/* ndbm.c - The NDBM interface. */

/*  This file is part of GDBM, the GNU data base manager, by Philip A. Nelson.
    Copyright (C) 1990, 1991, 1993  Free Software Foundation, Inc.

    GDBM is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 2, or (at your option)
    any later version.

    GDBM is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with GDBM; see the file COPYING.  If not, write to
    the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.

    You may contact the author by:
       e-mail:  phil@cs.wwu.edu
      us-mail:  Philip A. Nelson
                Computer Science Department
                Western Washington University
                Bellingham, WA 98226

*************************************************************************/



#include "gdbmdefs.h"
#include "gdbmerrno.h"
#include "extern.h"

/* Initialize ndbm system.  FILE is a pointer to the file name.  In
   standard dbm, the database is found in files called FILE.pag and
   FILE.dir.  To make gdbm compatable with dbm using the dbminit call,
   the same file names are used.  Specifically, dbminit will use the file
   name FILE.pag in its call to gdbm open.  If the file (FILE.pag) has a
   size of zero bytes, a file initialization procedure is performed,
   setting up the initial structure in the file.  Any error detected will
   cause a return value of -1.  No errors cause the return value of 0.
   NOTE: file.dir will be ignored and will always have a size of zero.
   FLAGS and MODE are the same as the open (2) call.  This call will
   look at the FLAGS and decide what call to make to gdbm_open.  For
   FLAGS == O_RDONLY, it will be a GDBM_READER, if FLAGS == O_RDWR|O_CREAT,
   it will be a GDBM_WRCREAT (creater and writer) and if the FLAGS == O_RDWR,
   it will be a GDBM_WRITER and if FLAGS contain O_TRUNC then it will be
   a GDBM_NEWDB.  All other values of FLAGS in the flags are
   ignored. */

gdbm_file_info *dbm_open (char* file, int flags, int mode)
{
  char *pag_file;               /* Used to construct "file.pag". */
  char *dir_file;               /* Used to construct "file.dir". */
  struct stat dir_stat;         /* Stat information for "file.dir". */
  gdbm_file_info *temp_dbf;     /* Temporary file pointer storage. */


  /* Prepare the correct names of "file.pag" and "file.dir". */
  pag_file = (char *) malloc (strlen (file) + 5);
  dir_file = (char *) malloc (strlen (file) + 5);
  if ((pag_file == NULL) || (dir_file == NULL)) {
    gdbm_errno = GDBM_MALLOC_ERROR;     /* For the hell of it. */
    return NULL;
  }

  strcpy (pag_file, file);
  strcat (pag_file, ".pag");
  strcpy (dir_file, file);
  strcat (dir_file, ".dir");


  /* Call the actual routine, saving the pointer to the file information. */
  flags &= O_RDONLY | O_RDWR | O_CREAT | O_TRUNC;
  if (flags == O_RDONLY) {
    temp_dbf = gdbm_open (pag_file, 0, GDBM_READER, 0, NULL);
  } else if (flags == (O_RDWR | O_CREAT)) {
    temp_dbf = gdbm_open (pag_file, 0, GDBM_WRCREAT, mode, NULL);
  } else if ((flags & O_TRUNC) == O_TRUNC) {
    temp_dbf = gdbm_open (pag_file, 0, GDBM_NEWDB, mode, NULL);
  } else {
    temp_dbf = gdbm_open (pag_file, 0, GDBM_WRITER, 0, NULL);
  }

  /* Did we successfully open the file? */
  if (temp_dbf == NULL) {
    gdbm_errno = GDBM_FILE_OPEN_ERROR;
    goto done;
  }

  /* If the database is new, link "file.dir" to "file.pag". This is done
     so the time stamp on both files is the same. */
  if (stat (dir_file, &dir_stat) == 0) {
    if (dir_stat.st_size == 0)
      if (open (dir_file, O_RDWR | O_TRUNC, S_IREAD | S_IWRITE) < 0) {
        gdbm_errno = GDBM_FILE_OPEN_ERROR;
        gdbm_close (temp_dbf);
        temp_dbf = NULL;
        goto done;
      }
  } else {
    /* Since we can't stat it, we assume it is not there and try
       to link the dir_file to the pag_file. */
    if (open (dir_file, O_RDWR | O_CREAT | O_TRUNC, S_IREAD | S_IWRITE) < 0) {
      gdbm_errno = GDBM_FILE_OPEN_ERROR;
      gdbm_close (temp_dbf);
      temp_dbf = NULL;
      goto done;
    }
  }

done:
  free (pag_file);
  free (dir_file);
  return temp_dbf;
}


/* Close the DBF file. */

void dbm_close (gdbm_file_info *dbf)
{
  gdbm_close (dbf);
}


/* NDBM Look up a given KEY and return the information associated with that
   KEY. The pointer in the structure that is  returned is a pointer to
   dynamically allocated memory block.  */

datum dbm_fetch (gdbm_file_info *dbf, datum key)
{
  datum ret_val;                /* The return value. */

  /* Free previous dynamic memory, do actual call, and save pointer to new
     memory. */
  ret_val = gdbm_fetch (dbf, key);
  if (_gdbm_fetch_val != NULL)
    free (_gdbm_fetch_val);
  _gdbm_fetch_val = ret_val.dptr;

  /* Return the new value. */
  return ret_val;
}


/* NDBM add a new element to the database.  CONTENT is keyed by KEY.
   The file on disk is updated to reflect the structure of the new
   database before returning from this procedure.  */

int dbm_store (gdbm_file_info *dbf, datum key, datum content, int flags)
{
  return gdbm_store (dbf, key, content, flags);
}


/* Remove the KEYed item and the KEY from the database DBF. */

int dbm_delete (gdbm_file_info *dbf, datum key)
{
  return gdbm_delete (dbf, key);
}


/* NDBM Start the visit of all keys in the database.  This produces
   something in hash order, not in any sorted order.  DBF is the dbm file
   information pointer. */

datum dbm_firstkey (gdbm_file_info *dbf)
{
  datum ret_val;

  /* Free previous dynamic memory, do actual call, and save pointer to new
     memory. */
  ret_val = gdbm_firstkey (dbf);
  if (_gdbm_memory.dptr != NULL)
    free (_gdbm_memory.dptr);
  _gdbm_memory = ret_val;

  /* Return the new value. */
  return ret_val;
}


/* NDBM Continue visiting all keys.  The next key in the sequence is returned.
   DBF is the file information pointer. */

datum dbm_nextkey (gdbm_file_info *dbf)
{
  datum ret_val;

  /* Make sure we have a valid key. */
  if (_gdbm_memory.dptr == NULL)
    return _gdbm_memory;

  /* Call gdbm nextkey with the old value. After that, free the old value. */
  ret_val = gdbm_nextkey (dbf, _gdbm_memory);
  if (_gdbm_memory.dptr != NULL)
    free (_gdbm_memory.dptr);
  _gdbm_memory = ret_val;

  /* Return the new value. */
  return ret_val;
}


/* Return the file number of the DBF file.  NDBM original wanted the .dir
   file number.  Since we have only one file number, we return it. */

int dbm_dirfno (gdbm_file_info *dbf)
{
  return (dbf->desc);
}


/* Return the file number of the DBF file.  NDBM original wanted the .pag
   file number.  Since we have only one file number, we return it. */

int dbm_pagfno (gdbm_file_info *dbf)
{
  return (dbf->desc);
}


/* not much of a routine, but should be a function for compatibility. */

int dbm_rdonly (gdbm_file_info *dbf)
{
  return (dbf->read_write == GDBM_READER);
}