1/* gdbmstore.c - Add a new key/data pair to the database. */
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
37/* Add a new element to the database.  CONTENT is keyed by KEY.  The
38   file on disk is updated to reflect the structure of the new database
39   before returning from this procedure.  The FLAGS define the action to
40   take when the KEY is already in the database.  The value GDBM_REPLACE
41   asks that the old data be replaced by the new CONTENT.  The value
42   GDBM_INSERT asks that an error be returned and no action taken.  A
43   return value of 0 means no errors.  A return value of -1 means that
44   the item was not stored in the data base because the caller was not an
45   official writer. A return value of 0 means that the item was not stored
46   because the argument FLAGS was GDBM_INSERT and the KEY was already in
47   the database. */
48
49int
50gdbm_store (dbf, key, content, flags)
51     gdbm_file_info *dbf;
52     datum key;
53     datum content;
54     int flags;
55{
56  int  new_hash_val;		/* The new hash value. */
57  int  elem_loc;		/* The location in hash bucket. */
58  off_t file_adr;		/* The address of new space in the file.  */
59  off_t file_pos;		/* The position after a lseek. */
60  int  num_bytes;		/* Used for error detection. */
61  off_t free_adr;		/* For keeping track of a freed section. */
62  int  free_size;
63  int   new_size;		/* Used in allocating space. */
64  char *temp;			/* Used in _gdbm_findkey call. */
65
66
67  /* First check to make sure this guy is a writer. */
68  if (dbf->read_write == GDBM_READER)
69    {
70      gdbm_errno = GDBM_READER_CANT_STORE;
71      return -1;
72    }
73
74  /* Check for illegal data values.  A NULL dptr field is illegal because
75     NULL dptr returned by a lookup procedure indicates an error. */
76  if ((key.dptr == NULL) || (content.dptr == NULL))
77    {
78      gdbm_errno = GDBM_ILLEGAL_DATA;
79      return -1;
80    }
81
82  /* Initialize the gdbm_errno variable. */
83  gdbm_errno = GDBM_NO_ERROR;
84
85  /* Look for the key in the file.
86     A side effect loads the correct bucket and calculates the hash value. */
87  elem_loc = _gdbm_findkey (dbf, key, &temp, &new_hash_val);
88
89  /* Initialize these. */
90  file_adr = 0;
91  new_size = key.dsize + content.dsize;
92
93  /* Did we find the item? */
94  if (elem_loc != -1)
95    {
96      if (flags == GDBM_REPLACE)
97	{
98	  /* Just replace the data. */
99	  free_adr = dbf->bucket->h_table[elem_loc].data_pointer;
100	  free_size = dbf->bucket->h_table[elem_loc].key_size
101	              + dbf->bucket->h_table[elem_loc].data_size;
102	  if (free_size != new_size)
103	    {
104	      _gdbm_free (dbf, free_adr, free_size);
105	    }
106	  else
107	    {
108	      /* Just reuse the same address! */
109	      file_adr = free_adr;
110	    }
111	}
112      else
113	{
114	  gdbm_errno = GDBM_CANNOT_REPLACE;
115	  return 1;
116	}
117    }
118
119
120  /* Get the file address for the new space.
121     (Current bucket's free space is first place to look.) */
122  if (file_adr == 0)
123    {
124      file_adr = _gdbm_alloc (dbf, new_size);
125    }
126
127  /* If this is a new entry in the bucket, we need to do special things. */
128  if (elem_loc == -1)
129    {
130      if (dbf->bucket->count == dbf->header->bucket_elems)
131	{
132	  /* Split the current bucket. */
133	  _gdbm_split_bucket (dbf, new_hash_val);
134	}
135
136      /* Find space to insert into bucket and set elem_loc to that place. */
137      elem_loc = new_hash_val % dbf->header->bucket_elems;
138      while (dbf->bucket->h_table[elem_loc].hash_value != -1)
139	{  elem_loc = (elem_loc + 1) % dbf->header->bucket_elems; }
140
141      /* We now have another element in the bucket.  Add the new information.*/
142      dbf->bucket->count += 1;
143      dbf->bucket->h_table[elem_loc].hash_value = new_hash_val;
144      bcopy (key.dptr, dbf->bucket->h_table[elem_loc].key_start,
145	     (SMALL < key.dsize ? SMALL : key.dsize));
146    }
147
148
149  /* Update current bucket data pointer and sizes. */
150  dbf->bucket->h_table[elem_loc].data_pointer = file_adr;
151  dbf->bucket->h_table[elem_loc].key_size = key.dsize;
152  dbf->bucket->h_table[elem_loc].data_size = content.dsize;
153
154  /* Write the data to the file. */
155  file_pos = lseek (dbf->desc, file_adr, L_SET);
156  if (file_pos != file_adr) _gdbm_fatal (dbf, "lseek error");
157  num_bytes = write (dbf->desc, key.dptr, key.dsize);
158  if (num_bytes != key.dsize) _gdbm_fatal (dbf, "write error");
159  num_bytes = write (dbf->desc, content.dptr, content.dsize);
160  if (num_bytes != content.dsize) _gdbm_fatal (dbf, "write error");
161
162  /* Current bucket has changed. */
163  dbf->cache_entry->ca_changed = TRUE;
164  dbf->bucket_changed = TRUE;
165
166  /* Write everything that is needed to the disk. */
167  _gdbm_end_update (dbf);
168  return 0;
169
170}
171