1 | /*- |
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2 | * Copyright (c) 2006,2008 Joseph Koshy |
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3 | * All rights reserved. |
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4 | * |
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5 | * Redistribution and use in source and binary forms, with or without |
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6 | * modification, are permitted provided that the following conditions |
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7 | * are met: |
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8 | * 1. Redistributions of source code must retain the above copyright |
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9 | * notice, this list of conditions and the following disclaimer. |
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10 | * 2. Redistributions in binary form must reproduce the above copyright |
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11 | * notice, this list of conditions and the following disclaimer in the |
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12 | * documentation and/or other materials provided with the distribution. |
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13 | * |
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14 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND |
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15 | * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
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16 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
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17 | * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE |
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18 | * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL |
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19 | * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS |
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20 | * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) |
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21 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT |
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22 | * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY |
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23 | * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF |
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24 | * SUCH DAMAGE. |
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25 | */ |
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26 | |
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27 | #include <sys/cdefs.h> |
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28 | |
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29 | #include <assert.h> |
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30 | #include <gelf.h> |
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31 | #include <libelf.h> |
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32 | #include <stdlib.h> |
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33 | |
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34 | #include "_libelf.h" |
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35 | |
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36 | LIBELF_VCSID("$Id: libelf_ehdr.c 1677 2011-07-28 04:35:53Z jkoshy $"); |
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37 | |
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38 | /* |
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39 | * Retrieve counts for sections, phdrs and the section string table index |
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40 | * from section header #0 of the ELF object. |
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41 | */ |
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42 | static int |
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43 | _libelf_load_extended(Elf *e, int ec, uint64_t shoff, uint16_t phnum, |
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44 | uint16_t strndx) |
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45 | { |
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46 | Elf_Scn *scn; |
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47 | size_t fsz; |
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48 | int (*xlator)(char *_d, size_t _dsz, char *_s, size_t _c, int _swap); |
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49 | uint32_t shtype; |
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50 | |
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51 | assert(STAILQ_EMPTY(&e->e_u.e_elf.e_scn)); |
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52 | |
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53 | fsz = _libelf_fsize(ELF_T_SHDR, ec, e->e_version, 1); |
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54 | assert(fsz > 0); |
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55 | |
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56 | if (e->e_rawsize < shoff + fsz) { /* raw file too small */ |
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57 | LIBELF_SET_ERROR(HEADER, 0); |
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58 | return (0); |
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59 | } |
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60 | |
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61 | if ((scn = _libelf_allocate_scn(e, (size_t) 0)) == NULL) |
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62 | return (0); |
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63 | |
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64 | xlator = _libelf_get_translator(ELF_T_SHDR, ELF_TOMEMORY, ec); |
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65 | (*xlator)((char *) &scn->s_shdr, sizeof(scn->s_shdr), |
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66 | e->e_rawfile + shoff, (size_t) 1, |
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67 | e->e_byteorder != LIBELF_PRIVATE(byteorder)); |
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68 | |
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69 | #define GET_SHDR_MEMBER(M) ((ec == ELFCLASS32) ? scn->s_shdr.s_shdr32.M : \ |
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70 | scn->s_shdr.s_shdr64.M) |
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71 | |
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72 | if ((shtype = GET_SHDR_MEMBER(sh_type)) != SHT_NULL) { |
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73 | LIBELF_SET_ERROR(SECTION, 0); |
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74 | return (0); |
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75 | } |
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76 | |
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77 | e->e_u.e_elf.e_nscn = GET_SHDR_MEMBER(sh_size); |
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78 | e->e_u.e_elf.e_nphdr = (phnum != PN_XNUM) ? phnum : |
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79 | GET_SHDR_MEMBER(sh_info); |
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80 | e->e_u.e_elf.e_strndx = (strndx != SHN_XINDEX) ? strndx : |
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81 | GET_SHDR_MEMBER(sh_link); |
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82 | #undef GET_SHDR_MEMBER |
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83 | |
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84 | return (1); |
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85 | } |
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86 | |
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87 | #define EHDR_INIT(E,SZ) do { \ |
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88 | Elf##SZ##_Ehdr *eh = (E); \ |
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89 | eh->e_ident[EI_MAG0] = ELFMAG0; \ |
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90 | eh->e_ident[EI_MAG1] = ELFMAG1; \ |
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91 | eh->e_ident[EI_MAG2] = ELFMAG2; \ |
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92 | eh->e_ident[EI_MAG3] = ELFMAG3; \ |
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93 | eh->e_ident[EI_CLASS] = ELFCLASS##SZ; \ |
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94 | eh->e_ident[EI_DATA] = ELFDATANONE; \ |
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95 | eh->e_ident[EI_VERSION] = LIBELF_PRIVATE(version); \ |
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96 | eh->e_machine = EM_NONE; \ |
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97 | eh->e_type = ELF_K_NONE; \ |
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98 | eh->e_version = LIBELF_PRIVATE(version); \ |
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99 | } while (0) |
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100 | |
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101 | void * |
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102 | _libelf_ehdr(Elf *e, int ec, int allocate) |
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103 | { |
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104 | void *ehdr; |
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105 | size_t fsz, msz; |
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106 | uint16_t phnum, shnum, strndx; |
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107 | uint64_t shoff; |
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108 | int (*xlator)(char *_d, size_t _dsz, char *_s, size_t _c, int _swap); |
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109 | |
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110 | assert(ec == ELFCLASS32 || ec == ELFCLASS64); |
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111 | |
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112 | if (e == NULL || e->e_kind != ELF_K_ELF) { |
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113 | LIBELF_SET_ERROR(ARGUMENT, 0); |
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114 | return (NULL); |
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115 | } |
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116 | |
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117 | if (e->e_class != ELFCLASSNONE && e->e_class != ec) { |
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118 | LIBELF_SET_ERROR(CLASS, 0); |
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119 | return (NULL); |
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120 | } |
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121 | |
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122 | if (e->e_version != EV_CURRENT) { |
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123 | LIBELF_SET_ERROR(VERSION, 0); |
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124 | return (NULL); |
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125 | } |
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126 | |
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127 | if (e->e_class == ELFCLASSNONE) |
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128 | e->e_class = ec; |
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129 | |
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130 | if (ec == ELFCLASS32) |
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131 | ehdr = (void *) e->e_u.e_elf.e_ehdr.e_ehdr32; |
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132 | else |
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133 | ehdr = (void *) e->e_u.e_elf.e_ehdr.e_ehdr64; |
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134 | |
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135 | if (ehdr != NULL) /* already have a translated ehdr */ |
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136 | return (ehdr); |
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137 | |
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138 | fsz = _libelf_fsize(ELF_T_EHDR, ec, e->e_version, (size_t) 1); |
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139 | assert(fsz > 0); |
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140 | |
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141 | if (e->e_cmd != ELF_C_WRITE && e->e_rawsize < fsz) { |
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142 | LIBELF_SET_ERROR(HEADER, 0); |
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143 | return (NULL); |
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144 | } |
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145 | |
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146 | msz = _libelf_msize(ELF_T_EHDR, ec, EV_CURRENT); |
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147 | |
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148 | assert(msz > 0); |
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149 | |
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150 | if ((ehdr = calloc((size_t) 1, msz)) == NULL) { |
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151 | LIBELF_SET_ERROR(RESOURCE, 0); |
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152 | return (NULL); |
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153 | } |
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154 | |
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155 | if (ec == ELFCLASS32) { |
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156 | e->e_u.e_elf.e_ehdr.e_ehdr32 = ehdr; |
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157 | EHDR_INIT(ehdr,32); |
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158 | } else { |
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159 | e->e_u.e_elf.e_ehdr.e_ehdr64 = ehdr; |
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160 | EHDR_INIT(ehdr,64); |
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161 | } |
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162 | |
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163 | if (allocate) |
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164 | e->e_flags |= ELF_F_DIRTY; |
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165 | |
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166 | if (e->e_cmd == ELF_C_WRITE) |
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167 | return (ehdr); |
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168 | |
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169 | xlator = _libelf_get_translator(ELF_T_EHDR, ELF_TOMEMORY, ec); |
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170 | (*xlator)(ehdr, msz, e->e_rawfile, (size_t) 1, |
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171 | e->e_byteorder != LIBELF_PRIVATE(byteorder)); |
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172 | |
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173 | /* |
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174 | * If extended numbering is being used, read the correct |
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175 | * number of sections and program header entries. |
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176 | */ |
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177 | if (ec == ELFCLASS32) { |
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178 | phnum = ((Elf32_Ehdr *) ehdr)->e_phnum; |
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179 | shnum = ((Elf32_Ehdr *) ehdr)->e_shnum; |
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180 | shoff = ((Elf32_Ehdr *) ehdr)->e_shoff; |
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181 | strndx = ((Elf32_Ehdr *) ehdr)->e_shstrndx; |
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182 | } else { |
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183 | phnum = ((Elf64_Ehdr *) ehdr)->e_phnum; |
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184 | shnum = ((Elf64_Ehdr *) ehdr)->e_shnum; |
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185 | shoff = ((Elf64_Ehdr *) ehdr)->e_shoff; |
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186 | strndx = ((Elf64_Ehdr *) ehdr)->e_shstrndx; |
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187 | } |
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188 | |
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189 | if (shnum >= SHN_LORESERVE || |
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190 | (shoff == 0LL && (shnum != 0 || phnum == PN_XNUM || |
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191 | strndx == SHN_XINDEX))) { |
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192 | LIBELF_SET_ERROR(HEADER, 0); |
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193 | return (NULL); |
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194 | } |
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195 | |
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196 | if (shnum != 0 || shoff == 0LL) { /* not using extended numbering */ |
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197 | e->e_u.e_elf.e_nphdr = phnum; |
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198 | e->e_u.e_elf.e_nscn = shnum; |
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199 | e->e_u.e_elf.e_strndx = strndx; |
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200 | } else if (_libelf_load_extended(e, ec, shoff, phnum, strndx) == 0) |
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201 | return (NULL); |
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202 | |
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203 | return (ehdr); |
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204 | } |
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