1/* gdbmseq.c - Routines to visit all keys. Not in sorted order. */ 2 3/* This file is part of GDBM, the GNU data base manager, by Philip A. Nelson. 4 Copyright (C) 1990, 1991, 1993 Free Software Foundation, Inc. 5 6 GDBM is free software; you can redistribute it and/or modify 7 it under the terms of the GNU General Public License as published by 8 the Free Software Foundation; either version 2, or (at your option) 9 any later version. 10 11 GDBM is distributed in the hope that it will be useful, 12 but WITHOUT ANY WARRANTY; without even the implied warranty of 13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 14 GNU General Public License for more details. 15 16 You should have received a copy of the GNU General Public License 17 along with GDBM; see the file COPYING. If not, write to 18 the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. 19 20 You may contact the author by: 21 e-mail: phil@cs.wwu.edu 22 us-mail: Philip A. Nelson 23 Computer Science Department 24 Western Washington University 25 Bellingham, WA 98226 26 27*************************************************************************/ 28 29 30/* include system configuration before all else. */ 31#include "autoconf.h" 32 33#include "gdbmdefs.h" 34#include "gdbmerrno.h" 35 36/* Special extern for this file. */ 37extern char *_gdbm_read_entry __P((gdbm_file_info *, int)); 38 39 40/* Find and read the next entry in the hash structure for DBF starting 41 at ELEM_LOC of the current bucket and using RETURN_VAL as the place to 42 put the data that is found. */ 43 44static void 45get_next_key (dbf, elem_loc, return_val) 46 gdbm_file_info *dbf; 47 int elem_loc; 48 datum *return_val; 49{ 50 int found; /* Have we found the next key. */ 51 char *find_data; /* Data pointer returned by find_key. */ 52 53 /* Find the next key. */ 54 found = FALSE; 55 while (!found) 56 { 57 /* Advance to the next location in the bucket. */ 58 elem_loc++; 59 if (elem_loc == dbf->header->bucket_elems) 60 { 61 /* We have finished the current bucket, get the next bucket. */ 62 elem_loc = 0; 63 64 /* Find the next bucket. It is possible several entries in 65 the bucket directory point to the same bucket. */ 66 while (dbf->bucket_dir < dbf->header->dir_size / sizeof (off_t) 67 && dbf->cache_entry->ca_adr == dbf->dir[dbf->bucket_dir]) 68 dbf->bucket_dir++; 69 70 /* Check to see if there was a next bucket. */ 71 if (dbf->bucket_dir < dbf->header->dir_size / sizeof (off_t)) 72 _gdbm_get_bucket (dbf, dbf->bucket_dir); 73 else 74 /* No next key, just return. */ 75 return ; 76 } 77 found = dbf->bucket->h_table[elem_loc].hash_value != -1; 78 } 79 80 /* Found the next key, read it into return_val. */ 81 find_data = _gdbm_read_entry (dbf, elem_loc); 82 return_val->dsize = dbf->bucket->h_table[elem_loc].key_size; 83 if (return_val->dsize == 0) 84 return_val->dptr = (char *) malloc (1); 85 else 86 return_val->dptr = (char *) malloc (return_val->dsize); 87 if (return_val->dptr == NULL) _gdbm_fatal (dbf, "malloc error"); 88 bcopy (find_data, return_val->dptr, return_val->dsize); 89} 90 91 92/* Start the visit of all keys in the database. This produces something in 93 hash order, not in any sorted order. */ 94 95datum 96gdbm_firstkey (dbf) 97 gdbm_file_info *dbf; 98{ 99 datum return_val; /* To return the first key. */ 100 101 /* Set the default return value for not finding a first entry. */ 102 return_val.dptr = NULL; 103 104 /* Initialize the gdbm_errno variable. */ 105 gdbm_errno = GDBM_NO_ERROR; 106 107 /* Get the first bucket. */ 108 _gdbm_get_bucket (dbf, 0); 109 110 /* Look for first entry. */ 111 get_next_key (dbf, -1, &return_val); 112 113 return return_val; 114} 115 116 117/* Continue visiting all keys. The next key following KEY is returned. */ 118 119datum 120gdbm_nextkey (dbf, key) 121 gdbm_file_info *dbf; 122 datum key; 123{ 124 datum return_val; /* The return value. */ 125 int elem_loc; /* The location in the bucket. */ 126 char *find_data; /* Data pointer returned by _gdbm_findkey. */ 127 int hash_val; /* Returned by _gdbm_findkey. */ 128 129 /* Initialize the gdbm_errno variable. */ 130 gdbm_errno = GDBM_NO_ERROR; 131 132 /* Set the default return value for no next entry. */ 133 return_val.dptr = NULL; 134 135 /* Do we have a valid key? */ 136 if (key.dptr == NULL) return return_val; 137 138 /* Find the key. */ 139 elem_loc = _gdbm_findkey (dbf, key, &find_data, &hash_val); 140 if (elem_loc == -1) return return_val; 141 142 /* Find the next key. */ 143 get_next_key (dbf, elem_loc, &return_val); 144 145 return return_val; 146} 147