From dfc9c1d4937d0e2eab2910665069faba814bca1e Mon Sep 17 00:00:00 2001
From: Emmanuel Vadot <manu@FreeBSD.org>
Date: Thu, 30 Dec 2021 09:47:06 +0100
Subject: [PATCH] loader: tftp: Copy the first block into the cache

tftp_open reads the first block so copy it in the cached data.
If we have more than one block (i.e. we called tftp_read before
tftp_preload) simply just reset the transfer.

Reported by:	mmel
Reviewed by:	mmel, tsoome
MFC after:	2 weeks
Sponsored by:	Beckhoff Automation GmbH & Co. KG
Differential Revision:	https://reviews.freebsd.org/D33697
---
 stand/libsa/tftp.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/stand/libsa/tftp.c b/stand/libsa/tftp.c
index 9d1c70236925..c520a9e3b3b1 100644
--- a/stand/libsa/tftp.c
+++ b/stand/libsa/tftp.c
@@ -680,6 +680,13 @@ tftp_preload(struct open_file *f)
 	start = getsecs();
 	printf("Preloading %s ", tftpfile->path);
 #endif
+	if (tftpfile->currblock == 1)
+		bcopy(tftpfile->tftp_hdr->th_data,
+		    cache,
+		    tftpfile->validsize);
+	else
+		tftpfile->currblock = 0;
+
 	while (tftpfile->islastblock == 0) {
 		twiddle(32);
 		rc = tftp_getnextblock(tftpfile);