From: Alexander Yastrebov <yastrebov.alex@gmail.com>
Date: Wed, 27 Sep 2023 02:01:46 +0000 (+0000)
Subject: internal/zstd: allow empty compressed blocks
X-Git-Tag: go1.22rc1~742
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=1a51b59c119034dfbcd98063bf775d92e6f76db4;p=gostls13.git

internal/zstd: allow empty compressed blocks

For #62513

Change-Id: I295e72f71165665b8ea999e68a5586fa785b546d
GitHub-Last-Rev: 902e952d88dba505f87393fd3c97c433ae291709
GitHub-Pull-Request: golang/go#63252
Reviewed-on: https://go-review.googlesource.com/c/go/+/531217
Auto-Submit: Ian Lance Taylor <iant@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Bryan Mills <bcmills@google.com>
Reviewed-by: Ian Lance Taylor <iant@google.com>
---

diff --git a/src/internal/zstd/block.go b/src/internal/zstd/block.go
index cf4c954c7d..8732661fa1 100644
--- a/src/internal/zstd/block.go
+++ b/src/internal/zstd/block.go
@@ -50,10 +50,9 @@ func (r *Reader) compressedBlock(blockSize int) error {
 		if off < len(data) {
 			return r.makeError(off, "extraneous data after no sequences")
 		}
-		if len(litbuf) == 0 {
-			return r.makeError(off, "no sequences and no literals")
-		}
+
 		r.buffer = append(r.buffer, litbuf...)
+
 		return nil
 	}
 
@@ -374,9 +373,7 @@ func (r *Reader) execSeqs(data block, off int, litbuf []byte, seqCount int) erro
 		}
 	}
 
-	if len(litbuf) > 0 {
-		r.buffer = append(r.buffer, litbuf...)
-	}
+	r.buffer = append(r.buffer, litbuf...)
 
 	if rbr.cnt != 0 {
 		return r.makeError(off, "extraneous data after sequences")
diff --git a/src/internal/zstd/zstd_test.go b/src/internal/zstd/zstd_test.go
index 22af814acf..c2914bb1f4 100644
--- a/src/internal/zstd/zstd_test.go
+++ b/src/internal/zstd/zstd_test.go
@@ -90,6 +90,11 @@ var tests = []struct {
 		"0\x00\x00\x00\x00\x000\x00\x00\x00\x00\x001\x00\x00\x00\x00\x000000",
 		"(\xb5/\xfd\x04X\x8d\x00\x00P0\x000\x001\x000000\x03T\x02\x00\x01\x01m\xf9\xb7G",
 	},
+	{
+		"empty block",
+		"",
+		"\x28\xb5\x2f\xfd\x00\x00\x15\x00\x00\x00\x00",
+	},
 }
 
 func TestSamples(t *testing.T) {