refs.c: change resolve_ref_unsafe reading argument to be a flags field

resolve_ref_unsafe takes a boolean argument for reading (a nonexistent ref
resolves successfully for writing but not for reading).  Change this to be
a flags field instead, and pass the new constant RESOLVE_REF_READING when
we want this behaviour.

While at it, swap two of the arguments in the function to put output
arguments at the end.  As a nice side effect, this ensures that we can
catch callers that were unaware of the new API so they can be audited.

Give the wrapper functions resolve_refdup and read_ref_full the same
treatment for consistency.

Signed-off-by: Ronnie Sahlberg <sahlberg@google.com>
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/remote.c b/remote.c
index ce785f8..f624217 100644
--- a/remote.c
+++ b/remote.c
@@ -508,7 +508,7 @@
 		return;
 	default_remote_name = "origin";
 	current_branch = NULL;
-	head_ref = resolve_ref_unsafe("HEAD", sha1, 0, &flag);
+	head_ref = resolve_ref_unsafe("HEAD", 0, sha1, &flag);
 	if (head_ref && (flag & REF_ISSYMREF) &&
 	    skip_prefix(head_ref, "refs/heads/", &head_ref)) {
 		current_branch = make_branch(head_ref, 0);
@@ -1138,7 +1138,8 @@
 	struct strbuf buf = STRBUF_INIT;
 	unsigned char sha1[20];
 
-	const char *r = resolve_ref_unsafe(peer->name, sha1, 1, NULL);
+	const char *r = resolve_ref_unsafe(peer->name, RESOLVE_REF_READING,
+					   sha1, NULL);
 	if (!r)
 		return NULL;
 
@@ -1199,7 +1200,9 @@
 		unsigned char sha1[20];
 		int flag;
 
-		dst_value = resolve_ref_unsafe(matched_src->name, sha1, 1, &flag);
+		dst_value = resolve_ref_unsafe(matched_src->name,
+					       RESOLVE_REF_READING,
+					       sha1, &flag);
 		if (!dst_value ||
 		    ((flag & REF_ISSYMREF) &&
 		     !starts_with(dst_value, "refs/heads/")))
@@ -1673,7 +1676,7 @@
 	unsigned char sha1[20];
 	int flag;
 
-	if (!resolve_ref_unsafe(refname, sha1, 0, &flag))
+	if (!resolve_ref_unsafe(refname, 0, sha1, &flag))
 		return 0; /* non-existing refs are OK */
 	return (flag & REF_ISSYMREF);
 }