root / prex-0.9.0 / usr / server / exec / exec_elf.c @ 03e9c04a
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1 | 03e9c04a | Brad Neuman | /*
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2 | * Copyright (c) 2005-2006, Kohsuke Ohtani
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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 | * 3. Neither the name of the author nor the names of any co-contributors
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14 | * may be used to endorse or promote products derived from this software
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15 | * without specific prior written permission.
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16 | *
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17 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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18 | * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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19 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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20 | * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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21 | * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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22 | * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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23 | * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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24 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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25 | * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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26 | * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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27 | * SUCH DAMAGE.
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28 | */
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29 | |||
30 | /*
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31 | * exec_elf.c - ELF file loader
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32 | */
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33 | |||
34 | #include <sys/prex.h> |
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35 | #include <ipc/fs.h> |
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36 | #include <ipc/proc.h> |
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37 | #include <sys/elf.h> |
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38 | #include <sys/param.h> |
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39 | |||
40 | #include <string.h> |
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41 | #include <limits.h> |
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42 | #include <stdio.h> |
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43 | #include <stdlib.h> |
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44 | #include <errno.h> |
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45 | |||
46 | #include "exec.h" |
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47 | |||
48 | #define SHF_VALID (SHF_ALLOC | SHF_EXECINSTR | SHF_ALLOC | SHF_WRITE)
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49 | |||
50 | #ifndef CONFIG_MMU
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51 | static char *sect_addr[32]; /* Array of section address */ |
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52 | #endif
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53 | |||
54 | #ifdef CONFIG_MMU
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55 | /*
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56 | * Load executable ELF file
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57 | */
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58 | static int |
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59 | load_exec(Elf32_Ehdr *ehdr, task_t task, int fd, vaddr_t *entry)
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60 | { |
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61 | Elf32_Phdr *phdr; |
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62 | void *addr, *mapped;
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63 | size_t size = 0;
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64 | int i;
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65 | |||
66 | phdr = (Elf32_Phdr *)((u_long)ehdr + ehdr->e_phoff); |
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67 | if (phdr == NULL) |
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68 | return ENOEXEC;
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69 | |||
70 | for (i = 0; i < (int)ehdr->e_phnum; i++, phdr++) { |
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71 | if (phdr->p_type != PT_LOAD)
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72 | continue;
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73 | |||
74 | addr = (void *)phdr->p_vaddr;
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75 | size = phdr->p_memsz; |
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76 | if (size == 0) |
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77 | continue;
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78 | |||
79 | if (vm_allocate(task, &addr, size, 0) != 0) |
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80 | return ENOMEM;
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81 | |||
82 | if (vm_map(task, (void *)phdr->p_vaddr, size, &mapped) != 0) |
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83 | return ENOEXEC;
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84 | if (phdr->p_filesz > 0) { |
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85 | if (lseek(fd, (off_t)phdr->p_offset, SEEK_SET)
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86 | == -(off_t)1)
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87 | goto err;
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88 | if (read(fd, mapped, phdr->p_filesz) < 0) |
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89 | goto err;
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90 | } |
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91 | |||
92 | vm_free(task_self(), mapped); |
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93 | |||
94 | /* Set read-only to text */
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95 | if (phdr->p_flags & PF_X) {
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96 | if (vm_attribute(task, addr, PROT_READ) != 0) |
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97 | return ENOEXEC;
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98 | } |
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99 | } |
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100 | *entry = (vaddr_t)ehdr->e_entry; |
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101 | return 0; |
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102 | |||
103 | err:
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104 | vm_free(task_self(), mapped); |
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105 | return EIO;
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106 | } |
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107 | #else /* !CONFIG_MMU */ |
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108 | |||
109 | static int |
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110 | relocate_section_rela(Elf32_Sym *sym_table, Elf32_Rela *rela, |
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111 | char *target_sect, int nr_reloc) |
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112 | { |
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113 | Elf32_Sym *sym; |
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114 | Elf32_Addr sym_val; |
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115 | int i;
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116 | |||
117 | for (i = 0; i < nr_reloc; i++) { |
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118 | sym = &sym_table[ELF32_R_SYM(rela->r_info)]; |
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119 | if (sym->st_shndx != STN_UNDEF) {
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120 | sym_val = (Elf32_Addr)sect_addr[sym->st_shndx] |
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121 | + sym->st_value; |
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122 | if (relocate_rela(rela, sym_val, target_sect) != 0) |
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123 | return -1; |
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124 | } else if (ELF32_ST_BIND(sym->st_info) == STB_WEAK) { |
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125 | DPRINTF(("undefined weak symbol for rela[%d]\n", i));
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126 | } |
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127 | rela++; |
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128 | } |
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129 | return 0; |
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130 | } |
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131 | |||
132 | static int |
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133 | relocate_section_rel(Elf32_Sym *sym_table, Elf32_Rel *rel, |
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134 | char *target_sect, int nr_reloc) |
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135 | { |
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136 | Elf32_Sym *sym; |
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137 | Elf32_Addr sym_val; |
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138 | int i;
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139 | |||
140 | for (i = 0; i < nr_reloc; i++) { |
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141 | sym = &sym_table[ELF32_R_SYM(rel->r_info)]; |
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142 | if (sym->st_shndx != STN_UNDEF) {
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143 | sym_val = (Elf32_Addr)sect_addr[sym->st_shndx] |
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144 | + sym->st_value; |
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145 | if (relocate_rel(rel, sym_val, target_sect) != 0) |
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146 | return -1; |
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147 | } else if (ELF32_ST_BIND(sym->st_info) == STB_WEAK) { |
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148 | DPRINTF(("undefined weak symbol for rel[%d]\n", i));
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149 | } |
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150 | rel++; |
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151 | } |
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152 | return 0; |
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153 | } |
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154 | |||
155 | /*
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156 | * Relocate ELF sections
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157 | */
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158 | static int |
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159 | relocate_section(Elf32_Shdr *shdr, char *rel_data)
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160 | { |
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161 | Elf32_Sym *sym_table; |
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162 | char *target_sect;
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163 | int nr_reloc, error;
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164 | |||
165 | if (shdr->sh_entsize == 0) |
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166 | return 0; |
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167 | if ((target_sect = sect_addr[shdr->sh_info]) == 0) |
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168 | return -1; |
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169 | if ((sym_table = (Elf32_Sym *)sect_addr[shdr->sh_link]) == 0) |
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170 | return -1; |
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171 | |||
172 | nr_reloc = (int)(shdr->sh_size / shdr->sh_entsize);
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173 | switch (shdr->sh_type) {
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174 | case SHT_REL:
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175 | error = relocate_section_rel(sym_table, (Elf32_Rel *)rel_data, |
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176 | target_sect, nr_reloc); |
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177 | break;
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178 | |||
179 | case SHT_RELA:
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180 | error = relocate_section_rela(sym_table, (Elf32_Rela *)rel_data, |
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181 | target_sect, nr_reloc); |
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182 | break;
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183 | |||
184 | default:
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185 | error = -1;
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186 | break;
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187 | } |
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188 | return error;
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189 | } |
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190 | |||
191 | /*
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192 | * Load ELF relocatable file.
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193 | */
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194 | static int |
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195 | load_reloc(Elf32_Ehdr *ehdr, task_t task, int fd, vaddr_t *entry)
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196 | { |
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197 | Elf32_Shdr *shdr; |
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198 | char *buf;
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199 | void *base, *addr, *mapped;
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200 | size_t shdr_size, total_size; |
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201 | int i, error = 0; |
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202 | |||
203 | DPRINTF(("exec: load_reloc\n"));
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204 | |||
205 | /* Read section header */
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206 | shdr_size = ehdr->e_shentsize * ehdr->e_shnum; |
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207 | if ((buf = malloc(shdr_size)) == NULL) { |
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208 | error = ENOMEM; |
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209 | goto out0;
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210 | } |
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211 | |||
212 | if (lseek(fd, ehdr->e_shoff, SEEK_SET) < 0) { |
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213 | error = EIO; |
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214 | goto out1;
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215 | } |
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216 | if (read(fd, buf, shdr_size) < 0) { |
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217 | error = EIO; |
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218 | goto out1;
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219 | } |
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220 | |||
221 | /* Allocate memory for text, data and bss. */
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222 | shdr = (Elf32_Shdr *)buf; |
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223 | total_size = 0;
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224 | for (i = 0; i < ehdr->e_shnum; i++, shdr++) { |
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225 | if (shdr->sh_type == SHT_NOBITS) { /* bss? */ |
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226 | total_size = shdr->sh_addr + shdr->sh_size; |
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227 | break;
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228 | } |
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229 | } |
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230 | if (total_size == 0) { |
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231 | error = ENOEXEC; |
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232 | goto out1;
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233 | } |
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234 | if (vm_allocate(task, &base, total_size, 1) != 0) { |
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235 | DPRINTF(("exec: out of text\n"));
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236 | error = ENOMEM; |
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237 | goto out1;
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238 | } |
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239 | |||
240 | if (vm_map(task, base, total_size, &mapped) != 0) { |
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241 | error = ENOMEM; |
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242 | goto out1;
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243 | } |
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244 | |||
245 | /* Copy sections */
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246 | shdr = (Elf32_Shdr *)buf; |
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247 | for (i = 0; i < ehdr->e_shnum; i++, shdr++) { |
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248 | /*
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249 | *DPRINTF(("section: type=%x addr=%x size=%d offset=%x flags=%x\n",
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250 | * shdr->sh_type, shdr->sh_addr, shdr->sh_size,
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251 | * shdr->sh_offset, shdr->sh_flags));
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252 | */
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253 | sect_addr[i] = 0;
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254 | if (shdr->sh_type == SHT_PROGBITS) {
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255 | switch (shdr->sh_flags & SHF_VALID) {
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256 | case (SHF_ALLOC | SHF_EXECINSTR): /* text */ |
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257 | case (SHF_ALLOC | SHF_WRITE): /* data */ |
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258 | case SHF_ALLOC: /* rodata */ |
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259 | break;
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260 | default:
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261 | continue;
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262 | } |
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263 | addr = (char *)((u_long)mapped + shdr->sh_addr);
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264 | if (shdr->sh_size == 0) { |
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265 | continue;
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266 | } |
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267 | } else if (shdr->sh_type == SHT_NOBITS) { |
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268 | /* bss */
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269 | sect_addr[i] = \ |
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270 | (char *)((u_long)mapped + shdr->sh_addr);
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271 | continue;
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272 | } else if (shdr->sh_type == SHT_SYMTAB || |
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273 | shdr->sh_type == SHT_RELA || |
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274 | shdr->sh_type == SHT_REL) |
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275 | { |
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276 | |||
277 | if ((addr = malloc(shdr->sh_size)) == NULL) { |
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278 | error = ENOMEM; |
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279 | goto out2;
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280 | } |
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281 | } else
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282 | continue;
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283 | |||
284 | if (lseek(fd, shdr->sh_offset, SEEK_SET) < 0) { |
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285 | error = EIO; |
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286 | goto out2;
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287 | } |
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288 | if (read(fd, addr, shdr->sh_size) < 0) { |
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289 | error = EIO; |
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290 | goto out2;
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291 | } |
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292 | sect_addr[i] = addr; |
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293 | } |
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294 | |||
295 | /* Process relocation */
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296 | shdr = (Elf32_Shdr *)buf; |
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297 | for (i = 0; i < ehdr->e_shnum; i++, shdr++) { |
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298 | if (shdr->sh_type == SHT_REL || shdr->sh_type == SHT_RELA) {
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299 | if (relocate_section(shdr, sect_addr[i]) != 0) { |
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300 | error = EIO; |
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301 | DPRINTF(("exec: relocation failed\n"));
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302 | goto out2;
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303 | } |
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304 | } |
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305 | } |
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306 | *entry = (vaddr_t)((u_long)mapped + ehdr->e_entry); |
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307 | DPRINTF(("exec: entry=%x\n", *entry));
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308 | out2:
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309 | /* Release symbol table */
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310 | shdr = (Elf32_Shdr *)buf; |
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311 | for (i = 0; i < ehdr->e_shnum; i++, shdr++) { |
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312 | if (shdr->sh_type == SHT_SYMTAB ||
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313 | shdr->sh_type == SHT_RELA || |
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314 | shdr->sh_type == SHT_REL) { |
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315 | if (sect_addr[i])
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316 | free(sect_addr[i]); |
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317 | } |
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318 | } |
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319 | vm_free(task_self(), mapped); |
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320 | out1:
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321 | free(buf); |
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322 | out0:
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323 | DPRINTF(("exec: load_reloc ret=%d\n", error));
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324 | return error;
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325 | } |
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326 | |||
327 | #endif /* !CONFIG_MMU */ |
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328 | |||
329 | |||
330 | /*
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331 | * Load ELF file
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332 | */
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333 | int
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334 | elf_load(struct exec *exec)
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335 | { |
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336 | int error, fd;
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337 | |||
338 | /*
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339 | * Check permission.
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340 | */
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341 | if (access(exec->path, X_OK) == -1) { |
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342 | DPRINTF(("exec: no exec access\n"));
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343 | return errno;
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344 | } |
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345 | |||
346 | if ((fd = open(exec->path, O_RDONLY)) == -1) |
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347 | return ENOENT;
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348 | |||
349 | #ifdef CONFIG_MMU
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350 | error = load_exec((Elf32_Ehdr *)exec->header, exec->task, |
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351 | fd, &exec->entry); |
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352 | #else
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353 | error = load_reloc((Elf32_Ehdr *)exec->header, exec->task, |
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354 | fd, &exec->entry); |
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355 | #endif
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356 | close(fd); |
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357 | return error;
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358 | } |
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359 | |||
360 | /*
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361 | * Probe ELF file
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362 | */
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363 | int
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364 | elf_probe(struct exec *exec)
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365 | { |
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366 | Elf32_Ehdr *ehdr; |
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367 | |||
368 | /* Check ELF header */
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369 | ehdr = (Elf32_Ehdr *)exec->header; |
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370 | DPRINTF(("exec: ELF magic %c %c %c %c\n",
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371 | ehdr->e_ident[EI_MAG0], |
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372 | ehdr->e_ident[EI_MAG1], |
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373 | ehdr->e_ident[EI_MAG2], |
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374 | ehdr->e_ident[EI_MAG3])); |
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375 | |||
376 | if ((ehdr->e_ident[EI_MAG0] != ELFMAG0) ||
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377 | (ehdr->e_ident[EI_MAG1] != ELFMAG1) || |
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378 | (ehdr->e_ident[EI_MAG2] != ELFMAG2) || |
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379 | (ehdr->e_ident[EI_MAG3] != ELFMAG3)) |
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380 | return PROBE_ERROR;
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381 | |||
382 | #ifdef CONFIG_MMU
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383 | if (ehdr->e_type != ET_EXEC)
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384 | return PROBE_ERROR;
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385 | #else
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386 | if (ehdr->e_type != ET_REL)
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387 | return PROBE_ERROR;
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388 | #endif
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389 | return PROBE_MATCH;
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390 | } |
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391 | |||
392 | void
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393 | elf_init(void)
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394 | { |
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395 | } |