1 | /* $NetBSD: hcreate.c,v 1.2 2001/02/19 21:26:04 ross Exp $ */ |
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2 | |
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3 | /* |
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4 | * Copyright (c) 2001 Christopher G. Demetriou |
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5 | * All rights reserved. |
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6 | * |
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7 | * Redistribution and use in source and binary forms, with or without |
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8 | * modification, are permitted provided that the following conditions |
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9 | * are met: |
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10 | * 1. Redistributions of source code must retain the above copyright |
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11 | * notice, this list of conditions and the following disclaimer. |
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12 | * 2. Redistributions in binary form must reproduce the above copyright |
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13 | * notice, this list of conditions and the following disclaimer in the |
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14 | * documentation and/or other materials provided with the distribution. |
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15 | * 3. The name of the author may not be used to endorse or promote products |
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16 | * derived from this software without specific prior written permission. |
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17 | * |
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18 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR |
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19 | * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES |
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20 | * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. |
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21 | * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, |
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22 | * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT |
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23 | * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
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24 | * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
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25 | * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
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26 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF |
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27 | * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
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28 | * |
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29 | * <<Id: LICENSE_GC,v 1.1 2001/10/01 23:24:05 cgd Exp>> |
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30 | */ |
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31 | |
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32 | /* |
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33 | * hcreate() / hsearch() / hdestroy() |
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34 | * |
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35 | * SysV/XPG4 hash table functions. |
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36 | * |
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37 | * Implementation done based on NetBSD manual page and Solaris manual page, |
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38 | * plus my own personal experience about how they're supposed to work. |
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39 | * |
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40 | * I tried to look at Knuth (as cited by the Solaris manual page), but |
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41 | * nobody had a copy in the office, so... |
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42 | */ |
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43 | |
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44 | #include <sys/cdefs.h> |
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45 | #if 0 |
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46 | #if defined(LIBC_SCCS) && !defined(lint) |
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47 | __RCSID("$NetBSD: hcreate.c,v 1.2 2001/02/19 21:26:04 ross Exp $"); |
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48 | #endif /* LIBC_SCCS and not lint */ |
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49 | #endif |
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50 | |
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51 | #include <sys/types.h> |
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52 | #include <sys/queue.h> |
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53 | #include <errno.h> |
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54 | #include <search.h> |
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55 | #include <stdlib.h> |
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56 | #include <string.h> |
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57 | |
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58 | /* |
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59 | * DO NOT MAKE THIS STRUCTURE LARGER THAN 32 BYTES (4 ptrs on 64-bit |
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60 | * ptr machine) without adjusting MAX_BUCKETS_LG2 below. |
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61 | */ |
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62 | struct internal_entry { |
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63 | SLIST_ENTRY(internal_entry) link; |
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64 | ENTRY ent; |
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65 | }; |
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66 | SLIST_HEAD(internal_head, internal_entry); |
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67 | |
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68 | #define MIN_BUCKETS_LG2 4 |
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69 | #define MIN_BUCKETS (1 << MIN_BUCKETS_LG2) |
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70 | |
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71 | /* |
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72 | * max * sizeof internal_entry must fit into size_t. |
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73 | * assumes internal_entry is <= 32 (2^5) bytes. |
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74 | */ |
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75 | #define MAX_BUCKETS_LG2 (sizeof (size_t) * 8 - 1 - 5) |
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76 | #define MAX_BUCKETS ((size_t)1 << MAX_BUCKETS_LG2) |
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77 | |
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78 | /* Default hash function, from db/hash/hash_func.c */ |
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79 | extern __uint32_t (*__default_hash)(const void *, size_t); |
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80 | |
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81 | int |
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82 | hcreate_r(size_t nel, struct hsearch_data *htab) |
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83 | { |
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84 | size_t idx; |
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85 | unsigned int p2; |
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86 | |
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87 | /* Make sure this this isn't called when a table already exists. */ |
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88 | if (htab->htable != NULL) { |
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89 | errno = EINVAL; |
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90 | return 0; |
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91 | } |
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92 | |
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93 | /* If nel is too small, make it min sized. */ |
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94 | if (nel < MIN_BUCKETS) |
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95 | nel = MIN_BUCKETS; |
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96 | |
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97 | /* If it's too large, cap it. */ |
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98 | if (nel > MAX_BUCKETS) |
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99 | nel = MAX_BUCKETS; |
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100 | |
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101 | /* If it's is not a power of two in size, round up. */ |
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102 | if ((nel & (nel - 1)) != 0) { |
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103 | for (p2 = 0; nel != 0; p2++) |
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104 | nel >>= 1; |
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105 | nel = 1 << p2; |
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106 | } |
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107 | |
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108 | /* Allocate the table. */ |
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109 | htab->htablesize = nel; |
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110 | htab->htable = malloc(htab->htablesize * sizeof htab->htable[0]); |
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111 | if (htab->htable == NULL) { |
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112 | errno = ENOMEM; |
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113 | return 0; |
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114 | } |
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115 | |
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116 | /* Initialize it. */ |
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117 | for (idx = 0; idx < htab->htablesize; idx++) |
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118 | SLIST_INIT(&(htab->htable[idx])); |
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119 | |
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120 | return 1; |
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121 | } |
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122 | |
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123 | void |
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124 | hdestroy_r(struct hsearch_data *htab) |
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125 | { |
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126 | #if 0 |
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127 | struct internal_entry *ie; |
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128 | size_t idx; |
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129 | #endif |
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130 | if (htab->htable == NULL) |
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131 | return; |
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132 | |
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133 | #if 0 |
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134 | for (idx = 0; idx < htab->htablesize; idx++) { |
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135 | while (!SLIST_EMPTY(&(htab->htable[idx]))) { |
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136 | ie = SLIST_FIRST(&(htab->htable[idx])); |
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137 | SLIST_REMOVE_HEAD(&(htab->htable[idx]), link); |
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138 | free(ie->ent.key); |
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139 | free(ie); |
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140 | } |
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141 | } |
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142 | #endif |
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143 | free(htab->htable); |
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144 | htab->htable = NULL; |
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145 | } |
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146 | |
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147 | int |
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148 | hsearch_r(ENTRY item, ACTION action, ENTRY **retval, struct hsearch_data *htab) |
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149 | { |
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150 | struct internal_head *head; |
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151 | struct internal_entry *ie; |
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152 | __uint32_t hashval; |
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153 | size_t len; |
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154 | |
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155 | len = strlen(item.key); |
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156 | hashval = (*__default_hash)(item.key, len); |
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157 | |
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158 | head = &(htab->htable[hashval & (htab->htablesize - 1)]); |
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159 | ie = SLIST_FIRST(head); |
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160 | while (ie != NULL) { |
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161 | if (strcmp(ie->ent.key, item.key) == 0) |
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162 | break; |
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163 | ie = SLIST_NEXT(ie, link); |
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164 | } |
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165 | |
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166 | if (ie != NULL) |
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167 | { |
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168 | *retval = &ie->ent; |
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169 | return 1; |
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170 | } |
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171 | else if (action == FIND) |
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172 | { |
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173 | *retval = NULL; |
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174 | return 0; |
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175 | } |
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176 | |
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177 | ie = malloc(sizeof *ie); |
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178 | if (ie == NULL) |
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179 | { |
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180 | *retval = NULL; |
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181 | return 0; |
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182 | } |
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183 | ie->ent.key = item.key; |
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184 | ie->ent.data = item.data; |
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185 | |
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186 | SLIST_INSERT_HEAD(head, ie, link); |
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187 | *retval = &ie->ent; |
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188 | return 1; |
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189 | } |
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