swapfs.c

操作系统源代码

  if (write(1, buf, BLOCK_SIZE) != BLOCK_SIZE)
	fail("write failed on output file");
}


static int convcpy(dst, src, format)
char *dst;
char *src;
int *format;
{
  char *old_src = src;
  register char tmp;
  int i;

  for (i = 0; format[i] > 0; i++) {
	switch (format[i]) {
	    case 1:	*dst++ = *src++;	break;
	    case 2:
		tmp = *src++;
		*dst++ = *src++;
		*dst++ = tmp;
		break;
	    case 4:
		tmp = src[0];
		dst[0] = src[3];
		dst[3] = tmp;
		tmp = src[1];
		dst[1] = src[2];
		dst[2] = tmp;
		src += 4;
		dst += 4;
		break;
	    default:
		fail("wrong format array for convcpy");
	}
  }
  return(src - old_src);
}


static void conv2_blkcpy(dst, src)
char *dst;
char *src;
{
  int i;
  register char tmp;

  for (i = 0; i < BLOCK_SIZE; i += 2) {
	tmp = *src++;
	*dst++ = *src++;
	*dst++ = tmp;
  }
}


static void conv4_blkcpy(dst, src)
char *dst;
char *src;
{
  int i;
  register char tmp;

  for (i = 0; i < BLOCK_SIZE; i += 4) {
	tmp = src[0];
	dst[0] = src[3];
	dst[3] = tmp;

	tmp = src[1];
	dst[1] = src[2];
	dst[2] = tmp;

	src += 4;
	dst += 4;
  }
}


static void conv2cpy(dst, src)
char *dst;
char *src;
{
  register char tmp;
  tmp = *src++;
  *dst++ = *src++;
  *dst++ = tmp;
}


static int inode_size(version)
int version;
{
  return(version == 1) ? V1_INODE_SIZE : V2_INODE_SIZE;
}


static void init_super(sp, buf)
super_t *sp;
char *buf;
{
  int magic;
  long imapblks, zmapblks;

  big_endian_fs = 0;		/* guess the file system is little endian */
  magic = two_bytes(buf + MAGIC_OFFSET);

  if (magic != V1_MAGIC && magic != V2_MAGIC) {
	big_endian_fs = 1;
	magic = two_bytes(buf + MAGIC_OFFSET);
  }
  switch (magic) {
      case V1_MAGIC:	sp->version = 1;	break;
      case V2_MAGIC:	sp->version = 2;	break;
      default:	fail("Not a Minix file system");
}

  if (verbose_flag) fprintf(stderr, "\nVersion = V%d, %s endian.\n",
		sp->version, big_endian_fs ? "big" : "little");

  sp->ninodes = two_bytes(buf + NINODES_OFFSET);
  imapblks = two_bytes(buf + IMAP_BLOCKS_OFFSET);
  sp->imap_blocks = imapblks;
  zmapblks = two_bytes(buf + ZMAP_BLOCKS_OFFSET);
  sp->zmap_blocks = zmapblks;
  sp->firstdatazone = two_bytes(buf + FIRSTDATAZONE_OFFSET);
  sp->log_zone_size = two_bytes(buf + LOG_ZONE_SIZE_OFFSET);

  if (sp->version == 1)
	sp->zones = two_bytes(buf + V1_ZONES_OFFSET);
  else
	sp->zones = four_bytes(buf + V2_ZONES_OFFSET);

  sp->inodes_per_block = BLOCK_SIZE / inode_size(sp->version);

  if (imapblks < 0 || zmapblks < 0 || sp->ninodes < 1 || sp->zones < 1)
	fail("Bad superblock");


  if (sp->log_zone_size != 0)
	fail("Can't swap file systems with different zone and block sizes");

  sp->first_imap_block = SUPER_BLOCK_OFF + 1;
  sp->first_zmap_block = sp->first_imap_block + sp->imap_blocks;
  sp->first_inode_block = sp->first_zmap_block + sp->zmap_blocks;

  sp->dzmap_size = sp->zones - sp->firstdatazone;
  if (verbose_flag) {
	fprintf(stderr, "nzones = %ld, ", sp->zones);
	fprintf(stderr, "ninodes = %u, ", sp->ninodes);
	fprintf(stderr, "first data zone = %ld.\n\n", sp->firstdatazone);
  }
}


static void get_inode(ip, buf, version)
inode_t *ip;
char *buf;
int version;
{
  int i;
  int mode;

  if (version == 1) {
	mode = two_bytes(buf + INODE1_MODE_OFF);
	ip->size = four_bytes(buf + INODE1_SIZE_OFF);
	ip->ind1 = two_bytes(buf + INODE1_IND1_OFF);
	ip->ind2 = two_bytes(buf + INODE1_IND2_OFF);
	ip->ind3 = 0;
	for (i = 0; i < NR_DIRECT_ZONES; i++)
		ip->direct[i] = two_bytes(buf + INODE1_DIRECT_OFF + 2 * i);
  } else {
	mode = two_bytes(buf + INODE2_MODE_OFF);
	ip->size = four_bytes(buf + INODE2_SIZE_OFF);
	ip->ind1 = four_bytes(buf + INODE2_IND1_OFF);
	ip->ind2 = four_bytes(buf + INODE2_IND2_OFF);
	ip->ind3 = four_bytes(buf + INODE2_IND3_OFF);
	for (i = 0; i < NR_DIRECT_ZONES; i++)
		ip->direct[i] = four_bytes(buf + INODE2_DIRECT_OFF + 4 * i);
  }

  if (mode == 0) {
	if (ip->size % DIR_ENTRY_SIZE == 0)
		ip->ztype = T_MAYBE_OLD_DIR;
	else
		ip->ztype = T_OLD_NON_DIR;
	if (was_blk_special(*ip)) ip->size = 0;
  } else {
	mode = mode & INODE_MODE_MASK;
	if (mode == INODE_BLK_SPECIAL_MODE || mode == INODE_CHR_SPECIAL_MODE)
		ip->size = 0;	/* prevent the use of the block numbers. */
	ip->ztype = (mode == INODE_DIR_MODE) ? T_DIR : T_NON_DIR;
  }
}


static int check_inode(inode, super)
inode_t inode;
super_t super;
{
  int i;

  for (i = 0; i < NR_DIRECT_ZONES; i++)
	if (!check_blk_number(inode.direct[i], super)) return 0;

  return(check_blk_number(inode.ind1, super) &&
	check_blk_number(inode.ind2, super) &&
	check_blk_number(inode.ind3, super));
}


static int check_blk_number(num, super)
blockn_t num;
super_t super;
{
  if (num == 0 || (num >= super.firstdatazone && num < super.zones))
	return 1;

  fprintf(stderr, "warning bad block number %ld in inode.\n", num);
  return 0;
}


static int was_blk_special(inode)
inode_t inode;
{
  int i, result;
  blockn_t block_size;

  if (inode.size % BLOCK_SIZE || inode.ind1) return 0;
  block_size = inode.size / BLOCK_SIZE;

  for (i = NR_DIRECT_ZONES - 1; i >= 0; i--)
	if (inode.direct[i] != 0) break;

  result = (i < 1 && block_size > i + 1);

  if (debug_flag && result) {
	fprintf(stderr, "old block special file detected (slot = %d).\n", i);
  }
  return result;
}


static void cw_inode_block(buf, ninodes, version)
char *buf;
inodesn_t ninodes;
int version;
{
  char output_buf[BLOCK_SIZE];
  char *src, *dst;
  inodesn_t i;
  int cnt, free_bytes;
  int *format;

  src = buf;
  dst = output_buf;

  format = (version == 1) ? inode1_format : inode2_format;
  for (i = 0; i < ninodes; i++) {
	cnt = convcpy(dst, src, format);
	src += cnt;
	dst += cnt;
  }

  assert(cnt == inode_size(version));

  free_bytes = BLOCK_SIZE - (src - buf);
  assert(free_bytes >= 0);
  if (verbose_flag && free_bytes > 0) {
	/* There is a small change that the last free inode has no
	 * matching bit in the last inode bit map block: e.g. if
	 * sp->ninodes == 8191. */
	fprintf(stderr, "%5d bytes (%d inodes) free in last inode block.\n",
		free_bytes, free_bytes / inode_size(version));
	memcpy(dst, src, (size_t) free_bytes);
  }
  write_block(output_buf);
}


static void proc_ind(dzmap, curr_ind, buf, super)
dzmap_t dzmap;
size_t curr_ind;
char *buf;
super_t super;
{
  int indnum, i, ztype;
  int word_size;		/* size of zone block number in ind. block in
			 * bytes */
  unsigned char dz, tmp_dz;
  blockn_t blk, ind_blk;
  int bad_range = 0, hidden_zero = 0, zero_flag = 0, expired = 0;
  size_t blk_index;

  dz = dzmap[curr_ind];
  indnum = dz & INDIRECT_MASK;
  ztype = dz & T_MASK;
  ind_blk = curr_ind + super.firstdatazone;

  word_size = (super.version == 1) ? 2 : 4;
  assert(indnum > 0);

  for (i = 0; i < BLOCK_SIZE; i += word_size) {
	if (word_size == 2)
		blk = two_bytes(buf + i);
	else
		blk = four_bytes(buf + i);

	if (blk == 0)
		zero_flag = 1;
	else if (blk < super.firstdatazone || blk >= super.zones)
		bad_range = 1;
	else {
		if (zero_flag) hidden_zero = 1;
		blk_index = blk - super.firstdatazone;
		tmp_dz = dzmap[blk_index];
		if (ztype_class(tmp_dz & T_MASK) == In_use_zone) expired = 1;
	}

  }

  if (ztype_class(ztype) == In_use_zone) {
	if (bad_range) {
		fprintf(stderr, "%s zone block contains ", ind_str[indnum]);
		fail("illegal value");
	}
	if ((ztype == T_DIR || indnum > 1) && hidden_zero) {
		fprintf(stderr, "WARNING: %s zone block %ld contains ",
			ind_str[indnum], ind_blk);
		fprintf(stderr, "unexpected zero block numbers\n");
	}
  } else {
	if (expired) {
		dzmap[curr_ind] &= ~(INDIRECT_MASK & IND_CONFLICT_BIT);
		return;
	}

	/* Not yet implemented. :-( if (bad_range || (indnum > 1 &&
	 * hidden_zero) || equal_values(buf, super.version ) { } */
  }

  for (i = 0; i < BLOCK_SIZE; i += word_size) {
	if (word_size == 2)
		blk = two_bytes(buf + i);
	else
		blk = four_bytes(buf + i);

	if (blk == 0) continue;
	blk_index = blk - super.firstdatazone;
	tmp_dz = dzmap[blk_index];
	if (ztype_class(tmp_dz & T_MASK) == In_use_zone) {	/* trouble */
		if ((tmp_dz & INDIRECT_MASK) == indnum - 1 &&
		    (tmp_dz & T_MASK) == ztype)
			fprintf(stderr, "WARNING: %s zone block %ld used more \
than once\n", ind_str[indnum - 1], blk);
		else {
			fprintf(stderr, "Block %ld used more than ", blk);
			fail("once with different types");
		}
	}
	dzmap[blk_index] = (dz & ~INDIRECT_MASK) | (indnum - 1);
  }
  dzmap[curr_ind] |= IND_PROCESSED_BIT;
}


static void cw_dir_block(buf)
char *buf;
{
  char output_buf[BLOCK_SIZE];
  int ino, i, old_ino_offset;

  memcpy(output_buf, buf, BLOCK_SIZE);

  for (i = 0; i < BLOCK_SIZE; i += DIR_ENTRY_SIZE) {
	ino = two_bytes(buf + i);
	if (ino == 0) {
		old_ino_offset = i + DIR_ENTRY_SIZE - 2;
		conv2cpy(output_buf + old_ino_offset, buf + old_ino_offset);
	} else
		conv2cpy(output_buf + i, buf + i);
  }
  write_block(output_buf);
}


static void dzmap_add_inode(dzmap, inode, super)
dzmap_t dzmap;
inode_t inode;
super_t super;
{
  int i;

  if (inode.size == 0 || !check_inode(inode, super)) return;

  for (i = 0; i < NR_DIRECT_ZONES; i++)
	dz_update(dzmap, inode.direct[i], 0, inode.ztype, super);

  dz_update(dzmap, inode.ind1, 1, inode.ztype, super);
  dz_update(dzmap, inode.ind2, 2, inode.ztype, super);
  dz_update(dzmap, inode.ind3, 3, inode.ztype, super);
}


static void dz_update(dzmap, blknum, new_indnum, new_ztype, super)
dzmap_t dzmap;
blockn_t blknum;
int new_indnum;
int new_ztype;
super_t super;
{
  size_t dznum;
  int old_indnum;
  int old_ztype;
  unsigned char *dz;
  char new_dz;


  if (blknum == 0) return;

  dznum = (size_t) (blknum - super.firstdatazone);

  dz = &dzmap[dznum];
  old_indnum = *dz & INDIRECT_MASK;
  old_ztype = *dz & T_MASK;

  new_dz = new_ztype | new_indnum;

  if (ztype_class(new_ztype) > ztype_class(old_ztype)) {
	*dz = new_dz;
	return;
  } else if (ztype_class(new_ztype) < ztype_class(old_ztype))
	return;

  /* Collision: old and new have the same class */

  if (ztype_class(old_ztype) == In_use_zone) {	/* trouble */
	if (new_indnum == old_indnum && new_ztype == old_ztype) {
		fprintf(stderr, "WARNING: file system corrupt, zone block %ld \
is used more than once.\n", blknum);
		return;
	}
	fprintf(stderr, "ERROR: file system corrupt, zone block %ld is used \
more than once.\n", blknum);
	fail("Can't determine its type");
  }
  assert(ztype_class(old_ztype) == Old_zone);


  if (new_indnum != old_indnum) {
	*dz |= IND_CONFLICT_BIT;
	if (new_indnum > old_indnum) {
		*dz &= ~INDIRECT_MASK;
		*dz |= new_indnum;
	}
  }
  if (new_ztype == T_MAYBE_OLD_DIR || old_ztype == T_MAYBE_OLD_DIR) {
	*dz |= TYPE_CONFLICT_BIT;
	*dz &= ~T_MASK;
	*dz |= T_MAYBE_OLD_DIR;
  }
}


static class_t ztype_class(ztype)
int ztype;
{
  class_t class;

  if (ztype == T_MAYBE_OLD_DIR || ztype == T_OLD_NON_DIR)
	class = Old_zone;
  else if (ztype == T_DIR || ztype == T_NON_DIR)
	class = In_use_zone;
  else
	class = Unused_zone;

  return class;
}


static void fail(str)
char *str;
{
  fprintf(stderr, "%s\n", str);
  exit(1);
}


static unsigned int two_bytes(buf)
char buf[2];
{
  unsigned char *ubuf = (unsigned char *) buf;

  if (big_endian_fs)
	return(ubuf[0] << 8) | ubuf[1];
  else
	return(ubuf[1] << 8) | ubuf[0];
}


static long four_bytes(buf)
char buf[4];
{
  unsigned char *ubuf = (unsigned char *) buf;
  register int r1, r2;

  if (big_endian_fs) {
	r1 = (ubuf[0] << 8) | ubuf[1];
	r2 = (ubuf[2] << 8) | ubuf[3];
  } else {
	r2 = (ubuf[1] << 8) | ubuf[0];
	r1 = (ubuf[3] << 8) | ubuf[2];
  }
  return((long) r1 << 16) | r2;
}


static void usage(arg0)
char *arg0;
{
  fprintf(stderr, "usage: %s [-v] srcfs [destfs]\n", arg0);
  exit(2);
}