Merge branch 'kn/packed-refs-verbatim-write' into jch

The routine that rewrites the packed-refs file has been optimized to
directly pass unmodified reference records verbatim to the output
via fwrite(3p), instead of redundantly re-formatting them with
fprintf(3p).

* kn/packed-refs-verbatim-write:
  packed-refs: use `fwrite()` when passing refs verbatim

refs/packed-backend.c

@@ -879,6 +879,9 @@ struct packed_ref_iterator {
 	/* The current position in the snapshot's buffer: */
 	const char *pos;
 
+	/* The starting position of the current ref record. */
+	const char *record_start;
+
 	/* The end of the part of the buffer that will be iterated over: */
 	const char *eof;
 
@@ -933,6 +936,7 @@ static int next_record(struct packed_ref_iterator *iter)
 	if (iter->pos == iter->eof)
 		return ITER_DONE;
 
+	iter->record_start = iter->pos;
 	iter->base.ref.flags = REF_ISPACKED;
 	p = iter->pos;
 
@@ -1530,9 +1534,15 @@ static enum ref_transaction_error write_with_updates(struct packed_ref_store *re
 		}
 
 		if (cmp < 0) {
-			/* Pass the old reference through. */
-			if (write_packed_entry(out, iter->ref.name,
-					       iter->ref.oid, iter->ref.peeled_oid))
+			const struct packed_ref_iterator *packed_iter =
+				(const struct packed_ref_iterator *)iter;
+			size_t len = packed_iter->pos - packed_iter->record_start;
+
+			/*
+			 * Skip any formatting and directly write to the packed-refs file
+			 * when deleting references and writing the remaining refs verbatim.
+			 */
+			if (fwrite(packed_iter->record_start, len, 1, out) != 1)
 				goto write_error;
 
 			if ((ok = ref_iterator_advance(iter)) != ITER_OK) {