1 | /* gdbmstore.c - Add a new key/data pair to the database. */
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2 |
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3 | /* This file is part of GDBM, the GNU data base manager, by Philip A. Nelson.
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4 | Copyright (C) 1990, 1991, 1993 Free Software Foundation, Inc.
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5 |
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6 | GDBM is free software; you can redistribute it and/or modify
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7 | it under the terms of the GNU General Public License as published by
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8 | the Free Software Foundation; either version 2, or (at your option)
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9 | any later version.
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10 |
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11 | GDBM is distributed in the hope that it will be useful,
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12 | but WITHOUT ANY WARRANTY; without even the implied warranty of
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13 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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14 | GNU General Public License for more details.
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15 |
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16 | You should have received a copy of the GNU General Public License
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17 | along with GDBM; see the file COPYING. If not, write to
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18 | the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
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19 |
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20 | You may contact the author by:
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21 | e-mail: [email protected]
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22 | us-mail: Philip A. Nelson
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23 | Computer Science Department
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24 | Western Washington University
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25 | Bellingham, WA 98226
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26 |
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27 | *************************************************************************/
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28 |
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29 |
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30 | /* include system configuration before all else. */
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31 | #include "autoconf.h"
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32 |
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33 | #include "gdbmdefs.h"
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34 | #include "gdbmerrno.h"
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35 |
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36 |
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37 | /* Add a new element to the database. CONTENT is keyed by KEY. The
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38 | file on disk is updated to reflect the structure of the new database
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39 | before returning from this procedure. The FLAGS define the action to
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40 | take when the KEY is already in the database. The value GDBM_REPLACE
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41 | asks that the old data be replaced by the new CONTENT. The value
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42 | GDBM_INSERT asks that an error be returned and no action taken. A
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43 | return value of 0 means no errors. A return value of -1 means that
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44 | the item was not stored in the data base because the caller was not an
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45 | official writer. A return value of 0 means that the item was not stored
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46 | because the argument FLAGS was GDBM_INSERT and the KEY was already in
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47 | the database. */
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48 |
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49 | int
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50 | gdbm_store (dbf, key, content, flags)
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51 | gdbm_file_info *dbf;
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52 | datum key;
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53 | datum content;
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54 | int flags;
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55 | {
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56 | int new_hash_val; /* The new hash value. */
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57 | int elem_loc; /* The location in hash bucket. */
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58 | off_t file_adr; /* The address of new space in the file. */
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59 | off_t file_pos; /* The position after a lseek. */
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60 | int num_bytes; /* Used for error detection. */
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61 | off_t free_adr; /* For keeping track of a freed section. */
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62 | int free_size;
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63 | int new_size; /* Used in allocating space. */
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64 | char *temp; /* Used in _gdbm_findkey call. */
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65 |
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66 |
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67 | /* First check to make sure this guy is a writer. */
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68 | if (dbf->read_write == GDBM_READER)
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69 | {
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70 | gdbm_errno = GDBM_READER_CANT_STORE;
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71 | return -1;
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72 | }
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73 |
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74 | /* Check for illegal data values. A NULL dptr field is illegal because
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75 | NULL dptr returned by a lookup procedure indicates an error. */
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76 | if ((key.dptr == NULL) || (content.dptr == NULL))
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77 | {
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78 | gdbm_errno = GDBM_ILLEGAL_DATA;
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79 | return -1;
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80 | }
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81 |
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82 | /* Initialize the gdbm_errno variable. */
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83 | gdbm_errno = GDBM_NO_ERROR;
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84 |
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85 | /* Look for the key in the file.
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86 | A side effect loads the correct bucket and calculates the hash value. */
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87 | elem_loc = _gdbm_findkey (dbf, key, &temp, &new_hash_val);
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88 |
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89 | /* Initialize these. */
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90 | file_adr = 0;
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91 | new_size = key.dsize + content.dsize;
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92 |
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93 | /* Did we find the item? */
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94 | if (elem_loc != -1)
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95 | {
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96 | if (flags == GDBM_REPLACE)
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97 | {
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98 | /* Just replace the data. */
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99 | free_adr = dbf->bucket->h_table[elem_loc].data_pointer;
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100 | free_size = dbf->bucket->h_table[elem_loc].key_size
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101 | + dbf->bucket->h_table[elem_loc].data_size;
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102 | if (free_size != new_size)
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103 | {
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104 | _gdbm_free (dbf, free_adr, free_size);
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105 | }
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106 | else
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107 | {
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108 | /* Just reuse the same address! */
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109 | file_adr = free_adr;
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110 | }
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111 | }
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112 | else
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113 | {
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114 | gdbm_errno = GDBM_CANNOT_REPLACE;
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115 | return 1;
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116 | }
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117 | }
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118 |
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119 |
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120 | /* Get the file address for the new space.
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121 | (Current bucket's free space is first place to look.) */
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122 | if (file_adr == 0)
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123 | {
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124 | file_adr = _gdbm_alloc (dbf, new_size);
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125 | }
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126 |
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127 | /* If this is a new entry in the bucket, we need to do special things. */
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128 | if (elem_loc == -1)
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129 | {
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130 | if (dbf->bucket->count == dbf->header->bucket_elems)
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131 | {
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132 | /* Split the current bucket. */
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133 | _gdbm_split_bucket (dbf, new_hash_val);
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134 | }
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135 |
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136 | /* Find space to insert into bucket and set elem_loc to that place. */
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137 | elem_loc = new_hash_val % dbf->header->bucket_elems;
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138 | while (dbf->bucket->h_table[elem_loc].hash_value != -1)
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139 | { elem_loc = (elem_loc + 1) % dbf->header->bucket_elems; }
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140 |
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141 | /* We now have another element in the bucket. Add the new information.*/
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142 | dbf->bucket->count += 1;
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143 | dbf->bucket->h_table[elem_loc].hash_value = new_hash_val;
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144 | bcopy (key.dptr, dbf->bucket->h_table[elem_loc].key_start,
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145 | (SMALL < key.dsize ? SMALL : key.dsize));
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146 | }
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147 |
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148 |
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149 | /* Update current bucket data pointer and sizes. */
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150 | dbf->bucket->h_table[elem_loc].data_pointer = file_adr;
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151 | dbf->bucket->h_table[elem_loc].key_size = key.dsize;
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152 | dbf->bucket->h_table[elem_loc].data_size = content.dsize;
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153 |
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154 | /* Write the data to the file. */
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155 | file_pos = lseek (dbf->desc, file_adr, L_SET);
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156 | if (file_pos != file_adr) _gdbm_fatal (dbf, "lseek error");
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157 | num_bytes = write (dbf->desc, key.dptr, key.dsize);
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158 | if (num_bytes != key.dsize) _gdbm_fatal (dbf, "write error");
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159 | num_bytes = write (dbf->desc, content.dptr, content.dsize);
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160 | if (num_bytes != content.dsize) _gdbm_fatal (dbf, "write error");
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161 |
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162 | /* Current bucket has changed. */
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163 | dbf->cache_entry->ca_changed = TRUE;
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164 | dbf->bucket_changed = TRUE;
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165 |
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166 | /* Write everything that is needed to the disk. */
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167 | _gdbm_end_update (dbf);
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168 | return 0;
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169 |
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170 | }
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