catfile: Detect object hash used by repository

The catfile package needs to parse object hashes in multiple locations
and thus needs to know about the object hash format used by a specific
repository. Detect the object hash at runtime to support both SHA1 and
SHA256 repositories.

3 files changed, 24 insertions, 6 deletions

diff --git a/internal/git/catfile/object_info_reader.go b/internal/git/catfile/object_info_reader.go
index 62e714e5b..595f6d52e 100644
--- a/internal/git/catfile/object_info_reader.go
+++ b/internal/git/catfile/object_info_reader.go
@@ -126,7 +126,8 @@ type ObjectInfoQueue interface {
 // long-lived  `git cat-file --batch-check` process such that we do not have to spawn a separate
 // process per object info we're about to read.
 type objectInfoReader struct {
-	cmd *command.Command
+	cmd        *command.Command
+	objectHash git.ObjectHash
 
 	counter *prometheus.CounterVec
 
@@ -153,12 +154,19 @@ func newObjectInfoReader(
 		return nil, err
 	}
 
+	objectHash, err := repo.ObjectHash(ctx)
+	if err != nil {
+		return nil, fmt.Errorf("detecting object hash: %w", err)
+	}
+
 	objectInfoReader := &objectInfoReader{
-		cmd:     batchCmd,
-		counter: counter,
+		cmd:        batchCmd,
+		objectHash: objectHash,
+		counter:    counter,
 		queue: requestQueue{
-			stdout: bufio.NewReader(batchCmd),
-			stdin:  bufio.NewWriter(batchCmd),
+			objectHash: objectHash,
+			stdout:     bufio.NewReader(batchCmd),
+			stdin:      bufio.NewWriter(batchCmd),
 		},
 	}
 
diff --git a/internal/git/catfile/object_reader.go b/internal/git/catfile/object_reader.go
index 516050301..243e70865 100644
--- a/internal/git/catfile/object_reader.go
+++ b/internal/git/catfile/object_reader.go
@@ -73,10 +73,16 @@ func newObjectReader(
 		return nil, err
 	}
 
+	objectHash, err := repo.ObjectHash(ctx)
+	if err != nil {
+		return nil, fmt.Errorf("detecting object hash: %w", err)
+	}
+
 	objectReader := &objectReader{
 		cmd:     batchCmd,
 		counter: counter,
 		queue: requestQueue{
+			objectHash:    objectHash,
 			isObjectQueue: true,
 			stdout:        bufio.NewReader(batchCmd),
 			stdin:         bufio.NewWriter(batchCmd),
diff --git a/internal/git/catfile/request_queue.go b/internal/git/catfile/request_queue.go
index 634e30332..232d731b1 100644
--- a/internal/git/catfile/request_queue.go
+++ b/internal/git/catfile/request_queue.go
@@ -21,6 +21,10 @@ const (
 )
 
 type requestQueue struct {
+	// objectHash is the object hash used by the repository the request queue has been
+	// spawned for.
+	objectHash git.ObjectHash
+
 	// outstandingRequests is the number of requests which have been queued up. Gets incremented
 	// on request, and decremented when starting to read an object (not when that object has
 	// been fully consumed).
@@ -212,5 +216,5 @@ func (q *requestQueue) readInfo() (*ObjectInfo, error) {
 		return nil, fmt.Errorf("concurrent read on request queue")
 	}
 
-	return ParseObjectInfo(git.ObjectHashSHA1, q.stdout)
+	return ParseObjectInfo(q.objectHash, q.stdout)
 }