1 // script.h -- handle linker scripts for gold -*- C++ -*-
3 // Copyright 2006, 2007, 2008, 2009, 2010 Free Software Foundation, Inc.
4 // Written by Ian Lance Taylor <iant@google.com>.
6 // This file is part of gold.
8 // This program is free software; you can redistribute it and/or modify
9 // it under the terms of the GNU General Public License as published by
10 // the Free Software Foundation; either version 3 of the License, or
11 // (at your option) any later version.
13 // This program is distributed in the hope that it will be useful,
14 // but WITHOUT ANY WARRANTY; without even the implied warranty of
15 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 // GNU General Public License for more details.
18 // You should have received a copy of the GNU General Public License
19 // along with this program; if not, write to the Free Software
20 // Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
21 // MA 02110-1301, USA.
23 // We implement a subset of the original GNU ld linker script language
24 // for compatibility. The goal is not to implement the entire
25 // language. It is merely to implement enough to handle common uses.
26 // In particular we need to handle /usr/lib/libc.so on a typical
27 // GNU/Linux system, and we want to handle linker scripts used by the
28 // Linux kernel build.
37 #include "script-sections.h"
42 class General_options;
48 class Input_arguments;
55 struct Version_dependency_list;
56 struct Version_expression_list;
58 struct Version_expression;
61 // This class represents an expression in a linker script.
66 // These should only be created by child classes.
74 // Return the value of the expression which is not permitted to
75 // refer to the dot symbol. CHECK_ASSERTIONS is true if we should
76 // check whether assertions are true.
78 eval(const Symbol_table*, const Layout*, bool check_assertions);
80 // Return the value of an expression which is permitted to refer to
81 // the dot symbol. DOT_VALUE is the absolute value of the dot
82 // symbol. DOT_SECTION is the section in which dot is defined; it
83 // should be NULL if the dot symbol has an absolute value (e.g., is
84 // defined in a SECTIONS clause outside of any output section
85 // definition). This sets *RESULT_SECTION to indicate where the
86 // value is defined. If the value is absolute *RESULT_SECTION will
87 // be NULL. Note that the returned value is still an absolute
88 // value; to get a section relative value the caller must subtract
89 // the section address.
91 eval_with_dot(const Symbol_table*, const Layout*, bool check_assertions,
92 uint64_t dot_value, Output_section* dot_section,
93 Output_section** result_section);
95 // Return the value of an expression which may or may not be
96 // permitted to refer to the dot symbol, depending on
99 eval_maybe_dot(const Symbol_table*, const Layout*, bool check_assertions,
100 bool is_dot_available, uint64_t dot_value,
101 Output_section* dot_section,
102 Output_section** result_section);
104 // Print the expression to the FILE. This is for debugging.
106 print(FILE*) const = 0;
109 struct Expression_eval_info;
112 // Compute the value of the expression (implemented by child class).
113 // This is public rather than protected because it is called
114 // directly by children of Expression on other Expression objects.
116 value(const Expression_eval_info*) = 0;
119 // May not be copied.
120 Expression(const Expression&);
121 Expression& operator=(const Expression&);
125 // Version_script_info stores information parsed from the version
126 // script, either provided by --version-script or as part of a linker
127 // script. A single Version_script_info object per target is owned by
130 class Version_script_info
133 // The languages which can be specified in a versionn script.
136 LANGUAGE_C, // No demangling.
137 LANGUAGE_CXX, // C++ demangling.
138 LANGUAGE_JAVA, // Java demangling.
142 Version_script_info();
144 ~Version_script_info();
150 // Finalize the version control information.
154 // Return whether the information is finalized.
157 { return this->is_finalized_; }
159 // Return whether any version were defined in the version script.
162 { return this->version_trees_.empty(); }
164 // If there is a version associated with SYMBOL, return true, and
165 // set *VERSION to the version, and *IS_GLOBAL to whether the symbol
166 // should be global. Otherwise, return false.
168 get_symbol_version(const char* symbol, std::string* version,
169 bool* is_global) const;
171 // Return whether this symbol matches the local: section of some
174 symbol_is_local(const char* symbol) const
177 return (this->get_symbol_version(symbol, NULL, &is_global)
181 // Return the names of versions defined in the version script.
182 std::vector<std::string>
183 get_versions() const;
185 // Return the list of dependencies for this version.
186 std::vector<std::string>
187 get_dependencies(const char* version) const;
189 // The following functions should only be used by the bison helper
190 // functions. They allocate new structs whose memory belongs to
191 // Version_script_info. The bison functions copy the information
192 // from the version script into these structs.
193 struct Version_dependency_list*
194 allocate_dependency_list();
196 struct Version_expression_list*
197 allocate_expression_list();
200 allocate_version_tree();
202 // Build the lookup tables after all data have been read.
204 build_lookup_tables();
206 // Give an error if there are any unmatched names in the version
209 check_unmatched_names(const Symbol_table*) const;
211 // Print contents to the FILE. This is for debugging.
217 print_expression_list(FILE* f, const Version_expression_list*) const;
220 get_symbol_version_helper(const char* symbol,
222 std::string* pversion) const;
224 // Fast lookup information for a given language.
226 // We map from exact match strings to Version_tree's. Historically
227 // version scripts sometimes have the same symbol multiple times,
228 // which is ambiguous. We warn about that case by storing the
229 // second Version_tree we see.
230 struct Version_tree_match
232 Version_tree_match(const Version_tree* r, bool ig,
233 const Version_expression* e)
234 : real(r), is_global(ig), expression(e), ambiguous(NULL)
237 // The Version_tree that we return.
238 const Version_tree* real;
239 // True if this is a global match for the REAL member, false if it
242 // Point back to the Version_expression for which we created this
244 const Version_expression* expression;
245 // If not NULL, another Version_tree that defines the symbol.
246 const Version_tree* ambiguous;
249 // Map from an exact match string to a Version_tree.
251 typedef Unordered_map<std::string, Version_tree_match> Exact;
253 // Fast lookup information for a glob pattern.
257 : expression(NULL), version(NULL), is_global(false)
260 Glob(const Version_expression* e, const Version_tree* v, bool ig)
261 : expression(e), version(v), is_global(ig)
264 // A pointer to the version expression holding the pattern to
265 // match and the language to use for demangling the symbol before
267 const Version_expression* expression;
268 // The Version_tree we use if this pattern matches.
269 const Version_tree* version;
270 // True if this is a global symbol.
274 typedef std::vector<Glob> Globs;
277 unquote(std::string*) const;
280 add_exact_match(const std::string&, const Version_tree*, bool is_global,
281 const Version_expression*, Exact*);
284 build_expression_list_lookup(const Version_expression_list*,
285 const Version_tree*, bool);
288 get_name_to_match(const char*, int,
289 Lazy_demangler*, Lazy_demangler*) const;
291 // All the version dependencies we allocate.
292 std::vector<Version_dependency_list*> dependency_lists_;
293 // All the version expressions we allocate.
294 std::vector<Version_expression_list*> expression_lists_;
295 // The list of versions.
296 std::vector<Version_tree*> version_trees_;
297 // Exact matches for global symbols, by language.
298 Exact* exact_[LANGUAGE_COUNT];
299 // A vector of glob patterns mapping to Version_trees.
301 // The default version to use, if there is one. This is from a
303 const Version_tree* default_version_;
304 // True if the default version is global.
305 bool default_is_global_;
306 // Whether this has been finalized.
310 // This class manages assignments to symbols. These can appear in
311 // three different locations in scripts: outside of a SECTIONS clause,
312 // within a SECTIONS clause, and within an output section definition
313 // within a SECTIONS clause. This can also appear on the command line
314 // via the --defsym command line option.
316 class Symbol_assignment
319 Symbol_assignment(const char* name, size_t namelen, bool is_defsym,
320 Expression* val, bool provide, bool hidden)
321 : name_(name, namelen), val_(val), is_defsym_(is_defsym),
322 provide_(provide), hidden_(hidden), sym_(NULL)
325 // Add the symbol to the symbol table.
327 add_to_table(Symbol_table*);
329 // Finalize the symbol value.
331 finalize(Symbol_table*, const Layout*);
333 // Finalize the symbol value when it can refer to the dot symbol.
335 finalize_with_dot(Symbol_table*, const Layout*, uint64_t dot_value,
336 Output_section* dot_section);
338 // Set the symbol value, but only if the value is absolute. This is
339 // used while processing a SECTIONS clause. We assume that dot is
340 // an absolute value here. We do not check assertions.
342 set_if_absolute(Symbol_table*, const Layout*, bool is_dot_available,
345 // Print the assignment to the FILE. This is for debugging.
350 // Shared by finalize and finalize_with_dot.
352 finalize_maybe_dot(Symbol_table*, const Layout*, bool is_dot_available,
353 uint64_t dot_value, Output_section* dot_section);
355 // Sized version of finalize.
358 sized_finalize(Symbol_table*, const Layout*, bool is_dot_available,
359 uint64_t dot_value, Output_section*);
363 // Expression to assign to symbol.
365 // True if this symbol is defined by a --defsym, false if it is
366 // defined in a linker script.
368 // Whether the assignment should be provided (only set if there is
369 // an undefined reference to the symbol.
371 // Whether the assignment should be hidden.
373 // The entry in the symbol table.
377 // This class manages assertions in linker scripts. These can appear
378 // in all the places where a Symbol_assignment can appear.
380 class Script_assertion
383 Script_assertion(Expression* check, const char* message,
385 : check_(check), message_(message, messagelen)
388 // Check the assertion.
390 check(const Symbol_table*, const Layout*);
392 // Print the assertion to the FILE. This is for debugging.
397 // The expression to check.
399 // The message to issue if the expression fails.
400 std::string message_;
403 // We can read a linker script in two different contexts: when
404 // initially parsing the command line, and when we find an input file
405 // which is actually a linker script. Also some of the data which can
406 // be set by a linker script can also be set via command line options
407 // like -e and --defsym. This means that we have a type of data which
408 // can be set both during command line option parsing and while
409 // reading input files. We store that data in an instance of this
410 // object. We will keep pointers to that instance in both the
411 // Command_line and Layout objects.
418 // Add a symbol to be defined.
420 add_symbol_assignment(const char* name, size_t length, bool is_defsym,
421 Expression* value, bool provide, bool hidden);
425 add_assertion(Expression* check, const char* message, size_t messagelen);
427 // Define a symbol from the command line.
429 define_symbol(const char* definition);
431 // Create sections required by any linker scripts.
433 create_script_sections(Layout*);
435 // Add all symbol definitions to the symbol table.
437 add_symbols_to_table(Symbol_table*);
439 // Finalize the symbol values. Also check assertions.
441 finalize_symbols(Symbol_table*, const Layout*);
443 // Version information parsed from a version script. Everything
444 // else has a pointer to this object.
446 version_script_info()
447 { return &this->version_script_info_; }
449 const Version_script_info*
450 version_script_info() const
451 { return &this->version_script_info_; }
453 // A SECTIONS clause parsed from a linker script. Everything else
454 // has a pointer to this object.
457 { return &this->script_sections_; }
459 const Script_sections*
460 script_sections() const
461 { return &this->script_sections_; }
463 // Whether we saw a SECTIONS clause.
465 saw_sections_clause() const
466 { return this->script_sections_.saw_sections_clause(); }
468 // Whether we saw a PHDRS clause.
470 saw_phdrs_clause() const
471 { return this->script_sections_.saw_phdrs_clause(); }
473 // Set section addresses using a SECTIONS clause. Return the
474 // segment which should hold the file header and segment headers;
475 // this may return NULL, in which case the headers are not in a
478 set_section_addresses(Symbol_table*, Layout*);
480 // Print the script to the FILE. This is for debugging.
485 // We keep a list of symbol assignments which occur outside of a
487 typedef std::vector<Symbol_assignment*> Symbol_assignments;
489 // We keep a list of all assertions whcih occur outside of a
491 typedef std::vector<Script_assertion*> Assertions;
493 // The entry address. This will be empty if not set.
496 Symbol_assignments symbol_assignments_;
497 // Assertions to check.
498 Assertions assertions_;
499 // Version information parsed from a version script.
500 Version_script_info version_script_info_;
501 // Information from any SECTIONS clauses.
502 Script_sections script_sections_;
505 // Information about a script input that will persist during the whole linker
506 // run. Needed only during an incremental build to retrieve the input files
507 // added by this script.
512 Script_info(Input_arguments* inputs)
516 // Returns the input files included because of this script.
519 { return this->inputs_; }
522 Input_arguments* inputs_;
525 // FILE was found as an argument on the command line, but was not
526 // recognized as an ELF file. Try to read it as a script. Return
527 // true if the file was handled. This has to handle /usr/lib/libc.so
528 // on a GNU/Linux system. *USED_NEXT_BLOCKER is set to indicate
529 // whether the function took over NEXT_BLOCKER.
532 read_input_script(Workqueue*, Symbol_table*, Layout*, Dirsearch*, int,
533 Input_objects*, Mapfile*, Input_group*,
534 const Input_argument*, Input_file*,
535 Task_token* next_blocker, bool* used_next_blocker);
537 // FILE was found as an argument to --script (-T).
538 // Read it as a script, and execute its contents immediately.
541 read_commandline_script(const char* filename, Command_line* cmdline);
543 // FILE was found as an argument to --version-script. Read it as a
544 // version script, and store its contents in
545 // cmdline->script_options()->version_script_info().
548 read_version_script(const char* filename, Command_line* cmdline);
550 // FILENAME was found as an argument to --dynamic-list. Read it as a
551 // version script (actually, a versym_node from a version script), and
552 // store its contents in DYNAMIC_LIST.
555 read_dynamic_list(const char* filename, Command_line* cmdline,
556 Script_options* dynamic_list);
558 } // End namespace gold.
560 #endif // !defined(GOLD_SCRIPT_H)