[src/trunk]: src/sbin/fdisk Add -g flag to preserve GPT headers when updating...

[jmcneill <jmcneill%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/a562b7d1822a
branches:  trunk
changeset: 933319:a562b7d1822a
user:      jmcneill <jmcneill%NetBSD.org@localhost>
date:      Sun May 24 18:42:48 2020 +0000

description:
Add -g flag to preserve GPT headers when updating MBR.

diffstat:

 sbin/fdisk/fdisk.8 |  12 ++++++++----
 sbin/fdisk/fdisk.c |  13 ++++++++++---
 2 files changed, 18 insertions(+), 7 deletions(-)

diffs (96 lines):

diff -r 4de1c85260f0 -r a562b7d1822a sbin/fdisk/fdisk.8
--- a/sbin/fdisk/fdisk.8        Sun May 24 18:42:20 2020 +0000
+++ b/sbin/fdisk/fdisk.8        Sun May 24 18:42:48 2020 +0000
@@ -1,6 +1,6 @@
-.\"    $NetBSD: fdisk.8,v 1.90 2019/12/15 11:49:28 wiz Exp $
+.\"    $NetBSD: fdisk.8,v 1.91 2020/05/24 18:42:48 jmcneill Exp $
 .\"
-.Dd December 14, 2019
+.Dd May 24, 2020
 .Dt FDISK 8
 .Os
 .Sh NAME
@@ -8,7 +8,7 @@
 .Nd MS-DOS partition maintenance program
 .Sh SYNOPSIS
 .Nm
-.Op Fl aBFfIiSuv
+.Op Fl aBFfgIiSuv
 .Oo
 .Fl 0 | 1 | 2 | 3 | E Ar number
 .Op Fl s Oo Ar id Oc Ns Oo / Ns Oo Ar start Oc Ns Oo / Ns Oo Ar size Oc Ns Oo / Ns Oo Ar bootmenu Oc Oc Oc Oc
@@ -114,7 +114,9 @@
 If partition data is going to be updated and the disk carries GUID Partition
 Tables,
 .Nm
-will remove both primary and backup GPT headers from the disk.
+will remove both primary and backup GPT headers from the disk unless the
+.Fl g
+flag is specified.
 See
 .Xr gpt 8
 for information on how to manipulate GUID Partition Tables.
@@ -262,6 +264,8 @@
 fields
 .Pq only Ar start No and Ar size No can be specified by Fl s No option .
 They will be automatically computed using the BIOS geometry.
+.It Fl g
+Preserve existing GPT headers when updating partitions.
 .It Fl I
 Ignore errors from overlapping partitions.
 Some devices (cameras CHDK) require overlapping partitions to support
diff -r 4de1c85260f0 -r a562b7d1822a sbin/fdisk/fdisk.c
--- a/sbin/fdisk/fdisk.c        Sun May 24 18:42:20 2020 +0000
+++ b/sbin/fdisk/fdisk.c        Sun May 24 18:42:48 2020 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: fdisk.c,v 1.157 2019/10/07 20:56:07 christos Exp $ */
+/*     $NetBSD: fdisk.c,v 1.158 2020/05/24 18:42:48 jmcneill Exp $ */
 
 /*
  * Mach Operating System
@@ -39,7 +39,7 @@
 #include <sys/cdefs.h>
 
 #ifndef lint
-__RCSID("$NetBSD: fdisk.c,v 1.157 2019/10/07 20:56:07 christos Exp $");
+__RCSID("$NetBSD: fdisk.c,v 1.158 2020/05/24 18:42:48 jmcneill Exp $");
 #endif /* not lint */
 
 #define MBRPTYPENAMES
@@ -141,7 +141,7 @@
 #define BOOTSEL_OPTIONS        
 #define change_part(e, p, id, st, sz, bm) change__part(e, p, id, st, sz)
 #endif
-#define OPTIONS        BOOTSEL_OPTIONS "0123FSafiIluvA:b:c:E:r:s:w:z:"
+#define OPTIONS        BOOTSEL_OPTIONS "0123FSafgiIluvA:b:c:E:r:s:w:z:"
 
 /*
  * Disk geometry and partition alignment.
@@ -215,6 +215,7 @@
 static int v_flag;             /* more verbose */
 static int sh_flag;            /* Output data as shell defines */
 static int f_flag;             /* force --not interactive */
+static int g_flag;             /* preserve GPT headers */
 static int s_flag;             /* set id,offset,size */
 static int b_flag;             /* Set cyl, heads, secs (as c/h/s) */
 static int B_flag;             /* Edit/install bootselect code */
@@ -430,6 +431,9 @@
                case 'f':       /* Non interactive */
                        f_flag = 1;
                        break;
+               case 'g':       /* Preserve GPT headers */
+                       g_flag = 1;
+                       break;
                case 'i':       /* Always update bootcode */
                        i_flag = 1;
                        break;
@@ -3058,6 +3062,9 @@
        char buf[512];
        struct gpt_hdr *hdr = (void *)buf;
 
+       if (g_flag)
+               return 0;       /* preserve existing GPT headers */
+
        if (gptp->hdr_size == 0)
                return 0;