/* $NetBSD: sunlabel.c,v 1.26 2023/08/11 07:05:39 mrg Exp $ */

/*-
* Copyright (c) 2002 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This code is derived from software contributed to The NetBSD Foundation
* by der Mouse.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
*    notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
*    notice, this list of conditions and the following disclaimer in the
*    documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/

#if HAVE_NBTOOL_CONFIG_H
#include "nbtool_config.h"
#endif

#include <sys/cdefs.h>
#if defined(__RCSID) && !defined(lint)
__RCSID("$NetBSD: sunlabel.c,v 1.26 2023/08/11 07:05:39 mrg Exp $");
#endif

#include <stdio.h>
#include <errno.h>
#include <fcntl.h>
#include <ctype.h>
#include <stdlib.h>
#include <unistd.h>
#ifndef NO_TERMCAP_WIDTH
#include <termcap.h>
#endif
#include <string.h>
#include <strings.h>
#include <inttypes.h>
#include <err.h>

#include <sys/ioctl.h>

/* If neither S_COMMAND nor NO_S_COMMAND is defined, guess. */
#if !defined(S_COMMAND) && !defined(NO_S_COMMAND)
#define S_COMMAND
#include <util.h>
#include <sys/disklabel.h>
#endif

/*
* NPART is the total number of partitions.  This must be <= 43, given the
* amount of space available to store extended partitions. It also must be
* <=26, given the use of single letters to name partitions.  The 8 is the
* number of `standard' partitions; this arguably should be a #define, since
* it occurs not only here but scattered throughout the code.
*/
#define NPART 16
#define NXPART (NPART - 8)
#define PARTLETTER(i) ((i) + 'a')
#define LETTERPART(i) ((i) - 'a')

/*
* A partition.  We keep redundant information around, making sure
* that whenever we change one, we keep another constant and update
* the third.  Which one is which depends.  Arguably a partition
* should also know its partition number; here, if we need that we
* cheat, using (effectively) ptr-&label.partitions[0].
*/
struct part {
       uint32_t    startcyl;
       uint32_t    nblk;
       uint32_t    endcyl;
};

/*
* A label.  As the embedded comments indicate, much of this structure
* corresponds directly to Sun's struct dk_label.  Some of the values
* here are historical holdovers.  Apparently really old Suns did
* their own sparing in software, so a sector or two per cylinder,
* plus a whole cylinder or two at the end, got set aside as spares.
* acyl and apc count those spares, and this is also why ncyl and pcyl
* both exist.  These days the spares generally are hidden from the
* host by the disk, and there's no reason not to set
* ncyl=pcyl=ceil(device size/spc) and acyl=apc=0.
*
* Note also that the geometry assumptions behind having nhead and
* nsect assume that the sect/trk and trk/cyl values are constant
* across the whole drive.  The latter is still usually true; the
* former isn't.  In my experience, you can just put fixed values
* here; the basis for software knowing the drive geometry is also
* mostly invalid these days anyway.  (I just use nhead=32 nsect=64,
* which gives me 1M "cylinders", a convenient size.)
*/
struct label {
       /* BEGIN fields taken directly from struct dk_label */
       char asciilabel[128];
       uint32_t rpm;   /* Spindle rotation speed - useless now */
       uint32_t pcyl;  /* Physical cylinders */
       uint32_t apc;   /* Alternative sectors per cylinder */
       uint32_t obs1;  /* Obsolete? */
       uint32_t obs2;  /* Obsolete? */
       uint32_t intrlv;        /* Interleave - never anything but 1 IME */
       uint32_t ncyl;  /* Number of usable cylinders */
       uint32_t acyl;  /* Alternative cylinders - pcyl minus ncyl */
       uint32_t nhead; /* Tracks-per-cylinder (usually # of heads) */
       uint32_t nsect; /* Sectors-per-track */
       uint32_t obs3;  /* Obsolete? */
       uint32_t obs4;  /* Obsolete? */
       /* END fields taken directly from struct dk_label */
       uint32_t spc;   /* Sectors per cylinder - nhead*nsect */
       uint32_t dirty:1;/* Modified since last read */
       struct part partitions[NPART];/* The partitions themselves */
};

/*
* Describes a field in the label.
*
* tag is a short name for the field, like "apc" or "nsect".  loc is a
* pointer to the place in the label where it's stored.  print is a
* function to print the value; the second argument is the current
* column number, and the return value is the new current column
* number.  (This allows print functions to do proper line wrapping.)
* chval is called to change a field; the first argument is the
* command line portion that contains the new value (in text form).
* The chval function is responsible for parsing and error-checking as
* well as doing the modification.  changed is a function which does
* field-specific actions necessary when the field has been changed.
* This could be rolled into the chval function, but I believe this
* way provides better code sharing.
*
* Note that while the fields in the label vary in size (8, 16, or 32
* bits), we store everything as ints in the label struct, above, and
* convert when packing and unpacking.  This allows us to have only
* one numeric chval function.
*/
struct field {
       const char *tag;
       void *loc;
       int (*print)(struct field *, int);
       void (*chval)(const char *, struct field *);
       void (*changed)(void);
       int taglen;
};

/* LABEL_MAGIC was chosen by Sun and cannot be trivially changed. */
#define LABEL_MAGIC 0xdabe
/*
* LABEL_XMAGIC needs to agree between here and any other code that uses
* extended partitions (mainly the kernel).
*/
#define LABEL_XMAGIC (0x199d1fe2+8)

static int diskfd;                      /* fd on the disk */
static const char *diskname;            /* name of the disk, for messages */
static int readonly;                    /* true iff it's open RO */
static unsigned char labelbuf[512];     /* Buffer holding the label sector */
static struct label label;              /* The label itself. */
static int fixmagic;                    /* -m, ignore bad magic #s */
static int fixcksum;                    /* -s, ignore bad cksums */
static int newlabel;                    /* -n, ignore all on-disk values */
static int quiet;                       /* -q, don't print chatter */

/*
* The various functions that go in the field function pointers.  The
* _ascii functions are for 128-byte string fields (the ASCII label);
* the _int functions are for int-valued fields (everything else).
* update_spc is a `changed' function for updating the spc value when
* changing one of the two values that make it up.
*/
static int print_ascii(struct field *, int);
static void chval_ascii(const char *, struct field *);
static int print_int(struct field *, int);
static void chval_int(const char *, struct field *);
static void update_spc(void);

/* The fields themselves. */
static struct field fields[] =
{
       {"ascii", &label.asciilabel[0], print_ascii, chval_ascii, 0, 0 },
       {"rpm", &label.rpm, print_int, chval_int, 0, 0 },
       {"pcyl", &label.pcyl, print_int, chval_int, 0, 0 },
       {"apc", &label.apc, print_int, chval_int, 0, 0 },
       {"obs1", &label.obs1, print_int, chval_int, 0, 0 },
       {"obs2", &label.obs2, print_int, chval_int, 0, 0 },
       {"intrlv", &label.intrlv, print_int, chval_int, 0, 0 },
       {"ncyl", &label.ncyl, print_int, chval_int, 0, 0 },
       {"acyl", &label.acyl, print_int, chval_int, 0, 0 },
       {"nhead", &label.nhead, print_int, chval_int, update_spc, 0 },
       {"nsect", &label.nsect, print_int, chval_int, update_spc, 0 },
       {"obs3", &label.obs3, print_int, chval_int, 0, 0 },
       {"obs4", &label.obs4, print_int, chval_int, 0, 0 },
       {NULL, NULL, NULL, NULL, 0, 0 }
};

/*
* We'd _like_ to use howmany() from the include files, but can't count
*  on its being present or working.
*/
static inline uint32_t how_many(uint32_t amt, uint32_t unit)
   __attribute__((const));
static inline uint32_t
how_many(uint32_t amt, uint32_t unit)
{
       return ((amt + unit - 1) / unit);
}

/*
* Try opening the disk, given a name.  If mustsucceed is true, we
*  "cannot fail"; failures produce gripe-and-exit, and if we return,
*  our return value is 1.  Otherwise, we return 1 on success and 0 on
*  failure.
*/
static int
trydisk(const char *s, int mustsucceed)
{
       int ro = 0;

       diskname = s;
       if ((diskfd = open(s, O_RDWR)) == -1 ||
           (diskfd = open(s, O_RDWR | O_NONBLOCK)) == -1) {
               if ((diskfd = open(s, O_RDONLY)) == -1) {
                       if (mustsucceed)
                               err(1, "Cannot open `%s'", s);
                       else
                               return 0;
               }
               ro = 1;
       }
       if (ro && !quiet)
               warnx("No write access, label is readonly");
       readonly = ro;
       return 1;
}

/*
* Set the disk device, given the user-supplied string.  Note that even
* if we malloc, we never free, because either trydisk eventually
* succeeds, in which case the string is saved in diskname, or it
* fails, in which case we exit and freeing is irrelevant.
*/
static void
setdisk(const char *s)
{
       char *tmp;

       if (strchr(s, '/')) {
               trydisk(s, 1);
               return;
       }
       if (trydisk(s, 0))
               return;
#ifndef DISTRIB /* native tool: search in /dev */
       asprintf(&tmp, "/dev/%s", s);
       if (!tmp)
               err(1, "malloc");
       if (trydisk(tmp, 0)) {
               free(tmp);
               return;
       }
       free(tmp);
       asprintf(&tmp, "/dev/%s%c", s, getrawpartition() + 'a');
       if (!tmp)
               err(1, "malloc");
       if (trydisk(tmp, 0)) {
               free(tmp);
               return;
       }
#endif
       errx(1, "Can't find device for disk `%s'", s);
}

static void usage(void) __dead;
static void
usage(void)
{
       (void)fprintf(stderr, "usage: %s [-mnqs] disk\n", getprogname());
       exit(1);
}

/*
* Command-line arguments.  We can have at most one non-flag
*  argument, which is the disk name; we can also have flags
*
*      -m
*              Turns on fixmagic, which causes bad magic numbers to be
*              ignored (though a complaint is still printed), rather
*              than being fatal errors.
*
*      -s
*              Turns on fixcksum, which causes bad checksums to be
*              ignored (though a complaint is still printed), rather
*              than being fatal errors.
*
*      -n
*              Turns on newlabel, which means we're creating a new
*              label and anything in the label sector should be
*              ignored.  This is a bit like -m -s, except that it
*              doesn't print complaints and it ignores possible
*              garbage on-disk.
*
*      -q
*              Turns on quiet, which suppresses printing of prompts
*              and other irrelevant chatter.  If you're trying to use
*              sunlabel in an automated way, you probably want this.
*/
static void
handleargs(int ac, char **av)
{
       int c;

       while ((c = getopt(ac, av, "mnqs")) != -1) {
               switch (c) {
               case 'm':
                       fixmagic++;
                       break;
               case 'n':
                       newlabel++;
                       break;
               case 'q':
                       quiet++;
                       break;
               case 's':
                       fixcksum++;
                       break;
               case '?':
                       warnx("Illegal option `%c'", c);
                       usage();
               }
       }
       ac -= optind;
       av += optind;
       if (ac != 1)
               usage();
       setdisk(av[0]);
}

/*
* Sets the ending cylinder for a partition.  This exists mainly to
* centralize the check.  (If spc is zero, cylinder numbers make
* little sense, and the code would otherwise die on divide-by-0 if we
* barged blindly ahead.)  We need to call this on a partition
* whenever we change it; we need to call it on all partitions
* whenever we change spc.
*/
static void
set_endcyl(struct part *p)
{
       if (label.spc == 0) {
               p->endcyl = p->startcyl;
       } else {
               p->endcyl = p->startcyl + how_many(p->nblk, label.spc);
       }
}

/*
* Unpack a label from disk into the in-core label structure.  If
* newlabel is set, we don't actually do so; we just synthesize a
* blank label instead.  This is where knowledge of the Sun label
* format is kept for read; pack_label is the corresponding routine
* for write.  We are careful to use labelbuf, l_s, or l_l as
* appropriate to avoid byte-sex issues, so we can work on
* little-endian machines.
*
* Note that a bad magic number for the extended partition information
* is not considered an error; it simply indicates there is no
* extended partition information.  Arguably this is the Wrong Thing,
* and we should take zero as meaning no info, and anything other than
* zero or LABEL_XMAGIC as reason to gripe.
*/
static const char *
unpack_label(void)
{
       unsigned short int l_s[256];
       unsigned long int l_l[128];
       int i;
       unsigned long int sum;
       int have_x;

       if (newlabel) {
               bzero(&label.asciilabel[0], 128);
               label.rpm = 0;
               label.pcyl = 0;
               label.apc = 0;
               label.obs1 = 0;
               label.obs2 = 0;
               label.intrlv = 0;
               label.ncyl = 0;
               label.acyl = 0;
               label.nhead = 0;
               label.nsect = 0;
               label.obs3 = 0;
               label.obs4 = 0;
               for (i = 0; i < NPART; i++) {
                       label.partitions[i].startcyl = 0;
                       label.partitions[i].nblk = 0;
                       set_endcyl(&label.partitions[i]);
               }
               label.spc = 0;
               label.dirty = 1;
               return (0);
       }
       for (i = 0; i < 256; i++)
               l_s[i] = (labelbuf[i + i] << 8) | labelbuf[i + i + 1];
       for (i = 0; i < 128; i++)
               l_l[i] = (l_s[i + i] << 16) | l_s[i + i + 1];
       if (l_s[254] != LABEL_MAGIC) {
               if (fixmagic) {
                       label.dirty = 1;
                       warnx("ignoring incorrect magic number.");
               } else {
                       return "bad magic number";
               }
       }
       sum = 0;
       for (i = 0; i < 256; i++)
               sum ^= l_s[i];
       label.dirty = 0;
       if (sum != 0) {
               if (fixcksum) {
                       label.dirty = 1;
                       warnx("ignoring incorrect checksum.");
               } else {
                       return "checksum wrong";
               }
       }
       (void)memcpy(&label.asciilabel[0], &labelbuf[0], 128);
       label.rpm = l_s[210];
       label.pcyl = l_s[211];
       label.apc = l_s[212];
       label.obs1 = l_s[213];
       label.obs2 = l_s[214];
       label.intrlv = l_s[215];
       label.ncyl = l_s[216];
       label.acyl = l_s[217];
       label.nhead = l_s[218];
       label.nsect = l_s[219];
       label.obs3 = l_s[220];
       label.obs4 = l_s[221];
       label.spc = label.nhead * label.nsect;
       for (i = 0; i < 8; i++) {
               label.partitions[i].startcyl = (uint32_t)l_l[i + i + 111];
               label.partitions[i].nblk = (uint32_t)l_l[i + i + 112];
               set_endcyl(&label.partitions[i]);
       }
       have_x = 0;
       if (l_l[33] == LABEL_XMAGIC) {
               sum = 0;
               for (i = 0; i < ((NXPART * 2) + 1); i++)
                       sum += l_l[33 + i];
               if (sum != l_l[32]) {
                       if (fixcksum) {
                               label.dirty = 1;
                               warnx("Ignoring incorrect extended-partition checksum.");
                               have_x = 1;
                       } else {
                               warnx("Extended-partition magic right but checksum wrong.");
                       }
               } else {
                       have_x = 1;
               }
       }
       if (have_x) {
               for (i = 0; i < NXPART; i++) {
                       int j = i + i + 34;
                       label.partitions[i + 8].startcyl = (uint32_t)l_l[j++];
                       label.partitions[i + 8].nblk = (uint32_t)l_l[j++];
                       set_endcyl(&label.partitions[i + 8]);
               }
       } else {
               for (i = 0; i < NXPART; i++) {
                       label.partitions[i + 8].startcyl = 0;
                       label.partitions[i + 8].nblk = 0;
                       set_endcyl(&label.partitions[i + 8]);
               }
       }
       return 0;
}

/*
* Pack a label from the in-core label structure into on-disk format.
* This is where knowledge of the Sun label format is kept for write;
* unpack_label is the corresponding routine for read.  If all
* partitions past the first 8 are size=0 cyl=0, we store all-0s in
* the extended partition space, to be fully compatible with Sun
* labels.  Since AFIAK nothing works in that case that would break if
* we put extended partition info there in the same format we'd use if
* there were real info there, this is arguably unnecessary, but it's
* easy to do.
*
* We are careful to avoid endianness issues by constructing everything
* in an array of shorts.  We do this rather than using chars or longs
* because the checksum is defined in terms of shorts; using chars or
* longs would simplify small amounts of code at the price of
* complicating more.
*/
static void
pack_label(void)
{
       unsigned short int l_s[256];
       int i;
       unsigned short int sum;

       memset(&l_s[0], 0, 512);
       memcpy(&labelbuf[0], &label.asciilabel[0], 128);
       for (i = 0; i < 64; i++)
               l_s[i] = (labelbuf[i + i] << 8) | labelbuf[i + i + 1];
       l_s[210] = label.rpm;
       l_s[211] = label.pcyl;
       l_s[212] = label.apc;
       l_s[213] = label.obs1;
       l_s[214] = label.obs2;
       l_s[215] = label.intrlv;
       l_s[216] = label.ncyl;
       l_s[217] = label.acyl;
       l_s[218] = label.nhead;
       l_s[219] = label.nsect;
       l_s[220] = label.obs3;
       l_s[221] = label.obs4;
       for (i = 0; i < 8; i++) {
               l_s[(i * 4) + 222] = label.partitions[i].startcyl >> 16;
               l_s[(i * 4) + 223] = label.partitions[i].startcyl & 0xffff;
               l_s[(i * 4) + 224] = label.partitions[i].nblk >> 16;
               l_s[(i * 4) + 225] = label.partitions[i].nblk & 0xffff;
       }
       for (i = 0; i < NXPART; i++) {
               if (label.partitions[i + 8].startcyl ||
                   label.partitions[i + 8].nblk)
                       break;
       }
       if (i < NXPART) {
               unsigned long int xsum;
               l_s[66] = LABEL_XMAGIC >> 16;
               l_s[67] = LABEL_XMAGIC & 0xffff;
               for (i = 0; i < NXPART; i++) {
                       int j = (i * 4) + 68;
                       l_s[j++] = label.partitions[i + 8].startcyl >> 16;
                       l_s[j++] = label.partitions[i + 8].startcyl & 0xffff;
                       l_s[j++] = label.partitions[i + 8].nblk >> 16;
                       l_s[j++] = label.partitions[i + 8].nblk & 0xffff;
               }
               xsum = 0;
               for (i = 0; i < ((NXPART * 2) + 1); i++)
                       xsum += (l_s[i + i + 66] << 16) | l_s[i + i + 67];
               l_s[64] = (int32_t)(xsum >> 16);
               l_s[65] = (int32_t)(xsum & 0xffff);
       }
       l_s[254] = LABEL_MAGIC;
       sum = 0;
       for (i = 0; i < 255; i++)
               sum ^= l_s[i];
       l_s[255] = sum;
       for (i = 0; i < 256; i++) {
               labelbuf[i + i] = ((uint32_t)l_s[i]) >> 8;
               labelbuf[i + i + 1] = l_s[i] & 0xff;
       }
}

/*
* Get the label.  Read it off the disk and unpack it.  This function
*  is nothing but lseek, read, unpack_label, and error checking.
*/
static void
getlabel(void)
{
       int rv;
       const char *lerr;

       if (lseek(diskfd, (off_t)0, SEEK_SET) == (off_t)-1)
               err(1, "lseek to 0 on `%s' failed", diskname);

       if ((rv = read(diskfd, &labelbuf[0], 512)) == -1)
               err(1, "read label from `%s' failed", diskname);

       if (rv != 512)
               errx(1, "short read from `%s' wanted %d, got %d.", diskname,
                   512, rv);

       lerr = unpack_label();
       if (lerr)
               errx(1, "bogus label on `%s' (%s)", diskname, lerr);
}

/*
* Put the label.  Pack it and write it to the disk.  This function is
*  little more than pack_label, lseek, write, and error checking.
*/
static void
putlabel(void)
{
       int rv;

       if (readonly) {
               warnx("No write access to `%s'", diskname);
               return;
       }

       if (lseek(diskfd, (off_t)0, SEEK_SET) < (off_t)-1)
               err(1, "lseek to 0 on `%s' failed", diskname);

       pack_label();

       if ((rv = write(diskfd, &labelbuf[0], 512)) == -1) {
               err(1, "write label to `%s' failed", diskname);
               exit(1);
       }

       if (rv != 512)
               errx(1, "short write to `%s': wanted %d, got %d",
                   diskname, 512, rv);

       label.dirty = 0;
}

/*
* Skip whitespace.  Used several places in the command-line parsing
* code.
*/
static void
skipspaces(const char **cpp)
{
       const char *cp = *cpp;
       while (*cp && isspace((unsigned char)*cp))
               cp++;
       *cpp = cp;
}

/*
* Scan a number.  The first arg points to the char * that's moving
*  along the string.  The second arg points to where we should store
*  the result.  The third arg says what we're scanning, for errors.
*  The return value is 0 on error, or nonzero if all goes well.
*/
static int
scannum(const char **cpp, uint32_t *np, const char *tag)
{
       uint32_t v;
       int nd;
       const char *cp;

       skipspaces(cpp);
       v = 0;
       nd = 0;

       cp = *cpp;
       while (*cp && isdigit((unsigned char)*cp)) {
               v = (10 * v) + (*cp++ - '0');
               nd++;
       }
       *cpp = cp;

       if (nd == 0) {
               printf("Missing/invalid %s: %s\n", tag, cp);
               return (0);
       }
       *np = v;
       return (1);
}

/*
* Change a partition.  pno is the number of the partition to change;
*  numbers is a pointer to the string containing the specification for
*  the new start and size.  This always takes the form "start size",
*  where start can be
*
*      a number
*              The partition starts at the beginning of that cylinder.
*
*      start-X
*              The partition starts at the same place partition X does.
*
*      end-X
*              The partition starts at the place partition X ends.  If
*              partition X does not exactly on a cylinder boundary, it
*              is effectively rounded up.
*
*  and size can be
*
*      a number
*              The partition is that many sectors long.
*
*      num/num/num
*              The three numbers are cyl/trk/sect counts.  n1/n2/n3 is
*              equivalent to specifying a single number
*              ((n1*label.nhead)+n2)*label.nsect)+n3.  In particular,
*              if label.nhead or label.nsect is zero, this has limited
*              usefulness.
*
*      end-X
*              The partition ends where partition X ends.  It is an
*              error for partition X to end before the specified start
*              point.  This always goes to exactly where partition X
*              ends, even if that's partway through a cylinder.
*
*      start-X
*              The partition extends to end exactly where partition X
*              begins.  It is an error for partition X to begin before
*              the specified start point.
*
*      size-X
*              The partition has the same size as partition X.
*
* If label.spc is nonzero but the partition size is not a multiple of
*  it, a warning is printed, since you usually don't want this.  Most
*  often, in my experience, this comes from specifying a cylinder
*  count as a single number N instead of N/0/0.
*/
static void
chpart(int pno, const char *numbers)
{
       uint32_t cyl0;
       uint32_t size;
       uint32_t sizec;
       uint32_t sizet;
       uint32_t sizes;

       skipspaces(&numbers);
       if (!memcmp(numbers, "end-", 4) && numbers[4]) {
               int epno = LETTERPART(numbers[4]);
               if ((epno >= 0) && (epno < NPART)) {
                       cyl0 = label.partitions[epno].endcyl;
                       numbers += 5;
               } else {
                       if (!scannum(&numbers, &cyl0, "starting cylinder"))
                               return;
               }
       } else if (!memcmp(numbers, "start-", 6) && numbers[6]) {
               int spno = LETTERPART(numbers[6]);
               if ((spno >= 0) && (spno < NPART)) {
                       cyl0 = label.partitions[spno].startcyl;
                       numbers += 7;
               } else {
                       if (!scannum(&numbers, &cyl0, "starting cylinder"))
                               return;
               }
       } else {
               if (!scannum(&numbers, &cyl0, "starting cylinder"))
                       return;
       }
       skipspaces(&numbers);
       if (!memcmp(numbers, "end-", 4) && numbers[4]) {
               int epno = LETTERPART(numbers[4]);
               if ((epno >= 0) && (epno < NPART)) {
                       if (label.partitions[epno].endcyl <= cyl0) {
                               warnx("Partition %c ends before cylinder %u",
                                   PARTLETTER(epno), cyl0);
                               return;
                       }
                       size = label.partitions[epno].nblk;
                       /* Be careful of unsigned arithmetic */
                       if (cyl0 > label.partitions[epno].startcyl) {
                               size -= (cyl0 - label.partitions[epno].startcyl)
                                   * label.spc;
                       } else if (cyl0 < label.partitions[epno].startcyl) {
                               size += (label.partitions[epno].startcyl - cyl0)
                                   * label.spc;
                       }
                       numbers += 5;
               } else {
                       if (!scannum(&numbers, &size, "partition size"))
                               return;
               }
       } else if (!memcmp(numbers, "start-", 6) && numbers[6]) {
               int  spno = LETTERPART(numbers[6]);
               if ((spno >= 0) && (spno < NPART)) {
                       if (label.partitions[spno].startcyl <= cyl0) {
                               warnx("Partition %c starts before cylinder %u",
                                   PARTLETTER(spno), cyl0);
                               return;
                       }
                       size = (label.partitions[spno].startcyl - cyl0)
                           * label.spc;
                       numbers += 7;
               } else {
                       if (!scannum(&numbers, &size, "partition size"))
                               return;
               }
       } else if (!memcmp(numbers, "size-", 5) && numbers[5]) {
               int spno = LETTERPART(numbers[5]);
               if ((spno >= 0) && (spno < NPART)) {
                       size = label.partitions[spno].nblk;
                       numbers += 6;
               } else {
                       if (!scannum(&numbers, &size, "partition size"))
                               return;
               }
       } else {
               if (!scannum(&numbers, &size, "partition size"))
                       return;
               skipspaces(&numbers);
               if (*numbers == '/') {
                       sizec = size;
                       numbers++;
                       if (!scannum(&numbers, &sizet,
                           "partition size track value"))
                               return;
                       skipspaces(&numbers);
                       if (*numbers != '/') {
                               warnx("Invalid c/t/s syntax - no second slash");
                               return;
                       }
                       numbers++;
                       if (!scannum(&numbers, &sizes,
                           "partition size sector value"))
                               return;
                       size = sizes + (label.nsect * (sizet
                           + (label.nhead * sizec)));
               }
       }
       if (label.spc && (size % label.spc)) {
               warnx("Size is not a multiple of cylinder size (is %u/%u/%u)",
                   size / label.spc,
                   (size % label.spc) / label.nsect, size % label.nsect);
       }
       label.partitions[pno].startcyl = cyl0;
       label.partitions[pno].nblk = size;
       set_endcyl(&label.partitions[pno]);
       if ((label.partitions[pno].startcyl * label.spc)
           + label.partitions[pno].nblk > label.spc * label.ncyl) {
               warnx("Partition extends beyond end of disk");
       }
       label.dirty = 1;
}

/*
* Change a 128-byte-string field.  There's currently only one such,
*  the ASCII label field.
*/
static void
chval_ascii(const char *cp, struct field *f)
{
       const char *nl;

       skipspaces(&cp);
       if ((nl = strchr(cp, '\n')) == NULL)
               nl = cp + strlen(cp);
       if (nl - cp > 128) {
               warnx("Ascii label string too long - max 128 characters");
       } else {
               memset(f->loc, 0, 128);
               memcpy(f->loc, cp, (size_t)(nl - cp));
               label.dirty = 1;
       }
}
/*
* Change an int-valued field.  As noted above, there's only one
*  function, regardless of the field size in the on-disk label.
*/
static void
chval_int(const char *cp, struct field *f)
{
       uint32_t v;

       if (!scannum(&cp, &v, "value"))
               return;
       *(uint32_t *)f->loc = v;
       label.dirty = 1;
}
/*
* Change a field's value.  The string argument contains the field name
*  and the new value in text form.  Look up the field and call its
*  chval and changed functions.
*/
static void
chvalue(const char *str)
{
       const char *cp;
       int i;
       size_t n;

       if (fields[0].taglen < 1) {
               for (i = 0; fields[i].tag; i++)
                       fields[i].taglen = strlen(fields[i].tag);
       }
       skipspaces(&str);
       cp = str;
       while (*cp && !isspace((unsigned char)*cp))
               cp++;
       n = cp - str;
       for (i = 0; fields[i].tag; i++) {
               if (((int)n == fields[i].taglen) && !memcmp(str, fields[i].tag, n)) {
                       (*fields[i].chval) (cp, &fields[i]);
                       if (fields[i].changed)
                               (*fields[i].changed)();
                       break;
               }
       }
       if (!fields[i].tag)
               warnx("Bad name %.*s - see L output for names", (int)n, str);
}

/*
* `changed' function for the ntrack and nsect fields; update label.spc
*  and call set_endcyl on all partitions.
*/
static void
update_spc(void)
{
       int i;

       label.spc = label.nhead * label.nsect;
       for (i = 0; i < NPART; i++)
               set_endcyl(&label.partitions[i]);
}

/*
* Print function for 128-byte-string fields.  Currently only the ASCII
*  label, but we don't depend on that.
*/
static int
print_ascii(struct field *f, int sofar)
{
       printf("%s: %.128s\n", f->tag, (char *)f->loc);
       return 0;
}

/*
* Print an int-valued field.  We are careful to do proper line wrap,
*  making each value occupy 16 columns.
*/
static int
print_int(struct field *f, int sofar)
{
       if (sofar >= 60) {
               printf("\n");
               sofar = 0;
       }
       printf("%s: %-*u", f->tag, 14 - (int)strlen(f->tag),
           *(uint32_t *)f->loc);
       return sofar + 16;
}

/*
* Print the whole label.  Just call the print function for each field,
*  then append a newline if necessary.
*/
static void
print_label(void)
{
       int i;
       int c;

       c = 0;
       for (i = 0; fields[i].tag; i++)
               c = (*fields[i].print) (&fields[i], c);
       if (c > 0)
               printf("\n");
}

/*
* Figure out how many columns wide the screen is.  We impose a minimum
*  width of 20 columns; I suspect the output code has some issues if
*  we have fewer columns than partitions.
*/
static int
screen_columns(void)
{
       int ncols;
#ifndef NO_TERMCAP_WIDTH
       char *term;
       char tbuf[1024];
#endif
#if defined(TIOCGWINSZ)
       struct winsize wsz;
#elif defined(TIOCGSIZE)
       struct ttysize tsz;
#endif

       ncols = 80;
#ifndef NO_TERMCAP_WIDTH
       term = getenv("TERM");
       if (term && (tgetent(&tbuf[0], term) == 1)) {
               int n = tgetnum("co");
               if (n > 1)
                       ncols = n;
       }
#endif
#if defined(TIOCGWINSZ)
       if ((ioctl(1, TIOCGWINSZ, &wsz) == 0) && (wsz.ws_col > 0)) {
               ncols = wsz.ws_col;
       }
#elif defined(TIOCGSIZE)
       if ((ioctl(1, TIOCGSIZE, &tsz) == 0) && (tsz.ts_cols > 0)) {
               ncols = tsz.ts_cols;
       }
#endif
       if (ncols < 20)
               ncols = 20;
       return ncols;
}

/*
* Print the partitions.  The argument is true iff we should print all
* partitions, even those set start=0 size=0.  We generate one line
* per partition (or, if all==0, per `interesting' partition), plus a
* visually graphic map of partition letters.  Most of the hair in the
* visual display lies in ensuring that nothing takes up less than one
* character column, that if two boundaries appear visually identical,
* they _are_ identical.  Within that constraint, we try to make the
* number of character columns proportional to the size....
*/
static void
print_part(int all)
{
       int i, j, k, n, r, c;
       size_t ncols;
       uint32_t edges[2 * NPART];
       int ce[2 * NPART] = {0}; /* XXXGCC12 */
       int row[NPART];
       unsigned char table[2 * NPART][NPART];
       char *line;
       struct part *p = label.partitions;

       for (i = 0; i < NPART; i++) {
               if (all || p[i].startcyl || p[i].nblk) {
                       printf("%c: start cyl = %6u, size = %8u (",
                           PARTLETTER(i), p[i].startcyl, p[i].nblk);
                       if (label.spc) {
                               printf("%u/%u/%u - ", p[i].nblk / label.spc,
                                   (p[i].nblk % label.spc) / label.nsect,
                                   p[i].nblk % label.nsect);
                       }
                       printf("%gMb)\n", p[i].nblk / 2048.0);
               }
       }

       j = 0;
       for (i = 0; i < NPART; i++) {
               if (p[i].nblk > 0) {
                       edges[j++] = p[i].startcyl;
                       edges[j++] = p[i].endcyl;
               }
       }

       do {
               n = 0;
               for (i = 1; i < j; i++) {
                       if (edges[i] < edges[i - 1]) {
                               uint32_t    t;
                               t = edges[i];
                               edges[i] = edges[i - 1];
                               edges[i - 1] = t;
                               n++;
                       }
               }
       } while (n > 0);

       for (i = 1; i < j; i++) {
               if (edges[i] != edges[n]) {
                       n++;
                       if (n != i)
                               edges[n] = edges[i];
               }
       }

       n++;
       for (i = 0; i < NPART; i++) {
               if (p[i].nblk > 0) {
                       for (j = 0; j < n; j++) {
                               if ((p[i].startcyl <= edges[j]) &&
                                   (p[i].endcyl > edges[j])) {
                                       table[j][i] = 1;
                               } else {
                                       table[j][i] = 0;
                               }
                       }
               }
       }

       ncols = screen_columns() - 2;
       for (i = 0; i < n; i++)
               ce[i] = (edges[i] * ncols) / (double) edges[n - 1];

       for (i = 1; i < n; i++)
               if (ce[i] <= ce[i - 1])
                       ce[i] = ce[i - 1] + 1;

       if ((size_t)ce[n - 1] > ncols) {
               ce[n - 1] = ncols;
               for (i = n - 1; (i > 0) && (ce[i] <= ce[i - 1]); i--)
                       ce[i - 1] = ce[i] - 1;
               if (ce[0] < 0)
                       for (i = 0; i < n; i++)
                               ce[i] = i;
       }

       printf("\n");
       for (i = 0; i < NPART; i++) {
               if (p[i].nblk > 0) {
                       r = -1;
                       do {
                               r++;
                               for (j = i - 1; j >= 0; j--) {
                                       if (row[j] != r)
                                               continue;
                                       for (k = 0; k < n; k++)
                                               if (table[k][i] && table[k][j])
                                                       break;
                                       if (k < n)
                                               break;
                               }
                       } while (j >= 0);
                       row[i] = r;
               } else {
                       row[i] = -1;
               }
       }
       r = row[0];
       for (i = 1; i < NPART; i++)
               if (row[i] > r)
                       r = row[i];

       if ((line = malloc(ncols + 1)) == NULL)
               err(1, "Can't allocate memory");

       for (i = 0; i <= r; i++) {
               for (j = 0; (size_t)j < ncols; j++)
                       line[j] = ' ';
               for (j = 0; j < NPART; j++) {
                       if (row[j] != i)
                               continue;
                       k = 0;
                       for (k = 0; k < n; k++) {
                               if (table[k][j]) {
                                       for (c = ce[k]; c < ce[k + 1]; c++)
                                               line[c] = 'a' + j;
                               }
                       }
               }
               for (j = ncols - 1; (j >= 0) && (line[j] == ' '); j--);
               printf("%.*s\n", j + 1, line);
       }
       free(line);
}

#ifdef S_COMMAND
/*
* This computes an appropriate checksum for an in-core label.  It's
* not really related to the S command, except that it's needed only
* by setlabel(), which is #ifdef S_COMMAND.
*/
static unsigned short int
dkcksum(const struct disklabel *lp)
{
       const unsigned short int *start;
       const unsigned short int *end;
       unsigned short int sum;
       const unsigned short int *p;

       start = (const void *)lp;
       end = (const void *)&lp->d_partitions[lp->d_npartitions];
       sum = 0;
       for (p = start; p < end; p++)
               sum ^= *p;
       return (sum);
}

/*
* Set the in-core label.  This is basically putlabel, except it builds
* a struct disklabel instead of a Sun label buffer, and uses
* DIOCSDINFO instead of lseek-and-write.
*/
static void
setlabel(void)
{
       union {
               struct disklabel l;
               char pad[sizeof(struct disklabel) -
                    (MAXPARTITIONS * sizeof(struct partition)) +
                     (16 * sizeof(struct partition))];
       } u;
       int i;
       struct part *p = label.partitions;

       if (ioctl(diskfd, DIOCGDINFO, &u.l) == -1) {
               warn("ioctl DIOCGDINFO failed");
               return;
       }
       if (u.l.d_secsize != 512) {
               warnx("Disk claims %d-byte sectors", (int)u.l.d_secsize);
       }
       u.l.d_nsectors = label.nsect;
       u.l.d_ntracks = label.nhead;
       u.l.d_ncylinders = label.ncyl;
       u.l.d_secpercyl = label.nsect * label.nhead;
       u.l.d_rpm = label.rpm;
       u.l.d_interleave = label.intrlv;
       u.l.d_npartitions = getmaxpartitions();
       memset(&u.l.d_partitions[0], 0,
           u.l.d_npartitions * sizeof(struct partition));
       for (i = 0; i < u.l.d_npartitions; i++) {
               u.l.d_partitions[i].p_size = p[i].nblk;
               u.l.d_partitions[i].p_offset = p[i].startcyl
                   * label.nsect * label.nhead;
               u.l.d_partitions[i].p_fsize = 0;
               u.l.d_partitions[i].p_fstype = (i == 1) ? FS_SWAP :
                   (i == 2) ? FS_UNUSED : FS_BSDFFS;
               u.l.d_partitions[i].p_frag = 0;
               u.l.d_partitions[i].p_cpg = 0;
       }
       u.l.d_checksum = 0;
       u.l.d_checksum = dkcksum(&u.l);
       if (ioctl(diskfd, DIOCSDINFO, &u.l) == -1) {
               warn("ioctl DIOCSDINFO failed");
               return;
       }
}
#endif

static const char *help[] = {
       "?\t- print this help",
       "L\t- print label, except for partition table",
       "P\t- print partition table",
       "PP\t- print partition table including size=0 offset=0 entries",
       "[abcdefghijklmnop] <cylno> <size> - change partition",
       "V <name> <value> - change a non-partition label value",
       "W\t- write (possibly modified) label out",
#ifdef S_COMMAND
       "S\t- set label in the kernel (orthogonal to W)",
#endif
       "Q\t- quit program (error if no write since last change)",
       "Q!\t- quit program (unconditionally) [EOF also quits]",
       NULL
};

/*
* Read and execute one command line from the user.
*/
static void
docmd(void)
{
       char cmdline[512];
       int i;

       if (!quiet)
               printf("sunlabel> ");
       if (fgets(&cmdline[0], sizeof(cmdline), stdin) != &cmdline[0])
               exit(0);
       switch (cmdline[0]) {
       case '?':
               for (i = 0; help[i]; i++)
                       printf("%s\n", help[i]);
               break;
       case 'L':
               print_label();
               break;
       case 'P':
               print_part(cmdline[1] == 'P');
               break;
       case 'W':
               putlabel();
               break;
       case 'S':
#ifdef S_COMMAND
               setlabel();
#else
               printf("This compilation doesn't support S.\n");
#endif
               break;
       case 'Q':
               if ((cmdline[1] == '!') || !label.dirty)
                       exit(0);
               printf("Label is dirty - use w to write it\n");
               printf("Use Q! to quit anyway.\n");
               break;
       case 'a':
       case 'b':
       case 'c':
       case 'd':
       case 'e':
       case 'f':
       case 'g':
       case 'h':
       case 'i':
       case 'j':
       case 'k':
       case 'l':
       case 'm':
       case 'n':
       case 'o':
       case 'p':
               chpart(LETTERPART(cmdline[0]), &cmdline[1]);
               break;
       case 'V':
               chvalue(&cmdline[1]);
               break;
       case '\n':
               break;
       default:
               printf("(Unrecognized command character %c ignored.)\n",
                   cmdline[0]);
               break;
       }
}

/*
* main() (duh!).  Pretty boring.
*/
int
main(int ac, char **av)
{
       handleargs(ac, av);
       getlabel();
       for (;;)
               docmd();
}