70aab734dd1ba900fd45d811ab681e940 Mon Sep 17 00:00:00 2001
From: greatroar <61184462+greatroar@users.noreply.github.com>
Date: Mon, 19 Dec 2022 14:49:13 +0100
Subject: [PATCH] zstd: Trigger BCE by switching on lengths (#716)

This patches reduces the number of bounds checks in zstd, as reported by

	go build -gcflags="-d=ssa/check_bce/debug=1" |& wc -l

from 723 to 693.
---
 zstd/decodeheader.go | 4 ++--
 zstd/framedec.go     | 4 ++--
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/zstd/decodeheader.go b/zstd/decodeheader.go
index 1f5d41bf41..f6a240970d 100644
--- a/zstd/decodeheader.go
+++ b/zstd/decodeheader.go
@@ -152,7 +152,7 @@ func (h *Header) Decode(in []byte) error {
 		}
 		b, in = in[:size], in[size:]
 		h.HeaderSize += int(size)
-		switch size {
+		switch len(b) {
 		case 1:
 			h.DictionaryID = uint32(b[0])
 		case 2:
@@ -182,7 +182,7 @@ func (h *Header) Decode(in []byte) error {
 		}
 		b, in = in[:fcsSize], in[fcsSize:]
 		h.HeaderSize += int(fcsSize)
-		switch fcsSize {
+		switch len(b) {
 		case 1:
 			h.FrameContentSize = uint64(b[0])
 		case 2:
diff --git a/zstd/framedec.go b/zstd/framedec.go
index 6cb3b4e55f..65984bf07c 100644
--- a/zstd/framedec.go
+++ b/zstd/framedec.go
@@ -167,7 +167,7 @@ func (d *frameDec) reset(br byteBuffer) error {
 			return err
 		}
 		var id uint32
-		switch size {
+		switch len(b) {
 		case 1:
 			id = uint32(b[0])
 		case 2:
@@ -204,7 +204,7 @@ func (d *frameDec) reset(br byteBuffer) error {
 			println("Reading Frame content", err)
 			return err
 		}
-		switch fcsSize {
+		switch len(b) {
 		case 1:
 			d.FrameContentSize = uint64(b[0])
 		case 2: