git: Move `EmptyTreeOID` into `ObjectHash` structure

Move the `EmptyTreeOID` variable into the `ObjectHash` structure to make
it dependent on the hash function used.

8 files changed, 14 insertions, 15 deletions

diff --git a/cmd/gitaly-git2go-v15/conflicts_test.go b/cmd/gitaly-git2go-v15/conflicts_test.go
index 39829c7ae..5b09130a0 100644
--- a/cmd/gitaly-git2go-v15/conflicts_test.go
+++ b/cmd/gitaly-git2go-v15/conflicts_test.go
@@ -245,7 +245,7 @@ func TestConflicts_checkError(t *testing.T) {
 		},
 		{
 			desc:   "invalid object type",
-			ours:   glgit.EmptyTreeOID,
+			ours:   glgit.ObjectHashSHA1.EmptyTreeOID,
 			theirs: validOID,
 			expErr: status.Error(codes.InvalidArgument, "the requested type does not match the type in the ODB"),
 		},
diff --git a/internal/git/gittest/repository_suite.go b/internal/git/gittest/repository_suite.go
index d1b7a8043..83db63614 100644
--- a/internal/git/gittest/repository_suite.go
+++ b/internal/git/gittest/repository_suite.go
@@ -96,7 +96,7 @@ func testRepositoryHasBranches(t *testing.T, cfg config.Cfg, getRepository GetRe
 
 	repo, repoPath := getRepository(ctx, t, false)
 
-	emptyCommit := text.ChompBytes(Exec(t, cfg, "-C", repoPath, "commit-tree", git.EmptyTreeOID.String()))
+	emptyCommit := text.ChompBytes(Exec(t, cfg, "-C", repoPath, "commit-tree", git.ObjectHashSHA1.EmptyTreeOID.String()))
 
 	Exec(t, cfg, "-C", repoPath, "update-ref", "refs/headsbranch", emptyCommit)
 
diff --git a/internal/git/gittest/sha1.go b/internal/git/gittest/sha1.go
index 38fd11759..3cfb3dc26 100644
--- a/internal/git/gittest/sha1.go
+++ b/internal/git/gittest/sha1.go
@@ -4,10 +4,8 @@ package gittest
 
 import "gitlab.com/gitlab-org/gitaly/v15/internal/git"
 
-const (
-	// EmptyTreeOID is the Git tree object hash that corresponds to an empty tree (directory)
-	EmptyTreeOID = git.EmptyTreeOID
-)
+// EmptyTreeOID is the Git tree object hash that corresponds to an empty tree (directory)
+var EmptyTreeOID = git.ObjectHashSHA1.EmptyTreeOID
 
 var initRepoExtraArgs = []string{}
 
diff --git a/internal/git/object_id.go b/internal/git/object_id.go
index 0be8857c8..85afd4aa7 100644
--- a/internal/git/object_id.go
+++ b/internal/git/object_id.go
@@ -8,9 +8,6 @@ import (
 )
 
 const (
-	// EmptyTreeOID is the Git tree object hash that corresponds to an empty tree (directory)
-	EmptyTreeOID = ObjectID("4b825dc642cb6eb9a060e54bf8d69288fbee4904")
-
 	// ZeroOID is the special value that Git uses to signal a ref or object does not exist
 	ZeroOID = ObjectID("0000000000000000000000000000000000000000")
 )
@@ -18,12 +15,14 @@ const (
 var (
 	// ObjectHashSHA1 is the implementation of an object ID via SHA1.
 	ObjectHashSHA1 = ObjectHash{
-		regexp: regexp.MustCompile(`\A[0-9a-f]{40}\z`),
+		regexp:       regexp.MustCompile(`\A[0-9a-f]{40}\z`),
+		EmptyTreeOID: ObjectID("4b825dc642cb6eb9a060e54bf8d69288fbee4904"),
 	}
 
 	// ObjectHashSHA256 is the implementation of an object ID via SHA256.
 	ObjectHashSHA256 = ObjectHash{
-		regexp: regexp.MustCompile(`\A[0-9a-f]{64}\z`),
+		regexp:       regexp.MustCompile(`\A[0-9a-f]{64}\z`),
+		EmptyTreeOID: ObjectID("6ef19b41225c5369f1c104d45d8d85efa9b057b53b14b4b9b939dd74decc5321"),
 	}
 
 	// ErrInvalidObjectID is returned in case an object ID's string
@@ -34,6 +33,8 @@ var (
 // ObjectHash is a hash-function specific implementation of an object ID.
 type ObjectHash struct {
 	regexp *regexp.Regexp
+	// EmptyTreeOID is the object ID of the tree object that has no directory entries.
+	EmptyTreeOID ObjectID
 }
 
 // FromHex constructs a new ObjectID from the given hex representation of the object ID. Returns
diff --git a/internal/git/object_id_test.go b/internal/git/object_id_test.go
index 62306d285..22f8d9a6c 100644
--- a/internal/git/object_id_test.go
+++ b/internal/git/object_id_test.go
@@ -192,7 +192,7 @@ func TestIsZeroOID(t *testing.T) {
 		},
 		{
 			desc:   "zero object ID",
-			oid:    EmptyTreeOID,
+			oid:    ObjectHashSHA1.EmptyTreeOID,
 			isZero: false,
 		},
 	} {
diff --git a/internal/gitaly/service/commit/stats.go b/internal/gitaly/service/commit/stats.go
index 644d5b344..1b9ba0286 100644
--- a/internal/gitaly/service/commit/stats.go
+++ b/internal/gitaly/service/commit/stats.go
@@ -39,7 +39,7 @@ func (s *server) commitStats(ctx context.Context, in *gitalypb.CommitStatsReques
 	var args []string
 
 	if len(commit.GetParentIds()) == 0 {
-		args = append(args, git.EmptyTreeOID.String(), commit.Id)
+		args = append(args, git.ObjectHashSHA1.EmptyTreeOID.String(), commit.Id)
 	} else {
 		args = append(args, commit.Id+"^", commit.Id)
 	}
diff --git a/internal/gitaly/service/ref/find_all_tags_test.go b/internal/gitaly/service/ref/find_all_tags_test.go
index 4396c8a99..53726710b 100644
--- a/internal/gitaly/service/ref/find_all_tags_test.go
+++ b/internal/gitaly/service/ref/find_all_tags_test.go
@@ -249,7 +249,7 @@ func TestFindAllTags_simpleNestedTags(t *testing.T) {
 					Body:     []byte("message"),
 					BodySize: 7,
 					Subject:  []byte("message"),
-					TreeId:   git.EmptyTreeOID.String(),
+					TreeId:   git.ObjectHashSHA1.EmptyTreeOID.String(),
 					Author: &gitalypb.CommitAuthor{
 						Name:     []byte("Scrooge McDuck"),
 						Email:    []byte("scrooge@mcduck.com"),
diff --git a/internal/gitaly/service/repository/raw_changes.go b/internal/gitaly/service/repository/raw_changes.go
index ab7956440..4fb96257f 100644
--- a/internal/gitaly/service/repository/raw_changes.go
+++ b/internal/gitaly/service/repository/raw_changes.go
@@ -59,7 +59,7 @@ func (s *server) getRawChanges(stream gitalypb.RepositoryService_GetRawChangesSe
 	}
 
 	if git.ObjectID(from).IsZeroOID() {
-		from = git.EmptyTreeOID.String()
+		from = git.ObjectHashSHA1.EmptyTreeOID.String()
 	}
 
 	ctx := stream.Context()