1 files changed, 43 insertions, 0 deletions
diff --git a/replace-object.h b/replace-object.h
new file mode 100644
index 0000000000..3fbc32eb7b
--- /dev/null
+++ b/replace-object.h
@@ -0,0 +1,43 @@
+#ifndef REPLACE_OBJECT_H
+#define REPLACE_OBJECT_H
+
+#include "oidmap.h"
+#include "repository.h"
+#include "object-store.h"
+
+struct replace_object {
+	struct oidmap_entry original;
+	struct object_id replacement;
+};
+
+void prepare_replace_object(struct repository *r);
+
+/*
+ * This internal function is only declared here for the benefit of
+ * lookup_replace_object().  Please do not call it directly.
+ */
+const struct object_id *do_lookup_replace_object(struct repository *r,
+						 const struct object_id *oid);
+
+/*
+ * If object sha1 should be replaced, return the replacement object's
+ * name (replaced recursively, if necessary).  The return value is
+ * either sha1 or a pointer to a permanently-allocated value.  When
+ * object replacement is suppressed, always return sha1.
+ *
+ * Note: some thread debuggers might point a data race on the
+ * replace_map_initialized reading in this function. However, we know there's no
+ * problem in the value being updated by one thread right after another one read
+ * it here (and it should be written to only once, anyway).
+ */
+static inline const struct object_id *lookup_replace_object(struct repository *r,
+							    const struct object_id *oid)
+{
+	if (!read_replace_refs ||
+	    (r->objects->replace_map_initialized &&
+	     r->objects->replace_map->map.tablesize == 0))
+		return oid;
+	return do_lookup_replace_object(r, oid);
+}
+
+#endif /* REPLACE_OBJECT_H */