mkfs, mkproto: minor improvements

[minix.git] / usr.sbin / mkfs.mfs / mkfs.c

/* mkfs  -  make the MINIX filesystem   Authors: Tanenbaum et al. */

/*      Authors: Andy Tanenbaum, Paul Ogilvie, Frans Meulenbroeks, Bruce Evans
 *
 * This program can make version 1, 2 and 3 file systems, as follows:
 *      mkfs /dev/fd0 1200      # Version 3 (default)
 *      mkfs -1 /dev/fd0 360    # Version 1
 *
 * Note that the version 1 and 2 file systems produced by this program are not
 * compatible with the original version 1 and 2 file system layout.
 */

#include <sys/types.h>
#include <sys/stat.h>
#include <stdio.h>
#include <errno.h>
#include <fcntl.h>
#include <limits.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include <unistd.h>
#include <stdint.h>
#include "const.h"
#include "type.h"
#include "mfsdir.h"
#if defined(__minix)
#include <minix/partition.h>
#include <minix/u64.h>
#include <sys/ioctl.h>
#endif
#include <dirent.h>

#undef EXTERN
#define EXTERN                  /* get rid of EXTERN by making it null */
#include "super.h"

#ifndef max
#define max(a,b) ((a) > (b) ? (a) : (b))
#endif

#ifndef DOS
#ifndef UNIX
#define UNIX
#endif
#endif

#define INODE_MAP            2
#define MAX_TOKENS          10
#define LINE_LEN           200
#define BIN                  2
#define BINGRP               2
#define BIT_MAP_SHIFT       13
#define INODE_MAX       ((unsigned) 65535)
#define SECTOR_SIZE        512


#ifdef DOS
maybedefine O_RDONLY 4          /* O_RDONLY | BINARY_BIT */
 maybedefine BWRITE 5           /* O_WRONLY | BINARY_BIT */
#endif

#if !defined(__minix)
#define mul64u(a,b)     ((a) * (b))
#define lseek64(a,b,c,d) lseek(a,b,c)
#ifdef __linux__
#include <mntent.h>
#endif
#endif

#if !defined(__minix)
typedef uint32_t block_t;
typedef uint32_t zone_t;
#endif

extern char *optarg;
extern int optind;

int next_zone, next_inode, zone_size, zone_shift = 0, zoff;
block_t nrblocks;
int inode_offset, lct = 0, disk, fd, print = 0, file = 0;
unsigned int nrinodes;
int override = 0, simple = 0, dflag;
int donttest;                   /* skip test if it fits on medium */
char *progname;

uint32_t current_time, bin_time;
char *zero, *lastp;
char *umap_array;       /* bit map tells if block read yet */
int umap_array_elements = 0;
block_t zone_map;               /* where is zone map? (depends on # inodes) */
int inodes_per_block;
int fs_version;
size_t block_size;
int extra_space_percent;

FILE *proto;

#if defined(__NBSD_LIBC) || !defined(__minix)
#define getline _mkfs_getline
#endif

int main(int argc, char **argv);
block_t sizeup(char *device);
void super(zone_t zones, ino_t inodes);
void rootdir(ino_t inode);
void eat_dir(ino_t parent);
void eat_file(ino_t inode, int f);
void enter_dir(ino_t parent, char *name, ino_t child);
void incr_size(ino_t n, size_t count);
static ino_t alloc_inode(int mode, int usrid, int grpid);
static zone_t alloc_zone(void);
void add_zone(ino_t n, zone_t z, size_t bytes, uint32_t cur_time);
void add_z_1(ino_t n, zone_t z, size_t bytes, uint32_t cur_time);
void add_z_2(ino_t n, zone_t z, size_t bytes, uint32_t cur_time);
void incr_link(ino_t n);
void insert_bit(block_t block, int bit);
int mode_con(char *p);
void getline(char line[LINE_LEN], char *parse[MAX_TOKENS]);
void check_mtab(char *devname);
uint32_t file_time(int f);
void pexit(char *s);
void copy(char *from, char *to, size_t count);
void print_fs(void);
int read_and_set(block_t n);
void special(char *string);
void get_block(block_t n, char *buf);
void get_super_block(char *buf);
void put_block(block_t n, char *buf);
void cache_init(void);
void flush(void);
void mx_read(int blocknr, char *buf);
void mx_write(int blocknr, char *buf);
void dexit(char *s, int sectnum, int err);
void usage(void);
char *alloc_block(void);

ino_t inocount;
zone_t zonecount;
block_t blockcount;

void detect_fs_size(void);
void sizeup_dir(void);
void detect_size(void);
void size_dir(void);
static int bitmapsize(uint32_t nr_bits, size_t block_size);

/*================================================================
 *                    mkfs  -  make filesystem
 *===============================================================*/
int main(argc, argv)
int argc;
char *argv[];
{
  int nread, mode, usrid, grpid, ch;
  block_t blocks, maxblocks;
  size_t i;
  ino_t root_inum;
  ino_t inodes;
  zone_t zones;
  char *token[MAX_TOKENS], line[LINE_LEN];
  struct stat statbuf;

  /* Get two times, the current time and the mod time of the binary of
   * mkfs itself.  When the -d flag is used, the later time is put into
   * the i_mtimes of all the files.  This feature is useful when
   * producing a set of file systems, and one wants all the times to be
   * identical. First you set the time of the mkfs binary to what you
   * want, then go.
   */
  current_time = time((time_t *) 0);    /* time mkfs is being run */
  stat(argv[0], &statbuf);
  bin_time = statbuf.st_mtime;  /* time when mkfs binary was last modified */

  /* Process switches. */
  progname = argv[0];
  blocks = 0;
  i = 0;
  fs_version = 3;
  inodes_per_block = 0;
  block_size = 0;
  extra_space_percent = 0;
  while ((ch = getopt(argc, argv, "12b:di:lotB:x:")) != EOF)
        switch (ch) {
            case '1':
                fs_version = 1;
                inodes_per_block = V1_INODES_PER_BLOCK;
                break;
            case '2':
                fs_version = 2;
                break;
            case 'b':
                blocks = strtoul(optarg, (char **) NULL, 0);
                break;
            case 'd':
                dflag = 1;
                current_time = bin_time;
                break;
            case 'i':
                i = strtoul(optarg, (char **) NULL, 0);
                break;
            case 'l':   print = 1;      break;
            case 'o':   override = 1;   break;
            case 't':   donttest = 1;   break;
            case 'B':   block_size = atoi(optarg);      break;
            case 'x':   extra_space_percent = atoi(optarg); break;
            default:    usage();
        }

  if (argc == optind) usage();

  /* Percentage of extra size must be nonnegative.
   * It can legitimately be bigger than 100 but has to make some sort of sense.
   */
  if(extra_space_percent < 0 || extra_space_percent > 2000) usage();

  if(fs_version == 3) {
        if(!block_size) block_size = _MAX_BLOCK_SIZE; /* V3 default block size */
        if(block_size%SECTOR_SIZE || block_size < _MIN_BLOCK_SIZE) {
                fprintf(stderr, "block size must be multiple of sector (%d) "
                        "and at least %d bytes\n",
                        SECTOR_SIZE, _MIN_BLOCK_SIZE);
                pexit("specified block size illegal");
        }
        if(block_size%V2_INODE_SIZE) {
                fprintf(stderr, "block size must be a multiple of inode size (%d bytes)\n",
                        V2_INODE_SIZE);
                pexit("specified block size illegal");
        }
  } else {
        if(block_size) {
                pexit("Can't specify a block size if FS version is <3");
        }
        block_size = _STATIC_BLOCK_SIZE;        /* V1/V2 block size */
  }

  zone_shift = 0;               /* for future use */
  zone_size = 1 << zone_shift;  /* nr of blocks per zone */

  if(!inodes_per_block)
        inodes_per_block = V2_INODES_PER_BLOCK(block_size);

  /* now that the block size is known, do buffer allocations where
   * possible.
   */
  zero = alloc_block();
  bzero(zero, block_size);

  /* Determine the size of the device if not specified as -b or proto. */
  maxblocks = sizeup(argv[optind]);
  if (argc - optind == 1 && blocks == 0) {
        blocks = maxblocks;
        /* blocks == 0 is checked later, but leads to a funny way of
         * reporting a 0-sized device (displays usage).
         */
        if(blocks < 1) {
                fprintf(stderr, "%s: zero size device.\n", progname);
                return 1;
        }
  }

  /* The remaining args must be 'special proto', or just 'special' if the
   * no. of blocks has already been specified.
   */
  if (argc - optind != 2 && (argc - optind != 1 || blocks == 0)) usage();

  if (blocks > maxblocks) {
        fprintf(stderr, "%s: %s: number of blocks too large for device.\n",
                progname, argv[optind]);
        return 1;
  }

  /* Check special. */
  check_mtab(argv[optind]);

  /* Check and start processing proto. */
  optarg = argv[++optind];
  if (optind < argc && (proto = fopen(optarg, "r")) != NULL) {
        /* Prototype file is readable. */
        lct = 1;
        getline(line, token);   /* skip boot block info */

        /* Read the line with the block and inode counts. */
        getline(line, token);
        blocks = atol(token[0]);
        inodes = atoi(token[1]);

        /* Process mode line for root directory. */
        getline(line, token);
        mode = mode_con(token[0]);
        usrid = atoi(token[1]);
        grpid = atoi(token[2]);

        if(blocks <= 0 && inodes <= 0){
                block_t extrablocks = 0;
                ino_t extrainodes = 0;
                if(blocks < 0) extrablocks = -blocks;
                if(inodes < 0) extrainodes = -inodes;
                detect_fs_size();
                blocks = blockcount + extrablocks;
                inodes = inocount + extrainodes;
                blocks += blocks*extra_space_percent/100;
                inodes += inodes*extra_space_percent/100;
                printf("dynamically sized filesystem: %d blocks, %d inodes\n", blocks, 
                        (unsigned int) inodes);
        }               
  } else {
        lct = 0;
        if (optind < argc) {
                /* Maybe the prototype file is just a size.  Check. */
                blocks = strtoul(optarg, (char **) NULL, 0);
                if (blocks == 0) pexit("Can't open prototype file");
        }
        if (i == 0) {
#if defined(__minix)
                uint32_t kb = div64u(mul64u(blocks, block_size), 1024);
#else
                uint32_t kb = ((unsigned long long) blocks * block_size) / 1024;
#endif
                i = kb / 2;
                if (kb >= 100000) i = kb / 4;

                /* round up to fill inode block */
                i += inodes_per_block - 1;
                i = i / inodes_per_block * inodes_per_block;
                if (i > INODE_MAX && fs_version < 3) i = INODE_MAX;

        }
        if (blocks < 5) pexit("Block count too small");
        if (i < 1) pexit("Inode count too small");
        if (i > INODE_MAX && fs_version < 3) pexit("Inode count too large");
        inodes = (ino_t) i;

        /* Make simple file system of the given size, using defaults. */
        mode = 040777;
        usrid = BIN;
        grpid = BINGRP;
        simple = 1;
  }

  nrblocks = blocks;
  nrinodes = inodes;

{
  size_t bytes;
  bytes = 1 + blocks/8;
  if(!(umap_array = malloc(bytes))) {
        fprintf(stderr, "mkfs: can't allocate block bitmap (%u bytes).\n",
                bytes);
        exit(1);
  }
  umap_array_elements = bytes;
}

  /* Open special. */
  special(argv[--optind]);

#ifdef UNIX
  if (!donttest) {
        short *testb;
        ssize_t w;

        testb = (short *) alloc_block();

        /* Try writing the last block of partition or diskette. */
        if(lseek64(fd, mul64u(blocks - 1, block_size), SEEK_SET, NULL) < 0) {
                pexit("couldn't seek to last block to test size (1)");
        }
        testb[0] = 0x3245;
        testb[1] = 0x11FF;
        testb[block_size/2-1] = 0x1F2F;
        if ((w=write(fd, (char *) testb, block_size)) != block_size) {
                if(w < 0) perror("write");
                printf("%d/%u\n", w, block_size);
                pexit("File system is too big for minor device (write)");
        }
        sync();                 /* flush write, so if error next read fails */
        if(lseek64(fd, mul64u(blocks - 1, block_size), SEEK_SET, NULL) < 0) {
                pexit("couldn't seek to last block to test size (2)");
        }
        testb[0] = 0;
        testb[1] = 0;
        nread = read(fd, (char *) testb, block_size);
        if (nread != block_size || testb[0] != 0x3245 || testb[1] != 0x11FF ||
                testb[block_size/2-1] != 0x1F2F) {
                if(nread < 0) perror("read");
printf("nread = %d\n", nread);
printf("testb = 0x%x 0x%x 0x%x\n", testb[0], testb[1], testb[block_size-1]);
                pexit("File system is too big for minor device (read)");
        }
        lseek64(fd, mul64u(blocks - 1, block_size), SEEK_SET, NULL);
        testb[0] = 0;
        testb[1] = 0;
        if (write(fd, (char *) testb, block_size) != block_size)
                pexit("File system is too big for minor device (write2)");
        lseek(fd, 0L, SEEK_SET);
        free(testb);
  }
#endif

  /* Make the file-system */

  cache_init();

        put_block((block_t) 0, zero);   /* Write a null boot block. */

  zones = nrblocks >> zone_shift;

  super(zones, inodes);

  root_inum = alloc_inode(mode, usrid, grpid);
  rootdir(root_inum);
  if (simple == 0) eat_dir(root_inum);

  if (print) print_fs();
  flush();
  return(0);

  /* NOTREACHED */
}                               /* end main */

/*================================================================
 *        detect_fs_size  -  determine image size dynamically
 *===============================================================*/
void detect_fs_size()
{
  uint32_t point = ftell(proto);
  
  inocount = 1; /* root directory node */
  zonecount = 0;
  blockcount = 0;
  sizeup_dir();
        
  uint32_t initb;

  initb = bitmapsize((uint32_t) (1 + inocount), block_size);
  initb += bitmapsize((uint32_t) zonecount, block_size);
  initb += START_BLOCK;
  initb += (inocount + inodes_per_block - 1) / inodes_per_block;
  initb = (initb + (1 << zone_shift) - 1) >> zone_shift;

  blockcount = initb+zonecount*zone_size;
  fseek(proto, point, SEEK_SET);
}

void sizeup_dir()
{
  char *token[MAX_TOKENS], *p;
  char line[LINE_LEN]; 
  FILE *f;
  size_t size;
  int dir_entries = 2;
  zone_t dir_zones = 0;
  zone_t nr_dzones;

  if (fs_version == 1) {
        nr_dzones = V1_NR_DZONES;
  } else {
        nr_dzones = V2_NR_DZONES;
  }

  while (1) {
        getline(line, token);
        p = token[0];
        if (*p == '$') {
                dir_zones = (dir_entries / (NR_DIR_ENTRIES(block_size) * zone_size));           
                if(dir_entries % (NR_DIR_ENTRIES(block_size) * zone_size))
                        dir_zones++;
                /* Assumes directory fits in direct blocks */
                zonecount += dir_zones;
                return;
        }

        p = token[1];
        inocount++;
        dir_entries++;

        if (*p == 'd') {
                sizeup_dir();
        } else if (*p == 'b' || *p == 'c') {

        } else {
                if ((f = fopen(token[4], "r")) == NULL) {
                        fprintf(stderr, "%s: Can't open %s: %s\n",
                                progname, token[4], strerror(errno));
                                pexit("dynamic size detection failed");
                } else {
                        if (fseek(f, 0, SEEK_END) < 0) {
                        fprintf(stderr, "%s: Can't seek to end of %s\n",
                                progname, token[4]);
                                pexit("dynamic size detection failed");
                        }
                        size = ftell(f);
                        fclose(f);
                        zone_t fzones= (size / (zone_size * block_size));
                        if (size % (zone_size * block_size))
                                fzones++;
                        if (fzones > nr_dzones)
                                fzones++;       /* Assumes files fit within single indirect */
                        zonecount += fzones;
                }
        }
  }
}

/*================================================================
 *                    sizeup  -  determine device size
 *===============================================================*/
block_t sizeup(device)
char *device;
{
  block_t d;
#if defined(__minix)
  u64_t bytes, resize;
  u32_t rem;
#else
  off_t size;
#endif


  if ((fd = open(device, O_RDONLY)) == -1) {
        if (errno != ENOENT)
                perror("sizeup open");
        return 0;
  }

#if defined(__minix)
  if(minix_sizeup(device, &bytes) < 0) {
       perror("sizeup");
       return 0;
  }

  d = div64u(bytes, block_size);
  rem = rem64u(bytes, block_size);

  resize = add64u(mul64u(d, block_size), rem);
  if(cmp64(resize, bytes) != 0) {
        d = ULONG_MAX;
        fprintf(stderr, "mkfs: truncating FS at %u blocks\n", d);
  }
#else
  size = lseek(fd, 0, SEEK_END);
  if (size == (off_t) -1) {
          fprintf(stderr, "Cannot get device size fd=%d\n", fd);
          exit(-1);
  }
  d = size / block_size;
#endif

  return d;
}

/*
 * copied from fslib
 */
static int bitmapsize(nr_bits, block_size)
uint32_t nr_bits;
size_t block_size;
{
  block_t nr_blocks;

  nr_blocks = (int) (nr_bits / FS_BITS_PER_BLOCK(block_size));
  if (((uint32_t) nr_blocks * FS_BITS_PER_BLOCK(block_size)) < nr_bits) ++nr_blocks;
  return(nr_blocks);
}

/*================================================================
 *                 super  -  construct a superblock
 *===============================================================*/

void super(zones, inodes)
zone_t zones;
ino_t inodes;
{
  unsigned int i;
  int inodeblks;
  int initblks;
  uint32_t nb;
  zone_t v1sq, v2sq;
  zone_t zo;
  struct super_block *sup;
  char *buf, *cp;

  buf = alloc_block();

  for (cp = buf; cp < &buf[block_size]; cp++) *cp = 0;
  sup = (struct super_block *) buf;     /* lint - might use a union */

  /* The assumption is that mkfs will create a clean FS. */
  sup->s_flags = MFSFLAG_CLEAN;

  sup->s_ninodes = inodes;
  if (fs_version == 1) {
        sup->s_nzones = zones;
        if (sup->s_nzones != zones) pexit("too many zones");
  } else {
        sup->s_nzones = 0;      /* not used in V2 - 0 forces errors early */
        sup->s_zones = zones;
  }
  
#define BIGGERBLOCKS "Please try a larger block size for an FS of this size.\n"
  sup->s_imap_blocks = nb = bitmapsize((uint32_t) (1 + inodes), block_size);
  if(sup->s_imap_blocks != nb) {
        fprintf(stderr, "mkfs: too many inode bitmap blocks.\n" BIGGERBLOCKS);
        exit(1);
  }
  sup->s_zmap_blocks = nb = bitmapsize((uint32_t) zones, block_size);
  if(nb != sup->s_zmap_blocks) {
        fprintf(stderr, "mkfs: too many block bitmap blocks.\n" BIGGERBLOCKS);
        exit(1);
  }
  inode_offset = START_BLOCK + sup->s_imap_blocks + sup->s_zmap_blocks;
  inodeblks = (inodes + inodes_per_block - 1) / inodes_per_block;
  initblks = inode_offset + inodeblks;
  sup->s_firstdatazone_old = nb =
        (initblks + (1 << zone_shift) - 1) >> zone_shift;
  if(nb >= zones) pexit("bit maps too large");
  if(nb != sup->s_firstdatazone_old) {
        /* The field is too small to store the value. Fortunately, the value
         * can be computed from other fields. We set the on-disk field to zero
         * to indicate that it must not be used. Eventually, we can always set
         * the on-disk field to zero, and stop using it.
         */
        sup->s_firstdatazone_old = 0;
  }
  sup->s_firstdatazone = nb;
  zoff = sup->s_firstdatazone - 1;
  sup->s_log_zone_size = zone_shift;
  if (fs_version == 1) {
        sup->s_magic = SUPER_MAGIC;     /* identify super blocks */
        v1sq = (zone_t) V1_INDIRECTS * V1_INDIRECTS;
        zo = V1_NR_DZONES + (int) V1_INDIRECTS + v1sq;
        sup->s_max_size = zo * block_size;
  } else {
        v2sq = (zone_t) V2_INDIRECTS(block_size) * V2_INDIRECTS(block_size);
        zo = V2_NR_DZONES + (zone_t) V2_INDIRECTS(block_size) + v2sq;
        if(fs_version == 2) {
                sup->s_magic = SUPER_V2;/* identify super blocks */
                sup->s_max_size = zo * block_size;
        } else {
                sup->s_magic = SUPER_V3;
                sup->s_block_size = block_size;
                sup->s_disk_version = 0;
#define MAX_MAX_SIZE    (INT_MAX)
                if(MAX_MAX_SIZE/block_size < zo) {
                        sup->s_max_size = (int32_t) MAX_MAX_SIZE;
                }
                else {
                        sup->s_max_size = zo * block_size;
                }
        }
  }

  if (lseek(fd, (off_t) _STATIC_BLOCK_SIZE, SEEK_SET) == (off_t) -1) {
        pexit("super() couldn't seek");
  }
  if (write(fd, buf, _STATIC_BLOCK_SIZE) != _STATIC_BLOCK_SIZE) {
        pexit("super() couldn't write");
  }

  /* Clear maps and inodes. */
  for (i = START_BLOCK; i < initblks; i++) put_block((block_t) i, zero);

  next_zone = sup->s_firstdatazone;
  next_inode = 1;

  zone_map = INODE_MAP + sup->s_imap_blocks;

  insert_bit(zone_map, 0);      /* bit zero must always be allocated */
  insert_bit((block_t) INODE_MAP, 0);   /* inode zero not used but
                                         * must be allocated */

  free(buf);
}


/*================================================================
 *              rootdir  -  install the root directory
 *===============================================================*/
void rootdir(inode)
ino_t inode;
{
  zone_t z;

  z = alloc_zone();
  add_zone(inode, z, 2 * sizeof(struct direct), current_time);
  enter_dir(inode, ".", inode);
  enter_dir(inode, "..", inode);
  incr_link(inode);
  incr_link(inode);
}


/*================================================================
 *          eat_dir  -  recursively install directory
 *===============================================================*/
void eat_dir(parent)
ino_t parent;
{
  /* Read prototype lines and set up directory. Recurse if need be. */
  char *token[MAX_TOKENS], *p;
  char line[LINE_LEN];
  int mode, usrid, grpid, maj, min, f;
  ino_t n;
  zone_t z;
  size_t size;

  while (1) {
        getline(line, token);
        p = token[0];
        if (*p == '$') return;
        p = token[1];
        mode = mode_con(p);
        usrid = atoi(token[2]);
        grpid = atoi(token[3]);
        n = alloc_inode(mode, usrid, grpid);

        /* Enter name in directory and update directory's size. */
        enter_dir(parent, token[0], n);
        incr_size(parent, sizeof(struct direct));

        /* Check to see if file is directory or special. */
        incr_link(n);
        if (*p == 'd') {
                /* This is a directory. */
                z = alloc_zone();       /* zone for new directory */
                add_zone(n, z, 2 * sizeof(struct direct), current_time);
                enter_dir(n, ".", n);
                enter_dir(n, "..", parent);
                incr_link(parent);
                incr_link(n);
                eat_dir(n);
        } else if (*p == 'b' || *p == 'c') {
                /* Special file. */
                maj = atoi(token[4]);
                min = atoi(token[5]);
                size = 0;
                if (token[6]) size = atoi(token[6]);
                size = block_size * size;
                add_zone(n, (zone_t) (makedev(maj,min)), size, current_time);
        } else {
                /* Regular file. Go read it. */
                if ((f = open(token[4], O_RDONLY)) < 0) {
                        fprintf(stderr, "%s: Can't open %s: %s\n",
                                progname, token[4], strerror(errno));
                } else {
                        eat_file(n, f);
                }
        }
  }

}

/*================================================================
 *              eat_file  -  copy file to MINIX
 *===============================================================*/
/* Zonesize >= blocksize */
void eat_file(inode, f)
ino_t inode;
int f;
{
  int ct, i, j, k;
  zone_t z;
  char *buf;
  uint32_t timeval;

  buf = alloc_block();

  do {
        for (i = 0, j = 0; i < zone_size; i++, j += ct) {
                for (k = 0; k < block_size; k++) buf[k] = 0;
                if ((ct = read(f, buf, block_size)) > 0) {
                        if (i == 0) z = alloc_zone();
                        put_block((z << zone_shift) + i, buf);
                }
        }
        timeval = (dflag ? current_time : file_time(f));
        if (ct) add_zone(inode, z, (size_t) j, timeval);
  } while (ct == block_size);
  close(f);
  free(buf);
}



/*================================================================
 *          directory & inode management assist group
 *===============================================================*/
void enter_dir(parent, name, child)
ino_t parent, child;
char *name;
{
  /* Enter child in parent directory */
  /* Works for dir > 1 block and zone > block */
  unsigned int i, j, k, l, off;
  block_t b;
  zone_t z;
  char *p1, *p2;
  struct direct *dir_entry;
  d1_inode ino1[V1_INODES_PER_BLOCK];
  d2_inode *ino2;
  int nr_dzones;

  b = ((parent - 1) / inodes_per_block) + inode_offset;
  off = (parent - 1) % inodes_per_block;

  if(!(dir_entry = malloc(NR_DIR_ENTRIES(block_size) * sizeof(*dir_entry))))
        pexit("couldn't allocate directory entry");

  if(!(ino2 = malloc(V2_INODES_PER_BLOCK(block_size) * sizeof(*ino2))))
        pexit("couldn't allocate block of inodes entry");

  if (fs_version == 1) {
        get_block(b, (char *) ino1);
        nr_dzones = V1_NR_DZONES;
  } else {
        get_block(b, (char *) ino2);
        nr_dzones = V2_NR_DZONES;
  }
  for (k = 0; k < nr_dzones; k++) {
        if (fs_version == 1) {
                z = ino1[off].d1_zone[k];
                if (z == 0) {
                        z = alloc_zone();
                        ino1[off].d1_zone[k] = z;
                }
        } else {
                z = ino2[off].d2_zone[k];
                if (z == 0) {
                        z = alloc_zone();
                        ino2[off].d2_zone[k] = z;
                }
        }
        for (l = 0; l < zone_size; l++) {
                get_block((z << zone_shift) + l, (char *) dir_entry);
                for (i = 0; i < NR_DIR_ENTRIES(block_size); i++) {
                        if (dir_entry[i].mfs_d_ino == 0) {
                                dir_entry[i].mfs_d_ino = child;
                                p1 = name;
                                p2 = dir_entry[i].mfs_d_name;
                                j = sizeof(dir_entry[i].mfs_d_name);
                                j = 60;
                                while (j--) {
                                        *p2++ = *p1;
                                        if (*p1 != 0) p1++;
                                }
                                put_block((z << zone_shift) + l, (char *) dir_entry);
                                if (fs_version == 1) {
                                        put_block(b, (char *) ino1);
                                } else {
                                        put_block(b, (char *) ino2);
                                }
                                free(dir_entry);
                                free(ino2);
                                return;
                        }
                }
        }
  }

  printf("Directory-inode %lu beyond direct blocks.  Could not enter %s\n",
         parent, name);
  pexit("Halt");
}


void add_zone(ino_t n, zone_t z, size_t bytes, uint32_t cur_time)
{
  if (fs_version == 1) {
        add_z_1(n, z, bytes, cur_time);
  } else {
        add_z_2(n, z, bytes, cur_time);
  }
}

void add_z_1(ino_t n, zone_t z, size_t bytes, uint32_t cur_time)
{
  /* Add zone z to inode n. The file has grown by 'bytes' bytes. */

  int off, i;
  block_t b;
  zone_t indir;
  uint16_t blk[V1_INDIRECTS];
  d1_inode *p;
  d1_inode inode[V1_INODES_PER_BLOCK];

  b = ((n - 1) / V1_INODES_PER_BLOCK) + inode_offset;
  off = (n - 1) % V1_INODES_PER_BLOCK;
  get_block(b, (char *) inode);
  p = &inode[off];
  p->d1_size += bytes;
  p->d1_mtime = cur_time;
  for (i = 0; i < V1_NR_DZONES; i++)
        if (p->d1_zone[i] == 0) {
                p->d1_zone[i] = (uint16_t) z;
                put_block(b, (char *) inode);
                return;
        }
  put_block(b, (char *) inode);

  /* File has grown beyond a small file. */
  if (p->d1_zone[V1_NR_DZONES] == 0)
        p->d1_zone[V1_NR_DZONES] = (uint16_t) alloc_zone();
  indir = p->d1_zone[V1_NR_DZONES];
  put_block(b, (char *) inode);
  b = indir << zone_shift;
  get_block(b, (char *) blk);
  for (i = 0; i < V1_INDIRECTS; i++)
        if (blk[i] == 0) {
                blk[i] = (uint16_t) z;
                put_block(b, (char *) blk);
                return;
        }
  pexit("File has grown beyond single indirect");
}

void add_z_2(ino_t n, zone_t z, size_t bytes, uint32_t cur_time)
{
  /* Add zone z to inode n. The file has grown by 'bytes' bytes. */

  int off, i;
  block_t b;
  zone_t indir;
  zone_t *blk;
  d2_inode *p;
  d2_inode *inode;

  if(!(blk = malloc(V2_INDIRECTS(block_size)*sizeof(*blk))))
        pexit("Couldn't allocate indirect block");

  if(!(inode = malloc(V2_INODES_PER_BLOCK(block_size)*sizeof(*inode))))
        pexit("Couldn't allocate block of inodes");

  b = ((n - 1) / V2_INODES_PER_BLOCK(block_size)) + inode_offset;
  off = (n - 1) % V2_INODES_PER_BLOCK(block_size);
  get_block(b, (char *) inode);
  p = &inode[off];
  p->d2_size += bytes;
  p->d2_mtime = cur_time;
  for (i = 0; i < V2_NR_DZONES; i++)
        if (p->d2_zone[i] == 0) {
                p->d2_zone[i] = z;
                put_block(b, (char *) inode);
                free(blk);
                free(inode);
                return;
        }
  put_block(b, (char *) inode);

  /* File has grown beyond a small file. */
  if (p->d2_zone[V2_NR_DZONES] == 0) p->d2_zone[V2_NR_DZONES] = alloc_zone();
  indir = p->d2_zone[V2_NR_DZONES];
  put_block(b, (char *) inode);
  b = indir << zone_shift;
  get_block(b, (char *) blk);
  for (i = 0; i < V2_INDIRECTS(block_size); i++)
        if (blk[i] == 0) {
                blk[i] = z;
                put_block(b, (char *) blk);
                free(blk);
                free(inode);
                return;
        }
  pexit("File has grown beyond single indirect");
}


void incr_link(n)
ino_t n;
{
  /* Increment the link count to inode n */
  int off;
  static int enter = 0;
  block_t b;

  if(enter) exit(1);

  b = ((n - 1) / inodes_per_block) + inode_offset;
  off = (n - 1) % inodes_per_block;
  if (fs_version == 1) {
        d1_inode inode1[V1_INODES_PER_BLOCK];

        get_block(b, (char *) inode1);
        inode1[off].d1_nlinks++;
        put_block(b, (char *) inode1);
  } else {
        static d2_inode *inode2 = NULL;
        int n;

        n = sizeof(*inode2) * V2_INODES_PER_BLOCK(block_size);
        if(!inode2 && !(inode2 = malloc(n)))
                pexit("couldn't allocate a block of inodes");

        get_block(b, (char *) inode2);
        inode2[off].d2_nlinks++;
        put_block(b, (char *) inode2);
  }
  enter = 0;
}


void incr_size(n, count)
ino_t n;
size_t count;
{
  /* Increment the file-size in inode n */
  block_t b;
  int off;

  b = ((n - 1) / inodes_per_block) + inode_offset;
  off = (n - 1) % inodes_per_block;
  if (fs_version == 1) {
        d1_inode inode1[V1_INODES_PER_BLOCK];

        get_block(b, (char *) inode1);
        inode1[off].d1_size += count;
        put_block(b, (char *) inode1);
  } else {
        d2_inode *inode2;
        if(!(inode2 = malloc(V2_INODES_PER_BLOCK(block_size) * sizeof(*inode2))))
                pexit("couldn't allocate a block of inodes");

        get_block(b, (char *) inode2);
        inode2[off].d2_size += count;
        put_block(b, (char *) inode2);
        free(inode2);
  }
}


/*================================================================
 *                   allocation assist group
 *===============================================================*/
static ino_t alloc_inode(mode, usrid, grpid)
int mode, usrid, grpid;
{
  ino_t num;
  int off;
  block_t b;

  num = next_inode++;
  if (num > nrinodes) {
        fprintf(stderr, "have %d inodoes\n", nrinodes);
        pexit("File system does not have enough inodes");
  }
  b = ((num - 1) / inodes_per_block) + inode_offset;
  off = (num - 1) % inodes_per_block;
  if (fs_version == 1) {
        d1_inode inode1[V1_INODES_PER_BLOCK];

        get_block(b, (char *) inode1);
        inode1[off].d1_mode = mode;
        inode1[off].d1_uid = usrid;
        inode1[off].d1_gid = grpid;
        put_block(b, (char *) inode1);
  } else {
        d2_inode *inode2;

        if(!(inode2 = malloc(V2_INODES_PER_BLOCK(block_size) * sizeof(*inode2))))
                pexit("couldn't allocate a block of inodes");

        get_block(b, (char *) inode2);
        inode2[off].d2_mode = mode;
        inode2[off].d2_uid = usrid;
        inode2[off].d2_gid = grpid;
        put_block(b, (char *) inode2);

        free(inode2);
  }

  /* Set the bit in the bit map. */
  /* DEBUG FIXME.  This assumes the bit is in the first inode map block. */
  insert_bit((block_t) INODE_MAP, (int) num);
  return(num);
}


static zone_t alloc_zone()
{
  /* Allocate a new zone */
  /* Works for zone > block */
  block_t b;
  int i;
  zone_t z;

  z = next_zone++;
  b = z << zone_shift;
  if ((b + zone_size) > nrblocks)
        pexit("File system not big enough for all the files");
  for (i = 0; i < zone_size; i++)
        put_block(b + i, zero); /* give an empty zone */
  /* DEBUG FIXME.  This assumes the bit is in the first zone map block. */
  insert_bit(zone_map, (int) (z - zoff));       /* lint, NOT OK because
                                                 * z hasn't been broken
                                                 * up into block +
                                                 * offset yet. */
  return(z);
}


void insert_bit(block, bit)
block_t block;
int bit;
{
  /* Insert 'count' bits in the bitmap */
  int w, s;
#if defined(__minix)
  bitchunk_t *buf;
#else
  uint32_t *buf;
#endif

#if defined(__minix)
  buf = (bitchunk_t *) alloc_block();
#else
  buf = (uint32_t *) alloc_block();
#endif

  get_block(block, (char *) buf);
#if defined(__minix)
  w = bit / (8 * sizeof(bitchunk_t));
  s = bit % (8 * sizeof(bitchunk_t));
#else
  w = bit / (8 * sizeof(uint32_t));
  s = bit % (8 * sizeof(uint32_t));
#endif
  buf[w] |= (1 << s);
  put_block(block, (char *) buf);

  free(buf);
}


/*================================================================
 *              proto-file processing assist group
 *===============================================================*/
int mode_con(p)
char *p;
{
  /* Convert string to mode */
  int o1, o2, o3, mode;
  char c1, c2, c3;

  c1 = *p++;
  c2 = *p++;
  c3 = *p++;
  o1 = *p++ - '0';
  o2 = *p++ - '0';
  o3 = *p++ - '0';
  mode = (o1 << 6) | (o2 << 3) | o3;
  if (c1 == 'd') mode |= S_IFDIR;
  if (c1 == 'b') mode |= S_IFBLK;
  if (c1 == 'c') mode |= S_IFCHR;
  if (c1 == '-') mode |= S_IFREG;
  if (c2 == 'u') mode |= S_ISUID;
  if (c3 == 'g') mode |= S_ISGID;
  return(mode);
}

void getline(line, parse)
char *parse[MAX_TOKENS];
char line[LINE_LEN];
{
  /* Read a line and break it up in tokens */
  int k;
  char c, *p;
  int d;

  for (k = 0; k < MAX_TOKENS; k++) parse[k] = 0;
  for (k = 0; k < LINE_LEN; k++) line[k] = 0;
  k = 0;
  parse[0] = 0;
  p = line;
  while (1) {
        if (++k > LINE_LEN) pexit("Line too long");
        d = fgetc(proto);
        if (d == EOF) pexit("Unexpected end-of-file");
        *p = d;
        if (*p == '\n') lct++;
        if (*p == ' ' || *p == '\t') *p = 0;
        if (*p == '\n') {
                *p++ = 0;
                *p = '\n';
                break;
        }
        p++;
  }

  k = 0;
  p = line;
  lastp = line;
  while (1) {
        c = *p++;
        if (c == '\n') return;
        if (c == 0) continue;
        parse[k++] = p - 1;
        do {
                c = *p++;
        } while (c != 0 && c != '\n');
  }
}


/*================================================================
 *                      other stuff
 *===============================================================*/
void check_mtab(device)
char *device;                   /* /dev/hd1 or whatever */
{
/* Check to see if the special file named in s is mounted. */
#if defined(__minix)
  int n, r;
  struct stat sb;
  char special[PATH_MAX + 1], mounted_on[PATH_MAX + 1], version[10], rw_flag[10];

  r= stat(device, &sb);
  if (r == -1)
  {
        if (errno == ENOENT)
                return; /* Does not exist, and therefore not mounted. */
        fprintf(stderr, "%s: stat %s failed: %s\n",
                progname, device, strerror(errno));
        exit(1);
  }
  if (!S_ISBLK(sb.st_mode))
  {
        /* Not a block device and therefore not mounted. */
        return;
  }

  if (load_mtab("mkfs") < 0) return;
  while (1) {
        n = get_mtab_entry(special, mounted_on, version, rw_flag);
        if (n < 0) return;
        if (strcmp(device, special) == 0) {
                /* Can't mkfs on top of a mounted file system. */
                fprintf(stderr, "%s: %s is mounted on %s\n",
                        progname, device, mounted_on);
                exit(1);
        }
  }
#elif defined(__linux__)
/* XXX: this code is copyright Theodore T'so and distributed under the GPLv2. Rewrite.
 */
        struct mntent   *mnt;
        struct stat     st_buf;
        dev_t           file_dev=0, file_rdev=0;
        ino_t           file_ino=0;
        FILE            *f;
        int             fd;
        char            *mtab_file = "/proc/mounts";

        if ((f = setmntent (mtab_file, "r")) == NULL)
                goto error;

        if (stat(device, &st_buf) == 0) {
                if (S_ISBLK(st_buf.st_mode)) {
                        file_rdev = st_buf.st_rdev;
                } else {
                        file_dev = st_buf.st_dev;
                        file_ino = st_buf.st_ino;
                }
        }
        
        while ((mnt = getmntent (f)) != NULL) {
                if (strcmp(device, mnt->mnt_fsname) == 0)
                        break;
                if (stat(mnt->mnt_fsname, &st_buf) == 0) {
                        if (S_ISBLK(st_buf.st_mode)) {
                                if (file_rdev && (file_rdev == st_buf.st_rdev))
                                        break;
                        } else {
                                if (file_dev && ((file_dev == st_buf.st_dev) &&
                                                 (file_ino == st_buf.st_ino)))
                                        break;
                        }
                }
        }

        if (mnt == NULL) {
                /*
                 * Do an extra check to see if this is the root device.  We
                 * can't trust /etc/mtab, and /proc/mounts will only list
                 * /dev/root for the root filesystem.  Argh.  Instead we
                 * check if the given device has the same major/minor number
                 * as the device that the root directory is on.
                 */
                if (file_rdev && stat("/", &st_buf) == 0) {
                        if (st_buf.st_dev == file_rdev) {
                                goto is_root;
                        }
                }
                goto test_busy;
        }
        /* Validate the entry in case /etc/mtab is out of date */
        /* 
         * We need to be paranoid, because some broken distributions
         * (read: Slackware) don't initialize /etc/mtab before checking
         * all of the non-root filesystems on the disk.
         */
        if (stat(mnt->mnt_dir, &st_buf) < 0) {
                if (errno == ENOENT) {
                        goto test_busy;
                }
                goto error;
        }
        if (file_rdev && (st_buf.st_dev != file_rdev)) {
                goto error;
        }

        fprintf(stderr, "Device %s is mounted, exiting\n", device);
        exit(-1);

        /*
         * Check to see if we're referring to the root filesystem.
         * If so, do a manual check to see if we can open /etc/mtab
         * read/write, since if the root is mounted read/only, the
         * contents of /etc/mtab may not be accurate.
         */
        if (!strcmp(mnt->mnt_dir, "/")) {
is_root:
                fprintf(stderr, "Device %s is mounted as root file system!\n",
                                device);
                exit(-1);
        }
        
test_busy:

        endmntent (f);
        if ((stat(device, &st_buf) != 0) ||
                        !S_ISBLK(st_buf.st_mode))
                return;
        fd = open(device, O_RDONLY | O_EXCL);
        if (fd < 0) {
                if (errno == EBUSY) {
                        fprintf(stderr, "Device %s is used by the system\n", device);
                        exit(-1);
                }
        } else
                close(fd);

        return;

error:
        endmntent (f);
        fprintf(stderr, "Error while checking if device %s is mounted\n", device);
        exit(-1);
#endif
}


uint32_t file_time(f)
int f;
{
#ifdef UNIX
  struct stat statbuf;
  fstat(f, &statbuf);
  return(statbuf.st_mtime);
#else                           /* fstat not supported by DOS */
  return(0L);
#endif
}


void pexit(s)
char *s;
{
  fprintf(stderr, "%s: %s\n", progname, s);
  if (lct != 0)
        fprintf(stderr, "Line %d being processed when error detected.\n", lct);
  flush();
  exit(2);
}


void copy(from, to, count)
char *from, *to;
size_t count;
{
  while (count--) *to++ = *from++;
}

char *alloc_block()
{
        char *buf;

        if(!(buf = malloc(block_size))) {
                pexit("couldn't allocate filesystem buffer");
        }
        bzero(buf, block_size);

        return buf;
}

void print_fs()
{
  int i, j;
  ino_t k;
  d1_inode inode1[V1_INODES_PER_BLOCK];
  d2_inode *inode2;
  unsigned short *usbuf;
  block_t b;
  struct direct *dir;

  if(!(inode2 = malloc(V2_INODES_PER_BLOCK(block_size) * sizeof(*inode2))))
        pexit("couldn't allocate a block of inodes");

  if(!(dir = malloc(NR_DIR_ENTRIES(block_size)*sizeof(*dir))))
        pexit("malloc of directory entry failed");

  usbuf = (unsigned short *) alloc_block();

  get_super_block((char *) usbuf);
  printf("\nSuperblock: ");
  for (i = 0; i < 8; i++) printf("%06o ", usbuf[i]);
  get_block((block_t) 2, (char *) usbuf);
  printf("...\nInode map:  ");
  for (i = 0; i < 9; i++) printf("%06o ", usbuf[i]);
  get_block((block_t) 3, (char *) usbuf);
  printf("...\nZone  map:  ");
  for (i = 0; i < 9; i++) printf("%06o ", usbuf[i]);
  printf("...\n");

  free(usbuf);
  usbuf = NULL;

  k = 0;
  for (b = inode_offset; k < nrinodes; b++) {
        if (fs_version == 1) {
                get_block(b, (char *) inode1);
        } else {
                get_block(b, (char *) inode2);
        }
        for (i = 0; i < inodes_per_block; i++) {
                k = inodes_per_block * (int) (b - inode_offset) + i + 1;
                /* Lint but OK */
                if (k > nrinodes) break;
                if (fs_version == 1) {
                        if (inode1[i].d1_mode != 0) {
                                printf("Inode %2lu:  mode=", k);
                                printf("%06o", inode1[i].d1_mode);
                                printf("  uid=%2d  gid=%2d  size=",
                                inode1[i].d1_uid, inode1[i].d1_gid);
                                printf("%6d", inode1[i].d1_size);
                                printf("  zone[0]=%d\n", inode1[i].d1_zone[0]);
                        }
                        if ((inode1[i].d1_mode & S_IFMT) == S_IFDIR) {
                                /* This is a directory */
                                get_block(inode1[i].d1_zone[0], (char *) dir);
                                for (j = 0; j < NR_DIR_ENTRIES(block_size); j++)
                                        if (dir[j].mfs_d_ino)
                                                printf("\tInode %2u: %s\n", dir[j].mfs_d_ino, dir[j].mfs_d_name);
                        }
                } else {
                        if (inode2[i].d2_mode != 0) {
                                printf("Inode %2lu:  mode=", k);
                                printf("%06o", inode2[i].d2_mode);
                                printf("  uid=%2d  gid=%2d  size=",
                                inode2[i].d2_uid, inode2[i].d2_gid);
                                printf("%6d", inode2[i].d2_size);
                                printf("  zone[0]=%u\n", inode2[i].d2_zone[0]);
                        }
                        if ((inode2[i].d2_mode & S_IFMT) == S_IFDIR) {
                                /* This is a directory */
                                get_block(inode2[i].d2_zone[0], (char *) dir);
                                for (j = 0; j < NR_DIR_ENTRIES(block_size); j++)
                                        if (dir[j].mfs_d_ino)
                                                printf("\tInode %2u: %s\n", dir[j].mfs_d_ino, dir[j].mfs_d_name);
                        }
                }
        }
  }

  printf("%d inodes used.     %d zones used.\n", next_inode - 1, next_zone);
  free(dir);
  free(inode2);
}


int read_and_set(n)
block_t n;
{
/* The first time a block is read, it returns all 0s, unless there has
 * been a write.  This routine checks to see if a block has been accessed.
 */

  int w, s, mask, r;

  w = n / 8;
  if(w >= umap_array_elements) {
        pexit("umap array too small - this can't happen");
  }
  s = n % 8;
  mask = 1 << s;
  r = (umap_array[w] & mask ? 1 : 0);
  umap_array[w] |= mask;
  return(r);
}

void usage()
{
  fprintf(stderr,
          "Usage: %s [-12dlot] [-b blocks] [-i inodes]\n"
                "\t[-x extra] [-B blocksize] special [proto]\n",
          progname);
  exit(1);
}

/*================================================================
 *                    get_block & put_block for MS-DOS
 *===============================================================*/
#ifdef DOS

/*
 *      These are the get_block and put_block routines
 *      when compiling & running mkfs.c under MS-DOS.
 *
 *      It requires the (asembler) routines absread & abswrite
 *      from the file diskio.asm. Since these routines just do
 *      as they are told (read & write the sector specified),
 *      a local cache is used to minimize the i/o-overhead for
 *      frequently used blocks.
 *
 *      The global variable "file" determines whether the output
 *      is to a disk-device or to a binary file.
 */


#define PH_SECTSIZE        512  /* size of a physical disk-sector */


char *derrtab[14] = {
             "no error",
             "disk is read-only",
             "unknown unit",
             "device not ready",
             "bad command",
             "data error",
             "internal error: bad request structure length",
             "seek error",
             "unknown media type",
             "sector not found",
             "printer out of paper (?)",
             "write fault",
             "read error",
             "general error"
};

#define CACHE_SIZE      20      /* 20 block-buffers */


struct cache {
  char blockbuf[BLOCK_SIZE];
  block_t blocknum;
  int dirty;
  int usecnt;
} cache[CACHE_SIZE];


void special(string)
char *string;
{

  if (string[1] == ':' && string[2] == 0) {
        /* Format: d: or d:fname */
        disk = (string[0] & ~32) - 'A';
        if (disk > 1 && !override)      /* safety precaution */
                pexit("Bad drive specifier for special");
  } else {
        file = 1;
        if ((fd = creat(string, BWRITE)) == 0)
                pexit("Can't open special file");
  }
}

void get_block(n, buf)
block_t n;
char *buf;
{
  /* Get a block to the user */
  struct cache *bp, *fp;

  /* First access returns a zero block */
  if (read_and_set(n) == 0) {
        copy(zero, buf, block_size);
        return;
  }

  /* Look for block in cache */
  fp = 0;
  for (bp = cache; bp < &cache[CACHE_SIZE]; bp++) {
        if (bp->blocknum == n) {
                copy(bp, buf, block_size);
                bp->usecnt++;
                return;
        }

        /* Remember clean block */
        if (bp->dirty == 0)
                if (fp) {
                        if (fp->usecnt > bp->usecnt) fp = bp;
                } else
                        fp = bp;
  }

  /* Block not in cache, get it */
  if (!fp) {
        /* No clean buf, flush one */
        for (bp = cache, fp = cache; bp < &cache[CACHE_SIZE]; bp++)
                if (fp->usecnt > bp->usecnt) fp = bp;
        mx_write(fp->blocknum, fp);
  }
  mx_read(n, fp);
  fp->dirty = 0;
  fp->usecnt = 0;
  fp->blocknum = n;
  copy(fp, buf, block_size);
}

void put_block(n, buf)
block_t n;
char *buf;
{   
  /* Accept block from user */
  struct cache *fp, *bp;

  (void) read_and_set(n);

  /* Look for block in cache */
  fp = 0;
  for (bp = cache; bp < &cache[CACHE_SIZE]; bp++) {
        if (bp->blocknum == n) {
                copy(buf, bp, block_size);
                bp->dirty = 1;
                return;
        }

        /* Remember clean block */
        if (bp->dirty == 0)
                if (fp) {
                        if (fp->usecnt > bp->usecnt) fp = bp;
                } else
                        fp = bp;
  }

  /* Block not in cache */
  if (!fp) {
        /* No clean buf, flush one */
        for (bp = cache, fp = cache; bp < &cache[CACHE_SIZE]; bp++)
                if (fp->usecnt > bp->usecnt) fp = bp;
        mx_write(fp->blocknum, fp);
  }
  fp->dirty = 1;
  fp->usecnt = 1;
  fp->blocknum = n;
  copy(buf, fp, block_size);
}

void cache_init()
{
  struct cache *bp;
  for (bp = cache; bp < &cache[CACHE_SIZE]; bp++) bp->blocknum = -1;
}

void flush()
{
  /* Flush all dirty blocks to disk */
  struct cache *bp;

  for (bp = cache; bp < &cache[CACHE_SIZE]; bp++)
        if (bp->dirty) {
                mx_write(bp->blocknum, bp);
                bp->dirty = 0;
        }
}

/*==================================================================
 *                      hard read & write etc.
 *=================================================================*/
#define MAX_RETRIES     5


void mx_read(blocknr, buf)
int blocknr;
char *buf;
{

  /* Read the requested MINIX-block in core */
  char (*bp)[PH_SECTSIZE];
  int sectnum, retries, err;

  if (file) {
        lseek(fd, (off_t) blocknr * block_size, 0);
        if (read(fd, buf, block_size) != block_size)
                pexit("mx_read: error reading file");
  } else {
        sectnum = blocknr * (block_size / PH_SECTSIZE);
        for (bp = buf; bp < &buf[block_size]; bp++) {
                retries = MAX_RETRIES;
                do
                        err = absread(disk, sectnum, bp);
                while (err && --retries);

                if (retries) {
                        sectnum++;
                } else {
                        dexit("mx_read", sectnum, err);
                }
        }
  }
}

void mx_write(blocknr, buf)
int blocknr;
char *buf;
{
  /* Write the MINIX-block to disk */
  char (*bp)[PH_SECTSIZE];
  int retries, sectnum, err;

  if (file) {
        lseek(fd, blocknr * block_size, 0);
        if (write(fd, buf, block_size) != block_size) {
                pexit("mx_write: error writing file");
        }
  } else {
        sectnum = blocknr * (block_size / PH_SECTSIZE);
        for (bp = buf; bp < &buf[block_size]; bp++) {
                retries = MAX_RETRIES;
                do {
                        err = abswrite(disk, sectnum, bp);
                } while (err && --retries);

                if (retries) {
                        sectnum++;
                } else {
                        dexit("mx_write", sectnum, err);
                }
        }
  }
}


void dexit(s, sectnum, err)
int sectnum, err;
char *s;
{
  printf("Error: %s, sector: %d, code: %d, meaning: %s\n",
         s, sectnum, err, derrtab[err]);
  exit(2);
}

#endif

/*================================================================
 *                    get_block & put_block for UNIX
 *===============================================================*/
#ifdef UNIX

void special(string)
char *string;
{
  fd = creat(string, 0777);
  close(fd);
  fd = open(string, O_RDWR);
  if (fd < 0) pexit("Can't open special file");
}



void get_block(n, buf)
block_t n;
char *buf;
{
/* Read a block. */

  int k;

  /* First access returns a zero block */
  if (read_and_set(n) == 0) {
        copy(zero, buf, block_size);
        return;
  }
  lseek64(fd, mul64u(n, block_size), SEEK_SET, NULL);
  k = read(fd, buf, block_size);
  if (k != block_size) {
        pexit("get_block couldn't read");
  }
}

void get_super_block(buf)
char *buf;
{
/* Read a block. */

  int k;

  if(lseek(fd, (off_t) SUPER_BLOCK_BYTES, SEEK_SET) < 0) {
        perror("lseek");
        pexit("seek failed");
  }
  k = read(fd, buf, _STATIC_BLOCK_SIZE);
  if (k != _STATIC_BLOCK_SIZE) {
        pexit("get_super_block couldn't read");
  }
}

void put_block(n, buf)
block_t n;
char *buf;
{
/* Write a block. */

  (void) read_and_set(n);

  /* XXX - check other lseeks too. */
  if (lseek64(fd, mul64u(n, block_size), SEEK_SET, NULL) == (off_t) -1) {
        pexit("put_block couldn't seek");
  }
  if (write(fd, buf, block_size) != block_size) {
        pexit("put_block couldn't write");
  }
}


/* Dummy routines to keep source file clean from #ifdefs */

void flush()
{
  return;
}

void cache_init()
{
  return;
}

#endif