Revert incorrect tweaks to disk geometry calculations and

non '-b' MBR disk initialization.

Detected by bluhm@'s ever vigilant regress testing.

diff --git a/sbin/fdisk/disk.c b/sbin/fdisk/disk.c
index 60a9d3d..ee1111a 100644 (file)
--- a/sbin/fdisk/disk.c
+++ b/sbin/fdisk/disk.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: disk.c,v 1.67 2021/07/17 14:16:34 krw Exp $   */
+/*     $OpenBSD: disk.c,v 1.68 2021/07/19 14:30:08 krw Exp $   */
 
 /*
  * Copyright (c) 1997 Tobias Weingartner
@@ -64,29 +64,33 @@ DISK_open(const char *name, const int oflags)
        /* Set geometry to use in MBR partitions. */
        if (disk.dk_size > 0) {
                /* -l has set disk size. */
-               sz = DL_BLKTOSEC(&dl, disk.dk_size);
+               sz = disk.dk_size;
                disk.dk_heads = 1;
                disk.dk_sectors = 64;
+               disk.dk_size = DL_BLKTOSEC(&dl, sz);
+               disk.dk_cylinders = disk.dk_size / disk.dk_sectors;
        } else if (disk.dk_cylinders > 0) {
-               /* -c/-h/-c has set disk geometry. */
+               /* -c/-h/-s has set disk geometry & therefore size. */
                sz = disk.dk_cylinders * disk.dk_heads * disk.dk_sectors;
-               sz = DL_BLKTOSEC(&dl, sz);
+               disk.dk_size = DL_BLKTOSEC(&dl, sz);
                disk.dk_sectors = DL_BLKTOSEC(&dl, disk.dk_sectors);
        } else {
-               sz = DL_GETDSIZE(&dl);
+               disk.dk_sectors = dl.d_nsectors;
+               disk.dk_cylinders = dl.d_ncylinders;
                disk.dk_heads = dl.d_ntracks;
                disk.dk_sectors = dl.d_nsectors;
+               /* MBR handles only first UINT32_MAX sectors. */
+               spc = (uint64_t)disk.dk_heads * disk.dk_sectors;
+               sz = DL_GETDSIZE(&dl);
+               if (sz > UINT32_MAX) {
+                       disk.dk_cylinders = UINT32_MAX / spc;
+                       disk.dk_size = disk.dk_cylinders * spc;
+               } else
+                       disk.dk_size = sz;
        }
 
-       if (sz > UINT32_MAX)
-               sz = UINT32_MAX;        /* MBR knows nothing > UINT32_MAX. */
-
-       spc = disk.dk_heads * disk.dk_sectors;
-       disk.dk_cylinders = sz / spc;
-       disk.dk_size = disk.dk_cylinders * spc;
-
        if (disk.dk_size == 0)
-               errx(1, "dk_size == 0");
+               errx(1, "disk size is 0");
 
        if (disk.dk_bootprt.prt_ns > 0) {
                ns = disk.dk_bootprt.prt_ns + DL_BLKSPERSEC(&dl) - 1;

diff --git a/sbin/fdisk/mbr.c b/sbin/fdisk/mbr.c
index a13ccd6..22a1012 100644 (file)
--- a/sbin/fdisk/mbr.c
+++ b/sbin/fdisk/mbr.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: mbr.c,v 1.89 2021/07/18 21:40:13 krw Exp $    */
+/*     $OpenBSD: mbr.c,v 1.90 2021/07/19 14:30:08 krw Exp $    */
 
 /*
  * Copyright (c) 1997 Tobias Weingartner
@@ -132,12 +132,14 @@ MBR_init(struct mbr *mbr)
        /* Fix up start/length fields */
        PRT_fix_BN(&mbr->mbr_prt[3], 3);
 #else
-       mbr->mbr_prt[0] = disk.dk_bootprt;
-       PRT_fix_CHS(&mbr->mbr_prt[0]);
-       mbr->mbr_prt[3].prt_ns += mbr->mbr_prt[3].prt_bs;
-       mbr->mbr_prt[3].prt_bs = mbr->mbr_prt[0].prt_bs + mbr->mbr_prt[0].prt_ns;
-       mbr->mbr_prt[3].prt_ns -= mbr->mbr_prt[3].prt_bs;
-       PRT_fix_CHS(&mbr->mbr_prt[3]);
+       if (disk.dk_bootprt.prt_ns > 0) {
+               mbr->mbr_prt[0] = disk.dk_bootprt;
+               PRT_fix_CHS(&mbr->mbr_prt[0]);
+               mbr->mbr_prt[3].prt_ns += mbr->mbr_prt[3].prt_bs;
+               mbr->mbr_prt[3].prt_bs = mbr->mbr_prt[0].prt_bs + mbr->mbr_prt[0].prt_ns;
+               mbr->mbr_prt[3].prt_ns -= mbr->mbr_prt[3].prt_bs;
+               PRT_fix_CHS(&mbr->mbr_prt[3]);
+       }
 #endif
 
        /* Start OpenBSD MBR partition on a power of 2 block number. */