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