write_ref_to_lockfile(): new function, extracted from write_ref_sha1()

This is the first step towards separating the checking and writing of
the new reference value to committing the change.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/refs.c b/refs.c
index 6664423f8d402b98a3aae90c932f64cff4d88cb2..9e40c35cf5d8816a8ae79caff09443e009321540 100644 (file)
--- a/refs.c
+++ b/refs.c
@@ -3048,23 +3048,15 @@ int is_branch(const char *refname)
 }
 
 /*
- * Write sha1 into the ref specified by the lock. Make sure that errno
- * is sane on error.
+ * Write sha1 into the open lockfile, then close the lockfile. On
+ * errors, rollback the lockfile and set errno to reflect the problem.
  */
-static int write_ref_sha1(struct ref_lock *lock,
-       const unsigned char *sha1, const char *logmsg)
+static int write_ref_to_lockfile(struct ref_lock *lock,
+                                const unsigned char *sha1)
 {
        static char term = '\n';
        struct object *o;
 
-       if (!lock) {
-               errno = EINVAL;
-               return -1;
-       }
-       if (!lock->force_write && !hashcmp(lock->old_sha1, sha1)) {
-               unlock_ref(lock);
-               return 0;
-       }
        o = parse_object(sha1);
        if (!o) {
                error("Trying to write ref %s with nonexistent object %s",
@@ -3089,6 +3081,28 @@ static int write_ref_sha1(struct ref_lock *lock,
                errno = save_errno;
                return -1;
        }
+       return 0;
+}
+
+/*
+ * Write sha1 into the ref specified by the lock. Make sure that errno
+ * is sane on error.
+ */
+static int write_ref_sha1(struct ref_lock *lock,
+       const unsigned char *sha1, const char *logmsg)
+{
+       if (!lock) {
+               errno = EINVAL;
+               return -1;
+       }
+       if (!lock->force_write && !hashcmp(lock->old_sha1, sha1)) {
+               unlock_ref(lock);
+               return 0;
+       }
+
+       if (write_ref_to_lockfile(lock, sha1))
+               return -1;
+
        clear_loose_ref_cache(&ref_cache);
        if (log_ref_write(lock->ref_name, lock->old_sha1, sha1, logmsg) < 0 ||
            (strcmp(lock->ref_name, lock->orig_ref_name) &&