1 // script.h -- handle linker scripts for gold -*- C++ -*-
3 // Copyright 2006, 2007, 2008 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;
54 struct Version_dependency_list;
55 struct Version_expression_list;
58 // This class represents an expression in a linker script.
63 // These should only be created by child classes.
71 // Return the value of the expression which is not permitted to
72 // refer to the dot symbol. CHECK_ASSERTIONS is true if we should
73 // check whether assertions are true.
75 eval(const Symbol_table*, const Layout*, bool check_assertions);
77 // Return the value of an expression which is permitted to refer to
78 // the dot symbol. DOT_VALUE is the absolute value of the dot
79 // symbol. DOT_SECTION is the section in which dot is defined; it
80 // should be NULL if the dot symbol has an absolute value (e.g., is
81 // defined in a SECTIONS clause outside of any output section
82 // definition). This sets *RESULT_SECTION to indicate where the
83 // value is defined. If the value is absolute *RESULT_SECTION will
84 // be NULL. Note that the returned value is still an absolute
85 // value; to get a section relative value the caller must subtract
86 // the section address.
88 eval_with_dot(const Symbol_table*, const Layout*, bool check_assertions,
89 uint64_t dot_value, Output_section* dot_section,
90 Output_section** result_section);
92 // Return the value of an expression which may or may not be
93 // permitted to refer to the dot symbol, depending on
96 eval_maybe_dot(const Symbol_table*, const Layout*, bool check_assertions,
97 bool is_dot_available, uint64_t dot_value,
98 Output_section* dot_section,
99 Output_section** result_section);
101 // Print the expression to the FILE. This is for debugging.
103 print(FILE*) const = 0;
106 struct Expression_eval_info;
109 // Compute the value of the expression (implemented by child class).
110 // This is public rather than protected because it is called
111 // directly by children of Expression on other Expression objects.
113 value(const Expression_eval_info*) = 0;
116 // May not be copied.
117 Expression(const Expression&);
118 Expression& operator=(const Expression&);
122 // Version_script_info stores information parsed from the version
123 // script, either provided by --version-script or as part of a linker
124 // script. A single Version_script_info object per target is owned by
127 class Version_script_info
130 ~Version_script_info();
136 // Return whether any version were defined in the version script.
139 { return this->version_trees_.empty(); }
141 // Return the version associated with the given symbol name.
142 // Strings are allocated out of the stringpool given in the
143 // constructor. Strings are allocated out of the stringpool given
144 // in the constructor.
146 get_symbol_version(const char* symbol) const
147 { return get_symbol_version_helper(symbol, true); }
149 // Return whether this symbol matches the local: section of a
150 // version script (it doesn't matter which).
152 symbol_is_local(const char* symbol) const
154 return (get_symbol_version(symbol).empty()
155 && !get_symbol_version_helper(symbol, false).empty());
158 // Return the names of versions defined in the version script.
159 // Strings are allocated out of the stringpool given in the
161 std::vector<std::string>
162 get_versions() const;
164 // Return the list of dependencies for this version.
165 std::vector<std::string>
166 get_dependencies(const char* version) const;
168 // The following functions should only be used by the bison helper
169 // functions. They allocate new structs whose memory belongs to
170 // Version_script_info. The bison functions copy the information
171 // from the version script into these structs.
172 struct Version_dependency_list*
173 allocate_dependency_list();
175 struct Version_expression_list*
176 allocate_expression_list();
179 allocate_version_tree();
181 // Print contents to the FILE. This is for debugging.
187 print_expression_list(FILE* f, const Version_expression_list*) const;
189 const std::string& get_symbol_version_helper(const char* symbol,
190 bool check_global) const;
192 std::vector<struct Version_dependency_list*> dependency_lists_;
193 std::vector<struct Version_expression_list*> expression_lists_;
194 std::vector<struct Version_tree*> version_trees_;
197 // This class manages assignments to symbols. These can appear in
198 // three different locations in scripts: outside of a SECTIONS clause,
199 // within a SECTIONS clause, and within an output section definition
200 // within a SECTIONS clause. This can also appear on the command line
201 // via the --defsym command line option.
203 class Symbol_assignment
206 Symbol_assignment(const char* name, size_t namelen, Expression* val,
207 bool provide, bool hidden)
208 : name_(name, namelen), val_(val), provide_(provide), hidden_(hidden),
212 // Add the symbol to the symbol table.
214 add_to_table(Symbol_table*);
216 // Finalize the symbol value.
218 finalize(Symbol_table*, const Layout*);
220 // Finalize the symbol value when it can refer to the dot symbol.
222 finalize_with_dot(Symbol_table*, const Layout*, uint64_t dot_value,
223 Output_section* dot_section);
225 // Set the symbol value, but only if the value is absolute. This is
226 // used while processing a SECTIONS clause. We assume that dot is
227 // an absolute value here. We do not check assertions.
229 set_if_absolute(Symbol_table*, const Layout*, bool is_dot_available,
232 // Print the assignment to the FILE. This is for debugging.
237 // Shared by finalize and finalize_with_dot.
239 finalize_maybe_dot(Symbol_table*, const Layout*, bool is_dot_available,
240 uint64_t dot_value, Output_section* dot_section);
242 // Sized version of finalize.
245 sized_finalize(Symbol_table*, const Layout*, bool is_dot_available,
246 uint64_t dot_value, Output_section*);
250 // Expression to assign to symbol.
252 // Whether the assignment should be provided (only set if there is
253 // an undefined reference to the symbol.
255 // Whether the assignment should be hidden.
257 // The entry in the symbol table.
261 // This class manages assertions in linker scripts. These can appear
262 // in all the places where a Symbol_assignment can appear.
264 class Script_assertion
267 Script_assertion(Expression* check, const char* message,
269 : check_(check), message_(message, messagelen)
272 // Check the assertion.
274 check(const Symbol_table*, const Layout*);
276 // Print the assertion to the FILE. This is for debugging.
281 // The expression to check.
283 // The message to issue if the expression fails.
284 std::string message_;
287 // We can read a linker script in two different contexts: when
288 // initially parsing the command line, and when we find an input file
289 // which is actually a linker script. Also some of the data which can
290 // be set by a linker script can also be set via command line options
291 // like -e and --defsym. This means that we have a type of data which
292 // can be set both during command line option parsing and while
293 // reading input files. We store that data in an instance of this
294 // object. We will keep pointers to that instance in both the
295 // Command_line and Layout objects.
302 // Add a symbol to be defined.
304 add_symbol_assignment(const char* name, size_t length, Expression* value,
305 bool provide, bool hidden);
309 add_assertion(Expression* check, const char* message, size_t messagelen);
311 // Define a symbol from the command line.
313 define_symbol(const char* definition);
315 // Create sections required by any linker scripts.
317 create_script_sections(Layout*);
319 // Add all symbol definitions to the symbol table.
321 add_symbols_to_table(Symbol_table*);
323 // Finalize the symbol values. Also check assertions.
325 finalize_symbols(Symbol_table*, const Layout*);
327 // Version information parsed from a version script. Everything
328 // else has a pointer to this object.
330 version_script_info()
331 { return &this->version_script_info_; }
333 const Version_script_info*
334 version_script_info() const
335 { return &this->version_script_info_; }
337 // A SECTIONS clause parsed from a linker script. Everything else
338 // has a pointer to this object.
341 { return &this->script_sections_; }
343 const Script_sections*
344 script_sections() const
345 { return &this->script_sections_; }
347 // Whether we saw a SECTIONS clause.
349 saw_sections_clause() const
350 { return this->script_sections_.saw_sections_clause(); }
352 // Whether we saw a PHDRS clause.
354 saw_phdrs_clause() const
355 { return this->script_sections_.saw_phdrs_clause(); }
357 // Set section addresses using a SECTIONS clause. Return the
358 // segment which should hold the file header and segment headers;
359 // this may return NULL, in which case the headers are not in a
362 set_section_addresses(Symbol_table*, Layout*);
364 // Print the script to the FILE. This is for debugging.
369 // We keep a list of symbol assignments which occur outside of a
371 typedef std::vector<Symbol_assignment*> Symbol_assignments;
373 // We keep a list of all assertions whcih occur outside of a
375 typedef std::vector<Script_assertion*> Assertions;
377 // The entry address. This will be empty if not set.
380 Symbol_assignments symbol_assignments_;
381 // Assertions to check.
382 Assertions assertions_;
383 // Version information parsed from a version script.
384 Version_script_info version_script_info_;
385 // Information from any SECTIONS clauses.
386 Script_sections script_sections_;
389 // FILE was found as an argument on the command line, but was not
390 // recognized as an ELF file. Try to read it as a script. Return
391 // true if the file was handled. This has to handle /usr/lib/libc.so
392 // on a GNU/Linux system. *USED_NEXT_BLOCKER is set to indicate
393 // whether the function took over NEXT_BLOCKER.
396 read_input_script(Workqueue*, const General_options&, Symbol_table*, Layout*,
397 Dirsearch*, Input_objects*, Mapfile*, Input_group*,
398 const Input_argument*, Input_file*,
399 Task_token* next_blocker, bool* used_next_blocker);
401 // FILE was found as an argument to --script (-T).
402 // Read it as a script, and execute its contents immediately.
405 read_commandline_script(const char* filename, Command_line*);
407 // FILE was found as an argument to --version-script. Read it as a
408 // version script, and store its contents in
409 // cmdline->script_options()->version_script_info().
412 read_version_script(const char* filename, Command_line* cmdline);
415 } // End namespace gold.
417 #endif // !defined(GOLD_SCRIPT_H)