lf_to_crlf_filter(): tell the caller we added "\n" when draining

This can only happen when the input size is multiple of the
buffer size of the cascade filter (16k) and ends with an LF,
but in such a case, the code forgot to tell the caller that
it added the "\n" it could not add during the last round.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

convert.c

@@ -879,7 +879,7 @@ int is_null_stream_filter(struct stream_filter *filter)
 
 struct lf_to_crlf_filter {
 	struct stream_filter filter;
-	int want_lf;
+	unsigned want_lf:1;
 };
 
 static int lf_to_crlf_filter_fn(struct stream_filter *filter,
@@ -895,8 +895,11 @@ static int lf_to_crlf_filter_fn(struct stream_filter *filter,
 		lf_to_crlf->want_lf = 0;
 	}
 
-	if (!input)
-		return 0; /* We've already dealt with the state */
+	/* We are told to drain */
+	if (!input) {
+		*osize_p -= o;
+		return 0;
+	}
 
 	count = *isize_p;
 	if (count) {
@@ -931,10 +934,9 @@ static struct stream_filter_vtbl lf_to_crlf_vtbl = {
 
 static struct stream_filter *lf_to_crlf_filter(void)
 {
-	struct lf_to_crlf_filter *lf_to_crlf = xmalloc(sizeof(*lf_to_crlf));
+	struct lf_to_crlf_filter *lf_to_crlf = xcalloc(1, sizeof(*lf_to_crlf));
 
 	lf_to_crlf->filter.vtbl = &lf_to_crlf_vtbl;
-	lf_to_crlf->want_lf = 0;
 	return (struct stream_filter *)lf_to_crlf;
 }