cg_link => cg_firstfield; fs_link => fs_firstfield

[unix-history] / usr / src / sbin / fsck / setup.c

diff --git a/usr/src/sbin/fsck/setup.c b/usr/src/sbin/fsck/setup.c
index e8e81d1..fa6899f 100644 (file)
--- a/usr/src/sbin/fsck/setup.c
+++ b/usr/src/sbin/fsck/setup.c
@@ -1,73 +1,272 @@
+/*
+ * Copyright (c) 1980, 1986, 1993
+ *     The Regents of the University of California.  All rights reserved.
+ *
+ * %sccs.include.redist.c%
+ */
+

 #ifndef lint
 #ifndef lint

-static char version[] = "@(#)setup.c   3.2 (Berkeley) %G%";
-#endif
+static char sccsid[] = "@(#)setup.c    8.4 (Berkeley) %G%";
+#endif /* not lint */

 
 

+#define DKTYPENAMES

 #include <sys/param.h>
 #include <sys/param.h>

-#include <sys/inode.h>
-#include <sys/fs.h>
+#include <sys/time.h>
+#include <ufs/ufs/dinode.h>
+#include <ufs/ffs/fs.h>

 #include <sys/stat.h>
 #include <sys/stat.h>

+#include <sys/ioctl.h>
+#include <sys/disklabel.h>
+#include <sys/file.h>
+#include <errno.h>
+#include <stdlib.h>
+#include <string.h>
+#include <ctype.h>

 #include "fsck.h"
 
 #include "fsck.h"
 

-char   *calloc();
+struct bufarea asblk;
+#define altsblock (*asblk.b_un.b_fs)
+#define POWEROF2(num)  (((num) & ((num) - 1)) == 0)
+
+struct disklabel *getdisklabel();

 
 setup(dev)
        char *dev;
 {
 
 setup(dev)
        char *dev;
 {

-       dev_t rootdev;
+       long cg, size, asked, i, j;
+       long bmapsize;
+       struct disklabel *lp;
+       off_t sizepb;

        struct stat statb;
        struct stat statb;

-       daddr_t super = bflag ? bflag : SBLOCK;
-       int i, j;
-       long size;
-       BUFAREA asblk;
-#      define altsblock asblk.b_un.b_fs
+       struct fs proto;

 
 

-       if (stat("/", &statb) < 0)
-               errexit("Can't stat root\n");
-       rootdev = statb.st_dev;
+       havesb = 0;
+       fswritefd = -1;

        if (stat(dev, &statb) < 0) {
        if (stat(dev, &statb) < 0) {

-               printf("Can't stat %s\n", dev);
+               printf("Can't stat %s: %s\n", dev, strerror(errno));

                return (0);
        }
                return (0);
        }

-       rawflg = 0;
-       if ((statb.st_mode & S_IFMT) == S_IFBLK)
-               ;
-       else if ((statb.st_mode & S_IFMT) == S_IFCHR)
-               rawflg++;
-       else {
-               if (reply("file is not a block or character device; OK") == 0)
+       if ((statb.st_mode & S_IFMT) != S_IFCHR) {
+               pfatal("%s is not a character device", dev);
+               if (reply("CONTINUE") == 0)

                        return (0);
        }
                        return (0);
        }

-       if (rootdev == statb.st_rdev)
-               hotroot++;
-       if ((dfile.rfdes = open(dev, 0)) < 0) {
-               printf("Can't open %s\n", dev);
+       if ((fsreadfd = open(dev, O_RDONLY)) < 0) {
+               printf("Can't open %s: %s\n", dev, strerror(errno));

                return (0);
        }
        if (preen == 0)
                printf("** %s", dev);
                return (0);
        }
        if (preen == 0)
                printf("** %s", dev);

-       if (nflag || (dfile.wfdes = open(dev, 1)) < 0) {
-               dfile.wfdes = -1;
+       if (nflag || (fswritefd = open(dev, O_WRONLY)) < 0) {
+               fswritefd = -1;

                if (preen)
                        pfatal("NO WRITE ACCESS");
                printf(" (NO WRITE)");
        }
        if (preen == 0)
                printf("\n");
                if (preen)
                        pfatal("NO WRITE ACCESS");
                printf(" (NO WRITE)");
        }
        if (preen == 0)
                printf("\n");

-       fixcg = 0; inosumbad = 0; offsumbad = 0; frsumbad = 0; sbsumbad = 0;
-       dfile.mod = 0;
-       n_files = n_blks = n_ffree = n_bfree = 0;
-       muldup = enddup = &duplist[0];
-       badlnp = &badlncnt[0];
+       fsmodified = 0;

        lfdir = 0;
        initbarea(&sblk);
        lfdir = 0;
        initbarea(&sblk);

-       initbarea(&fileblk);
-       initbarea(&inoblk);
-       initbarea(&cgblk);

        initbarea(&asblk);
        initbarea(&asblk);

+       sblk.b_un.b_buf = malloc(SBSIZE);
+       asblk.b_un.b_buf = malloc(SBSIZE);
+       if (sblk.b_un.b_buf == NULL || asblk.b_un.b_buf == NULL)
+               errexit("cannot allocate space for superblock\n");
+       if (lp = getdisklabel((char *)NULL, fsreadfd))
+               dev_bsize = secsize = lp->d_secsize;
+       else
+               dev_bsize = secsize = DEV_BSIZE;
+       /*
+        * Read in the superblock, looking for alternates if necessary
+        */
+       if (readsb(1) == 0) {
+               if (bflag || preen || calcsb(dev, fsreadfd, &proto) == 0)
+                       return(0);
+               if (reply("LOOK FOR ALTERNATE SUPERBLOCKS") == 0)
+                       return (0);
+               for (cg = 0; cg < proto.fs_ncg; cg++) {
+                       bflag = fsbtodb(&proto, cgsblock(&proto, cg));
+                       if (readsb(0) != 0)
+                               break;
+               }
+               if (cg >= proto.fs_ncg) {
+                       printf("%s %s\n%s %s\n%s %s\n",
+                               "SEARCH FOR ALTERNATE SUPER-BLOCK",
+                               "FAILED. YOU MUST USE THE",
+                               "-b OPTION TO FSCK TO SPECIFY THE",
+                               "LOCATION OF AN ALTERNATE",
+                               "SUPER-BLOCK TO SUPPLY NEEDED",
+                               "INFORMATION; SEE fsck(8).");
+                       return(0);
+               }
+               pwarn("USING ALTERNATE SUPERBLOCK AT %d\n", bflag);
+       }
+       maxfsblock = sblock.fs_size;
+       maxino = sblock.fs_ncg * sblock.fs_ipg;
+       /*
+        * Check and potentially fix certain fields in the super block.
+        */
+       if (sblock.fs_optim != FS_OPTTIME && sblock.fs_optim != FS_OPTSPACE) {
+               pfatal("UNDEFINED OPTIMIZATION IN SUPERBLOCK");
+               if (reply("SET TO DEFAULT") == 1) {
+                       sblock.fs_optim = FS_OPTTIME;
+                       sbdirty();
+               }
+       }
+       if ((sblock.fs_minfree < 0 || sblock.fs_minfree > 99)) {
+               pfatal("IMPOSSIBLE MINFREE=%d IN SUPERBLOCK",
+                       sblock.fs_minfree);
+               if (reply("SET TO DEFAULT") == 1) {
+                       sblock.fs_minfree = 10;
+                       sbdirty();
+               }
+       }
+       if (sblock.fs_interleave < 1 || 
+           sblock.fs_interleave > sblock.fs_nsect) {
+                       sblock.fs_interleave);
+               sblock.fs_interleave = 1;
+                       sbdirty();
+                       dirty(&asblk);
+               }
+       }
+       if (sblock.fs_npsect < sblock.fs_nsect || 
+           sblock.fs_npsect > sblock.fs_nsect*2) {
+                       sblock.fs_npsect);
+               sblock.fs_npsect = sblock.fs_nsect;
+                       sbdirty();
+                       dirty(&asblk);
+               }
+       }
+       if (sblock.fs_inodefmt >= FS_44INODEFMT) {
+               newinofmt = 1;
+       } else {
+               sblock.fs_qbmask = ~sblock.fs_bmask;
+               sblock.fs_qfmask = ~sblock.fs_fmask;
+               newinofmt = 0;
+       }

        /*
        /*

-        * Read in the super block and its summary info.
+        * Convert to new inode format.

         */
         */

-       if (bread(&dfile, (char *)&sblock, super, (long)SBSIZE) == 0)
+       if (cvtlevel >= 2 && sblock.fs_inodefmt < FS_44INODEFMT) {
+               if (preen)
+                       pwarn("CONVERTING TO NEW INODE FORMAT\n");
+               else if (!reply("CONVERT TO NEW INODE FORMAT"))
+                       return(0);
+               doinglevel2++;
+               sblock.fs_inodefmt = FS_44INODEFMT;
+               sizepb = sblock.fs_bsize;
+               sblock.fs_maxfilesize = sblock.fs_bsize * NDADDR - 1;
+               for (i = 0; i < NIADDR; i++) {
+                       sizepb *= NINDIR(&sblock);
+                       sblock.fs_maxfilesize += sizepb;
+               }
+               sblock.fs_maxsymlinklen = MAXSYMLINKLEN;
+               sblock.fs_qbmask = ~sblock.fs_bmask;
+               sblock.fs_qfmask = ~sblock.fs_fmask;
+               sbdirty();
+               dirty(&asblk);
+       }
+       /*
+        * Convert to new cylinder group format.
+        */
+       if (cvtlevel >= 1 && sblock.fs_postblformat == FS_42POSTBLFMT) {
+               if (preen)
+                       pwarn("CONVERTING TO NEW CYLINDER GROUP FORMAT\n");
+               else if (!reply("CONVERT TO NEW CYLINDER GROUP FORMAT"))
+                       return(0);
+               doinglevel1++;
+               sblock.fs_postblformat = FS_DYNAMICPOSTBLFMT;
+               sblock.fs_nrpos = 8;
+               sblock.fs_postbloff =
+                   (char *)(&sblock.fs_opostbl[0][0]) -
+                   (char *)(&sblock.fs_firstfield);
+               sblock.fs_rotbloff = &sblock.fs_space[0] -
+                   (u_char *)(&sblock.fs_firstfield);
+               sblock.fs_cgsize =
+                       fragroundup(&sblock, CGSIZE(&sblock));
+               sbdirty();
+               dirty(&asblk);
+       }
+       if (asblk.b_dirty) {
+               bcopy((char *)&sblock, (char *)&altsblock,
+                       (size_t)sblock.fs_sbsize);
+               flush(fswritefd, &asblk);
+       }
+       /*
+        * read in the summary info.
+        */
+       asked = 0;
+       for (i = 0, j = 0; i < sblock.fs_cssize; i += sblock.fs_bsize, j++) {
+               size = sblock.fs_cssize - i < sblock.fs_bsize ?
+                   sblock.fs_cssize - i : sblock.fs_bsize;
+               sblock.fs_csp[j] = (struct csum *)calloc(1, (unsigned)size);
+               if (bread(fsreadfd, (char *)sblock.fs_csp[j],
+                   fsbtodb(&sblock, sblock.fs_csaddr + j * sblock.fs_frag),
+                   size) != 0 && !asked) {
+                       pfatal("BAD SUMMARY INFORMATION");
+                       if (reply("CONTINUE") == 0)
+                               errexit("");
+                       asked++;
+               }
+       }
+       /*
+        * allocate and initialize the necessary maps
+        */
+       bmapsize = roundup(howmany(maxfsblock, NBBY), sizeof(short));
+       blockmap = calloc((unsigned)bmapsize, sizeof (char));
+       if (blockmap == NULL) {
+               printf("cannot alloc %u bytes for blockmap\n",
+                   (unsigned)bmapsize);
+               goto badsb;
+       }
+       statemap = calloc((unsigned)(maxino + 1), sizeof(char));
+       if (statemap == NULL) {
+               printf("cannot alloc %u bytes for statemap\n",
+                   (unsigned)(maxino + 1));
+               goto badsb;
+       }
+       typemap = calloc((unsigned)(maxino + 1), sizeof(char));
+       if (typemap == NULL) {
+               printf("cannot alloc %u bytes for typemap\n",
+                   (unsigned)(maxino + 1));
+               goto badsb;
+       }
+       lncntp = (short *)calloc((unsigned)(maxino + 1), sizeof(short));
+       if (lncntp == NULL) {
+               printf("cannot alloc %u bytes for lncntp\n", 
+                   (unsigned)(maxino + 1) * sizeof(short));
+               goto badsb;
+       }
+       numdirs = sblock.fs_cstotal.cs_ndir;
+       inplast = 0;
+       listmax = numdirs + 10;
+       inpsort = (struct inoinfo **)calloc((unsigned)listmax,
+           sizeof(struct inoinfo *));
+       inphead = (struct inoinfo **)calloc((unsigned)numdirs,
+           sizeof(struct inoinfo *));
+       if (inpsort == NULL || inphead == NULL) {
+               printf("cannot alloc %u bytes for inphead\n", 
+                   (unsigned)numdirs * sizeof(struct inoinfo *));
+               goto badsb;
+       }
+       bufinit();
+       return (1);
+
+badsb:
+       ckfini();
+       return (0);
+}
+
+/*
+ * Read in the super block and its summary info.
+ */
+readsb(listerr)
+       int listerr;
+{
+       daddr_t super = bflag ? bflag : SBOFF / dev_bsize;
+
+       if (bread(fsreadfd, (char *)&sblock, super, (long)SBSIZE) != 0)

                return (0);
        sblk.b_bno = super;
        sblk.b_size = SBSIZE;
                return (0);
        sblk.b_bno = super;
        sblk.b_size = SBSIZE;


@@ -75,28 +274,36 @@ setup(dev)
         * run a few consistency checks of the super block
         */
        if (sblock.fs_magic != FS_MAGIC)
         * run a few consistency checks of the super block
         */
        if (sblock.fs_magic != FS_MAGIC)

-               { badsb("MAGIC NUMBER WRONG"); return (0); }
+               { badsb(listerr, "MAGIC NUMBER WRONG"); return (0); }

        if (sblock.fs_ncg < 1)
        if (sblock.fs_ncg < 1)

-               { badsb("NCG OUT OF RANGE"); return (0); }
-       if (sblock.fs_cpg < 1 || sblock.fs_cpg > MAXCPG)
-               { badsb("CPG OUT OF RANGE"); return (0); }
+               { badsb(listerr, "NCG OUT OF RANGE"); return (0); }
+       if (sblock.fs_cpg < 1)
+               { badsb(listerr, "CPG OUT OF RANGE"); return (0); }

        if (sblock.fs_ncg * sblock.fs_cpg < sblock.fs_ncyl ||
            (sblock.fs_ncg - 1) * sblock.fs_cpg >= sblock.fs_ncyl)
        if (sblock.fs_ncg * sblock.fs_cpg < sblock.fs_ncyl ||
            (sblock.fs_ncg - 1) * sblock.fs_cpg >= sblock.fs_ncyl)

-               { badsb("NCYL DOES NOT JIVE WITH NCG*CPG"); return (0); }
+               { badsb(listerr, "NCYL LESS THAN NCG*CPG"); return (0); }

        if (sblock.fs_sbsize > SBSIZE)
        if (sblock.fs_sbsize > SBSIZE)

-               { badsb("SIZE PREPOSTEROUSLY LARGE"); return (0); }
+               { badsb(listerr, "SIZE PREPOSTEROUSLY LARGE"); return (0); }
+       /*
+        * Compute block size that the filesystem is based on,
+        * according to fsbtodb, and adjust superblock block number
+        * so we can tell if this is an alternate later.
+        */
+       super *= dev_bsize;
+       dev_bsize = sblock.fs_fsize / fsbtodb(&sblock, 1);
+       sblk.b_bno = super / dev_bsize;
+       if (bflag) {
+               havesb = 1;
+               return (1);
+       }

        /*
         * Set all possible fields that could differ, then do check
         * of whole super block against an alternate super block.
         * When an alternate super-block is specified this check is skipped.
         */
        /*
         * Set all possible fields that could differ, then do check
         * of whole super block against an alternate super block.
         * When an alternate super-block is specified this check is skipped.
         */

-       if (bflag)
-               goto sbok;
-       if (getblk(&asblk, cgsblock(&sblock, sblock.fs_ncg - 1),
-           sblock.fs_sbsize) == 0)
+       getblk(&asblk, cgsblock(&sblock, sblock.fs_ncg - 1), sblock.fs_sbsize);
+       if (asblk.b_errs)

                return (0);
                return (0);

-       altsblock.fs_link = sblock.fs_link;
-       altsblock.fs_rlink = sblock.fs_rlink;

        altsblock.fs_time = sblock.fs_time;
        altsblock.fs_cstotal = sblock.fs_cstotal;
        altsblock.fs_cgrotor = sblock.fs_cgrotor;
        altsblock.fs_time = sblock.fs_time;
        altsblock.fs_cstotal = sblock.fs_cstotal;
        altsblock.fs_cgrotor = sblock.fs_cgrotor;


@@ -106,71 +313,119 @@ setup(dev)
        altsblock.fs_flags = sblock.fs_flags;
        altsblock.fs_maxcontig = sblock.fs_maxcontig;
        altsblock.fs_minfree = sblock.fs_minfree;
        altsblock.fs_flags = sblock.fs_flags;
        altsblock.fs_maxcontig = sblock.fs_maxcontig;
        altsblock.fs_minfree = sblock.fs_minfree;

+       altsblock.fs_optim = sblock.fs_optim;

        altsblock.fs_rotdelay = sblock.fs_rotdelay;
        altsblock.fs_maxbpg = sblock.fs_maxbpg;
        bcopy((char *)sblock.fs_csp, (char *)altsblock.fs_csp,
                sizeof sblock.fs_csp);
        bcopy((char *)sblock.fs_fsmnt, (char *)altsblock.fs_fsmnt,
                sizeof sblock.fs_fsmnt);
        altsblock.fs_rotdelay = sblock.fs_rotdelay;
        altsblock.fs_maxbpg = sblock.fs_maxbpg;
        bcopy((char *)sblock.fs_csp, (char *)altsblock.fs_csp,
                sizeof sblock.fs_csp);
        bcopy((char *)sblock.fs_fsmnt, (char *)altsblock.fs_fsmnt,
                sizeof sblock.fs_fsmnt);

-       if (bcmp((char *)&sblock, (char *)&altsblock, (int)sblock.fs_sbsize))
-               { badsb("TRASHED VALUES IN SUPER BLOCK"); return (0); }
-sbok:
-       fmax = sblock.fs_size;
-       imax = sblock.fs_ncg * sblock.fs_ipg;
-       n_bad = cgsblock(&sblock, 0); /* boot block plus dedicated sblock */
+       bcopy((char *)sblock.fs_sparecon, (char *)altsblock.fs_sparecon,
+               sizeof sblock.fs_sparecon);

        /*
        /*

-        * read in the summary info.
+        * The following should not have to be copied.

         */
         */

-       for (i = 0, j = 0; i < sblock.fs_cssize; i += sblock.fs_bsize, j++) {
-               size = sblock.fs_cssize - i < sblock.fs_bsize ?
-                   sblock.fs_cssize - i : sblock.fs_bsize;
-               sblock.fs_csp[j] = (struct csum *)calloc(1, (unsigned)size);
-               if (bread(&dfile, (char *)sblock.fs_csp[j],
-                   fsbtodb(&sblock, sblock.fs_csaddr + j * sblock.fs_frag),
-                   size) == 0)
-                       return (0);
-       }
-       /*
-        * allocate and initialize the necessary maps
-        */
-       bmapsz = roundup(howmany(fmax, NBBY), sizeof(short));
-       blockmap = calloc((unsigned)bmapsz, sizeof (char));
-       if (blockmap == NULL) {
-               printf("cannot alloc %d bytes for blockmap\n", bmapsz);
-               goto badsb;
-       }
-       freemap = calloc((unsigned)bmapsz, sizeof (char));
-       if (freemap == NULL) {
-               printf("cannot alloc %d bytes for freemap\n", bmapsz);
-               goto badsb;
+       altsblock.fs_fsbtodb = sblock.fs_fsbtodb;
+       altsblock.fs_interleave = sblock.fs_interleave;
+       altsblock.fs_npsect = sblock.fs_npsect;
+       altsblock.fs_nrpos = sblock.fs_nrpos;
+       altsblock.fs_state = sblock.fs_state;
+       altsblock.fs_qbmask = sblock.fs_qbmask;
+       altsblock.fs_qfmask = sblock.fs_qfmask;
+       altsblock.fs_state = sblock.fs_state;
+       altsblock.fs_maxfilesize = sblock.fs_maxfilesize;
+       if (bcmp((char *)&sblock, (char *)&altsblock, (int)sblock.fs_sbsize)) {
+               badsb(listerr,
+               "VALUES IN SUPER BLOCK DISAGREE WITH THOSE IN FIRST ALTERNATE");
+               return (0);

        }
        }

-       statemap = calloc((unsigned)(imax + 1), sizeof(char));
-       if (statemap == NULL) {
-               printf("cannot alloc %d bytes for statemap\n", imax + 1);
-               goto badsb;
+       havesb = 1;
+       return (1);
+}
+
+badsb(listerr, s)
+       int listerr;
+       char *s;
+{
+
+       if (!listerr)
+               return;
+       if (preen)
+               printf("%s: ", cdevname);
+       pfatal("BAD SUPER BLOCK: %s\n", s);
+}
+
+/*
+ * Calculate a prototype superblock based on information in the disk label.
+ * When done the cgsblock macro can be calculated and the fs_ncg field
+ * can be used. Do NOT attempt to use other macros without verifying that
+ * their needed information is available!
+ */
+calcsb(dev, devfd, fs)
+       char *dev;
+       int devfd;
+       register struct fs *fs;
+{
+       register struct disklabel *lp;
+       register struct partition *pp;
+       register char *cp;
+       int i;
+
+       cp = index(dev, '\0') - 1;
+       if (cp == (char *)-1 || (*cp < 'a' || *cp > 'h') && !isdigit(*cp)) {
+               pfatal("%s: CANNOT FIGURE OUT FILE SYSTEM PARTITION\n", dev);
+               return (0);

        }
        }

-       lncntp = (short *)calloc((unsigned)(imax + 1), sizeof(short));
-       if (lncntp == NULL) {
-               printf("cannot alloc %d bytes for lncntp\n", 
-                   (imax + 1) * sizeof(short));
-               goto badsb;
+       lp = getdisklabel(dev, devfd);
+       if (isdigit(*cp))
+               pp = &lp->d_partitions[0];
+       else
+               pp = &lp->d_partitions[*cp - 'a'];
+       if (pp->p_fstype != FS_BSDFFS) {
+               pfatal("%s: NOT LABELED AS A BSD FILE SYSTEM (%s)\n",
+                       dev, pp->p_fstype < FSMAXTYPES ?
+                       fstypenames[pp->p_fstype] : "unknown");
+               return (0);

        }
        }

-
+       bzero((char *)fs, sizeof(struct fs));
+       fs->fs_fsize = pp->p_fsize;
+       fs->fs_frag = pp->p_frag;
+       fs->fs_cpg = pp->p_cpg;
+       fs->fs_size = pp->p_size;
+       fs->fs_ntrak = lp->d_ntracks;
+       fs->fs_nsect = lp->d_nsectors;
+       fs->fs_spc = lp->d_secpercyl;
+       fs->fs_nspf = fs->fs_fsize / lp->d_secsize;
+       fs->fs_sblkno = roundup(
+               howmany(lp->d_bbsize + lp->d_sbsize, fs->fs_fsize),
+               fs->fs_frag);
+       fs->fs_cgmask = 0xffffffff;
+       for (i = fs->fs_ntrak; i > 1; i >>= 1)
+               fs->fs_cgmask <<= 1;
+       if (!POWEROF2(fs->fs_ntrak))
+               fs->fs_cgmask <<= 1;
+       fs->fs_cgoffset = roundup(
+               howmany(fs->fs_nsect, NSPF(fs)), fs->fs_frag);
+       fs->fs_fpg = (fs->fs_cpg * fs->fs_spc) / NSPF(fs);
+       fs->fs_ncg = howmany(fs->fs_size / fs->fs_spc, fs->fs_cpg);
+       for (fs->fs_fsbtodb = 0, i = NSPF(fs); i > 1; i >>= 1)
+               fs->fs_fsbtodb++;
+       dev_bsize = lp->d_secsize;

        return (1);
        return (1);

-
-badsb:
-       ckfini();
-       return (0);
-#      undef altsblock

 }
 
 }
 

-badsb(s)
+struct disklabel *
+getdisklabel(s, fd)

        char *s;
        char *s;

+       int     fd;

 {
 {

+       static struct disklabel lab;

 
 

-       if (preen)
-               printf("%s: ", devname);
-       printf("BAD SUPER BLOCK: %s\n", s);
-       pwarn("USE -b OPTION TO FSCK TO SPECIFY LOCATION OF AN ALTERNATE\n");
-       pfatal("SUPER-BLOCK TO SUPPLY NEEDED INFORMATION; SEE fsck(8).\n");
+       if (ioctl(fd, DIOCGDINFO, (char *)&lab) < 0) {
+               if (s == NULL)
+                       return ((struct disklabel *)NULL);
+               pwarn("ioctl (GCINFO): %s\n", strerror(errno));
+               errexit("%s: can't read disk label\n", s);
+       }
+       return (&lab);

 }
 }