From a23e9c86ba686fb20d0c8be057803d4e85af566e Mon Sep 17 00:00:00 2001
From: greatroar <@>
Date: Mon, 9 Mar 2020 14:11:25 +0100
Subject: [PATCH 1/2] Remove closing logic from Packer.Finalize

The method only ever receives *hashing.Writers, which don't implement
io.Closer. These come from packerManager.findPacker and have their
actual writers closed in Repository.savePacker. Moving the closing logic
to hashing.Writer results in "file already closed" errors.
---
 internal/pack/pack.go | 8 +-------
 1 file changed, 1 insertion(+), 7 deletions(-)

diff --git a/internal/pack/pack.go b/internal/pack/pack.go
index 5bf046304..ce341e1f0 100644
--- a/internal/pack/pack.go
+++ b/internal/pack/pack.go
@@ -61,8 +61,7 @@ type headerEntry struct {
 }
 
 // Finalize writes the header for all added blobs and finalizes the pack.
-// Returned are the number of bytes written, including the header. If the
-// underlying writer implements io.Closer, it is closed.
+// Returned are the number of bytes written, including the header.
 func (p *Packer) Finalize() (uint, error) {
 	p.m.Lock()
 	defer p.m.Unlock()
@@ -101,11 +100,6 @@ func (p *Packer) Finalize() (uint, error) {
 	bytesWritten += uint(binary.Size(uint32(0)))
 
 	p.bytes = uint(bytesWritten)
-
-	if w, ok := p.wr.(io.Closer); ok {
-		return bytesWritten, w.Close()
-	}
-
 	return bytesWritten, nil
 }
 

From 74a64c47e416ebe6bdd01c004e660f435c8b17c7 Mon Sep 17 00:00:00 2001
From: greatroar <@>
Date: Mon, 9 Mar 2020 14:25:55 +0100
Subject: [PATCH 2/2] Move testing logic to test file in internal/pack

---
 internal/pack/pack.go      | 6 +-----
 internal/pack/pack_test.go | 2 +-
 2 files changed, 2 insertions(+), 6 deletions(-)

diff --git a/internal/pack/pack.go b/internal/pack/pack.go
index ce341e1f0..fbe0522dc 100644
--- a/internal/pack/pack.go
+++ b/internal/pack/pack.go
@@ -25,12 +25,8 @@ type Packer struct {
 	m sync.Mutex
 }
 
-// NewPacker returns a new Packer that can be used to pack blobs
-// together. If wr is nil, a bytes.Buffer is used.
+// NewPacker returns a new Packer that can be used to pack blobs together.
 func NewPacker(k *crypto.Key, wr io.Writer) *Packer {
-	if wr == nil {
-		wr = bytes.NewBuffer(nil)
-	}
 	return &Packer{k: k, wr: wr}
 }
 
diff --git a/internal/pack/pack_test.go b/internal/pack/pack_test.go
index 12e3600bb..69707ff8a 100644
--- a/internal/pack/pack_test.go
+++ b/internal/pack/pack_test.go
@@ -36,7 +36,7 @@ func newPack(t testing.TB, k *crypto.Key, lengths []int) ([]Buf, []byte, uint) {
 	}
 
 	// pack blobs
-	p := pack.NewPacker(k, nil)
+	p := pack.NewPacker(k, new(bytes.Buffer))
 	for _, b := range bufs {
 		p.Add(restic.TreeBlob, b.id, b.data)
 	}