1/* dbminit.c - Open the file for dbm operations. This looks like the
2   DBM interface. */
3
4/*  This file is part of GDBM, the GNU data base manager, by Philip A. Nelson.
5    Copyright (C) 1990, 1991, 1993  Free Software Foundation, Inc.
6
7    GDBM is free software; you can redistribute it and/or modify
8    it under the terms of the GNU General Public License as published by
9    the Free Software Foundation; either version 2, or (at your option)
10    any later version.
11
12    GDBM is distributed in the hope that it will be useful,
13    but WITHOUT ANY WARRANTY; without even the implied warranty of
14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
15    GNU General Public License for more details.
16
17    You should have received a copy of the GNU General Public License
18    along with GDBM; see the file COPYING.  If not, write to
19    the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
20
21    You may contact the author by:
22       e-mail:  phil@cs.wwu.edu
23      us-mail:  Philip A. Nelson
24                Computer Science Department
25                Western Washington University
26                Bellingham, WA 98226
27
28*************************************************************************/
29
30
31/* include system configuration before all else. */
32#include "autoconf.h"
33
34#include "gdbmdefs.h"
35#include "gdbmerrno.h"
36#include "extern.h"
37
38/* Initialize dbm system.  FILE is a pointer to the file name.  In
39   standard dbm, the database is found in files called FILE.pag and
40   FILE.dir.  To make gdbm compatable with dbm using the dbminit call,
41   the same file names are used.  Specifically, dbminit will use the file
42   name FILE.pag in its call to gdbm open.  If the file (FILE.pag) has a
43   size of zero bytes, a file initialization procedure is performed,
44   setting up the initial structure in the file.  Any error detected will
45   cause a return value of -1.  No errors cause the return value of 0.
46   NOTE: file.dir will be linked to file.pag. */
47
48int
49dbminit (file)
50     char *file;
51{
52  char* pag_file;	    /* Used to construct "file.pag". */
53  char* dir_file;	    /* Used to construct "file.dir". */
54  struct stat dir_stat;	    /* Stat information for "file.dir". */
55  int ret;
56
57
58  ret = 0;		    /* Default return value. */
59
60  /* Prepare the correct names of "file.pag" and "file.dir". */
61  pag_file = (char *) malloc (strlen (file)+5);
62  dir_file = (char *) malloc (strlen (file)+5);
63  if ((pag_file == NULL) || (dir_file == NULL))
64    {
65      gdbm_errno = GDBM_MALLOC_ERROR;	/* For the hell of it. */
66      return -1;
67    }
68
69  strcpy (pag_file, file);
70  strcat (pag_file, ".pag");
71  strcpy (dir_file, file);
72  strcat (dir_file, ".dir");
73
74  if (_gdbm_file != NULL)
75    gdbm_close (_gdbm_file);
76
77  /* Try to open the file as a writer.  DBM never created a file. */
78  _gdbm_file = gdbm_open (pag_file, 0, GDBM_WRITER, 0, NULL);
79
80  /* If it was not opened, try opening it as a reader. */
81  if (_gdbm_file == NULL)
82    {
83      _gdbm_file = gdbm_open (pag_file, 0, GDBM_READER, 0, NULL);
84
85      /* Did we successfully open the file? */
86      if (_gdbm_file == NULL)
87	{
88	  gdbm_errno = GDBM_FILE_OPEN_ERROR;
89	  ret = -1;
90	  goto done;
91	}
92    }
93
94  /* If the database is new, link "file.dir" to "file.pag". This is done
95     so the time stamp on both files is the same. */
96  if (stat (dir_file, &dir_stat) == 0)
97    {
98      if (dir_stat.st_size == 0)
99	if (unlink (dir_file) != 0 || link (pag_file, dir_file) != 0)
100	  {
101	    gdbm_errno = GDBM_FILE_OPEN_ERROR;
102	    gdbm_close (_gdbm_file);
103	    ret = -1;
104	    goto done;
105	  }
106    }
107  else
108    {
109      /* Since we can't stat it, we assume it is not there and try
110         to link the dir_file to the pag_file. */
111      if (link (pag_file, dir_file) != 0)
112	{
113	  gdbm_errno = GDBM_FILE_OPEN_ERROR;
114	  gdbm_close (_gdbm_file);
115	  ret = -1;
116	  goto done;
117	}
118    }
119
120  ret = 0;
121
122done:
123  free (dir_file);
124  free (pag_file);
125  return ret;
126}
127