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    Length: 5257 (0x1489)
    Types: TextFile
    Names: »gdbmstore.c«

└─⟦a05ed705a⟧ Bits:30007078 DKUUG GNU 2/12/89
    └─⟦847972ed9⟧ »./gdbm0.9.tar.Z« 
        └─⟦e41d67701⟧ 
            └─⟦this⟧ »gdbm/gdbmstore.c« 

TextFile

/* gdbmstore.c - Add a new key/data pair to the database. */

/*  GNU DBM  - DataBase Manager (database subroutines) by Philip A. Nelson
    Copyright (C) 1989  Free Software Foundation, Inc.

    This program 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.

    This program 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 this program; if not, write to the Free Software
    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.

    You may contact the author by:
       e-mail:  phil@wwu.edu
      us-mail:  Philip A. Nelson
                Computer Science Department
                Western Washington University
                Bellingham, WA 98226
        phone:  (206) 676-3035
       
*************************************************************************/


#include <stdio.h>
#include <sys/types.h>
#include <sys/file.h>
#include <sys/stat.h>
#include "gdbmdefs.h"
#include "systems.h"
#include "gdbmerrno.h"

extern gdbm_error gdbm_errno;	/* gdbm's error variable. */


/* 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.  A return value of 0 means no
   errors.  A return value of -1 means that the item was not stored in
   the data base because the caller was not an official writer. */

int
gdbm_store (dbf, key, content, flags)
     gdbm_file_info *dbf;
     datum key;
     datum content;
     int flags;
{
  int new_hash_val;		/* The new hash value. */
  int elem_loc;			/* The location in hash bucket. */
  int file_adr;			/* The address of new space in the file.  */
  int num_bytes;		/* Used for error detection. */
  int free_adr;			/* For keeping track of a freed section. */
  int free_size;

  char *write_data;		/* To write both key and data in 1 call. */
  char *src;			/* Used to prepare write_data. */
  char *dst;			/* Used to prepare write_data. */
  int   cnt;			/* Counter for loops to fill write_data. */
  int   index;			/* Used in the avail stuff. */
  int   new_size;		/* Used in allocating space. */
  char *temp;			/* Used in _gdbm_findkey call. */


  /* First check to make sure this guy is a writer. */
  if (dbf->read_write != GDBM_WRITER)
    {
      gdbm_errno = READER_CANT_STORE;
      return -1;
    }

  /* Look for the key in the file.
     A side effect loads the correct bucket and calculates the hash value. */
  elem_loc = _gdbm_findkey (dbf, key, &temp, &new_hash_val);


  /* Did we find the item? */
  if (elem_loc != -1)
    {
      if (flags == GDBM_REPLACE)
	{
	  /* Just replace the data. */
	  free_adr = dbf->bucket->h_table[elem_loc].data_pointer;
	  free_size = dbf->bucket->h_table[elem_loc].key_size
	              + dbf->bucket->h_table[elem_loc].data_size;
	  _gdbm_free (dbf, free_adr, free_size);
	}
      else
	{
	  gdbm_errno = CANNOT_REPLACE;
	  return 1;
	}
    }


  /* Get the file address for the new space.
     (Current bucket's free space is first place to look.) */
  new_size = key.dsize+content.dsize;
  file_adr = _gdbm_alloc (dbf, new_size);

  /* If this is a new entry in the bucket, we need to do special things. */
  if (elem_loc == -1)
    {
      if (dbf->bucket->count == dbf->header->bucket_elems)
	{
	  /* Split the current bucket. */
	  _gdbm_split_bucket(dbf, new_hash_val);
	}
      
      /* Find space to insert into bucket and set elem_loc to that place. */
      elem_loc = new_hash_val % dbf->header->bucket_elems;
      while (dbf->bucket->h_table[elem_loc].hash_value != -1)
	{  elem_loc = (elem_loc + 1) % dbf->header->bucket_elems; }

      /* We now have another element in the bucket.  Add the new information.*/
      dbf->bucket->count += 1;
      dbf->bucket->h_table[elem_loc].hash_value = new_hash_val;
      strncpy (dbf->bucket->h_table[elem_loc].key_start, key.dptr, SMALL);
    }


  /* Update current bucket data pointer and sizes. */
  dbf->bucket->h_table[elem_loc].data_pointer = file_adr;
  dbf->bucket->h_table[elem_loc].key_size = key.dsize;
  dbf->bucket->h_table[elem_loc].data_size = content.dsize;

  /* Prepare write_data. The key is written first.  */
  write_data = (char *) alloca (key.dsize+content.dsize);
  dst = write_data;
  src = key.dptr;
  for (cnt=0; cnt < key.dsize; cnt++)
    *(dst++) = *(src++);
  src = content.dptr;
  for (cnt=0; cnt < content.dsize; cnt++)
    *(dst++) = *(src++);

  /* Write the data to the file. */
  num_bytes = lseek (dbf->desc, file_adr, L_SET);
  if (num_bytes != file_adr) _gdbm_fatal (dbf, "lseek error");
  num_bytes = write (dbf->desc, write_data, key.dsize+content.dsize);
  if (num_bytes != key.dsize+content.dsize) _gdbm_fatal (dbf, "write error");

  /* Current bucket has changed. */
  dbf->cache_entry->ca_changed = TRUE;
  dbf->bucket_changed = TRUE;

  /* Write everything that is needed to the disk. */
  _gdbm_end_update (dbf);
  return 0;
  
}