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    Length: 3330 (0xd02)
    Types: TextFile
    Names: »update.c«

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

TextFile

/* update.c - The routines for updating the file to a consistent state. */

/*  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 "gdbmdefs.h"
#include "systems.h"


/* This procedure writes the header back to the file described by DBF. */

static 
write_header (dbf)
     gdbm_file_info *dbf;
{
  int num_bytes;

  num_bytes = lseek (dbf->desc, 0, L_SET);
  if (num_bytes != 0) _gdbm_fatal (dbf, "lseek error");
  num_bytes = write (dbf->desc, dbf->header, dbf->header->block_size);
  if (num_bytes != dbf->header->block_size)
    _gdbm_fatal (dbf, "write error");

  /* Wait for all output to be done. */
  fsync (dbf->desc);
}


/* After all changes have been made in memory, we now write them
   all to disk. */
_gdbm_end_update (dbf)
     gdbm_file_info *dbf;
{
  int num_bytes;	/* Return value for lseek and write. */
  
  /* Write the current bucket. */
  if (dbf->bucket_changed)
    {
      _gdbm_write_bucket (dbf, dbf->cache_entry);
      dbf->bucket_changed = FALSE;
    }

  /* Write the other changed buckets if there are any. */
  if (dbf->second_changed)
    {
      cache_elem *ca_entry;
      int index;

      for (index = 0; index < CACHE_SIZE; index++)
	if (dbf->bucket_cache[index].ca_changed)
	  {
	    _gdbm_write_bucket (dbf, &dbf->bucket_cache[index]);
	  }
      dbf->second_changed = FALSE;
    }
  
  /* Write the directory. */
  if (dbf->directory_changed)
    {
      num_bytes = lseek (dbf->desc, dbf->header->dir, L_SET);
      if (num_bytes != dbf->header->dir ) _gdbm_fatal (dbf, "lseek error");
      num_bytes = write (dbf->desc, dbf->dir, dbf->header->dir_size);
      if (num_bytes != dbf->header->dir_size )
	_gdbm_fatal (dbf, "write error");
      dbf->directory_changed = FALSE;
      if (!dbf->header_changed) fsync (dbf->desc);
    }

  /* Final write of the header. */
  if (dbf->header_changed)
    {
      write_header (dbf);
      dbf->header_changed = FALSE;
    }
}


/* If a fatal error is detected, come here and exit. VAL tells which fatal
   error occured. */
_gdbm_fatal (dbf, val)
     gdbm_file_info *dbf;
     char *val;
{
  if (dbf->fatal_err != NULL)
    (*dbf->fatal_err) (val);
  else
    fprintf (stderr, "dbm fatal: %s.\n", val);
  exit (-1);
}