[PATCH v2 1/2] rebase: refactor dwim_ref_or_die from merge-base.c

[Alex Torok <alext9@gmail.com>]

Pull logic for getting the full dwim ref name from a passed in ref name
out of the handle_fork_point function of merge-base.c. This will allow
git-rebase --fork-point to use the same method for getting the full ref
name before calling get_fork_point.

I saw other *_or_die methods in other places and using that pattern
seemed sane here.

I'm not 100% sure about the name or signature of dwim_ref_or_die. I feel
like it should be named something like dwim_ref_name_or_die,
unique_dwim_ref_or_die, or should be including the object_id argument
even though it isn't used by the calling merge_base code, and won't be
used in rebase.

This is my first patch submission for git, and I'd appreciate some
feedback on naming/style wrt to this.

Signed-off-by: Alex Torok <alext9@gmail.com>
---
 builtin/merge-base.c |  9 +--------
 refs.c               | 14 ++++++++++++++
 refs.h               |  1 +
 3 files changed, 16 insertions(+), 8 deletions(-)

diff --git a/builtin/merge-base.c b/builtin/merge-base.c
index e3f8da13b6..edd16f9fcd 100644
--- a/builtin/merge-base.c
+++ b/builtin/merge-base.c
@@ -118,14 +118,7 @@ static int handle_fork_point(int argc, const char **argv)
 	struct commit *derived, *fork_point;
 	const char *commitname;
 
-	switch (dwim_ref(argv[0], strlen(argv[0]), &oid, &refname)) {
-	case 0:
-		die("No such ref: '%s'", argv[0]);
-	case 1:
-		break; /* good */
-	default:
-		die("Ambiguous refname: '%s'", argv[0]);
-	}
+	dwim_ref_or_die(argv[0], strlen(argv[0]), &refname);
 
 	commitname = (argc == 2) ? argv[1] : "HEAD";
 	if (get_oid(commitname, &oid))
diff --git a/refs.c b/refs.c
index 1ab0bb54d3..3b778f2df9 100644
--- a/refs.c
+++ b/refs.c
@@ -639,6 +639,20 @@ int dwim_ref(const char *str, int len, struct object_id *oid, char **ref)
 	return repo_dwim_ref(the_repository, str, len, oid, ref);
 }
 
+void dwim_ref_or_die(const char *str, int len, char **ref)
+{
+	struct object_id discard;
+	switch (dwim_ref(str, len, &discard, ref)) {
+	case 0:
+		die("No such ref: '%s'", str);
+	case 1:
+		break; /* good */
+	default:
+		die("Ambiguous refname: '%s'", str);
+	}
+}
+
+
 int expand_ref(struct repository *repo, const char *str, int len,
 	       struct object_id *oid, char **ref)
 {
diff --git a/refs.h b/refs.h
index 730d05ad91..a961662382 100644
--- a/refs.h
+++ b/refs.h
@@ -154,6 +154,7 @@ int repo_dwim_log(struct repository *r, const char *str, int len, struct object_
 int dwim_ref(const char *str, int len, struct object_id *oid, char **ref);
 int dwim_log(const char *str, int len, struct object_id *oid, char **ref);
 
+void dwim_ref_or_die(const char *str, int len, char **ref);
 /*
  * A ref_transaction represents a collection of reference updates that
  * should succeed or fail together.
-- 
2.17.1