aboutsummaryrefslogtreecommitdiff
path: root/gold/dynobj.h
blob: 476b602f30b54c562d8e251cc18b14b6bbc4951d (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
// dynobj.h -- dynamic object support for gold   -*- C++ -*-

#ifndef GOLD_DYNOBJ_H
#define GOLD_DYNOBJ_H

#include <vector>

#include "stringpool.h"
#include "object.h"

namespace gold
{

class General_options;
class Stringpool;

// A dynamic object (ET_DYN).  This is an abstract base class itself.
// The implementations is the template class Sized_dynobj.

class Dynobj : public Object
{
 public:
  Dynobj(const std::string& name, Input_file* input_file, off_t offset = 0)
    : Object(name, input_file, true, offset), soname_()
  { }

  // Return the name to use in a DT_NEEDED entry for this object.
  const char*
  soname() const;

  // Compute the ELF hash code for a string.
  static uint32_t
  elf_hash(const char*);

  // Create a standard ELF hash table, setting *PPHASH and *PHASHLEN.
  // DYNSYMS is the global dynamic symbols.  LOCAL_DYNSYM_COUNT is the
  // number of local dynamic symbols, which is the index of the first
  // dynamic gobal symbol.
  static void
  create_elf_hash_table(const Target*, const std::vector<Symbol*>& dynsyms,
			unsigned int local_dynsym_count,
			unsigned char** pphash,
			unsigned int* phashlen);

  // Create a GNU hash table, setting *PPHASH and *PHASHLEN.  DYNSYMS
  // is the global dynamic symbols.  LOCAL_DYNSYM_COUNT is the number
  // of local dynamic symbols, which is the index of the first dynamic
  // gobal symbol.
  static void
  create_gnu_hash_table(const Target*, const std::vector<Symbol*>& dynsyms,
			unsigned int local_dynsym_count,
			unsigned char** pphash, unsigned int* phashlen);

 protected:
  // Set the DT_SONAME string.
  void
  set_soname_string(const char* s)
  { this->soname_.assign(s); }

 private:
  // Compute the GNU hash code for a string.
  static uint32_t
  gnu_hash(const char*);

  // Compute the number of hash buckets to use.
  static unsigned int
  compute_bucket_count(const std::vector<uint32_t>& hashcodes,
		       bool for_gnu_hash_table);

  // Sized version of create_elf_hash_table.
  template<bool big_endian>
  static void
  sized_create_elf_hash_table(const std::vector<uint32_t>& bucket,
			      const std::vector<uint32_t>& chain,
			      unsigned char* phash,
			      unsigned int hashlen);

  // Sized version of create_gnu_hash_table.
  template<int size, bool big_endian>
  static void
  sized_create_gnu_hash_table(const std::vector<Symbol*>& hashed_dynsyms,
			      const std::vector<uint32_t>& dynsym_hashvals,
			      unsigned int unhashed_dynsym_count,
			      unsigned char** pphash,
			      unsigned int* phashlen);

  // The DT_SONAME name, if any.
  std::string soname_;
};

// A dynamic object, size and endian specific version.

template<int size, bool big_endian>
class Sized_dynobj : public Dynobj
{
 public:
  Sized_dynobj(const std::string& name, Input_file* input_file, off_t offset,
	       const typename elfcpp::Ehdr<size, big_endian>&);

  // Set up the object file based on the ELF header.
  void
  setup(const typename elfcpp::Ehdr<size, big_endian>&);

  // Read the symbols.
  void
  do_read_symbols(Read_symbols_data*);

  // Lay out the input sections.
  void
  do_layout(const General_options&, Symbol_table*, Layout*,
	    Read_symbols_data*);

  // Add the symbols to the symbol table.
  void
  do_add_symbols(Symbol_table*, Read_symbols_data*);

  // Get the name of a section.
  std::string
  do_section_name(unsigned int shndx)
  { return this->elf_file_.section_name(shndx); }

  // Return a view of the contents of a section.  Set *PLEN to the
  // size.
  Object::Location
  do_section_contents(unsigned int shndx)
  { return this->elf_file_.section_contents(shndx); }

  // Return section flags.
  uint64_t
  do_section_flags(unsigned int shndx)
  { return this->elf_file_.section_flags(shndx); }

 private:
  // For convenience.
  typedef Sized_dynobj<size, big_endian> This;
  static const int shdr_size = elfcpp::Elf_sizes<size>::shdr_size;
  static const int sym_size = elfcpp::Elf_sizes<size>::sym_size;
  static const int dyn_size = elfcpp::Elf_sizes<size>::dyn_size;
  typedef elfcpp::Shdr<size, big_endian> Shdr;
  typedef elfcpp::Dyn<size, big_endian> Dyn;

  // Find the dynamic symbol table and the version sections, given the
  // section headers.
  void
  find_dynsym_sections(const unsigned char* pshdrs,
		       unsigned int* pdynshm_shndx,
		       unsigned int* pversym_shndx,
		       unsigned int* pverdef_shndx,
		       unsigned int* pverneed_shndx,
		       unsigned int* pdynamic_shndx);

  // Read the dynamic symbol section SHNDX.
  void
  read_dynsym_section(const unsigned char* pshdrs, unsigned int shndx,
		      elfcpp::SHT type, unsigned int link,
		      File_view** view, off_t* view_size,
		      unsigned int* view_info);

  // Set the SONAME from the SHT_DYNAMIC section at DYNAMIC_SHNDX.
  // The STRTAB parameters may have the relevant string table.
  void
  set_soname(const unsigned char* pshdrs, unsigned int dynamic_shndx,
	     unsigned int strtab_shndx, const unsigned char* strtabu,
	     off_t strtab_size);

  // Mapping from version number to version name.
  typedef std::vector<const char*> Version_map;

  // Create the version map.
  void
  make_version_map(Read_symbols_data* sd, Version_map*) const;

  // Add version definitions to the version map.
  void
  make_verdef_map(Read_symbols_data* sd, Version_map*) const;

  // Add version references to the version map.
  void
  make_verneed_map(Read_symbols_data* sd, Version_map*) const;

  // Add an entry to the version map.
  void
  set_version_map(Version_map*, unsigned int ndx, const char* name) const;

  // General access to the ELF file.
  elfcpp::Elf_file<size, big_endian, Object> elf_file_;
};

// A base class for Verdef and Verneed_version which just handles the
// version index which will be stored in the SHT_GNU_versym section.

class Version_base
{
 public:
  Version_base()
    : index_(-1U)
  { }

  virtual
  ~Version_base()
  { }

  // Return the version index.
  unsigned int
  index() const
  {
    gold_assert(this->index_ != -1U);
    return this->index_;
  }

  // Set the version index.
  void
  set_index(unsigned int index)
  {
    gold_assert(this->index_ == -1U);
    this->index_ = index;
  }

  // Clear the weak flag in a version definition.
  virtual void
  clear_weak() = 0;

 private:
  Version_base(const Version_base&);
  Version_base& operator=(const Version_base&);

  // The index of the version definition or reference.
  unsigned int index_;
};

// This class handles a version being defined in the file we are
// generating.

class Verdef : public Version_base
{
 public:
  Verdef(const char* name, bool is_base, bool is_weak, bool is_symbol_created)
    : name_(name), deps_(), is_base_(is_base), is_weak_(is_weak),
      is_symbol_created_(is_symbol_created)
  { }

  // Return the version name.
  const char*
  name() const
  { return this->name_; }

  // Return the number of dependencies.
  unsigned int
  count_dependencies() const
  { return this->deps_.size(); }

  // Add a dependency to this version.  The NAME should be
  // canonicalized in the dynamic Stringpool.
  void
  add_dependency(const char* name)
  { this->deps_.push_back(name); }

  // Return whether this definition is weak.
  bool
  is_weak() const
  { return this->is_weak_; }

  // Clear the weak flag.
  void
  clear_weak()
  { this->is_weak_ = false; }

  // Return whether a version symbol has been created for this
  // definition.
  bool
  is_symbol_created() const
  { return this->is_symbol_created_; }

  // Write contents to buffer.
  template<int size, bool big_endian>
  unsigned char*
  write(const Stringpool*, bool is_last, unsigned char*
        ACCEPT_SIZE_ENDIAN) const;

 private:
  Verdef(const Verdef&);
  Verdef& operator=(const Verdef&);

  // The type of the list of version dependencies.  Each dependency
  // should be canonicalized in the dynamic Stringpool.
  typedef std::vector<const char*> Deps;

  // The name of this version.  This should be canonicalized in the
  // dynamic Stringpool.
  const char* name_;
  // A list of other versions which this version depends upon.
  Deps deps_;
  // Whether this is the base version.
  bool is_base_;
  // Whether this version is weak.
  bool is_weak_;
  // Whether a version symbol has been created.
  bool is_symbol_created_;
};

// A referened version.  This will be associated with a filename by
// Verneed.

class Verneed_version : public Version_base
{
 public:
  Verneed_version(const char* version)
    : version_(version)
  { }

  // Return the version name.
  const char*
  version() const
  { return this->version_; }

  // Clear the weak flag.  This is invalid for a reference.
  void
  clear_weak()
  { gold_unreachable(); }

 private:
  Verneed_version(const Verneed_version&);
  Verneed_version& operator=(const Verneed_version&);

  const char* version_;
};

// Version references in a single dynamic object.

class Verneed
{
 public:
  Verneed(const char* filename)
    : filename_(filename), need_versions_()
  { }

  ~Verneed();

  // Return the file name.
  const char*
  filename() const
  { return this->filename_; }

  // Return the number of versions.
  unsigned int
  count_versions() const
  { return this->need_versions_.size(); }

  // Add a version name.  The name should be canonicalized in the
  // dynamic Stringpool.  If the name is already present, this does
  // nothing.
  Verneed_version*
  add_name(const char* name);

  // Set the version indexes, starting at INDEX.  Return the updated
  // INDEX.
  unsigned int
  finalize(unsigned int index);

  // Write contents to buffer.
  template<int size, bool big_endian>
  unsigned char*
  write(const Stringpool*, bool is_last, unsigned char*
        ACCEPT_SIZE_ENDIAN) const;

 private:
  Verneed(const Verneed&);
  Verneed& operator=(const Verneed&);

  // The type of the list of version names.  Each name should be
  // canonicalized in the dynamic Stringpool.
  typedef std::vector<Verneed_version*> Need_versions;

  // The filename of the dynamic object.  This should be
  // canonicalized in the dynamic Stringpool.
  const char* filename_;
  // The list of version names.
  Need_versions need_versions_;
};

// This class handles version definitions and references which go into
// the output file.

class Versions
{
 public:
  Versions()
    : defs_(), needs_(), version_table_(), is_finalized_(false)
  { }

  ~Versions();

  // SYM is going into the dynamic symbol table and has a version.
  // Record the appropriate version information.
  void
  record_version(const General_options*, Stringpool*, const Symbol* sym);

  // Set the version indexes.  DYNSYM_INDEX is the index we should use
  // for the next dynamic symbol.  We add new dynamic symbols to SYMS
  // and return an updated DYNSYM_INDEX.
  unsigned int
  finalize(const Target*, Symbol_table* symtab, unsigned int dynsym_index,
	   std::vector<Symbol*>* syms);

  // Return whether there are any version definitions.
  bool
  any_defs() const
  { return !this->defs_.empty(); }

  // Return whether there are any version references.
  bool
  any_needs() const
  { return !this->needs_.empty(); }

  // Build an allocated buffer holding the contents of the symbol
  // version section (.gnu.version).
  template<int size, bool big_endian>
  void
  symbol_section_contents(const Stringpool*, unsigned int local_symcount,
			  const std::vector<Symbol*>& syms,
			  unsigned char**, unsigned int*
                          ACCEPT_SIZE_ENDIAN) const;

  // Build an allocated buffer holding the contents of the version
  // definition section (.gnu.version_d).
  template<int size, bool big_endian>
  void
  def_section_contents(const Stringpool*, unsigned char**,
		       unsigned int* psize, unsigned int* pentries
                       ACCEPT_SIZE_ENDIAN) const;

  // Build an allocated buffer holding the contents of the version
  // reference section (.gnu.version_r).
  template<int size, bool big_endian>
  void
  need_section_contents(const Stringpool*, unsigned char**,
			unsigned int* psize, unsigned int* pentries
                        ACCEPT_SIZE_ENDIAN) const;

 private:
  // The type of the list of version definitions.
  typedef std::vector<Verdef*> Defs;

  // The type of the list of version references.
  typedef std::vector<Verneed*> Needs;

  // Handle a symbol SYM defined with version VERSION.
  void
  add_def(const General_options*, const Symbol* sym, const char* version,
	  Stringpool::Key);

  // Add a reference to version NAME in file FILENAME.
  void
  add_need(Stringpool*, const char* filename, const char* name,
	   Stringpool::Key);

  // Return the version index to use for SYM.
  unsigned int
  version_index(const Stringpool*, const Symbol* sym) const;

  // We keep a hash table mapping canonicalized name/version pairs to
  // a version base.
  typedef std::pair<Stringpool::Key, Stringpool::Key> Key;

  struct Version_table_hash
  {
    size_t
    operator()(const Key& k) const
    { return k.first + k.second; }
  };

  struct Version_table_eq
  {
    bool
    operator()(const Key& k1, const Key& k2) const
    { return k1.first == k2.first && k1.second == k2.second; }
  };

  typedef Unordered_map<Key, Version_base*, Version_table_hash,
			Version_table_eq> Version_table;

  // The version definitions.
  Defs defs_;
  // The version references.
  Needs needs_;
  // The mapping from a canonicalized version/filename pair to a
  // version index.  The filename may be NULL.
  Version_table version_table_;
  // Whether the version indexes have been set.
  bool is_finalized_;
};

} // End namespace gold.

#endif // !defined(GOLD_DYNOBJ_H)