1 files changed, 63 insertions, 0 deletions
diff --git a/replace-object.h b/replace-object.h
new file mode 100644
index 0000000..66c41b9
--- /dev/null
+++ b/replace-object.h
@@ -0,0 +1,63 @@
+#ifndef REPLACE_OBJECT_H
+#define REPLACE_OBJECT_H
+
+#include "oidmap.h"
+#include "repository.h"
+#include "object-store-ll.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);
+
+/*
+ * Some commands disable replace-refs unconditionally, and otherwise each
+ * repository could alter the core.useReplaceRefs config value.
+ *
+ * Return 1 if and only if all of the following are true:
+ *
+ *  a. disable_replace_refs() has not been called.
+ *  b. GIT_NO_REPLACE_OBJECTS is unset or zero.
+ *  c. the given repository does not have core.useReplaceRefs=false.
+ */
+int replace_refs_enabled(struct repository *r);
+
+/*
+ * 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 (!replace_refs_enabled(r) ||
+	    (r->objects->replace_map_initialized &&
+	     r->objects->replace_map->map.tablesize == 0))
+		return oid;
+	return do_lookup_replace_object(r, oid);
+}
+
+/*
+ * Some commands override config and environment settings for using
+ * replace references. Use this method to disable the setting and ensure
+ * those other settings will not override this choice. This applies
+ * globally to all in-process repositories.
+ */
+void disable_replace_refs(void);
+
+#endif /* REPLACE_OBJECT_H */