rerere: use "struct rerere_id" instead of "char *" for conflict ID

This gives a thin abstraction between the conflict ID that is a hash
value obtained by inspecting the conflicts and the name of the
directory under $GIT_DIR/rr-cache/, in which the previous resolution
is recorded to be replayed.  The plan is to make sure that the
presence of the directory does not imply the presense of a previous
resolution and vice-versa, and later allow us to have more than one
pair of <preimage, postimage> for a given conflict ID.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 11 insertions, 1 deletions

diff --git a/rerere.h b/rerere.h
index f998ebae6e..ce545d0c04 100644
--- a/rerere.h
+++ b/rerere.h
@@ -15,9 +15,19 @@ struct pathspec;
  */
 extern void *RERERE_RESOLVED;
 
+struct rerere_id {
+	char hex[41];
+};
+
 extern int setup_rerere(struct string_list *, int);
 extern int rerere(int);
-extern const char *rerere_path(const char *id, const char *file);
+/*
+ * Given the conflict ID and the name of a "file" used for replaying
+ * the recorded resolution (e.g. "preimage", "postimage"), return the
+ * path to that filesystem entity.  With "file" specified with NULL,
+ * return the path to the directory that houses these files.
+ */
+extern const char *rerere_path(const struct rerere_id *, const char *file);
 extern int rerere_forget(struct pathspec *);
 extern int rerere_remaining(struct string_list *);
 extern void rerere_clear(struct string_list *);