Ensure that the '-i' command line option and the 'reinit [mbr]'

editing commnd completely remove any existing on-disk GPT header
when writing the MBR.

'-ig'/'reinit gpt' must be used to create GPT format.

Previous interactions between '-i', '-b' and overly clever
'reinit' produced surprising, inconsistent and incorrect
behaviour.

ok deraadt@ kettenis@

diff --git a/sbin/fdisk/cmd.c b/sbin/fdisk/cmd.c
index 542035d..fe7c21f 100644 (file)
--- a/sbin/fdisk/cmd.c
+++ b/sbin/fdisk/cmd.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: cmd.c,v 1.115 2021/06/14 17:34:06 krw Exp $   */
+/*     $OpenBSD: cmd.c,v 1.116 2021/06/16 15:40:47 krw Exp $   */
 
 /*
  * Copyright (c) 1997 Tobias Weingartner
@@ -45,9 +45,9 @@ int
 Xreinit(char *args, struct mbr *mbr)
 {
        struct dos_mbr dos_mbr;
-       int efi, dogpt;
+       int dogpt;
 
-       efi = MBR_protective_mbr(mbr);
+       dogpt = 0;
 
        if (strncasecmp(args, "gpt", 3) == 0)
                dogpt = 1;
@@ -56,10 +56,7 @@ Xreinit(char *args, struct mbr *mbr)
        else if (strlen(args) > 0) {
                printf("Unrecognized modifier '%s'\n", args);
                return (CMD_CONT);
-       } else if (efi != -1)
-               dogpt = 1;
-       else
-               dogpt = 0;
+       }
 
        MBR_make(&initial_mbr, &dos_mbr);
        MBR_parse(&dos_mbr, mbr->offset, mbr->reloffset, mbr);
@@ -455,8 +452,7 @@ Xwrite(char *args, struct mbr *mbr)
                        return (CMD_CONT);
                }
        } else {
-               /* Ensure any on-disk GPT headers are zeroed. */
-               MBR_zapgpt(&dos_mbr, DL_GETDSIZE(&dl) - 1);
+               GPT_zap_headers();
        }
 
        /* Refresh in memory copy to reflect what was just written. */

diff --git a/sbin/fdisk/fdisk.8 b/sbin/fdisk/fdisk.8
index 45bc95a..fb08358 100644 (file)
--- a/sbin/fdisk/fdisk.8
+++ b/sbin/fdisk/fdisk.8
@@ -1,4 +1,4 @@
-.\"    $OpenBSD: fdisk.8,v 1.96 2021/01/30 15:15:20 naddy Exp $
+.\"    $OpenBSD: fdisk.8,v 1.97 2021/06/16 15:40:47 krw Exp $
 .\"
 .\"
 .\" Copyright (c) 1997 Tobias Weingartner
@@ -15,7 +15,7 @@
 .\" ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 .\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 .\"
-.Dd $Mdocdate: January 30 2021 $
+.Dd $Mdocdate: June 16 2021 $
 .Dt FDISK 8
 .Os
 .Sh NAME
@@ -371,19 +371,11 @@ Display this manual page.
 .It Cm reinit Op Cm gpt | Cm mbr
 Initialize the currently selected, in-memory copy of the
 boot block.
+.Pp
+By default an MBR is initialized.
 If
 .Cm gpt
 is specified a protective MBR and a GPT are initialized.
-If
-.Cm mbr
-is specified only an MBR is initialized.
-If neither
-.Cm mbr
-nor
-.Cm gpt
-are specified then a protective MBR and a GPT are initialized if a protective
-MBR already exists.
-Otherwise only an MBR is initialized.
 .It Cm disk
 Display the current drive geometry that
 .Nm

diff --git a/sbin/fdisk/gpt.c b/sbin/fdisk/gpt.c
index f123d87..b54e27f 100644 (file)
--- a/sbin/fdisk/gpt.c
+++ b/sbin/fdisk/gpt.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: gpt.c,v 1.29 2021/06/14 12:46:47 krw Exp $    */
+/*     $OpenBSD: gpt.c,v 1.30 2021/06/16 15:40:47 krw Exp $    */
 /*
  * Copyright (c) 2015 Markus Muller <mmu@grummel.net>
  * Copyright (c) 2015 Kenneth R Westerback <krw@openbsd.org>
@@ -451,6 +451,35 @@ GPT_init(void)
        return rslt;
 }
 
+void
+GPT_zap_headers(void)
+{
+       char *secbuf;
+       uint64_t sig;
+
+       secbuf = DISK_readsector(GPTSECTOR);
+       if (secbuf == NULL)
+               return;
+
+       memcpy(&sig, secbuf, sizeof(sig));
+       if (letoh64(sig) == GPTSIGNATURE) {
+               memset(secbuf, 0, dl.d_secsize);
+               DISK_writesector(secbuf, GPTSECTOR);
+       }
+       free(secbuf);
+
+       secbuf = DISK_readsector(DL_GETDSIZE(&dl) - 1);
+       if (secbuf == NULL)
+               return;
+
+       memcpy(&sig, secbuf, sizeof(sig));
+       if (letoh64(sig) == GPTSIGNATURE) {
+               memset(secbuf, 0, dl.d_secsize);
+               DISK_writesector(secbuf, DL_GETDSIZE(&dl) - 1);
+       }
+       free(secbuf);
+}
+
 int
 GPT_write(void)
 {

diff --git a/sbin/fdisk/gpt.h b/sbin/fdisk/gpt.h
index 93a8e47..f349b81 100644 (file)
--- a/sbin/fdisk/gpt.h
+++ b/sbin/fdisk/gpt.h
@@ -1,4 +1,4 @@
-/*     $OpenBSD: gpt.h,v 1.11 2021/06/12 17:19:13 krw Exp $    */
+/*     $OpenBSD: gpt.h,v 1.12 2021/06/16 15:40:47 krw Exp $    */
 /*
  * Copyright (c) 2015 Markus Muller <mmu@grummel.net>
  * Copyright (c) 2015 Kenneth R Westerback <krw@openbsd.org>
@@ -22,6 +22,7 @@ int           GPT_get_lba_end(unsigned int);
 
 int            GPT_init(void);
 int            GPT_write(void);
+void           GPT_zap_headers(void);
 void           GPT_print(char *, int);
 void           GPT_print_part(int, char *, int);
 void           GPT_print_parthdr(int);

diff --git a/sbin/fdisk/mbr.c b/sbin/fdisk/mbr.c
index 7238204..27fe2e4 100644 (file)
--- a/sbin/fdisk/mbr.c
+++ b/sbin/fdisk/mbr.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: mbr.c,v 1.75 2021/06/10 15:30:49 krw Exp $    */
+/*     $OpenBSD: mbr.c,v 1.76 2021/06/16 15:40:47 krw Exp $    */
 
 /*
  * Copyright (c) 1997 Tobias Weingartner
@@ -247,50 +247,6 @@ MBR_write(off_t where, struct dos_mbr *dos_mbr)
        return (0);
 }
 
-/*
- * If *dos_mbr has a 0xee or 0xef partition, nothing needs to happen. If no
- * such partition is present but the first or last sector on the disk has a
- * GPT, zero the GPT to ensure the MBR takes priority and fewer BIOSes get
- * confused.
- */
-void
-MBR_zapgpt(struct dos_mbr *dos_mbr, uint64_t lastsec)
-{
-       struct dos_partition dos_parts[NDOSPART];
-       char *secbuf;
-       uint64_t sig;
-       int i;
-
-       memcpy(dos_parts, dos_mbr->dmbr_parts, sizeof(dos_parts));
-
-       for (i = 0; i < NDOSPART; i++)
-               if ((dos_parts[i].dp_typ == DOSPTYP_EFI) ||
-                   (dos_parts[i].dp_typ == DOSPTYP_EFISYS))
-                       return;
-
-       secbuf = DISK_readsector(GPTSECTOR);
-       if (secbuf == NULL)
-               return;
-
-       memcpy(&sig, secbuf, sizeof(sig));
-       if (letoh64(sig) == GPTSIGNATURE) {
-               memset(secbuf, 0, sizeof(sig));
-               DISK_writesector(secbuf, GPTSECTOR);
-       }
-       free(secbuf);
-
-       secbuf = DISK_readsector(lastsec);
-       if (secbuf == NULL)
-               return;
-
-       memcpy(&sig, secbuf, sizeof(sig));
-       if (letoh64(sig) == GPTSIGNATURE) {
-               memset(secbuf, 0, sizeof(sig));
-               DISK_writesector(secbuf, lastsec);
-       }
-       free(secbuf);
-}
-
 /*
  * Return the index into dp[] of the EFI GPT (0xEE) partition, or -1 if no such
  * partition exists.

diff --git a/sbin/fdisk/mbr.h b/sbin/fdisk/mbr.h
index 29b704c..ccc5541 100644 (file)
--- a/sbin/fdisk/mbr.h
+++ b/sbin/fdisk/mbr.h
@@ -1,4 +1,4 @@
-/*     $OpenBSD: mbr.h,v 1.30 2021/05/20 14:27:14 krw Exp $    */
+/*     $OpenBSD: mbr.h,v 1.31 2021/06/16 15:40:47 krw Exp $    */
 
 /*
  * Copyright (c) 1997 Tobias Weingartner
@@ -36,7 +36,6 @@ void MBR_init(struct mbr *);
 void MBR_init_GPT(struct mbr *);
 int MBR_read(off_t, struct dos_mbr *);
 int MBR_write(off_t, struct dos_mbr *);
-void MBR_zapgpt(struct dos_mbr *, uint64_t);
 int MBR_protective_mbr(struct mbr *);
 
 #endif /* _MBR_H */