source: trunk/minix/commands/ibm/fdisk.c@ 10

/* fdisk - partition a hard disk        Author: Jakob Schripsema */

/* Run this with:
 *
 *      fdisk [-hheads] [-ssectors] [device]
 *
 * e.g.,
 *
 *      fdisk                           (to get the default)
 *      fdisk -h4 -s17 /dev/hd0         (MINIX default)
 *      fdisk -h4 -s17 c:               (DOS default)
 *      fdisk -h6 -s25 /dev/hd5         (second drive, probably RLL)
 *      fdisk junkfile                  (to experiment safely)
 *
 * The device is opened in read-only mode if the file permissions do not
 * permit read-write mode, so it is convenient to use a login account with
 * only read permission to look at the partition table safely.
 *
 * Compile with:
 *
 *      cc -i -o fdisk fdisk.c          (MINIX)
 *      cl -DDOS fdisk.c                (DOS with MS C compiler)
 *
 * This was modified extensively by Bruce Evans 28 Dec 89.
 * The new version has not been tried with DOS.  The open modes are suspect
 * (everyone should convert to use fcntl.h).
 *
 * Changed 18 Dec 92 by Kees J. Bot: Bootstrap code and geometry from device.
 *
 * modified 01 March 95 by asw: updated list of known partition types. Also
 * changed display format slightly to allow for partition type names of
 * up to 9 chars (previous format allowed for 7, but there were already
 * some 8 char names in the list).
*/

#include <sys/types.h>
#include <ibm/partition.h>
#include <minix/partition.h>
#include <sys/ioctl.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include <stdio.h>
#include <errno.h>

#ifdef DOS
#include <dos.h>
#define DEFAULT_DEV     "c:"
#define LOAD_OPEN_MODE  0x8000
#define SAVE_CREAT_MODE 0644
#else
#define DEFAULT_DEV     "/dev/hd0"
#define LOAD_OPEN_MODE  0
#define SAVE_CREAT_MODE 0644
#define UNIX                    /* for MINIX */
#endif

/* Constants */

#define DEFAULT_NHEAD   4       /* # heads               */
#define DEFAULT_NSEC    17      /* sectors / track       */
#define SECSIZE         512     /* sector size           */
#define OK              0
#define ERR             1

#define CYL_MASK        0xc0    /* mask to extract cyl bits from sec field */
#define CYL_SHIFT       2       /* shift to extract cyl bits from sec field */
#define SEC_MASK        0x3f    /* mask to extract sec bits from sec field */

/* Globals  */
char rawsecbuf[SECSIZE + sizeof(long)];
char *secbuf;
int badbases;
int badsizes;
int badorders;
char *devname;
int nhead;
int nsec;
int ncyl = 1024;
int readonly;
int override= 0;

_PROTOTYPE(int main, (int argc, char *argv []));
_PROTOTYPE(void getgeom, (void));
_PROTOTYPE(int getboot, (char *buffer));
_PROTOTYPE(int putboot, (char *buffer));
_PROTOTYPE(int load_from_file, (void));
_PROTOTYPE(int save_to_file, (void));
_PROTOTYPE(int dpl_partitions, (int rawflag));
_PROTOTYPE(int chk_table, (void));
_PROTOTYPE(int sec_to_hst, (long logsec, unsigned char *hd, unsigned char *sec,
                                                         unsigned char *cyl));
_PROTOTYPE(int mark_partition, (struct part_entry *pe));
_PROTOTYPE(int change_partition, (struct part_entry *entry));
_PROTOTYPE(int get_a_char, (void));
_PROTOTYPE(int print_menu, (void));
_PROTOTYPE(void adj_base, (struct part_entry *pe));
_PROTOTYPE(void adj_size, (struct part_entry *pe));
_PROTOTYPE(struct part_entry *ask_partition, (void));
_PROTOTYPE(void footnotes, (void));
_PROTOTYPE(int get_an_int, (char *prompt, int *intptr));
_PROTOTYPE(void list_part_types, (void));
_PROTOTYPE(void mark_npartition, (struct part_entry *pe));
_PROTOTYPE(int mygets, (char *buf, int length));
_PROTOTYPE(char *systype, (int type));
_PROTOTYPE(void toggle_active, (struct part_entry *pe));
_PROTOTYPE(void usage, (void));

/* One featureful master bootstrap. */
char bootstrap[] = {
0353,0001,0000,0061,0300,0216,0330,0216,0300,0372,0216,0320,0274,0000,0174,0373,
0275,0276,0007,0211,0346,0126,0277,0000,0006,0271,0000,0001,0374,0363,0245,0352,
0044,0006,0000,0000,0264,0002,0315,0026,0250,0010,0164,0033,0350,0071,0001,0174,
0007,0060,0344,0315,0026,0242,0205,0007,0054,0060,0074,0012,0163,0363,0120,0350,
0046,0001,0205,0007,0130,0353,0012,0240,0002,0006,0204,0300,0165,0003,0351,0147,
0000,0230,0262,0005,0366,0362,0262,0200,0000,0302,0210,0340,0120,0350,0234,0000,
0163,0003,0351,0147,0000,0130,0054,0001,0175,0003,0351,0141,0000,0276,0276,0175,
0211,0357,0271,0040,0000,0363,0245,0200,0301,0004,0211,0356,0215,0174,0020,0070,
0154,0004,0164,0016,0213,0135,0010,0053,0134,0010,0213,0135,0012,0033,0134,0012,
0163,0014,0212,0044,0206,0144,0020,0210,0044,0106,0071,0376,0162,0364,0211,0376,
0201,0376,0356,0007,0162,0326,0342,0322,0211,0356,0264,0020,0366,0344,0001,0306,
0200,0174,0004,0001,0162,0026,0353,0021,0204,0322,0175,0041,0211,0356,0200,0174,
0004,0000,0164,0013,0366,0004,0200,0164,0006,0350,0070,0000,0162,0053,0303,0203,
0306,0020,0201,0376,0376,0007,0162,0346,0350,0215,0000,0211,0007,0376,0302,0204,
0322,0174,0023,0315,0021,0321,0340,0321,0340,0200,0344,0003,0070,0342,0167,0355,
0350,0011,0000,0162,0350,0303,0350,0003,0000,0162,0146,0303,0211,0356,0214,0134,
0010,0214,0134,0012,0277,0003,0000,0122,0006,0127,0264,0010,0315,0023,0137,0007,
0200,0341,0077,0376,0306,0210,0310,0366,0346,0211,0303,0213,0104,0010,0213,0124,
0012,0367,0363,0222,0210,0325,0366,0361,0060,0322,0321,0352,0321,0352,0010,0342,
0210,0321,0376,0301,0132,0210,0306,0273,0000,0174,0270,0001,0002,0315,0023,0163,
0020,0200,0374,0200,0164,0011,0117,0174,0006,0060,0344,0315,0023,0163,0270,0371,
0303,0201,0076,0376,0175,0125,0252,0165,0001,0303,0350,0013,0000,0243,0007,0353,
0005,0350,0004,0000,0227,0007,0353,0376,0136,0255,0126,0211,0306,0254,0204,0300,
0164,0011,0264,0016,0273,0001,0000,0315,0020,0353,0362,0303,0057,0144,0145,0166,
0057,0150,0144,0077,0010,0000,0015,0012,0000,0116,0157,0156,0145,0040,0141,0143,
0164,0151,0166,0145,0015,0012,0000,0122,0145,0141,0144,0040,0145,0162,0162,0157,
0162,0040,0000,0116,0157,0164,0040,0142,0157,0157,0164,0141,0142,0154,0145,0040,
0000,0000,
};

main(argc, argv)
int argc;
char *argv[];
{
  int argn;
  char *argp;
  int ch;

  /* Init */

  nhead = DEFAULT_NHEAD;
  nsec = DEFAULT_NSEC;
  for (argn = 1; argn < argc && (argp = argv[argn])[0] == '-'; ++argn) {
        if (argp[1] == 'h')
                nhead = atoi(argp + 2);
        else
                if (argp[1] == 's') nsec = atoi(argp + 2);
        else
                usage();
        override= 1;
  }

  if (argn == argc)
        devname = DEFAULT_DEV;
  else if (argn == argc - 1)
        devname = argv[argn];
  else
        usage();

  /* Align the sector buffer in such a way that the partition table is at
   * a mod 4 offset in memory.  Some weird people add alignment checks to
   * their Minix!
   */
  secbuf = rawsecbuf;
  while ((long)(secbuf + PART_TABLE_OFF) % sizeof(long) != 0) secbuf++;

  getgeom();
  getboot(secbuf);
  chk_table();

  do {
        putchar('\n');
        dpl_partitions(0);
        printf(
          "\n(Enter 'h' for help.  A null line will abort any operation) ");
        ch = get_a_char();
        putchar('\n');
        switch (ch) {
            case '+':   footnotes();                    break;
            case 'a':   toggle_active(ask_partition()); break;
            case 'B':   adj_base(ask_partition());      break;
            case 'c':   change_partition(ask_partition());      break;
            case 'h':   print_menu();                   break;
            case 'l':   load_from_file();               break;
            case 'm':   mark_partition(ask_partition());        break;
            case 'n':   mark_npartition(ask_partition());       break;
            case 'p':   dpl_partitions(1);              break;
            case 0:
            case 'q':   exit(0);
            case 'S':   adj_size(ask_partition());      break;
            case 's':   save_to_file();                 break;
            case 't':   list_part_types();              break;
            case 'v':
                printf("Partition table is %svalid\n",
                        chk_table() == OK ? "" : "in");
                break;
            case 'w':
                if (readonly)
                        printf("Write disabled\n");
                else if(chk_table() == OK) {
                        putboot(secbuf);
                        printf(
        "Partition table has been updated and the file system synced.\n");
                        printf("Please reboot now.\n");
                        exit(0);
                } else
                        printf("Not written\n");
                break;
            default:    printf(" %c ????\n", ch);       break;
        }
  }
  while (1);
}


#ifdef UNIX

void getgeom()
{
  struct partition geom;
  int fd, r;

  if (override) return;

  if ((fd= open(devname, O_RDONLY)) < 0) return;

  r = ioctl(fd, DIOCGETP, &geom);
  close(fd);
  if (r < 0) return;

  nhead = geom.heads;
  nsec = geom.sectors;
  ncyl = geom.cylinders;

  printf("Geometry of %s: %dx%dx%d\n", devname, ncyl, nhead, nsec);
}

static int devfd;

getboot(buffer)
char *buffer;
{
  devfd = open(devname, 2);
  if (devfd < 0) {
        printf("No write permission on %s\n", devname);
        readonly = 1;
        devfd = open(devname, 0);
  }
  if (devfd < 0) {
        printf("Cannot open device %s\n", devname);
        exit(1);
  }
  if (read(devfd, buffer, SECSIZE) != SECSIZE) {
        printf("Cannot read boot sector\n");
        exit(1);
  }
  if (* (unsigned short *) &buffer[510] != 0xAA55) {
        printf("Invalid boot sector on %s.\n", devname);
        printf("Partition table reset and boot code installed.\n");
        memset(buffer, 0, 512);
        memcpy(buffer, bootstrap, sizeof(bootstrap));
        * (unsigned short *) &buffer[510] = 0xAA55;
  }
}

putboot(buffer)
char *buffer;
{
  if (lseek(devfd, 0L, 0) < 0) {
        printf("Seek error during write\n");
        exit(1);
  }
  if (write(devfd, buffer, SECSIZE) != SECSIZE) {
        printf("Write error\n");
        exit(1);
  }
  sync();
}

#endif


load_from_file()
{
/* Load buffer from file  */

  char file[80];
  int fd;

  printf("Enter name of file to load from: ");
  if (!mygets(file, (int) sizeof file)) return;
  fd = open(file, LOAD_OPEN_MODE);
  if (fd < 0) {
        printf("Cannot open %s\n", file);
        return;
  }
  if (read(fd, secbuf, SECSIZE) != SECSIZE || close(fd) != 0) {
        printf("Read error\n");
        exit(1);
  }
  printf("Loaded from %s OK\n", file);
  chk_table();
}


save_to_file()
{
/* Save to file  */

  char file[80];
  int fd;

  printf("Enter name of file to save to: ");
  if (!mygets(file, (int) sizeof file)) return;
  if(chk_table() != OK) printf("Saving anyway\n");
  fd = creat(file, SAVE_CREAT_MODE);
#ifdef DOS
  if (fd < 0) {
        printf("Cannot creat %s\n", file);
        return;
  }
  close(fd);
  fd = open(file, 0x8001);
#endif
  if (fd < 0)
        printf("Cannot open %s\n", file);
  else if (write(fd, secbuf, SECSIZE) != SECSIZE || close(fd) != 0)
        printf("Write error\n");
  else
        printf("Saved to %s OK\n", file);
}


dpl_partitions(rawflag)
int rawflag;
{
/* Display partition table */

  char active[5];
  char basefootnote;
  int cyl_mask;
  int devnum;
  char *format;
  int i;
  int i1;
  char orderfootnote;
  struct part_entry *pe;
  struct part_entry *pe1;
  int sec_mask;
  char sizefootnote;
  char type[10];

  badbases = 0;
  badsizes = 0;
  badorders = 0;
  if (rawflag) {
        cyl_mask = 0;           /* no contribution of cyl to sec */
        sec_mask = 0xff;
        format =
"%2d   %3d%c  %4s %-9s  x%02x %3d  x%02x   x%02x %3d  x%02x %7ld%c%7ld %7ld%c\n";
  } else {
        cyl_mask = CYL_MASK;
        sec_mask = SEC_MASK;
        format =
"%2d   %3d%c  %4s %-9s %4d %3d %3d   %4d %3d  %3d %7ld%c%7ld %7ld%c\n";
  }
  printf(
"                          ----first----  -----last----  --------sectors-------\n"
        );
  printf(
"Num Sorted Act  Type     Cyl Head Sec   Cyl Head Sec    Base    Last    Size\n"
        );
  pe = (struct part_entry *) &secbuf[PART_TABLE_OFF];
  for (i = 1; i <= NR_PARTITIONS; i++, pe++) {
        if (rawflag) {
                sprintf(active, "0x%02x", pe->bootind);
                sprintf(type, "0x%02x", pe->sysind);
        } else {
                sprintf(active, "%s", pe->bootind == ACTIVE_FLAG ? "A  " : "");
                sprintf(type, "%s", systype(pe->sysind));
        }

        /* Prepare warnings about confusing setups from old versions. */
        basefootnote = orderfootnote = sizefootnote = ' ';
        if (pe->sysind == MINIX_PART && pe->lowsec & 1) {
                basefootnote = '+';
                ++badbases;
        }
        if (pe->size & 1) {
                sizefootnote = '-';
                ++badsizes;
        }

        /* Calculate the "device numbers" resulting from the misguided sorting
         * in the wini drivers.  The drivers use this conditional for
         * swapping wn[j] > wn[j+1]:
         *
         *      if ((wn[j].wn_low == 0 && wn[j+1].wn_low != 0) ||
         *          (wn[j].wn_low > wn[j+1].wn_low && wn[j+1].wn_low != 0)) {
         *
         * which simplifies to:
         *
         *      if (wn[j+1].wn_low != 0 &&
         *          (wn[j].wn_low == 0 || wn[j].wn_low > wn[j+1].wn_low)) {
         */
        devnum = 1;
        for (i1 = 1, pe1 = (struct part_entry *) &secbuf[PART_TABLE_OFF];
             i1 <= NR_PARTITIONS; ++i1, ++pe1)
                if (pe1->lowsec == 0 && pe->lowsec == 0 && pe1 < pe ||
                    pe1->lowsec != 0 &&
                    (pe->lowsec == 0 || pe->lowsec > pe1->lowsec))
                        ++devnum;       /* pe1 contents < pe contents */
        if (devnum != i) {
                orderfootnote = '#';
                ++badorders;
        }

        printf(format,
                i,
                devnum,
                orderfootnote,
                active,
                type,
                pe->start_cyl + ((pe->start_sec & cyl_mask) << CYL_SHIFT),
                pe->start_head,
                pe->start_sec & sec_mask,
                pe->last_cyl + ((pe->last_sec & cyl_mask) << CYL_SHIFT),
                pe->last_head,
                pe->last_sec & sec_mask,
                pe->lowsec,
                basefootnote,
                pe->lowsec + (pe->size == 0 ? 0 : pe->size - 1),
                pe->size,
                sizefootnote);
  }
}


int chk_table()
{
/* Check partition table */

  int active;
  unsigned char cylinder;
  unsigned char head;
  int i;
  int i1;
  int maxhead;
  int maxsec;
  struct part_entry *pe;
  struct part_entry *pe1;
  unsigned char sector;
  int seenpart;
  int status;

  active = 0;
  maxhead = 0;
  maxsec = 0;
  pe = (struct part_entry *) &secbuf[PART_TABLE_OFF];
  seenpart = 0;
  status = OK;
  for (i = 1; i <= NR_PARTITIONS; i++, ++pe) {
        if (pe->bootind == ACTIVE_FLAG) active++;
        sec_to_hst(pe->lowsec, &head, &sector, &cylinder);
        if (pe->size == 0 && pe->lowsec == 0) sector = 0;
        if (head != pe->start_head || sector != pe->start_sec ||
            cylinder != pe->start_cyl) {
                printf("Inconsistent base in partition %d.\n", i);
                printf("Suspect head and sector parameters.\n");
                status = ERR;
        }
        if (pe->size != 0 || pe->lowsec != 0)
              sec_to_hst(pe->lowsec + pe->size - 1, &head, &sector, &cylinder);
        if (head != pe->last_head || sector != pe->last_sec ||
            cylinder != pe->last_cyl) {
                printf("Inconsistent size in partition %d.\n", i);
                printf("Suspect head and sector parameters.\n");
                status = ERR;
        }
        if (pe->size == 0) continue;
        seenpart = 1;
        for (i1 = i + 1, pe1 = pe + 1; i1 <= NR_PARTITIONS; ++i1, ++pe1) {
                if (pe->lowsec >= pe1->lowsec &&
                    pe->lowsec < pe1->lowsec + pe1->size ||
                    pe->lowsec + pe->size - 1 >= pe1->lowsec &&
                    pe->lowsec + pe->size - 1 < pe1->lowsec + pe1->size)
                {
                        printf("Overlap between partitions %d and %d\n",
                                i, i1);
                        status = ERR;
                }
        }
        if (pe->lowsec + pe->size < pe->lowsec) {
                printf("Overflow from preposterous size in partition %d.\n",
                        i);
                status = ERR;
        }
        if (maxhead < pe->start_head) maxhead = pe->start_head;
        if (maxhead < pe->last_head) maxhead = pe->last_head;
        if (maxsec < (pe->start_sec & SEC_MASK))
                maxsec = (pe->start_sec & SEC_MASK);
        if (maxsec < (pe->last_sec & SEC_MASK))
                maxsec = (pe->last_sec & SEC_MASK);
  }
  if (seenpart) {
        if (maxhead + 1 != nhead || maxsec != nsec) {
                printf(
        "Disk appears to have mis-specified number of heads or sectors.\n");
                printf("Try  fdisk -h%d -s%d %s  instead of\n",
                        maxhead + 1, maxsec, devname);
                printf("     fdisk -h%d -s%d %s\n", nhead, nsec, devname);
                seenpart = 0;
        }
  } else {
        printf(
        "Empty table - skipping test on number of heads and sectors.\n");
        printf("Assuming %d heads and %d sectors.\n", nhead, nsec);
  }
  if (!seenpart) printf("Do not write the table if you are not sure!.\n");
  if (active > 1) {
        printf("%d active partitions\n", active);
        status = ERR;   
  }
  return(status);
}

sec_to_hst(logsec, hd, sec, cyl)
long logsec;
unsigned char *hd, *sec, *cyl;
{
/* Convert a logical sector number to  head / sector / cylinder */

  int bigcyl;

  bigcyl = logsec / (nhead * nsec);
  *sec = (logsec % nsec) + 1 + ((bigcyl >> CYL_SHIFT) & CYL_MASK);
  *cyl = bigcyl;
  *hd = (logsec % (nhead * nsec)) / nsec;
}

mark_partition(pe)
struct part_entry *pe;
{
/* Mark a partition as being of type MINIX. */

  if (pe != NULL) {
        pe->sysind = MINIX_PART;
        printf("Partition type is now MINIX\n");
  }
}

change_partition(entry)
struct part_entry *entry;
{
/* Get partition info : first & last cylinder */

  int first, last;
  long low, high;
  int ch;

  if (entry == NULL) return;
  while (1) {
        if (!get_an_int("\tEnter first cylinder (an integer >= 0): ", &first))
                return;
        if (first >= 0) break;
        printf("\t\tThat looks like %d which is negative\n", first);
  }
  while (1) {
        if (!get_an_int(
        "\tEnter last cylinder (an integer >= the first cylinder): ", &last))
                return;
        if (last >= first) break;
        printf("\t\tThat looks like %d which is too small\n", last);
  }
  if (first == 0 && last == 0) {
        entry->bootind = 0;
        entry->start_head = 0;
        entry->start_sec = 0;
        entry->start_cyl = 0;
        entry->sysind = NO_PART;
        entry->last_head = 0;
        entry->last_sec = 0;
        entry->last_cyl = 0;
        entry->lowsec = 0;
        entry->size = 0;
        printf("Partition deleted\n");
        return;
  }
  low = first & 0xffff;
  low = low * nsec * nhead;
  if (low == 0) low = 1;        /* sec0 is master boot record */
  high = last & 0xffff;
  high = (high + 1) * nsec * nhead - 1;
  entry->lowsec = low;
  entry->size = high - low + 1;
  if (entry->size & 1) {
        /* Adjust size to even since Minix works with blocks of 2 sectors. */
        --high;
        --entry->size;
        printf("Size reduced by 1 to make it even\n");
  }
  sec_to_hst(low, &entry->start_head, &entry->start_sec, &entry->start_cyl);
  sec_to_hst(high, &entry->last_head, &entry->last_sec, &entry->last_cyl);
  printf("Base of partition changed to %ld, size changed to %ld\n",
         entry->lowsec, entry->size);

  /* Accept the MINIX partition type.  Usually ignore foreign types, so this
   * fdisk can be used on foreign partitions.  Don't allow NO_PART, because
   * many DOS fdisks crash on it.
   */
  if (entry->sysind == NO_PART) {
        entry->sysind = MINIX_PART;
        printf("Partition type changed from None to MINIX\n");
  } else if (entry->sysind == MINIX_PART)
        printf("Leaving partition type as MINIX\n");
  else while (1) {
        printf("\tChange partition type from %s to MINIX? (y/n) ",
                systype(entry->sysind));
        ch = get_a_char();
        if (ch == 0 || ch == 'n') {
                printf("Leaving partition type as %s\n",
                        systype(entry->sysind));
                break;
        } else if (ch == 'y') {
                entry->sysind = MINIX_PART;
                printf("Partition type changed from %s to MINIX\n",
                        systype(entry->sysind));
                break;
        }
  }

  if (entry->bootind == ACTIVE_FLAG)
        printf("Leaving partition active\n");
  else while (1) {
        printf("\tChange partition to active? (y/n) ");
        ch = get_a_char();
        if (ch == 0 || ch == 'n') {
                printf("Leaving partition inactive\n");
                break;
        } else if (ch == 'y') {
                toggle_active(entry);
                break;
        }
  }
}

get_a_char()
{
/* Read 1 character and discard rest of line */

  char buf[80];
  int ch;

  if (!mygets(buf, (int) sizeof buf)) return(0);
  return(*buf);
}

print_menu()
{
  printf("Type a command letter, then a carriage return:\n");
  printf("   + - explain any footnotes (+, -, #)\n");
  printf("   a - toggle an active flag\n");
  printf("   B - adjust a base sector\n");
  printf("   c - change a partition\n");
  printf("   l - load boot block (including partition table) from a file\n");
  printf("   m - mark a partition as a MINIX partition\n");
  printf("   n - mark a partition as a non-MINIX partition\n");
  printf("   p - print raw partition table\n");
  printf("   q - quit without making any changes\n");
  printf("   S - adjust a size (by changing the last sector)\n");
  printf("   s - save boot block (including partition table) on a file\n");
  printf("   t - print known partition types\n");
  printf("   v - verify partition table\n");
 if (readonly)
  printf("   w - write (disabled)\n");
 else
  printf("   w - write changed partition table back to disk and exit\n");
}


/* Here are the DOS routines for reading and writing the boot sector. */

#ifdef DOS

union REGS regs;
struct SREGS sregs;
int drivenum;

getboot(buffer)
char *buffer;
{
/* Read boot sector  */

  segread(&sregs);              /* get ds */

  if (devname[1] != ':') {
        printf("Invalid drive %s\n", devname);
        exit(1);
  }
  if (*devname >= 'a') *devname += 'A' - 'a';
  drivenum = (*devname - 'C') & 0xff;
  if (drivenum < 0 || drivenum > 7) {
        printf("Funny drive number %d\n", drivenum);
        exit(1);
  }
  regs.x.ax = 0x201;            /* read 1 sectors        */
  regs.h.ch = 0;                /* cylinder              */
  regs.h.cl = 1;                /* first sector = 1      */
  regs.h.dh = 0;                /* head = 0              */
  regs.h.dl = 0x80 + drivenum;  /* drive = 0             */
  sregs.es = sregs.ds;          /* buffer address        */
  regs.x.bx = (int) buffer;

  int86x(0x13, &regs, &regs, &sregs);
  if (regs.x.cflag) {
        printf("Cannot read boot sector\n");
        exit(1);
  }
}


putboot(buffer)
char *buffer;
{
/* Write boot sector  */

  regs.x.ax = 0x301;            /* read 1 sectors        */
  regs.h.ch = 0;                /* cylinder              */
  regs.h.cl = 1;                /* first sector = 1      */
  regs.h.dh = 0;                /* head = 0              */
  regs.h.dl = 0x80 + drivenum;  /* drive = 0             */
  sregs.es = sregs.ds;          /* buffer address        */
  regs.x.bx = (int) buffer;

  int86x(0x13, &regs, &regs, &sregs);
  if (regs.x.cflag) {
        printf("Cannot write boot sector\n");
        exit(1);
  }
}

#endif

void adj_base(pe)
struct part_entry *pe;
{
/* Adjust base sector of partition, usually to make it even. */

  int adj;

  if (pe == NULL) return;
  while (1) {
        
        if (!get_an_int("\tEnter adjustment to base (an integer): ", &adj))
                return;
        if (pe->lowsec + adj < 1)
                printf(
    "\t\tThat would make the base %d and too small\n", pe->lowsec + adj);
        else if (pe->size - adj < 1)
                printf(
    "\t\tThat would make the size %d and too small\n", pe->size - adj);
        else
                break;
  }
  pe->lowsec += adj; 
  pe->size -= adj;
  sec_to_hst(pe->lowsec, &pe->start_head, &pe->start_sec, &pe->start_cyl);
  printf("Base of partition adjusted to %ld, size adjusted to %ld\n",
         pe->lowsec, pe->size);
}

void adj_size(pe)
struct part_entry *pe;
{
/* Adjust size of partition by reducing high sector. */

  int adj;

  if (pe == NULL) return;
  while (1) {
        if (!get_an_int("\tEnter adjustment to size (an integer): ", &adj))
                return;
        if (pe->size + adj >= 1) break;
        printf("\t\tThat would make the size %d and too small \n",
                pe->size + adj);
  }
  pe->size += adj;
  sec_to_hst(pe->lowsec + pe->size - 1,
             &pe->last_head, &pe->last_sec, &pe->last_cyl);
  printf("Size of partition adjusted to %ld\n", pe->size);
}

struct part_entry *ask_partition()
{
/* Ask for a valid partition number and return its entry. */

  int num;

  while (1) {
        
        if (!get_an_int("Enter partition number (1 to 4): ", &num))
                return(NULL);
        if (num >= 1 && num <= NR_PARTITIONS) break;
        printf("\tThat does not look like 1 to 4\n");
  }
  printf("Partition %d\n", num);
  return((struct part_entry *) &secbuf[PART_TABLE_OFF] + (num - 1));
}

void footnotes()
{
/* Explain the footnotes. */

  if (badbases != 0) {
        printf(
"+ The old Minix wini drivers (before V1.5) discarded odd base sectors.\n");
        printf(
"  This causes some old (Minix) file systems to be offset by 1 sector.\n");
        printf(
"  To use these with the new drivers, increase the base by 1 using 'B'.\n");
  }

  if (badsizes != 0) {
        if (badbases != 0) putchar('\n');
        printf(
"- Minix cannot access the last sector on an odd-sized partition.  This\n");
        printf(
"  causes trouble for programs like dosread.  This program will by default\n");
        printf(
"  only create partitions with even sizes.  If possible, the current odd\n");
        printf(
"  sizes should be decreased by 1 using 'S'.  This is safe for all Minix\n");
        printf(
"  partitions, and may be safe for other partitions which are about to be\n");
        printf(
"  reformatted.\n");
  }

  if (badorders!= 0 ) {
        if (badbases != 0 || badsizes != 0) putchar('\n');
        printf(
"# The partitions are in a funny order. This is normal if they were created\n");
        printf(
"  by DOS fdisks prior to DOS 3.3.  The Minix wini drivers further confuse\n");
        printf(
"  the order by sorting the partitions on their base.  Be careful if the\n");
        printf(
"  device numbers of unchanged partitions have changed.\n");
  }
}

int get_an_int(prompt, intptr)
char *prompt;
int *intptr;
{
/* Read an int from the start of line of stdin, discard rest of line. */

  char buf[80];

  while (1) {
        printf("%s", prompt);
        if (!mygets(buf, (int) sizeof buf)) return(0);
        if ((sscanf(buf, "%d", intptr)) == 1) return(1);
        printf("\t\tThat does not look like an integer\n");
  }
}

void list_part_types()
{
/* Print all known partition types. */

  int column;
  int type;

  for (column = 0, type = 0; type < 0x100; ++type)
        if (strcmp(systype(type), "Unknown") != 0) {
                printf("0x%02x: %-9s", type, systype(type));
                column += 16;
                if (column < 80)
                        putchar(' ');
                else {
                        putchar('\n');
                        column = 0;
                }
        }
  if (column != 0) putchar('\n');
}

void mark_npartition(pe)
struct part_entry *pe;
{
/* Mark a partition with arbitrary type. */

  char buf[80];
  unsigned type;

  if (pe == NULL) return;
  printf("\nKnown partition types are:\n\n");
  list_part_types();
  while (1) {
        printf("\nEnter partition type (in 2-digit hex): ");
        if (!mygets(buf, (int) sizeof buf)) return;
        if (sscanf(buf, "%x", &type) != 1)
                printf("Invalid hex number\n");
        else if (type >= 0x100)
                printf("Hex number too large\n");
        else
                break;
  }
  pe->sysind = type;
  printf("Partition type changed to 0x%02x (%s)\n", type, systype(type));
}

int mygets(buf, length)
char *buf;
int length;                     /* as for fgets(), but must be >= 2 */
{
/* Get a non-empty line of maximum length 'length'. */

  while (1) {
        fflush(stdout);
        if (fgets(buf, length, stdin) == NULL) {
                putchar('\n');
                return(0);
        }
        if (strrchr(buf, '\n') != NULL) *strrchr(buf, '\n') = 0;
        if (*buf != 0) return(1);
        printf("Use the EOF character to create a null line.\n");
        printf("Otherwise, please type something before the newline: ");
  }
}

char *systype(type)
int type;
{
/* Convert system indicator into system name. */
/* asw 01.03.95: added types based on info in kjb's part.c and output
 * from Linux (1.0.8) fdisk. Note comments here, there are disagreements.
*/
  switch(type) {
        case NO_PART: 
                   return("None");
        case 1:    return("DOS-12");
        case 2:    return("XENIX");
        case 3:    return("XENIX usr");
        case 4:    return("DOS-16");
        case 5:    return("DOS-EXT");
        case 6:    return("DOS-BIG");
        case 7:    return("HPFS");
        case 8:    return("AIX");
        case 9:    return("COHERENT");  /* LINUX says AIX bootable */
        case 0x0a: return("OS/2");      /* LINUX says OPUS */
        case 0x10: return("OPUS");
        case 0x40: return("VENIX286");
        case 0x51: return("NOVELL?");
        case 0x52: return("MICROPORT");
        case 0x63: return("386/IX");    /*LINUX calls this GNU HURD */
        case 0x64: return("NOVELL286");
        case 0x65: return("NOVELL386");
        case 0x75: return("PC/IX");
        case 0x80: return("MINIX old");
        case 0x81: return("MINIX");
        case 0x82: return("LINUXswap");
        case 0x83: return("LINUX");
        case 0x93: return("AMOEBA");
        case 0x94: return("AMOEBAbad");
        case 0xa5: return("386BSD");
        case 0xb7: return("BSDI");
        case 0xb8: return("BSDIswap");
        case 0xc7: return("Syrinx");
        case 0xDB: return("CP/M");
        case 0xe1: return("DOS acc");
        case 0xe3: return("DOS r/o");
        case 0xf2: return("DOS 2ary");
        case 0xFF: return("Badblocks");
        default:   return("Unknown");
  }
}

void toggle_active(pe)
struct part_entry *pe;
{
/* Toggle active flag of a partition. */

  if (pe == NULL) return;
  pe->bootind = (pe->bootind == ACTIVE_FLAG) ? 0 : ACTIVE_FLAG;
  printf("Partition changed to %sactive\n", pe->bootind ? "" : "in");
}

void usage()
{
/* Print usage message and exit. */

  printf("Usage: fdisk [-hheads] [-ssectors] [device]\n");
  exit(1);
}