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5197 | serge | 1 | /* ELF strtab with GC and suffix merging support. |
6324 | serge | 2 | Copyright (C) 2001-2015 Free Software Foundation, Inc. |
5197 | serge | 3 | Written by Jakub Jelinek |
4 | |||
5 | This file is part of BFD, the Binary File Descriptor library. |
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6 | |||
7 | This program is free software; you can redistribute it and/or modify |
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8 | it under the terms of the GNU General Public License as published by |
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9 | the Free Software Foundation; either version 3 of the License, or |
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10 | (at your option) any later version. |
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11 | |||
12 | This program is distributed in the hope that it will be useful, |
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13 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
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14 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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15 | GNU General Public License for more details. |
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16 | |||
17 | You should have received a copy of the GNU General Public License |
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18 | along with this program; if not, write to the Free Software |
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19 | Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston, |
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20 | MA 02110-1301, USA. */ |
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21 | |||
22 | #include "sysdep.h" |
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23 | #include "bfd.h" |
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24 | #include "libbfd.h" |
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25 | #include "elf-bfd.h" |
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26 | #include "hashtab.h" |
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27 | #include "libiberty.h" |
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28 | |||
29 | /* An entry in the strtab hash table. */ |
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30 | |||
31 | struct elf_strtab_hash_entry |
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32 | { |
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33 | struct bfd_hash_entry root; |
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34 | /* Length of this entry. This includes the zero terminator. */ |
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35 | int len; |
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36 | unsigned int refcount; |
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37 | union { |
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38 | /* Index within the merged section. */ |
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39 | bfd_size_type index; |
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40 | /* Entry this is a suffix of (if len < 0). */ |
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41 | struct elf_strtab_hash_entry *suffix; |
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42 | } u; |
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43 | }; |
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44 | |||
45 | /* The strtab hash table. */ |
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46 | |||
47 | struct elf_strtab_hash |
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48 | { |
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49 | struct bfd_hash_table table; |
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50 | /* Next available index. */ |
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51 | bfd_size_type size; |
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52 | /* Number of array entries alloced. */ |
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53 | bfd_size_type alloced; |
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54 | /* Final strtab size. */ |
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55 | bfd_size_type sec_size; |
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56 | /* Array of pointers to strtab entries. */ |
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57 | struct elf_strtab_hash_entry **array; |
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58 | }; |
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59 | |||
60 | /* Routine to create an entry in a section merge hashtab. */ |
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61 | |||
62 | static struct bfd_hash_entry * |
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63 | elf_strtab_hash_newfunc (struct bfd_hash_entry *entry, |
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64 | struct bfd_hash_table *table, |
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65 | const char *string) |
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66 | { |
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67 | /* Allocate the structure if it has not already been allocated by a |
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68 | subclass. */ |
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69 | if (entry == NULL) |
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70 | entry = (struct bfd_hash_entry *) |
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71 | bfd_hash_allocate (table, sizeof (struct elf_strtab_hash_entry)); |
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72 | if (entry == NULL) |
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73 | return NULL; |
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74 | |||
75 | /* Call the allocation method of the superclass. */ |
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76 | entry = bfd_hash_newfunc (entry, table, string); |
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77 | |||
78 | if (entry) |
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79 | { |
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80 | /* Initialize the local fields. */ |
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81 | struct elf_strtab_hash_entry *ret; |
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82 | |||
83 | ret = (struct elf_strtab_hash_entry *) entry; |
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84 | ret->u.index = -1; |
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85 | ret->refcount = 0; |
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86 | ret->len = 0; |
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87 | } |
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88 | |||
89 | return entry; |
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90 | } |
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91 | |||
92 | /* Create a new hash table. */ |
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93 | |||
94 | struct elf_strtab_hash * |
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95 | _bfd_elf_strtab_init (void) |
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96 | { |
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97 | struct elf_strtab_hash *table; |
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98 | bfd_size_type amt = sizeof (struct elf_strtab_hash); |
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99 | |||
100 | table = (struct elf_strtab_hash *) bfd_malloc (amt); |
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101 | if (table == NULL) |
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102 | return NULL; |
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103 | |||
104 | if (!bfd_hash_table_init (&table->table, elf_strtab_hash_newfunc, |
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105 | sizeof (struct elf_strtab_hash_entry))) |
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106 | { |
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107 | free (table); |
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108 | return NULL; |
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109 | } |
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110 | |||
111 | table->sec_size = 0; |
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112 | table->size = 1; |
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113 | table->alloced = 64; |
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114 | amt = sizeof (struct elf_strtab_hasn_entry *); |
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115 | table->array = (struct elf_strtab_hash_entry **) |
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116 | bfd_malloc (table->alloced * amt); |
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117 | if (table->array == NULL) |
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118 | { |
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119 | free (table); |
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120 | return NULL; |
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121 | } |
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122 | |||
123 | table->array[0] = NULL; |
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124 | |||
125 | return table; |
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126 | } |
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127 | |||
128 | /* Free a strtab. */ |
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129 | |||
130 | void |
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131 | _bfd_elf_strtab_free (struct elf_strtab_hash *tab) |
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132 | { |
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133 | bfd_hash_table_free (&tab->table); |
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134 | free (tab->array); |
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135 | free (tab); |
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136 | } |
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137 | |||
138 | /* Get the index of an entity in a hash table, adding it if it is not |
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139 | already present. */ |
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140 | |||
141 | bfd_size_type |
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142 | _bfd_elf_strtab_add (struct elf_strtab_hash *tab, |
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143 | const char *str, |
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144 | bfd_boolean copy) |
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145 | { |
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146 | register struct elf_strtab_hash_entry *entry; |
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147 | |||
148 | /* We handle this specially, since we don't want to do refcounting |
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149 | on it. */ |
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150 | if (*str == '\0') |
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151 | return 0; |
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152 | |||
153 | BFD_ASSERT (tab->sec_size == 0); |
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154 | entry = (struct elf_strtab_hash_entry *) |
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155 | bfd_hash_lookup (&tab->table, str, TRUE, copy); |
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156 | |||
157 | if (entry == NULL) |
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158 | return (bfd_size_type) -1; |
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159 | |||
160 | entry->refcount++; |
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161 | if (entry->len == 0) |
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162 | { |
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163 | entry->len = strlen (str) + 1; |
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164 | /* 2G strings lose. */ |
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165 | BFD_ASSERT (entry->len > 0); |
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166 | if (tab->size == tab->alloced) |
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167 | { |
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168 | bfd_size_type amt = sizeof (struct elf_strtab_hash_entry *); |
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169 | tab->alloced *= 2; |
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170 | tab->array = (struct elf_strtab_hash_entry **) |
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171 | bfd_realloc_or_free (tab->array, tab->alloced * amt); |
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172 | if (tab->array == NULL) |
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173 | return (bfd_size_type) -1; |
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174 | } |
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175 | |||
176 | entry->u.index = tab->size++; |
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177 | tab->array[entry->u.index] = entry; |
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178 | } |
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179 | return entry->u.index; |
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180 | } |
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181 | |||
182 | void |
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183 | _bfd_elf_strtab_addref (struct elf_strtab_hash *tab, bfd_size_type idx) |
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184 | { |
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185 | if (idx == 0 || idx == (bfd_size_type) -1) |
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186 | return; |
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187 | BFD_ASSERT (tab->sec_size == 0); |
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188 | BFD_ASSERT (idx < tab->size); |
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189 | ++tab->array[idx]->refcount; |
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190 | } |
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191 | |||
192 | void |
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193 | _bfd_elf_strtab_delref (struct elf_strtab_hash *tab, bfd_size_type idx) |
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194 | { |
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195 | if (idx == 0 || idx == (bfd_size_type) -1) |
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196 | return; |
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197 | BFD_ASSERT (tab->sec_size == 0); |
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198 | BFD_ASSERT (idx < tab->size); |
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199 | BFD_ASSERT (tab->array[idx]->refcount > 0); |
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200 | --tab->array[idx]->refcount; |
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201 | } |
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202 | |||
203 | unsigned int |
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204 | _bfd_elf_strtab_refcount (struct elf_strtab_hash *tab, bfd_size_type idx) |
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205 | { |
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206 | return tab->array[idx]->refcount; |
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207 | } |
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208 | |||
209 | void |
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210 | _bfd_elf_strtab_clear_all_refs (struct elf_strtab_hash *tab) |
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211 | { |
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212 | bfd_size_type idx; |
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213 | |||
214 | for (idx = 1; idx < tab->size; idx++) |
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215 | tab->array[idx]->refcount = 0; |
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216 | } |
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217 | |||
218 | /* Downsizes strtab. Entries from IDX up to the current size are |
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219 | removed from the array. */ |
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220 | void |
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221 | _bfd_elf_strtab_restore_size (struct elf_strtab_hash *tab, bfd_size_type idx) |
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222 | { |
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223 | bfd_size_type curr_size = tab->size; |
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224 | |||
225 | BFD_ASSERT (tab->sec_size == 0); |
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226 | BFD_ASSERT (idx <= curr_size); |
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227 | tab->size = idx; |
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228 | for (; idx < curr_size; ++idx) |
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229 | { |
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230 | /* We don't remove entries from the hash table, just set their |
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231 | REFCOUNT to zero. Setting LEN zero will result in the size |
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232 | growing if the entry is added again. See _bfd_elf_strtab_add. */ |
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233 | tab->array[idx]->refcount = 0; |
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234 | tab->array[idx]->len = 0; |
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235 | } |
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236 | } |
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237 | |||
238 | bfd_size_type |
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239 | _bfd_elf_strtab_size (struct elf_strtab_hash *tab) |
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240 | { |
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241 | return tab->sec_size ? tab->sec_size : tab->size; |
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242 | } |
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243 | |||
244 | bfd_size_type |
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245 | _bfd_elf_strtab_offset (struct elf_strtab_hash *tab, bfd_size_type idx) |
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246 | { |
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247 | struct elf_strtab_hash_entry *entry; |
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248 | |||
249 | if (idx == 0) |
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250 | return 0; |
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251 | BFD_ASSERT (idx < tab->size); |
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252 | BFD_ASSERT (tab->sec_size); |
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253 | entry = tab->array[idx]; |
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254 | BFD_ASSERT (entry->refcount > 0); |
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255 | entry->refcount--; |
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256 | return tab->array[idx]->u.index; |
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257 | } |
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258 | |||
259 | bfd_boolean |
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260 | _bfd_elf_strtab_emit (register bfd *abfd, struct elf_strtab_hash *tab) |
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261 | { |
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262 | bfd_size_type off = 1, i; |
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263 | |||
264 | if (bfd_bwrite ("", 1, abfd) != 1) |
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265 | return FALSE; |
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266 | |||
267 | for (i = 1; i < tab->size; ++i) |
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268 | { |
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269 | register const char *str; |
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270 | register unsigned int len; |
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271 | |||
272 | BFD_ASSERT (tab->array[i]->refcount == 0); |
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273 | len = tab->array[i]->len; |
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274 | if ((int) len < 0) |
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275 | continue; |
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276 | |||
277 | str = tab->array[i]->root.string; |
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278 | if (bfd_bwrite (str, len, abfd) != len) |
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279 | return FALSE; |
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280 | |||
281 | off += len; |
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282 | } |
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283 | |||
284 | BFD_ASSERT (off == tab->sec_size); |
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285 | return TRUE; |
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286 | } |
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287 | |||
288 | /* Compare two elf_strtab_hash_entry structures. Called via qsort. */ |
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289 | |||
290 | static int |
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291 | strrevcmp (const void *a, const void *b) |
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292 | { |
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293 | struct elf_strtab_hash_entry *A = *(struct elf_strtab_hash_entry **) a; |
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294 | struct elf_strtab_hash_entry *B = *(struct elf_strtab_hash_entry **) b; |
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295 | unsigned int lenA = A->len; |
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296 | unsigned int lenB = B->len; |
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297 | const unsigned char *s = (const unsigned char *) A->root.string + lenA - 1; |
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298 | const unsigned char *t = (const unsigned char *) B->root.string + lenB - 1; |
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299 | int l = lenA < lenB ? lenA : lenB; |
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300 | |||
301 | while (l) |
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302 | { |
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303 | if (*s != *t) |
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304 | return (int) *s - (int) *t; |
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305 | s--; |
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306 | t--; |
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307 | l--; |
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308 | } |
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309 | return lenA - lenB; |
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310 | } |
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311 | |||
312 | static inline int |
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313 | is_suffix (const struct elf_strtab_hash_entry *A, |
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314 | const struct elf_strtab_hash_entry *B) |
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315 | { |
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316 | if (A->len <= B->len) |
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317 | /* B cannot be a suffix of A unless A is equal to B, which is guaranteed |
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318 | not to be equal by the hash table. */ |
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319 | return 0; |
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320 | |||
321 | return memcmp (A->root.string + (A->len - B->len), |
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322 | B->root.string, B->len - 1) == 0; |
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323 | } |
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324 | |||
325 | /* This function assigns final string table offsets for used strings, |
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326 | merging strings matching suffixes of longer strings if possible. */ |
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327 | |||
328 | void |
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329 | _bfd_elf_strtab_finalize (struct elf_strtab_hash *tab) |
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330 | { |
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331 | struct elf_strtab_hash_entry **array, **a, *e; |
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332 | bfd_size_type size, amt; |
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333 | |||
334 | /* GCC 2.91.66 (egcs-1.1.2) on i386 miscompiles this function when i is |
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335 | a 64-bit bfd_size_type: a 64-bit target or --enable-64-bit-bfd. |
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336 | Besides, indexing with a long long wouldn't give anything but extra |
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337 | cycles. */ |
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338 | size_t i; |
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339 | |||
340 | /* Sort the strings by suffix and length. */ |
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341 | amt = tab->size * sizeof (struct elf_strtab_hash_entry *); |
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342 | array = (struct elf_strtab_hash_entry **) bfd_malloc (amt); |
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343 | if (array == NULL) |
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344 | goto alloc_failure; |
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345 | |||
346 | for (i = 1, a = array; i < tab->size; ++i) |
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347 | { |
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348 | e = tab->array[i]; |
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349 | if (e->refcount) |
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350 | { |
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351 | *a++ = e; |
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352 | /* Adjust the length to not include the zero terminator. */ |
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353 | e->len -= 1; |
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354 | } |
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355 | else |
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356 | e->len = 0; |
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357 | } |
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358 | |||
359 | size = a - array; |
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360 | if (size != 0) |
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361 | { |
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362 | qsort (array, size, sizeof (struct elf_strtab_hash_entry *), strrevcmp); |
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363 | |||
364 | /* Loop over the sorted array and merge suffixes. Start from the |
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365 | end because we want eg. |
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366 | |||
367 | s1 -> "d" |
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368 | s2 -> "bcd" |
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369 | s3 -> "abcd" |
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370 | |||
371 | to end up as |
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372 | |||
373 | s3 -> "abcd" |
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374 | s2 _____^ |
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375 | s1 _______^ |
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376 | |||
377 | ie. we don't want s1 pointing into the old s2. */ |
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378 | e = *--a; |
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379 | e->len += 1; |
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380 | while (--a >= array) |
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381 | { |
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382 | struct elf_strtab_hash_entry *cmp = *a; |
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383 | |||
384 | cmp->len += 1; |
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385 | if (is_suffix (e, cmp)) |
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386 | { |
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387 | cmp->u.suffix = e; |
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388 | cmp->len = -cmp->len; |
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389 | } |
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390 | else |
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391 | e = cmp; |
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392 | } |
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393 | } |
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394 | |||
395 | alloc_failure: |
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396 | if (array) |
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397 | free (array); |
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398 | |||
399 | /* Assign positions to the strings we want to keep. */ |
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400 | size = 1; |
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401 | for (i = 1; i < tab->size; ++i) |
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402 | { |
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403 | e = tab->array[i]; |
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404 | if (e->refcount && e->len > 0) |
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405 | { |
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406 | e->u.index = size; |
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407 | size += e->len; |
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408 | } |
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409 | } |
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410 | |||
411 | tab->sec_size = size; |
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412 | |||
413 | /* Adjust the rest. */ |
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414 | for (i = 1; i < tab->size; ++i) |
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415 | { |
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416 | e = tab->array[i]; |
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417 | if (e->refcount && e->len < 0) |
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418 | e->u.index = e->u.suffix->u.index + (e->u.suffix->len + e->len); |
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419 | } |
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420 | }>>>>=>>>>>>=>>>>> |