File: script.h

package info (click to toggle)
binutils 2.28-5
  • links: PTS, VCS
  • area: main
  • in suites: stretch
  • size: 271,848 kB
  • sloc: ansic: 1,419,727; asm: 623,424; cpp: 125,042; exp: 64,226; makefile: 56,536; sh: 21,234; lisp: 15,206; yacc: 14,889; perl: 2,111; ada: 1,681; lex: 1,645; pascal: 1,438; cs: 879; sed: 195; python: 154; xml: 95; awk: 25
file content (596 lines) | stat: -rw-r--r-- 18,806 bytes parent folder | download
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
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
// script.h -- handle linker scripts for gold   -*- C++ -*-

// Copyright (C) 2006-2017 Free Software Foundation, Inc.
// Written by Ian Lance Taylor <iant@google.com>.

// This file is part of gold.

// This program is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation; either version 3 of the License, or
// (at your option) any later version.

// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
// MA 02110-1301, USA.

// We implement a subset of the original GNU ld linker script language
// for compatibility.  The goal is not to implement the entire
// language.  It is merely to implement enough to handle common uses.
// In particular we need to handle /usr/lib/libc.so on a typical
// GNU/Linux system, and we want to handle linker scripts used by the
// Linux kernel build.

#ifndef GOLD_SCRIPT_H
#define GOLD_SCRIPT_H

#include <cstdio>
#include <string>
#include <vector>

#include "elfcpp.h"
#include "script-sections.h"

namespace gold
{

class General_options;
class Command_line;
class Symbol_table;
class Layout;
class Mapfile;
class Input_argument;
class Input_arguments;
class Input_objects;
class Input_group;
class Input_file;
class Output_segment;
class Task_token;
class Workqueue;
struct Version_dependency_list;
struct Version_expression_list;
struct Version_tree;
struct Version_expression;
class Lazy_demangler;
class Incremental_script_entry;

// This class represents an expression in a linker script.

class Expression
{
 protected:
  // These should only be created by child classes.
  Expression()
  { }

 public:
  virtual ~Expression()
  { }

  // Return the value of the expression which is not permitted to
  // refer to the dot symbol.  CHECK_ASSERTIONS is true if we should
  // check whether assertions are true.
  uint64_t
  eval(const Symbol_table*, const Layout*, bool check_assertions);

  // Return the value of an expression which is permitted to refer to
  // the dot symbol.  DOT_VALUE is the absolute value of the dot
  // symbol.  DOT_SECTION is the section in which dot is defined; it
  // should be NULL if the dot symbol has an absolute value (e.g., is
  // defined in a SECTIONS clause outside of any output section
  // definition).  This sets *RESULT_SECTION to indicate where the
  // value is defined.  If the value is absolute *RESULT_SECTION will
  // be NULL.  Note that the returned value is still an absolute
  // value; to get a section relative value the caller must subtract
  // the section address.  If RESULT_ALIGNMENT is not NULL, this sets
  // *RESULT_ALIGNMENT to the alignment of the value of that alignment
  // is larger than *RESULT_ALIGNMENT; this will only be non-zero if
  // this is an ALIGN expression.  If IS_SECTION_DOT_ASSIGMENT is true,
  // we are evaluating an assignment to dot within an output section,
  // and an absolute value should be interpreted as an offset within
  // the section.
  uint64_t
  eval_with_dot(const Symbol_table*, const Layout*, bool check_assertions,
		uint64_t dot_value, Output_section* dot_section,
		Output_section** result_section, uint64_t* result_alignment,
		bool is_section_dot_assignment);

  // Return the value of an expression which may or may not be
  // permitted to refer to the dot symbol, depending on
  // is_dot_available.  If IS_SECTION_DOT_ASSIGMENT is true,
  // we are evaluating an assignment to dot within an output section,
  // and an absolute value should be interpreted as an offset within
  // the section.
  uint64_t
  eval_maybe_dot(const Symbol_table*, const Layout*, bool check_assertions,
		 bool is_dot_available, uint64_t dot_value,
		 Output_section* dot_section,
		 Output_section** result_section, uint64_t* result_alignment,
		 elfcpp::STT* type, elfcpp::STV* vis, unsigned char* nonvis,
		 bool is_section_dot_assignment, bool* is_valid_pointer);

  // Print the expression to the FILE.  This is for debugging.
  virtual void
  print(FILE*) const = 0;

 protected:
  struct Expression_eval_info;

 public:
  // Compute the value of the expression (implemented by child class).
  // This is public rather than protected because it is called
  // directly by children of Expression on other Expression objects.
  virtual uint64_t
  value(const Expression_eval_info*) = 0;

 private:
  // May not be copied.
  Expression(const Expression&);
  Expression& operator=(const Expression&);
};


// Version_script_info stores information parsed from the version
// script, either provided by --version-script or as part of a linker
// script.  A single Version_script_info object per target is owned by
// Script_options.

class Version_script_info
{
 public:
  // The languages which can be specified in a versionn script.
  enum Language
  {
    LANGUAGE_C,		// No demangling.
    LANGUAGE_CXX,	// C++ demangling.
    LANGUAGE_JAVA,	// Java demangling.
    LANGUAGE_COUNT
  };

  Version_script_info();

  ~Version_script_info();

  // Clear everything.
  void
  clear();

  // Finalize the version control information.
  void
  finalize();

  // Return whether the information is finalized.
  bool
  is_finalized() const
  { return this->is_finalized_; }

  // Return whether any version were defined in the version script.
  bool
  empty() const
  { return this->version_trees_.empty(); }

  // If there is a version associated with SYMBOL, return true, and
  // set *VERSION to the version, and *IS_GLOBAL to whether the symbol
  // should be global.  Otherwise, return false.
  bool
  get_symbol_version(const char* symbol, std::string* version,
		     bool* is_global) const;

  // Return whether this symbol matches the local: section of some
  // version.
  bool
  symbol_is_local(const char* symbol) const
  {
    bool is_global;
    return (this->get_symbol_version(symbol, NULL, &is_global)
	    && !is_global);
  }

  // Return the names of versions defined in the version script.
  std::vector<std::string>
  get_versions() const;

  // Return the list of dependencies for this version.
  std::vector<std::string>
  get_dependencies(const char* version) const;

  // The following functions should only be used by the bison helper
  // functions.  They allocate new structs whose memory belongs to
  // Version_script_info.  The bison functions copy the information
  // from the version script into these structs.
  struct Version_dependency_list*
  allocate_dependency_list();

  struct Version_expression_list*
  allocate_expression_list();

  struct Version_tree*
  allocate_version_tree();

  // Build the lookup tables after all data have been read.
  void
  build_lookup_tables();

  // Give an error if there are any unmatched names in the version
  // script.
  void
  check_unmatched_names(const Symbol_table*) const;

  // Print contents to the FILE.  This is for debugging.
  void
  print(FILE*) const;

 private:
  void
  print_expression_list(FILE* f, const Version_expression_list*) const;

  bool
  get_symbol_version_helper(const char* symbol,
			    bool check_global,
			    std::string* pversion) const;

  // Fast lookup information for a given language.

  // We map from exact match strings to Version_tree's.  Historically
  // version scripts sometimes have the same symbol multiple times,
  // which is ambiguous.  We warn about that case by storing the
  // second Version_tree we see.
  struct Version_tree_match
  {
    Version_tree_match(const Version_tree* r, bool ig,
		       const Version_expression* e)
      : real(r), is_global(ig), expression(e), ambiguous(NULL)
    { }

    // The Version_tree that we return.
    const Version_tree* real;
    // True if this is a global match for the REAL member, false if it
    // is a local match.
    bool is_global;
    // Point back to the Version_expression for which we created this
    // match.
    const Version_expression* expression;
    // If not NULL, another Version_tree that defines the symbol.
    const Version_tree* ambiguous;
  };

  // Map from an exact match string to a Version_tree.

  typedef Unordered_map<std::string, Version_tree_match> Exact;

  // Fast lookup information for a glob pattern.
  struct Glob
  {
    Glob()
      : expression(NULL), version(NULL), is_global(false)
    { }

    Glob(const Version_expression* e, const Version_tree* v, bool ig)
      : expression(e), version(v), is_global(ig)
    { }

    // A pointer to the version expression holding the pattern to
    // match and the language to use for demangling the symbol before
    // doing the match.
    const Version_expression* expression;
    // The Version_tree we use if this pattern matches.
    const Version_tree* version;
    // True if this is a global symbol.
    bool is_global;
  };

  typedef std::vector<Glob> Globs;

  bool
  unquote(std::string*) const;

  void
  add_exact_match(const std::string&, const Version_tree*, bool is_global,
		  const Version_expression*, Exact*);

  void
  build_expression_list_lookup(const Version_expression_list*,
			       const Version_tree*, bool);

  const char*
  get_name_to_match(const char*, int,
		    Lazy_demangler*, Lazy_demangler*) const;

  // All the version dependencies we allocate.
  std::vector<Version_dependency_list*> dependency_lists_;
  // All the version expressions we allocate.
  std::vector<Version_expression_list*> expression_lists_;
  // The list of versions.
  std::vector<Version_tree*> version_trees_;
  // Exact matches for global symbols, by language.
  Exact* exact_[LANGUAGE_COUNT];
  // A vector of glob patterns mapping to Version_trees.
  Globs globs_;
  // The default version to use, if there is one.  This is from a
  // pattern of "*".
  const Version_tree* default_version_;
  // True if the default version is global.
  bool default_is_global_;
  // Whether this has been finalized.
  bool is_finalized_;
};

// This class manages assignments to symbols.  These can appear in
// three different locations in scripts: outside of a SECTIONS clause,
// within a SECTIONS clause, and within an output section definition
// within a SECTIONS clause.  This can also appear on the command line
// via the --defsym command line option.

class Symbol_assignment
{
 public:
  Symbol_assignment(const char* name, size_t namelen, bool is_defsym,
		    Expression* val, bool provide, bool hidden)
    : name_(name, namelen), val_(val), is_defsym_(is_defsym),
      provide_(provide), hidden_(hidden), sym_(NULL)
  { }

  // Add the symbol to the symbol table.
  void
  add_to_table(Symbol_table*);

  // Finalize the symbol value.
  void
  finalize(Symbol_table*, const Layout*);

  // Finalize the symbol value when it can refer to the dot symbol.
  void
  finalize_with_dot(Symbol_table*, const Layout*, uint64_t dot_value,
		    Output_section* dot_section);

  // Set the symbol value, but only if the value is absolute or relative to
  // DOT_SECTION.  This is used while processing a SECTIONS clause.
  // We assume that dot is an absolute value here.  We do not check assertions.
  void
  set_if_absolute(Symbol_table*, const Layout*, bool is_dot_available,
		  uint64_t dot_value, Output_section* dot_section);

  const std::string&
  name() const
  { return this->name_; }

  // Print the assignment to the FILE.  This is for debugging.
  void
  print(FILE*) const;

 private:
  // Shared by finalize and finalize_with_dot.
  void
  finalize_maybe_dot(Symbol_table*, const Layout*, bool is_dot_available,
		     uint64_t dot_value, Output_section* dot_section);

  // Sized version of finalize.
  template<int size>
  void
  sized_finalize(Symbol_table*, const Layout*, bool is_dot_available,
		 uint64_t dot_value, Output_section*);

  // Symbol name.
  std::string name_;
  // Expression to assign to symbol.
  Expression* val_;
  // True if this symbol is defined by a --defsym, false if it is
  // defined in a linker script.
  bool is_defsym_;
  // Whether the assignment should be provided (only set if there is
  // an undefined reference to the symbol.
  bool provide_;
  // Whether the assignment should be hidden.
  bool hidden_;
  // The entry in the symbol table.
  Symbol* sym_;
};

// This class manages assertions in linker scripts.  These can appear
// in all the places where a Symbol_assignment can appear.

class Script_assertion
{
 public:
  Script_assertion(Expression* check, const char* message,
		   size_t messagelen)
    : check_(check), message_(message, messagelen)
  { }

  // Check the assertion.
  void
  check(const Symbol_table*, const Layout*);

  // Print the assertion to the FILE.  This is for debugging.
  void
  print(FILE*) const;

 private:
  // The expression to check.
  Expression* check_;
  // The message to issue if the expression fails.
  std::string message_;
};

// We can read a linker script in two different contexts: when
// initially parsing the command line, and when we find an input file
// which is actually a linker script.  Also some of the data which can
// be set by a linker script can also be set via command line options
// like -e and --defsym.  This means that we have a type of data which
// can be set both during command line option parsing and while
// reading input files.  We store that data in an instance of this
// object.  We will keep pointers to that instance in both the
// Command_line and Layout objects.

class Script_options
{
 public:
  Script_options();

  // Add a symbol to be defined.
  void
  add_symbol_assignment(const char* name, size_t length, bool is_defsym,
			Expression* value, bool provide, bool hidden);

  // Look for an assigned symbol.
  bool
  is_pending_assignment(const char* name);
  
  // Add a reference to a symbol.
  void
  add_symbol_reference(const char* name, size_t length);

  // Add an assertion.
  void
  add_assertion(Expression* check, const char* message, size_t messagelen);

  // Define a symbol from the command line.
  bool
  define_symbol(const char* definition);

  // Create sections required by any linker scripts.
  void
  create_script_sections(Layout*);

  // Add all symbol definitions to the symbol table.
  void
  add_symbols_to_table(Symbol_table*);

  // Used to iterate over symbols which are referenced in expressions
  // but not defined.
  typedef Unordered_set<std::string>::const_iterator referenced_const_iterator;

  referenced_const_iterator
  referenced_begin() const
  { return this->symbol_references_.begin(); }

  referenced_const_iterator
  referenced_end() const
  { return this->symbol_references_.end(); }

  // Return whether a symbol is referenced but not defined.
  bool
  is_referenced(const std::string& name) const
  {
    return (this->symbol_references_.find(name)
	    != this->symbol_references_.end());
  }

  // Return whether there are any symbols which were referenced but
  // not defined.
  bool
  any_unreferenced() const
  { return !this->symbol_references_.empty(); }

  // Finalize the symbol values.  Also check assertions.
  void
  finalize_symbols(Symbol_table*, const Layout*);

  // Version information parsed from a version script.  Everything
  // else has a pointer to this object.
  Version_script_info*
  version_script_info()
  { return &this->version_script_info_; }

  const Version_script_info*
  version_script_info() const
  { return &this->version_script_info_; }

  // A SECTIONS clause parsed from a linker script.  Everything else
  // has a pointer to this object.
  Script_sections*
  script_sections()
  { return &this->script_sections_; }

  const Script_sections*
  script_sections() const
  { return &this->script_sections_; }

  // Whether we saw a SECTIONS clause.
  bool
  saw_sections_clause() const
  { return this->script_sections_.saw_sections_clause(); }

  // Whether we saw a PHDRS clause.
  bool
  saw_phdrs_clause() const
  { return this->script_sections_.saw_phdrs_clause(); }

  // Set section addresses using a SECTIONS clause.  Return the
  // segment which should hold the file header and segment headers;
  // this may return NULL, in which case the headers are not in a
  // loadable segment.
  Output_segment*
  set_section_addresses(Symbol_table*, Layout*);

  // Print the script to the FILE.  This is for debugging.
  void
  print(FILE*) const;

 private:
  // We keep a list of symbol assignments which occur outside of a
  // SECTIONS clause.
  typedef std::vector<Symbol_assignment*> Symbol_assignments;

  // We keep a list of all assertions which occur outside of a
  // SECTIONS clause.
  typedef std::vector<Script_assertion*> Assertions;

  // The entry address.  This will be empty if not set.
  std::string entry_;
  // Symbols to set.
  Symbol_assignments symbol_assignments_;
  // Symbols defined in an expression, for faster lookup.
  Unordered_set<std::string> symbol_definitions_;
  // Symbols referenced in an expression.
  Unordered_set<std::string> symbol_references_;
  // Assertions to check.
  Assertions assertions_;
  // Version information parsed from a version script.
  Version_script_info version_script_info_;
  // Information from any SECTIONS clauses.
  Script_sections script_sections_;
};

// FILE was found as an argument on the command line, but was not
// recognized as an ELF file.  Try to read it as a script.  Return
// true if the file was handled.  This has to handle /usr/lib/libc.so
// on a GNU/Linux system.  *USED_NEXT_BLOCKER is set to indicate
// whether the function took over NEXT_BLOCKER.

bool
read_input_script(Workqueue*, Symbol_table*, Layout*, Dirsearch*, int,
		  Input_objects*, Mapfile*, Input_group*,
		  const Input_argument*, Input_file*,
		  Task_token* next_blocker, bool* used_next_blocker);

// FILE was found as an argument to --script (-T).
// Read it as a script, and execute its contents immediately.

bool
read_commandline_script(const char* filename, Command_line* cmdline);

// FILE was found as an argument to --version-script.  Read it as a
// version script, and store its contents in
// cmdline->script_options()->version_script_info().

bool
read_version_script(const char* filename, Command_line* cmdline);

// FILENAME was found as an argument to --dynamic-list.  Read it as a
// version script (actually, a versym_node from a version script), and
// store its contents in DYNAMIC_LIST.

bool
read_dynamic_list(const char* filename, Command_line* cmdline,
                  Script_options* dynamic_list);

} // End namespace gold.

#endif // !defined(GOLD_SCRIPT_H)