ndbm.h File Reference

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Data Structures
struct	DBM
struct	datum

Macros
#define	PBLKSIZ   1024
#define	DBLKSIZ   4096
#define	_DBM_RDONLY   0x01 /* data base open read-only */
#define	_DBM_IOERR   0x02 /* data base I/O error */
#define	dbm_rdonly(db)   ((db)->dbm_flags & _DBM_RDONLY)
#define	dbm_error(db)   ((db)->dbm_flags & _DBM_IOERR)
#define	dbm_clearerr(db)   ((db)->dbm_flags &= ~_DBM_IOERR)
#define	dbm_dirfno(db)   ((db)->dbm_dirf)
#define	dbm_pagfno(db)   ((db)->dbm_pagf)
#define	DBM_INSERT   0
#define	DBM_REPLACE   1

Functions
DBM *	dbm_open (char *file, int flags, int mode)
void	dbm_close (DBM *db)
datum	dbm_fetch (DBM *db, datum key)
datum	dbm_firstkey (DBM *db)
datum	dbm_nextkey (DBM *db)
long	dbm_forder (DBM *db, datum key)
int	dbm_delete (DBM *db, datum key)
int	dbm_store (DBM *db, datum key, datum dat, int replace)

---

Data Structure Documentation

DBM

struct DBM

Definition at line 54 of file ndbm.h.

Data Fields
long	dbm_bitno
long	dbm_blkno
long	dbm_blkptr
long	dbm_dirbno
char	dbm_dirbuf[DBLKSIZ]
int	dbm_dirf
int	dbm_flags
long	dbm_hmask
int	dbm_keyptr
long	dbm_maxbno
long	dbm_pagbno
char	dbm_pagbuf[PBLKSIZ]
int	dbm_pagf

datum

struct datum

Definition at line 83 of file ndbm.h.

Data Fields
char *	dptr
int	dsize

Macro Definition Documentation

_DBM_IOERR

#define _DBM_IOERR   0x02 /* data base I/O error */

Definition at line 71 of file ndbm.h.

_DBM_RDONLY

#define _DBM_RDONLY   0x01 /* data base open read-only */

Definition at line 70 of file ndbm.h.

DBLKSIZ

#define DBLKSIZ   4096

Definition at line 52 of file ndbm.h.

dbm_clearerr

#define dbm_clearerr

(

db

)

((db)->dbm_flags &= ~_DBM_IOERR)

Definition at line 77 of file ndbm.h.

dbm_dirfno

#define dbm_dirfno

(

db

)

((db)->dbm_dirf)

Definition at line 80 of file ndbm.h.

dbm_error

#define dbm_error

(

db

)

((db)->dbm_flags & _DBM_IOERR)

Definition at line 75 of file ndbm.h.

DBM_INSERT

#define DBM_INSERT   0

Definition at line 91 of file ndbm.h.

dbm_pagfno

#define dbm_pagfno

(

db

)

((db)->dbm_pagf)

Definition at line 81 of file ndbm.h.

dbm_rdonly

#define dbm_rdonly

(

db

)

((db)->dbm_flags & _DBM_RDONLY)

Definition at line 73 of file ndbm.h.

DBM_REPLACE

#define DBM_REPLACE   1

Definition at line 92 of file ndbm.h.

PBLKSIZ

#define PBLKSIZ   1024

Definition at line 50 of file ndbm.h.

Function Documentation

dbm_close()

void dbm_close

(

DBM *

db

)

Definition at line 97 of file ndbm.cc.

{
  (void) si_close(db->dbm_dirf);
  (void) si_close(db->dbm_pagf);
  free((char *)db);
}

dbm_delete()

int dbm_delete	(	DBM *	db,
		datum	key
	)

Definition at line 139 of file ndbm.cc.

{
  int i;
  // datum item;
 
  if (dbm_error(db))
    return (-1);
  if (dbm_rdonly(db))
  {
    errno = EPERM;
    return (-1);
  }
  dbm_access(db, dcalchash(key));
  if ((i = finddatum(db->dbm_pagbuf, key)) < 0)
    return (-1);
  if (!delitem(db->dbm_pagbuf, i))
    goto err;
  db->dbm_pagbno = db->dbm_blkno;
  (void) lseek(db->dbm_pagf, db->dbm_blkno*PBLKSIZ, SEEK_SET);
  if (si_write(db->dbm_pagf, db->dbm_pagbuf, PBLKSIZ) != PBLKSIZ)
  {
  err:
    db->dbm_flags |= _DBM_IOERR;
    return (-1);
  }
  return (0);
}

dbm_fetch()

datum dbm_fetch	(	DBM *	db,
		datum	key
	)

Definition at line 119 of file ndbm.cc.

{
  int i;
  datum item;
 
  if (dbm_error(db))
    goto err;
  dbm_access(db, dcalchash(key));
  if ((i = finddatum(db->dbm_pagbuf, key)) >= 0)
  {
    item = makdatum(db->dbm_pagbuf, i+1);
    if (item.dptr != NULL)
      return (item);
  }
err:
  item.dptr = NULL;
  item.dsize = 0;
  return (item);
}

dbm_firstkey()

datum dbm_firstkey

(

DBM *

db

)

Definition at line 252 of file ndbm.cc.

{
 
  db->dbm_blkptr = 0L;
  db->dbm_keyptr = 0;
  return (dbm_nextkey(db));
}

dbm_forder()

long dbm_forder	(	DBM *	db,
		datum	key
	)

Definition at line 104 of file ndbm.cc.

{
  long hash;
 
  hash = dcalchash(key);
  for (db->dbm_hmask=0;; db->dbm_hmask=(db->dbm_hmask<<1)+1)
  {
    db->dbm_blkno = hash & db->dbm_hmask;
    db->dbm_bitno = db->dbm_blkno + db->dbm_hmask;
    if (getbit(db) == 0)
      break;
  }
  return (db->dbm_blkno);
}

dbm_nextkey()

datum dbm_nextkey

(

DBM *

db

)

Definition at line 260 of file ndbm.cc.

{
  struct stat statb;
  datum item;
 
  if (dbm_error(db)
       || singular_fstat(db->dbm_pagf, &statb) < 0
  )
                goto err;
  statb.st_size /= PBLKSIZ;
  for (;;)
  {
    if (db->dbm_blkptr != db->dbm_pagbno)
    {
      db->dbm_pagbno = db->dbm_blkptr;
      (void) lseek(db->dbm_pagf, db->dbm_blkptr*PBLKSIZ, SEEK_SET);
      if (si_read(db->dbm_pagf, db->dbm_pagbuf, PBLKSIZ) != PBLKSIZ)
        memset(db->dbm_pagbuf, 0, PBLKSIZ);
#ifdef DEBUG
      else if (chkblk(db->dbm_pagbuf) < 0)
        db->dbm_flags |= _DBM_IOERR;
#endif
    }
    short tmp;
    memcpy(&tmp, db->dbm_pagbuf, sizeof(tmp));
    if (tmp != 0)
    {
      item = makdatum(db->dbm_pagbuf, db->dbm_keyptr);
      if (item.dptr != NULL)
      {
        db->dbm_keyptr += 2;
        return (item);
      }
      db->dbm_keyptr = 0;
    }
    if (++db->dbm_blkptr >= statb.st_size)
      break;
  }
err:
  item.dptr = NULL;
  item.dsize = 0;
  return (item);
}

dbm_open()

DBM * dbm_open	(	char *	file,
		int	flags,
		int	mode
	)

Definition at line 59 of file ndbm.cc.

{
  struct stat statb;
  DBM *db;
 
  if ((db = (DBM *)malloc(sizeof *db)) == 0)
  {
    errno = ENOMEM;
    return ((DBM *)0);
  }
#ifdef MSDOS
  // default mode of open is ascii, we need binary mode.
  flags |= O_BINARY;
#endif
  db->dbm_flags = (flags & 03) == O_RDONLY ? _DBM_RDONLY : 0;
  if ((flags & 03) == O_WRONLY)
    flags = (flags & ~03) | O_RDWR;
  strcpy(db->dbm_pagbuf, file);
  strcat(db->dbm_pagbuf, ".pag");
  db->dbm_pagf = si_open(db->dbm_pagbuf, flags, mode);
  if (db->dbm_pagf < 0)
    goto bad;
  strcpy(db->dbm_pagbuf, file);
  strcat(db->dbm_pagbuf, ".dir");
  db->dbm_dirf = si_open(db->dbm_pagbuf, flags, mode);
  if (db->dbm_dirf < 0)
    goto bad1;
  singular_fstat(db->dbm_dirf, &statb);
  db->dbm_maxbno = statb.st_size*BYTESIZ-1;
  db->dbm_pagbno = db->dbm_dirbno = -1;
  return (db);
bad1:
  (void) si_close(db->dbm_pagf);
bad:
  free((char *)db);
  return ((DBM *)0);
}

dbm_store()

int dbm_store	(	DBM *	db,
		datum	key,
		datum	dat,
		int	replace
	)

Definition at line 167 of file ndbm.cc.

{
  int i;
  int ret;
  datum item, item1;
  char ovfbuf[PBLKSIZ];
 
  if (dbm_error(db))
    return (-1);
  if (dbm_rdonly(db))
  {
    errno = EPERM;
    return (-1);
  }
 
_loop:
  dbm_access(db, dcalchash(key));
  if ((i = finddatum(db->dbm_pagbuf, key)) >= 0)
  {
    if (!replace)
      return (1);
    if (!delitem(db->dbm_pagbuf, i))
    {
      db->dbm_flags |= _DBM_IOERR;
      return (-1);
    }
  }
  if (!additem(db->dbm_pagbuf, key, dat))
    goto split;
  db->dbm_pagbno = db->dbm_blkno;
  (void) lseek(db->dbm_pagf, db->dbm_blkno*PBLKSIZ, SEEK_SET);
  if ( (ret=si_write(db->dbm_pagf, db->dbm_pagbuf, PBLKSIZ)) != PBLKSIZ)
  {
    db->dbm_flags |= _DBM_IOERR;
    return (-1);
  }
  return (0);
 
split:
  if (key.dsize+dat.dsize+3*sizeof(short) >= PBLKSIZ)
  {
    db->dbm_flags |= _DBM_IOERR;
    errno = ENOSPC;
    return (-1);
  }
  memset(ovfbuf, 0, PBLKSIZ);
  for (i=0;;) {
    item = makdatum(db->dbm_pagbuf, i);
    if (item.dptr == NULL)
      break;
    if (dcalchash(item) & (db->dbm_hmask+1))
    {
      item1 = makdatum(db->dbm_pagbuf, i+1);
      if (item1.dptr == NULL) {
        fprintf(stderr, "ndbm: split not paired\n");
        db->dbm_flags |= _DBM_IOERR;
        break;
      }
      if (!additem(ovfbuf, item, item1) ||
          !delitem(db->dbm_pagbuf, i))
      {
        db->dbm_flags |= _DBM_IOERR;
        return (-1);
      }
      continue;
    }
    i += 2;
  }
  db->dbm_pagbno = db->dbm_blkno;
  (void) lseek(db->dbm_pagf, db->dbm_blkno*PBLKSIZ, SEEK_SET);
  if (si_write(db->dbm_pagf, db->dbm_pagbuf, PBLKSIZ) != PBLKSIZ)
  {
    db->dbm_flags |= _DBM_IOERR;
    return (-1);
  }
  (void) lseek(db->dbm_pagf, (db->dbm_blkno+db->dbm_hmask+1)*PBLKSIZ, SEEK_SET);
  if (si_write(db->dbm_pagf, ovfbuf, PBLKSIZ) != PBLKSIZ)
  {
    db->dbm_flags |= _DBM_IOERR;
    return (-1);
  }
  setbit(db);
  goto _loop;
}