Add another epicycle to -A processing that ensures ONLY the

partition table is changed. Not the GPT header. Not the MBR. And
only write back as much partition table information as the header
claims to have room for.

At a minimum should make -A safer when operating on the Apple M1
GPT.

A major overhaul of this code is urgently needed before someone
sneezes too hard in its vicinity.

Feedback kettenis@ & ok deraadt@

1 files changed, 4 insertions, 4 deletions

diff --git a/sbin/fdisk/fdisk.c b/sbin/fdisk/fdisk.c
index b1f3870a964..59a43da8daf 100644
--- a/sbin/fdisk/fdisk.c
+++ b/sbin/fdisk/fdisk.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: fdisk.c,v 1.113 2021/06/25 19:24:53 krw Exp $	*/
+/*	$OpenBSD: fdisk.c,v 1.114 2021/06/28 19:50:30 krw Exp $	*/
 
 /*
  * Copyright (c) 1997 Tobias Weingartner
@@ -222,14 +222,14 @@ main(int argc, char *argv[])
 		if (letoh64(gh.gh_sig) != GPTSIGNATURE)
 			errx(1, "-A requires a valid GPT");
 		else {
-			MBR_init_GPT(&initial_mbr);
-			GPT_init();
+			initial_mbr = mbr;	/* Keep current MBR. */
+			GPT_init(GPONLY, b_sectors);
 			query = "Do you wish to write new GPT?";
 		}
 	} else if (i_flag) {
 		if (g_flag) {
 			MBR_init_GPT(&initial_mbr);
-			GPT_init();
+			GPT_init(GHANDGP, b_sectors);
 			query = "Do you wish to write new GPT?";
 		} else {
 			memset(&gh, 0, sizeof(gh));