File: gdbmseq.c

package info (click to toggle)
gdbm173 1.7.3-28
  • links: PTS
  • area: main
  • in suites: etch, etch-m68k, sarge
  • size: 540 kB
  • ctags: 343
  • sloc: ansic: 3,527; makefile: 218; sh: 81; cpp: 25
file content (146 lines) | stat: -rw-r--r-- 4,521 bytes parent folder | download | duplicates (7)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
/* gdbmseq.c - Routines to visit all keys.  Not in sorted order. */

/*  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 system configuration before all else. */
#include "autoconf.h"

#include "gdbmdefs.h"
#include "gdbmerrno.h"

/* Special extern for this file. */
extern char *_gdbm_read_entry _ARGS((gdbm_file_info *, int));


/* Find and read the next entry in the hash structure for DBF starting
   at ELEM_LOC of the current bucket and using RETURN_VAL as the place to
   put the data that is found. */

static void
get_next_key (dbf, elem_loc, return_val)
     gdbm_file_info *dbf;
     int elem_loc;
     datum *return_val;
{
  int   found;			/* Have we found the next key. */
  char  *find_data;		/* Data pointer returned by find_key. */

  /* Find the next key. */
  found = FALSE;
  while (!found)
    {
      /* Advance to the next location in the bucket. */
      elem_loc++;
      if (elem_loc == dbf->header->bucket_elems)
	{
	  /* We have finished the current bucket, get the next bucket.  */
	  elem_loc = 0;

	  /* Find the next bucket.  It is possible several entries in
	     the bucket directory point to the same bucket. */
	  while (dbf->bucket_dir < dbf->header->dir_size / sizeof (off_t)
		 && dbf->cache_entry->ca_adr == dbf->dir[dbf->bucket_dir])
	    dbf->bucket_dir++;

	  /* Check to see if there was a next bucket. */
	  if (dbf->bucket_dir < dbf->header->dir_size / sizeof (off_t))
	    _gdbm_get_bucket (dbf, dbf->bucket_dir);	      
	  else
	    /* No next key, just return. */
	    return ;
	}
      found = dbf->bucket->h_table[elem_loc].hash_value != -1;
    }
  
  /* Found the next key, read it into return_val. */
  find_data = _gdbm_read_entry (dbf, elem_loc);
  return_val->dsize = dbf->bucket->h_table[elem_loc].key_size;
  if (return_val->dsize == 0)
    return_val->dptr = (char *) malloc (1);
  else
    return_val->dptr = (char *) malloc (return_val->dsize);
  if (return_val->dptr == NULL) _gdbm_fatal (dbf, "malloc error");
  bcopy (find_data, return_val->dptr, return_val->dsize);
}


/* Start the visit of all keys in the database.  This produces something in
   hash order, not in any sorted order.  */

datum
gdbm_firstkey (dbf)
     gdbm_file_info *dbf;
{
  datum return_val;		/* To return the first key. */

  /* Set the default return value for not finding a first entry. */
  return_val.dptr = NULL;

  /* Initialize the gdbm_errno variable. */
  gdbm_errno = GDBM_NO_ERROR;

  /* Get the first bucket.  */
  _gdbm_get_bucket (dbf, 0);

  /* Look for first entry. */
  get_next_key (dbf, -1, &return_val);

  return return_val;
}


/* Continue visiting all keys.  The next key following KEY is returned. */

datum
gdbm_nextkey (dbf, key)
     gdbm_file_info *dbf;
     datum key;
{
  datum  return_val;		/* The return value. */
  int    elem_loc;		/* The location in the bucket. */
  char  *find_data;		/* Data pointer returned by _gdbm_findkey. */
  word_t hash_val;		/* Returned by _gdbm_findkey. */

  /* Initialize the gdbm_errno variable. */
  gdbm_errno = GDBM_NO_ERROR;

  /* Set the default return value for no next entry. */
  return_val.dptr = NULL;

  /* Do we have a valid key? */
  if (key.dptr == NULL) return return_val;

  /* Find the key.  */
  elem_loc = _gdbm_findkey (dbf, key, &find_data, &hash_val);
  if (elem_loc == -1) return return_val;

  /* Find the next key. */  
  get_next_key (dbf, elem_loc, &return_val);

  return return_val;
}