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[binutils.git] / elfcpp / elfcpp_file.h
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1 // elfcpp_file.h -- file access for elfcpp -*- C++ -*-
3 // Copyright 2006, 2007, Free Software Foundation, Inc.
4 // Written by Ian Lance Taylor <iant@google.com>.
6 // This file is part of elfcpp.
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.
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.)
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.
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.
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.
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));
56 #ifndef ELFPCP_FILE_H
57 #define ELFCPP_FILE_H
59 #include <string>
60 #include <cstring>
62 namespace elfcpp
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.
70 template<int size, bool big_endian, typename File>
71 class Elf_file
73 private:
74 typedef Elf_file<size, big_endian, File> This;
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;
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;
89 // Construct an Elf_file given an ELF file header.
90 Elf_file(File* file, const Ef_ehdr& ehdr)
91 { this->construct(file, ehdr); }
93 // Construct an ELF file.
94 inline
95 Elf_file(File* file);
97 // Return the file offset to the section headers.
98 off_t
99 shoff() const
100 { return this->shoff_; }
102 // Return the number of sections.
103 unsigned int
104 shnum()
106 this->initialize_shnum();
107 return this->shnum_;
110 // Return the section index of the section name string table.
111 unsigned int
112 shstrndx()
114 this->initialize_shnum();
115 return this->shstrndx_;
118 // Return the value to subtract from section indexes >=
119 // SHN_LORESERVE. See the comment in initialize_shnum.
121 large_shndx_offset()
123 this->initialize_shnum();
124 return this->large_shndx_offset_;
127 // Return the location of the header of section SHNDX.
128 typename File::Location
129 section_header(unsigned int shndx)
131 return typename File::Location(this->section_header_offset(shndx),
132 shdr_size);
135 // Return the name of section SHNDX.
136 std::string
137 section_name(unsigned int shndx);
139 // Return the location of the contents of section SHNDX.
140 typename File::Location
141 section_contents(unsigned int shndx);
143 // Return the size of section SHNDX.
144 typename Elf_types<size>::Elf_WXword
145 section_size(unsigned int shndx);
147 // Return the flags of section SHNDX.
148 typename Elf_types<size>::Elf_WXword
149 section_flags(unsigned int shndx);
151 // Return the address of section SHNDX.
152 typename Elf_types<size>::Elf_Addr
153 section_addr(unsigned int shndx);
155 // Return the type of section SHNDX.
156 Elf_Word
157 section_type(unsigned int shndx);
159 // Return the link field of section SHNDX.
160 Elf_Word
161 section_link(unsigned int shndx);
163 // Return the info field of section SHNDX.
164 Elf_Word
165 section_info(unsigned int shndx);
167 // Return the addralign field of section SHNDX.
168 typename Elf_types<size>::Elf_WXword
169 section_addralign(unsigned int shndx);
171 private:
172 // Shared constructor code.
173 void
174 construct(File* file, const Ef_ehdr& ehdr);
176 // Initialize shnum_ and shstrndx_.
177 void
178 initialize_shnum();
180 // Return the file offset of the header of section SHNDX.
181 off_t
182 section_header_offset(unsigned int shndx);
184 // The file we are reading.
185 File* file_;
186 // The file offset to the section headers.
187 off_t shoff_;
188 // The number of sections.
189 unsigned int shnum_;
190 // The section index of the section name string table.
191 unsigned int shstrndx_;
192 // Offset to add to sections larger than SHN_LORESERVE.
193 int large_shndx_offset_;
196 // Template function definitions.
198 // Construct an Elf_file given an ELF file header.
200 template<int size, bool big_endian, typename File>
201 void
202 Elf_file<size, big_endian, File>::construct(File* file, const Ef_ehdr& ehdr)
204 this->file_ = file;
205 this->shoff_ = ehdr.get_e_shoff();
206 this->shnum_ = ehdr.get_e_shnum();
207 this->shstrndx_ = ehdr.get_e_shstrndx();
208 this->large_shndx_offset_ = 0;
209 if (ehdr.get_e_ehsize() != This::ehdr_size)
210 file->error(_("bad e_ehsize (%d != %d)"),
211 ehdr.get_e_ehsize(), This::ehdr_size);
212 if (ehdr.get_e_shentsize() != This::shdr_size)
213 file->error(_("bad e_shentsize (%d != %d)"),
214 ehdr.get_e_shentsize(), This::shdr_size);
217 // Construct an ELF file.
219 template<int size, bool big_endian, typename File>
220 inline
221 Elf_file<size, big_endian, File>::Elf_file(File* file)
223 typename File::View v(file->view(file_header_offset, This::ehdr_size));
224 this->construct(file, Ef_ehdr(v.data()));
227 // Initialize the shnum_ and shstrndx_ fields, handling overflow.
229 template<int size, bool big_endian, typename File>
230 void
231 Elf_file<size, big_endian, File>::initialize_shnum()
233 if ((this->shnum_ == 0 || this->shstrndx_ == SHN_XINDEX)
234 && this->shoff_ != 0)
236 typename File::View v(this->file_->view(this->shoff_, This::shdr_size));
237 Ef_shdr shdr(v.data());
239 if (this->shnum_ == 0)
240 this->shnum_ = shdr.get_sh_size();
242 if (this->shstrndx_ == SHN_XINDEX)
244 this->shstrndx_ = shdr.get_sh_link();
246 // Versions of the GNU binutils between 2.12 and 2.18 did
247 // not handle objects with more than SHN_LORESERVE sections
248 // correctly. All large section indexes were offset by
249 // 0x100. Some information can be found here:
250 // http://sourceware.org/bugzilla/show_bug.cgi?id=5900 .
251 // Fortunately these object files are easy to detect, as the
252 // GNU binutils always put the section header string table
253 // near the end of the list of sections. Thus if the
254 // section header string table index is larger than the
255 // number of sections, then we know we have to subtract
256 // 0x100 to get the real section index.
257 if (this->shstrndx_ >= this->shnum_)
259 if (this->shstrndx_ >= elfcpp::SHN_LORESERVE + 0x100)
261 this->large_shndx_offset_ = - 0x100;
262 this->shstrndx_ -= 0x100;
264 if (this->shstrndx_ >= this->shnum_)
265 this->file_->error(_("bad shstrndx: %u >= %u"),
266 this->shstrndx_, this->shnum_);
272 // Return the file offset of the section header of section SHNDX.
274 template<int size, bool big_endian, typename File>
275 off_t
276 Elf_file<size, big_endian, File>::section_header_offset(unsigned int shndx)
278 if (shndx >= this->shnum())
279 this->file_->error(_("section_header_offset: bad shndx %u >= %u"),
280 shndx, this->shnum());
281 return this->shoff_ + This::shdr_size * shndx;
284 // Return the name of section SHNDX.
286 template<int size, bool big_endian, typename File>
287 std::string
288 Elf_file<size, big_endian, File>::section_name(unsigned int shndx)
290 File* const file = this->file_;
292 // Get the section name offset.
293 unsigned int sh_name;
295 typename File::View v(file->view(this->section_header_offset(shndx),
296 This::shdr_size));
297 Ef_shdr shdr(v.data());
298 sh_name = shdr.get_sh_name();
301 // Get the file offset for the section name string table data.
302 off_t shstr_off;
303 off_t shstr_size;
305 const unsigned int shstrndx = this->shstrndx_;
306 typename File::View v(file->view(this->section_header_offset(shstrndx),
307 This::shdr_size));
308 Ef_shdr shstr_shdr(v.data());
309 shstr_off = shstr_shdr.get_sh_offset();
310 shstr_size = shstr_shdr.get_sh_size();
313 if (sh_name >= shstr_size)
314 file->error(_("bad section name offset for section %u: %u"),
315 shndx, sh_name);
317 typename File::View v(file->view(shstr_off, shstr_size));
319 const unsigned char* datau = v.data();
320 const char* data = reinterpret_cast<const char*>(datau);
321 const void* p = ::memchr(data + sh_name, '\0', shstr_size - sh_name);
322 if (p == NULL)
323 file->error(_("missing null terminator for name of section %u"),
324 shndx);
326 size_t len = static_cast<const char*>(p) - (data + sh_name);
328 return std::string(data + sh_name, len);
331 // Return the contents of section SHNDX.
333 template<int size, bool big_endian, typename File>
334 typename File::Location
335 Elf_file<size, big_endian, File>::section_contents(unsigned int shndx)
337 File* const file = this->file_;
339 if (shndx >= this->shnum())
340 file->error(_("section_contents: bad shndx %u >= %u"),
341 shndx, this->shnum());
343 typename File::View v(file->view(this->section_header_offset(shndx),
344 This::shdr_size));
345 Ef_shdr shdr(v.data());
346 return typename File::Location(shdr.get_sh_offset(), shdr.get_sh_size());
349 // Get the size of section SHNDX.
351 template<int size, bool big_endian, typename File>
352 typename Elf_types<size>::Elf_WXword
353 Elf_file<size, big_endian, File>::section_size(unsigned int shndx)
355 File* const file = this->file_;
357 if (shndx >= this->shnum())
358 file->error(_("section_size: bad shndx %u >= %u"),
359 shndx, this->shnum());
361 typename File::View v(file->view(this->section_header_offset(shndx),
362 This::shdr_size));
364 Ef_shdr shdr(v.data());
365 return shdr.get_sh_size();
368 // Return the section flags of section SHNDX.
370 template<int size, bool big_endian, typename File>
371 typename Elf_types<size>::Elf_WXword
372 Elf_file<size, big_endian, File>::section_flags(unsigned int shndx)
374 File* const file = this->file_;
376 if (shndx >= this->shnum())
377 file->error(_("section_flags: bad shndx %u >= %u"),
378 shndx, this->shnum());
380 typename File::View v(file->view(this->section_header_offset(shndx),
381 This::shdr_size));
383 Ef_shdr shdr(v.data());
384 return shdr.get_sh_flags();
387 // Return the address of section SHNDX.
389 template<int size, bool big_endian, typename File>
390 typename Elf_types<size>::Elf_Addr
391 Elf_file<size, big_endian, File>::section_addr(unsigned int shndx)
393 File* const file = this->file_;
395 if (shndx >= this->shnum())
396 file->error(_("section_flags: bad shndx %u >= %u"),
397 shndx, this->shnum());
399 typename File::View v(file->view(this->section_header_offset(shndx),
400 This::shdr_size));
402 Ef_shdr shdr(v.data());
403 return shdr.get_sh_addr();
406 // Return the type of section SHNDX.
408 template<int size, bool big_endian, typename File>
409 Elf_Word
410 Elf_file<size, big_endian, File>::section_type(unsigned int shndx)
412 File* const file = this->file_;
414 if (shndx >= this->shnum())
415 file->error(_("section_type: bad shndx %u >= %u"),
416 shndx, this->shnum());
418 typename File::View v(file->view(this->section_header_offset(shndx),
419 This::shdr_size));
421 Ef_shdr shdr(v.data());
422 return shdr.get_sh_type();
425 // Return the sh_link field of section SHNDX.
427 template<int size, bool big_endian, typename File>
428 Elf_Word
429 Elf_file<size, big_endian, File>::section_link(unsigned int shndx)
431 File* const file = this->file_;
433 if (shndx >= this->shnum())
434 file->error(_("section_link: bad shndx %u >= %u"),
435 shndx, this->shnum());
437 typename File::View v(file->view(this->section_header_offset(shndx),
438 This::shdr_size));
440 Ef_shdr shdr(v.data());
441 return shdr.get_sh_link();
444 // Return the sh_info field of section SHNDX.
446 template<int size, bool big_endian, typename File>
447 Elf_Word
448 Elf_file<size, big_endian, File>::section_info(unsigned int shndx)
450 File* const file = this->file_;
452 if (shndx >= this->shnum())
453 file->error(_("section_info: bad shndx %u >= %u"),
454 shndx, this->shnum());
456 typename File::View v(file->view(this->section_header_offset(shndx),
457 This::shdr_size));
459 Ef_shdr shdr(v.data());
460 return shdr.get_sh_info();
463 // Return the sh_addralign field of section SHNDX.
465 template<int size, bool big_endian, typename File>
466 typename Elf_types<size>::Elf_WXword
467 Elf_file<size, big_endian, File>::section_addralign(unsigned int shndx)
469 File* const file = this->file_;
471 if (shndx >= this->shnum())
472 file->error(_("section_addralign: bad shndx %u >= %u"),
473 shndx, this->shnum());
475 typename File::View v(file->view(this->section_header_offset(shndx),
476 This::shdr_size));
478 Ef_shdr shdr(v.data());
479 return shdr.get_sh_addralign();
482 } // End namespace elfcpp.
484 #endif // !defined(ELFCPP_FILE_H)