| 1 | // elfcpp_file.h -- file access for elfcpp -*- C++ -*- |
| 2 | |
| 3 | // Copyright 2006, 2007, Free Software Foundation, Inc. |
| 4 | // Written by Ian Lance Taylor <iant@google.com>. |
| 5 | |
| 6 | // This file is part of elfcpp. |
| 7 | |
| 8 | // This program is free software; you can redistribute it and/or |
| 9 | // modify it under the terms of the GNU Library General Public License |
| 10 | // as published by the Free Software Foundation; either version 2, or |
| 11 | // (at your option) any later version. |
| 12 | |
| 13 | // In addition to the permissions in the GNU Library General Public |
| 14 | // License, the Free Software Foundation gives you unlimited |
| 15 | // permission to link the compiled version of this file into |
| 16 | // combinations with other programs, and to distribute those |
| 17 | // combinations without any restriction coming from the use of this |
| 18 | // file. (The Library Public License restrictions do apply in other |
| 19 | // respects; for example, they cover modification of the file, and |
| 20 | /// distribution when not linked into a combined executable.) |
| 21 | |
| 22 | // This program is distributed in the hope that it will be useful, but |
| 23 | // WITHOUT ANY WARRANTY; without even the implied warranty of |
| 24 | // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| 25 | // Library General Public License for more details. |
| 26 | |
| 27 | // You should have received a copy of the GNU Library General Public |
| 28 | // License along with this program; if not, write to the Free Software |
| 29 | // Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston, MA |
| 30 | // 02110-1301, USA. |
| 31 | |
| 32 | // This header file defines the class Elf_file which can be used to |
| 33 | // read useful data from an ELF file. The functions here are all |
| 34 | // templates which take a file interface object as a parameter. This |
| 35 | // type must have a subtype View. This type must support two methods: |
| 36 | // View view(off_t file_offset, off_t data_size) |
| 37 | // returns a View for the specified part of the file. |
| 38 | // void error(const char* printf_format, ...) |
| 39 | // prints an error message and does not return. The subtype View must |
| 40 | // support a method |
| 41 | // const unsigned char* data() |
| 42 | // which returns a pointer to a buffer containing the requested data. |
| 43 | // This general interface is used to read data from the file. Objects |
| 44 | // of type View will never survive longer than the elfcpp function. |
| 45 | |
| 46 | // Some of these functions must return a reference to part of the |
| 47 | // file. To use these, the file interface must support a subtype |
| 48 | // Location: |
| 49 | // Location(off_t file_offset, off_t data_size) |
| 50 | // To use this in conjunction with the accessors types Shdr, etc., the |
| 51 | // file interface should support an overload of view: |
| 52 | // View view(Location) |
| 53 | // This permits writing |
| 54 | // elfcpp::Shdr shdr(file, ef.section_header(n)); |
| 55 | |
| 56 | #ifndef ELFPCP_FILE_H |
| 57 | #define ELFCPP_FILE_H |
| 58 | |
| 59 | #include <string> |
| 60 | #include <cstring> |
| 61 | |
| 62 | namespace elfcpp |
| 63 | { |
| 64 | |
| 65 | // This object is used to read an ELF file. |
| 66 | // SIZE: The size of file, 32 or 64. |
| 67 | // BIG_ENDIAN: Whether the file is in big-endian format. |
| 68 | // FILE: A file reading type as described above. |
| 69 | |
| 70 | template<int size, bool big_endian, typename File> |
| 71 | class Elf_file |
| 72 | { |
| 73 | private: |
| 74 | typedef Elf_file<size, big_endian, File> This; |
| 75 | |
| 76 | public: |
| 77 | static const int ehdr_size = Elf_sizes<size>::ehdr_size; |
| 78 | static const int phdr_size = Elf_sizes<size>::phdr_size; |
| 79 | static const int shdr_size = Elf_sizes<size>::shdr_size; |
| 80 | static const int sym_size = Elf_sizes<size>::sym_size; |
| 81 | static const int rel_size = Elf_sizes<size>::rel_size; |
| 82 | static const int rela_size = Elf_sizes<size>::rela_size; |
| 83 | |
| 84 | typedef Ehdr<size, big_endian> Ef_ehdr; |
| 85 | typedef Phdr<size, big_endian> Ef_phdr; |
| 86 | typedef Shdr<size, big_endian> Ef_shdr; |
| 87 | typedef Sym<size, big_endian> Ef_sym; |
| 88 | |
| 89 | // Construct an Elf_file given an ELF file header. |
| 90 | Elf_file(File* file, const Ef_ehdr& ehdr) |
| 91 | { this->construct(file, ehdr); } |
| 92 | |
| 93 | // Construct an ELF file. |
| 94 | inline |
| 95 | Elf_file(File* file); |
| 96 | |
| 97 | // Return the file offset to the section headers. |
| 98 | off_t |
| 99 | shoff() const |
| 100 | { return this->shoff_; } |
| 101 | |
| 102 | // Return the number of sections. |
| 103 | unsigned int |
| 104 | shnum() |
| 105 | { |
| 106 | this->initialize_shnum(); |
| 107 | return this->shnum_; |
| 108 | } |
| 109 | |
| 110 | // Return the section index of the section name string table. |
| 111 | unsigned int |
| 112 | shstrndx() |
| 113 | { |
| 114 | this->initialize_shnum(); |
| 115 | return this->shstrndx_; |
| 116 | } |
| 117 | |
| 118 | // Return the location of the header of section SHNDX. |
| 119 | typename File::Location |
| 120 | section_header(unsigned int shndx) |
| 121 | { |
| 122 | return typename File::Location(this->section_header_offset(shndx), |
| 123 | shdr_size); |
| 124 | } |
| 125 | |
| 126 | // Return the name of section SHNDX. |
| 127 | std::string |
| 128 | section_name(unsigned int shndx); |
| 129 | |
| 130 | // Return the location of the contents of section SHNDX. |
| 131 | typename File::Location |
| 132 | section_contents(unsigned int shndx); |
| 133 | |
| 134 | // Return the size of section SHNDX. |
| 135 | typename Elf_types<size>::Elf_WXword |
| 136 | section_size(unsigned int shndx); |
| 137 | |
| 138 | // Return the flags of section SHNDX. |
| 139 | typename Elf_types<size>::Elf_WXword |
| 140 | section_flags(unsigned int shndx); |
| 141 | |
| 142 | // Return the address of section SHNDX. |
| 143 | typename Elf_types<size>::Elf_Addr |
| 144 | section_addr(unsigned int shndx); |
| 145 | |
| 146 | // Return the type of section SHNDX. |
| 147 | Elf_Word |
| 148 | section_type(unsigned int shndx); |
| 149 | |
| 150 | // Return the link field of section SHNDX. |
| 151 | Elf_Word |
| 152 | section_link(unsigned int shndx); |
| 153 | |
| 154 | // Return the info field of section SHNDX. |
| 155 | Elf_Word |
| 156 | section_info(unsigned int shndx); |
| 157 | |
| 158 | // Return the addralign field of section SHNDX. |
| 159 | typename Elf_types<size>::Elf_WXword |
| 160 | section_addralign(unsigned int shndx); |
| 161 | |
| 162 | private: |
| 163 | // Shared constructor code. |
| 164 | void |
| 165 | construct(File* file, const Ef_ehdr& ehdr); |
| 166 | |
| 167 | // Initialize shnum_ and shstrndx_. |
| 168 | void |
| 169 | initialize_shnum(); |
| 170 | |
| 171 | // Return the file offset of the header of section SHNDX. |
| 172 | off_t |
| 173 | section_header_offset(unsigned int shndx); |
| 174 | |
| 175 | // The file we are reading. |
| 176 | File* file_; |
| 177 | // The file offset to the section headers. |
| 178 | off_t shoff_; |
| 179 | // The number of sections. |
| 180 | unsigned int shnum_; |
| 181 | // The section index of the section name string table. |
| 182 | unsigned int shstrndx_; |
| 183 | }; |
| 184 | |
| 185 | // Template function definitions. |
| 186 | |
| 187 | // Construct an Elf_file given an ELF file header. |
| 188 | |
| 189 | template<int size, bool big_endian, typename File> |
| 190 | void |
| 191 | Elf_file<size, big_endian, File>::construct(File* file, const Ef_ehdr& ehdr) |
| 192 | { |
| 193 | this->file_ = file; |
| 194 | this->shoff_ = ehdr.get_e_shoff(); |
| 195 | this->shnum_ = ehdr.get_e_shnum(); |
| 196 | this->shstrndx_ = ehdr.get_e_shstrndx(); |
| 197 | if (ehdr.get_e_ehsize() != This::ehdr_size) |
| 198 | file->error(_("bad e_ehsize (%d != %d)"), |
| 199 | ehdr.get_e_ehsize(), This::ehdr_size); |
| 200 | if (ehdr.get_e_shentsize() != This::shdr_size) |
| 201 | file->error(_("bad e_shentsize (%d != %d)"), |
| 202 | ehdr.get_e_shentsize(), This::shdr_size); |
| 203 | } |
| 204 | |
| 205 | // Construct an ELF file. |
| 206 | |
| 207 | template<int size, bool big_endian, typename File> |
| 208 | inline |
| 209 | Elf_file<size, big_endian, File>::Elf_file(File* file) |
| 210 | { |
| 211 | typename File::View v(file->view(file_header_offset, This::ehdr_size)); |
| 212 | this->construct(file, Ef_ehdr(v.data())); |
| 213 | } |
| 214 | |
| 215 | // Initialize the shnum_ and shstrndx_ fields, handling overflow. |
| 216 | |
| 217 | template<int size, bool big_endian, typename File> |
| 218 | void |
| 219 | Elf_file<size, big_endian, File>::initialize_shnum() |
| 220 | { |
| 221 | if ((this->shnum_ == 0 || this->shstrndx_ == SHN_XINDEX) |
| 222 | && this->shoff_ != 0) |
| 223 | { |
| 224 | typename File::View v(this->file_->view(this->shoff_, This::shdr_size)); |
| 225 | Ef_shdr shdr(v.data()); |
| 226 | if (this->shnum_ == 0) |
| 227 | this->shnum_ = shdr.get_sh_size(); |
| 228 | if (this->shstrndx_ == SHN_XINDEX) |
| 229 | this->shstrndx_ = shdr.get_sh_link(); |
| 230 | } |
| 231 | } |
| 232 | |
| 233 | // Return the file offset of the section header of section SHNDX. |
| 234 | |
| 235 | template<int size, bool big_endian, typename File> |
| 236 | off_t |
| 237 | Elf_file<size, big_endian, File>::section_header_offset(unsigned int shndx) |
| 238 | { |
| 239 | if (shndx >= this->shnum()) |
| 240 | this->file_->error(_("section_header_offset: bad shndx %u >= %u"), |
| 241 | shndx, this->shnum()); |
| 242 | return this->shoff_ + This::shdr_size * shndx; |
| 243 | } |
| 244 | |
| 245 | // Return the name of section SHNDX. |
| 246 | |
| 247 | template<int size, bool big_endian, typename File> |
| 248 | std::string |
| 249 | Elf_file<size, big_endian, File>::section_name(unsigned int shndx) |
| 250 | { |
| 251 | File* const file = this->file_; |
| 252 | |
| 253 | // Get the section name offset. |
| 254 | unsigned int sh_name; |
| 255 | { |
| 256 | typename File::View v(file->view(this->section_header_offset(shndx), |
| 257 | This::shdr_size)); |
| 258 | Ef_shdr shdr(v.data()); |
| 259 | sh_name = shdr.get_sh_name(); |
| 260 | } |
| 261 | |
| 262 | // Get the file offset for the section name string table data. |
| 263 | off_t shstr_off; |
| 264 | off_t shstr_size; |
| 265 | { |
| 266 | const unsigned int shstrndx = this->shstrndx_; |
| 267 | typename File::View v(file->view(this->section_header_offset(shstrndx), |
| 268 | This::shdr_size)); |
| 269 | Ef_shdr shstr_shdr(v.data()); |
| 270 | shstr_off = shstr_shdr.get_sh_offset(); |
| 271 | shstr_size = shstr_shdr.get_sh_size(); |
| 272 | } |
| 273 | |
| 274 | if (sh_name >= shstr_size) |
| 275 | file->error(_("bad section name offset for section %u: %u"), |
| 276 | shndx, sh_name); |
| 277 | |
| 278 | typename File::View v(file->view(shstr_off, shstr_size)); |
| 279 | |
| 280 | const unsigned char* datau = v.data(); |
| 281 | const char* data = reinterpret_cast<const char*>(datau); |
| 282 | const void* p = ::memchr(data + sh_name, '\0', shstr_size - sh_name); |
| 283 | if (p == NULL) |
| 284 | file->error(_("missing null terminator for name of section %u"), |
| 285 | shndx); |
| 286 | |
| 287 | size_t len = static_cast<const char*>(p) - (data + sh_name); |
| 288 | |
| 289 | return std::string(data + sh_name, len); |
| 290 | } |
| 291 | |
| 292 | // Return the contents of section SHNDX. |
| 293 | |
| 294 | template<int size, bool big_endian, typename File> |
| 295 | typename File::Location |
| 296 | Elf_file<size, big_endian, File>::section_contents(unsigned int shndx) |
| 297 | { |
| 298 | File* const file = this->file_; |
| 299 | |
| 300 | if (shndx >= this->shnum()) |
| 301 | file->error(_("section_contents: bad shndx %u >= %u"), |
| 302 | shndx, this->shnum()); |
| 303 | |
| 304 | typename File::View v(file->view(this->section_header_offset(shndx), |
| 305 | This::shdr_size)); |
| 306 | Ef_shdr shdr(v.data()); |
| 307 | return typename File::Location(shdr.get_sh_offset(), shdr.get_sh_size()); |
| 308 | } |
| 309 | |
| 310 | // Get the size of section SHNDX. |
| 311 | |
| 312 | template<int size, bool big_endian, typename File> |
| 313 | typename Elf_types<size>::Elf_WXword |
| 314 | Elf_file<size, big_endian, File>::section_size(unsigned int shndx) |
| 315 | { |
| 316 | File* const file = this->file_; |
| 317 | |
| 318 | if (shndx >= this->shnum()) |
| 319 | file->error(_("section_size: bad shndx %u >= %u"), |
| 320 | shndx, this->shnum()); |
| 321 | |
| 322 | typename File::View v(file->view(this->section_header_offset(shndx), |
| 323 | This::shdr_size)); |
| 324 | |
| 325 | Ef_shdr shdr(v.data()); |
| 326 | return shdr.get_sh_size(); |
| 327 | } |
| 328 | |
| 329 | // Return the section flags of section SHNDX. |
| 330 | |
| 331 | template<int size, bool big_endian, typename File> |
| 332 | typename Elf_types<size>::Elf_WXword |
| 333 | Elf_file<size, big_endian, File>::section_flags(unsigned int shndx) |
| 334 | { |
| 335 | File* const file = this->file_; |
| 336 | |
| 337 | if (shndx >= this->shnum()) |
| 338 | file->error(_("section_flags: bad shndx %u >= %u"), |
| 339 | shndx, this->shnum()); |
| 340 | |
| 341 | typename File::View v(file->view(this->section_header_offset(shndx), |
| 342 | This::shdr_size)); |
| 343 | |
| 344 | Ef_shdr shdr(v.data()); |
| 345 | return shdr.get_sh_flags(); |
| 346 | } |
| 347 | |
| 348 | // Return the address of section SHNDX. |
| 349 | |
| 350 | template<int size, bool big_endian, typename File> |
| 351 | typename Elf_types<size>::Elf_Addr |
| 352 | Elf_file<size, big_endian, File>::section_addr(unsigned int shndx) |
| 353 | { |
| 354 | File* const file = this->file_; |
| 355 | |
| 356 | if (shndx >= this->shnum()) |
| 357 | file->error(_("section_flags: bad shndx %u >= %u"), |
| 358 | shndx, this->shnum()); |
| 359 | |
| 360 | typename File::View v(file->view(this->section_header_offset(shndx), |
| 361 | This::shdr_size)); |
| 362 | |
| 363 | Ef_shdr shdr(v.data()); |
| 364 | return shdr.get_sh_addr(); |
| 365 | } |
| 366 | |
| 367 | // Return the type of section SHNDX. |
| 368 | |
| 369 | template<int size, bool big_endian, typename File> |
| 370 | Elf_Word |
| 371 | Elf_file<size, big_endian, File>::section_type(unsigned int shndx) |
| 372 | { |
| 373 | File* const file = this->file_; |
| 374 | |
| 375 | if (shndx >= this->shnum()) |
| 376 | file->error(_("section_type: bad shndx %u >= %u"), |
| 377 | shndx, this->shnum()); |
| 378 | |
| 379 | typename File::View v(file->view(this->section_header_offset(shndx), |
| 380 | This::shdr_size)); |
| 381 | |
| 382 | Ef_shdr shdr(v.data()); |
| 383 | return shdr.get_sh_type(); |
| 384 | } |
| 385 | |
| 386 | // Return the sh_link field of section SHNDX. |
| 387 | |
| 388 | template<int size, bool big_endian, typename File> |
| 389 | Elf_Word |
| 390 | Elf_file<size, big_endian, File>::section_link(unsigned int shndx) |
| 391 | { |
| 392 | File* const file = this->file_; |
| 393 | |
| 394 | if (shndx >= this->shnum()) |
| 395 | file->error(_("section_link: bad shndx %u >= %u"), |
| 396 | shndx, this->shnum()); |
| 397 | |
| 398 | typename File::View v(file->view(this->section_header_offset(shndx), |
| 399 | This::shdr_size)); |
| 400 | |
| 401 | Ef_shdr shdr(v.data()); |
| 402 | return shdr.get_sh_link(); |
| 403 | } |
| 404 | |
| 405 | // Return the sh_info field of section SHNDX. |
| 406 | |
| 407 | template<int size, bool big_endian, typename File> |
| 408 | Elf_Word |
| 409 | Elf_file<size, big_endian, File>::section_info(unsigned int shndx) |
| 410 | { |
| 411 | File* const file = this->file_; |
| 412 | |
| 413 | if (shndx >= this->shnum()) |
| 414 | file->error(_("section_info: bad shndx %u >= %u"), |
| 415 | shndx, this->shnum()); |
| 416 | |
| 417 | typename File::View v(file->view(this->section_header_offset(shndx), |
| 418 | This::shdr_size)); |
| 419 | |
| 420 | Ef_shdr shdr(v.data()); |
| 421 | return shdr.get_sh_info(); |
| 422 | } |
| 423 | |
| 424 | // Return the sh_addralign field of section SHNDX. |
| 425 | |
| 426 | template<int size, bool big_endian, typename File> |
| 427 | typename Elf_types<size>::Elf_WXword |
| 428 | Elf_file<size, big_endian, File>::section_addralign(unsigned int shndx) |
| 429 | { |
| 430 | File* const file = this->file_; |
| 431 | |
| 432 | if (shndx >= this->shnum()) |
| 433 | file->error(_("section_addralign: bad shndx %u >= %u"), |
| 434 | shndx, this->shnum()); |
| 435 | |
| 436 | typename File::View v(file->view(this->section_header_offset(shndx), |
| 437 | This::shdr_size)); |
| 438 | |
| 439 | Ef_shdr shdr(v.data()); |
| 440 | return shdr.get_sh_addralign(); |
| 441 | } |
| 442 | |
| 443 | } // End namespace elfcpp. |
| 444 | |
| 445 | #endif // !defined(ELFCPP_FILE_H) |