/* dbminit.c - The DBM 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 dbm 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 linked to file.pag. */
int dbminit (char *file)
{
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". */
int ret;
ret = 0; /* Default return value. */
/* 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 -1;
}
strcpy (pag_file, file);
strcat (pag_file, ".pag");
strcpy (dir_file, file);
strcat (dir_file, ".dir");
if (_gdbm_file != NULL)
gdbm_close (_gdbm_file);
/* Try to open the file as a writer. DBM never created a file. */
_gdbm_file = gdbm_open (pag_file, 0, GDBM_WRITER, 0, NULL);
/* If it was not opened, try opening it as a reader. */
if (_gdbm_file == NULL) {
_gdbm_file = gdbm_open (pag_file, 0, GDBM_READER, 0, NULL);
/* Did we successfully open the file? */
if (_gdbm_file == NULL) {
gdbm_errno = GDBM_FILE_OPEN_ERROR;
ret = -1;
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 (_gdbm_file);
ret = -1;
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_TRUNC, S_IREAD | S_IWRITE) < 0) {
gdbm_errno = GDBM_FILE_OPEN_ERROR;
gdbm_close (_gdbm_file);
ret = -1;
goto done;
}
}
ret = 0;
done:
free (dir_file);
free (pag_file);
return ret;
}
/* 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. This DBM interface uses the NDBM interface. */
datum fetch (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 (_gdbm_file, key);
if (_gdbm_fetch_val != NULL)
free (_gdbm_fetch_val);
_gdbm_fetch_val = ret_val.dptr;
/* Return the new value. */
return ret_val;
}
/* 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 store (datum key, datum content)
{
return gdbm_store (_gdbm_file, key, content, GDBM_REPLACE);
}
/* Remove the KEYed item and the KEY from the database. */
int delete (datum key)
{
return gdbm_delete (_gdbm_file, key);
}
/* Start the visit of all keys in the database. This produces something in
hash order, not in any sorted order. */
datum firstkey (void)
{
datum ret_val;
/* Free previous dynamic memory, do actual call, and save pointer to new
memory. */
ret_val = gdbm_firstkey (_gdbm_file);
if (_gdbm_memory.dptr != NULL)
free (_gdbm_memory.dptr);
_gdbm_memory = ret_val;
/* Return the new value. */
return ret_val;
}
/* Continue visiting all keys. The next key following KEY is returned. */
datum nextkey (datum key)
{
datum ret_val;
/* Make sure we have a valid key. */
if (key.dptr == NULL)
return key;
/* Call gdbm nextkey with supplied value. After that, free the old value. */
ret_val = gdbm_nextkey (_gdbm_file, key);
if (_gdbm_memory.dptr != NULL)
free (_gdbm_memory.dptr);
_gdbm_memory = ret_val;
/* Return the new value. */
return ret_val;
}
/* it's unclear whether dbmclose() is *always* a void function in old
C libraries. we use int, here. */
int dbmclose ()
{
if (_gdbm_file != NULL) {
gdbm_close (_gdbm_file);
_gdbm_file = NULL;
if (_gdbm_memory.dptr != NULL)
free (_gdbm_memory.dptr);
_gdbm_memory.dptr = NULL;
_gdbm_memory.dsize = 0;
}
return (0);
}