refs: add REF_FORCE_CREATE_REFLOG flag

Add a flag to allow forcing the creation of a reflog even if the ref
name and core.logAllRefUpdates setting would not ordinarily cause ref
creation.

In a moment, we will use this to add options to git tag and git
update-ref to force reflog creation.

Signed-off-by: David Turner <dturner@twopensource.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

2 files changed, 22 insertions, 13 deletions

diff --git a/refs.c b/refs.c
index 57074b555c..97a75f3c31 100644
--- a/refs.c
+++ b/refs.c
@@ -63,6 +63,11 @@ static unsigned char refname_disposition[256] = {
 #define REF_NEEDS_COMMIT 0x20
 
 /*
+ * 0x40 is REF_FORCE_CREATE_REFLOG, so skip it if you're adding a
+ * value to ref_update::flags
+ */
+
+/*
  * Try to read one refname component from the front of refname.
  * Return the length of the component found, or -1 if the component is
  * not legal.  It is legal if it is something reasonable to have under
@@ -2914,7 +2919,7 @@ static int write_ref_to_lockfile(struct ref_lock *lock,
 				 const unsigned char *sha1, struct strbuf *err);
 static int commit_ref_update(struct ref_lock *lock,
 			     const unsigned char *sha1, const char *logmsg,
-			     struct strbuf *err);
+			     int flags, struct strbuf *err);
 
 int rename_ref(const char *oldrefname, const char *newrefname, const char *logmsg)
 {
@@ -2976,7 +2981,7 @@ int rename_ref(const char *oldrefname, const char *newrefname, const char *logms
 	hashcpy(lock->old_oid.hash, orig_sha1);
 
 	if (write_ref_to_lockfile(lock, orig_sha1, &err) ||
-	    commit_ref_update(lock, orig_sha1, logmsg, &err)) {
+	    commit_ref_update(lock, orig_sha1, logmsg, 0, &err)) {
 		error("unable to write current sha1 into %s: %s", newrefname, err.buf);
 		strbuf_release(&err);
 		goto rollback;
@@ -2995,7 +3000,7 @@ int rename_ref(const char *oldrefname, const char *newrefname, const char *logms
 	flag = log_all_ref_updates;
 	log_all_ref_updates = 0;
 	if (write_ref_to_lockfile(lock, orig_sha1, &err) ||
-	    commit_ref_update(lock, orig_sha1, NULL, &err)) {
+	    commit_ref_update(lock, orig_sha1, NULL, 0, &err)) {
 		error("unable to write current sha1 into %s: %s", oldrefname, err.buf);
 		strbuf_release(&err);
 	}
@@ -3152,7 +3157,8 @@ static int log_ref_write_fd(int fd, const unsigned char *old_sha1,
 
 static int log_ref_write_1(const char *refname, const unsigned char *old_sha1,
 			   const unsigned char *new_sha1, const char *msg,
-			   struct strbuf *sb_log_file, struct strbuf *err)
+			   struct strbuf *sb_log_file, int flags,
+			   struct strbuf *err)
 {
 	int logfd, result, oflags = O_APPEND | O_WRONLY;
 	char *log_file;
@@ -3160,7 +3166,7 @@ static int log_ref_write_1(const char *refname, const unsigned char *old_sha1,
 	if (log_all_ref_updates < 0)
 		log_all_ref_updates = !is_bare_repository();
 
-	result = log_ref_setup(refname, sb_log_file, err, 0);
+	result = log_ref_setup(refname, sb_log_file, err, flags & REF_FORCE_CREATE_REFLOG);
 
 	if (result)
 		return result;
@@ -3189,10 +3195,11 @@ static int log_ref_write_1(const char *refname, const unsigned char *old_sha1,
 
 static int log_ref_write(const char *refname, const unsigned char *old_sha1,
 			 const unsigned char *new_sha1, const char *msg,
-			 struct strbuf *err)
+			 int flags, struct strbuf *err)
 {
 	struct strbuf sb = STRBUF_INIT;
-	int ret = log_ref_write_1(refname, old_sha1, new_sha1, msg, &sb, err);
+	int ret = log_ref_write_1(refname, old_sha1, new_sha1, msg, &sb, flags,
+				  err);
 	strbuf_release(&sb);
 	return ret;
 }
@@ -3246,12 +3253,12 @@ static int write_ref_to_lockfile(struct ref_lock *lock,
  */
 static int commit_ref_update(struct ref_lock *lock,
 			     const unsigned char *sha1, const char *logmsg,
-			     struct strbuf *err)
+			     int flags, struct strbuf *err)
 {
 	clear_loose_ref_cache(&ref_cache);
-	if (log_ref_write(lock->ref_name, lock->old_oid.hash, sha1, logmsg, err) < 0 ||
+	if (log_ref_write(lock->ref_name, lock->old_oid.hash, sha1, logmsg, flags, err) < 0 ||
 	    (strcmp(lock->ref_name, lock->orig_ref_name) &&
-	     log_ref_write(lock->orig_ref_name, lock->old_oid.hash, sha1, logmsg, err) < 0)) {
+	     log_ref_write(lock->orig_ref_name, lock->old_oid.hash, sha1, logmsg, flags, err) < 0)) {
 		char *old_msg = strbuf_detach(err, NULL);
 		strbuf_addf(err, "Cannot update the ref '%s': %s",
 			    lock->ref_name, old_msg);
@@ -3281,7 +3288,7 @@ static int commit_ref_update(struct ref_lock *lock,
 		    !strcmp(head_ref, lock->ref_name)) {
 			struct strbuf log_err = STRBUF_INIT;
 			if (log_ref_write("HEAD", lock->old_oid.hash, sha1,
-					  logmsg, &log_err)) {
+					  logmsg, 0, &log_err)) {
 				error("%s", log_err.buf);
 				strbuf_release(&log_err);
 			}
@@ -3355,7 +3362,7 @@ int create_symref(const char *ref_target, const char *refs_heads_master,
 	done:
 #endif
 	if (logmsg && !read_ref(refs_heads_master, new_sha1) &&
-		log_ref_write(ref_target, old_sha1, new_sha1, logmsg, &err)) {
+		log_ref_write(ref_target, old_sha1, new_sha1, logmsg, 0, &err)) {
 		error("%s", err.buf);
 		strbuf_release(&err);
 	}
@@ -4032,7 +4039,8 @@ int ref_transaction_commit(struct ref_transaction *transaction,
 
 		if (update->flags & REF_NEEDS_COMMIT) {
 			if (commit_ref_update(update->lock,
-					      update->new_sha1, update->msg, err)) {
+					      update->new_sha1, update->msg,
+					      update->flags, err)) {
 				/* freed by commit_ref_update(): */
 				update->lock = NULL;
 				ret = TRANSACTION_GENERIC_ERROR;
diff --git a/refs.h b/refs.h
index de68a452b7..4f1b236568 100644
--- a/refs.h
+++ b/refs.h
@@ -187,6 +187,7 @@ extern int peel_ref(const char *refname, unsigned char *sha1);
  * Other flags are reserved for internal use.
  */
 #define REF_NODEREF	0x01
+#define REF_FORCE_CREATE_REFLOG 0x40
 
 /*
  * Setup reflog before using. Fill in err and return -1 on failure.