Function write_with_updates

refs/packed-backend.c:1358–1573

* Write the packed refs from the current snapshot to the packed-refs * tempfile, incorporating any changes from `updates`. `updates` must * be a sorted string list whose keys are the refnames and whose util * values are `struct ref_update *`. On error, rollback the tempfile, * write an error message to `err`, and return a nonzero value. * * The packfile must be locked before calling this fun

 * remain locked when it is done.
 */
static enum ref_transaction_error write_with_updates(struct packed_ref_store *refs,
						     struct ref_transaction *transaction,
						     struct strbuf *err)
{
	enum ref_transaction_error ret = REF_TRANSACTION_ERROR_GENERIC;
	struct string_list *updates = &transaction->refnames;
	struct ref_iterator *iter = NULL;
	size_t i;
	int ok;
	FILE *out;
	struct strbuf sb = STRBUF_INIT;
	char *packed_refs_path;

	if (!is_lock_file_locked(&refs->lock))
		BUG("write_with_updates() called while unlocked");

	/*
	 * If packed-refs is a symlink, we want to overwrite the
	 * symlinked-to file, not the symlink itself. Also, put the
	 * staging file next to it:
	 */
	packed_refs_path = get_locked_file_path(&refs->lock);
	strbuf_addf(&sb, "%s.new", packed_refs_path);
	free(packed_refs_path);
	refs->tempfile = create_tempfile(sb.buf);
	if (!refs->tempfile) {
		strbuf_addf(err, "unable to create file %s: %s",
			    sb.buf, strerror(errno));
		strbuf_release(&sb);
		return REF_TRANSACTION_ERROR_GENERIC;
	}
	strbuf_release(&sb);

	out = fdopen_tempfile(refs->tempfile, "w");
	if (!out) {
		strbuf_addf(err, "unable to fdopen packed-refs tempfile: %s",
			    strerror(errno));
		goto error;
	}

	if (fprintf(out, "%s", PACKED_REFS_HEADER) < 0)
		goto write_error;

	/*
	 * We iterate in parallel through the current list of refs and
	 * the list of updates, processing an entry from at least one
	 * of the lists each time through the loop. When the current
	 * list of refs is exhausted, set iter to NULL. When the list
	 * of updates is exhausted, leave i set to updates->nr.
	 */
	iter = packed_ref_iterator_begin(&refs->base, "", NULL,
					 REFS_FOR_EACH_INCLUDE_BROKEN);
	if ((ok = ref_iterator_advance(iter)) != ITER_OK) {
		ref_iterator_free(iter);
		iter = NULL;
	}

	i = 0;