From 7c1903e1ee9788f6d7d1f94da4a3074cb1619ca6 Mon Sep 17 00:00:00 2001
From: Michael Eischer <michael.eischer@fau.de>
Date: Fri, 29 Jan 2021 22:12:51 +0100
Subject: [PATCH] panic if hash returns an error

Add a sanity check that the interface contract is honoured.
---
 internal/backend/mem/mem_backend.go   | 5 ++++-
 internal/backend/test/tests.go        | 5 ++++-
 internal/restic/rewind_reader.go      | 5 ++++-
 internal/restic/rewind_reader_test.go | 5 ++++-
 4 files changed, 16 insertions(+), 4 deletions(-)

diff --git a/internal/backend/mem/mem_backend.go b/internal/backend/mem/mem_backend.go
index 983976519..8dae5d21d 100644
--- a/internal/backend/mem/mem_backend.go
+++ b/internal/backend/mem/mem_backend.go
@@ -91,7 +91,10 @@ func (be *MemoryBackend) Save(ctx context.Context, h restic.Handle, rd restic.Re
 
 	beHash := be.Hasher()
 	// must never fail according to interface
-	_, _ = beHash.Write(buf)
+	_, err = beHash.Write(buf)
+	if err != nil {
+		panic(err)
+	}
 	if !bytes.Equal(beHash.Sum(nil), rd.Hash()) {
 		return errors.Errorf("invalid file hash or content, got %s expected %s",
 			base64.RawStdEncoding.EncodeToString(beHash.Sum(nil)),
diff --git a/internal/backend/test/tests.go b/internal/backend/test/tests.go
index ebb209a3e..75e5ffeb5 100644
--- a/internal/backend/test/tests.go
+++ b/internal/backend/test/tests.go
@@ -547,7 +547,10 @@ func (s *Suite) TestSave(t *testing.T) {
 	if b.Hasher() != nil {
 		beHasher := b.Hasher()
 		// must never fail according to interface
-		_, _ = beHasher.Write(data)
+		_, err := beHasher.Write(data)
+		if err != nil {
+			panic(err)
+		}
 		beHash = beHasher.Sum(nil)
 	}
 	err = b.Save(context.TODO(), h, errorCloser{
diff --git a/internal/restic/rewind_reader.go b/internal/restic/rewind_reader.go
index 20339f222..c27724e02 100644
--- a/internal/restic/rewind_reader.go
+++ b/internal/restic/rewind_reader.go
@@ -56,7 +56,10 @@ func NewByteReader(buf []byte, hasher hash.Hash) *ByteReader {
 	var hash []byte
 	if hasher != nil {
 		// must never fail according to interface
-		_, _ = hasher.Write(buf)
+		_, err := hasher.Write(buf)
+		if err != nil {
+			panic(err)
+		}
 		hash = hasher.Sum(nil)
 	}
 	return &ByteReader{
diff --git a/internal/restic/rewind_reader_test.go b/internal/restic/rewind_reader_test.go
index 0e15ee686..b553cdfb0 100644
--- a/internal/restic/rewind_reader_test.go
+++ b/internal/restic/rewind_reader_test.go
@@ -54,7 +54,10 @@ func TestFileReader(t *testing.T) {
 			var hash []byte
 			if hasher != nil {
 				// must never fail according to interface
-				_, _ = hasher.Write(buf)
+				_, err := hasher.Write(buf)
+				if err != nil {
+					panic(err)
+				}
 				hash = hasher.Sum(nil)
 			}
 			rd, err := NewFileReader(f, hash)