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.
36 #include "script-sections.h"
41 class General_options;
52 struct Version_dependency_list;
53 struct Version_expression_list;
56 // This class represents an expression in a linker script.
61 // These should only be created by child classes.
69 // Return the value of the expression which is not permitted to
70 // refer to the dot symbol. CHECK_ASSERTIONS is true if we should
71 // check whether assertions are true.
73 eval(const Symbol_table*, const Layout*, bool check_assertions);
75 // Return the value of an expression which is permitted to refer to
76 // the dot symbol. DOT_VALUE is the absolute value of the dot
77 // symbol. DOT_SECTION is the section in which dot is defined; it
78 // should be NULL if the dot symbol has an absolute value (e.g., is
79 // defined in a SECTIONS clause outside of any output section
80 // definition). This sets *RESULT_SECTION to indicate where the
81 // value is defined. If the value is absolute *RESULT_SECTION will
82 // be NULL. Note that the returned value is still an absolute
83 // value; to get a section relative value the caller must subtract
84 // the section address.
86 eval_with_dot(const Symbol_table*, const Layout*, bool check_assertions,
87 uint64_t dot_value, Output_section* dot_section,
88 Output_section** result_section);
90 // Return the value of an expression which may or may not be
91 // permitted to refer to the dot symbol, depending on
94 eval_maybe_dot(const Symbol_table*, const Layout*, bool check_assertions,
95 bool is_dot_available, uint64_t dot_value,
96 Output_section* dot_section,
97 Output_section** result_section);
99 // Print the expression to the FILE. This is for debugging.
101 print(FILE*) const = 0;
104 struct Expression_eval_info;
107 // Compute the value of the expression (implemented by child class).
108 // This is public rather than protected because it is called
109 // directly by children of Expression on other Expression objects.
111 value(const Expression_eval_info*) = 0;
114 // May not be copied.
115 Expression(const Expression&);
116 Expression& operator=(const Expression&);
120 // Version_script_info stores information parsed from the version
121 // script, either provided by --version-script or as part of a linker
122 // script. A single Version_script_info object per target is owned by
125 class Version_script_info
128 ~Version_script_info();
134 // Return whether any version were defined in the version script.
137 { return this->version_trees_.empty(); }
139 // Return the version associated with the given symbol name.
140 // Strings are allocated out of the stringpool given in the
141 // constructor. Strings are allocated out of the stringpool given
142 // in the constructor.
144 get_symbol_version(const char* symbol) const
145 { return get_symbol_version_helper(symbol, true); }
147 // Return whether this symbol matches the local: section of a
148 // version script (it doesn't matter which).
150 symbol_is_local(const char* symbol) const
152 return (get_symbol_version(symbol).empty()
153 && !get_symbol_version_helper(symbol, false).empty());
156 // Return the names of versions defined in the version script.
157 // Strings are allocated out of the stringpool given in the
159 std::vector<std::string>
160 get_versions() const;
162 // Return the list of dependencies for this version.
163 std::vector<std::string>
164 get_dependencies(const char* version) const;
166 // The following functions should only be used by the bison helper
167 // functions. They allocate new structs whose memory belongs to
168 // Version_script_info. The bison functions copy the information
169 // from the version script into these structs.
170 struct Version_dependency_list*
171 allocate_dependency_list();
173 struct Version_expression_list*
174 allocate_expression_list();
177 allocate_version_tree();
179 // Print contents to the FILE. This is for debugging.
185 print_expression_list(FILE* f, const Version_expression_list*) const;
187 const std::string& get_symbol_version_helper(const char* symbol,
188 bool check_global) const;
190 std::vector<struct Version_dependency_list*> dependency_lists_;
191 std::vector<struct Version_expression_list*> expression_lists_;
192 std::vector<struct Version_tree*> version_trees_;
195 // This class manages assignments to symbols. These can appear in
196 // three different locations in scripts: outside of a SECTIONS clause,
197 // within a SECTIONS clause, and within an output section definition
198 // within a SECTIONS clause. This can also appear on the command line
199 // via the --defsym command line option.
201 class Symbol_assignment
204 Symbol_assignment(const char* name, size_t namelen, Expression* val,
205 bool provide, bool hidden)
206 : name_(name, namelen), val_(val), provide_(provide), hidden_(hidden),
210 // Add the symbol to the symbol table.
212 add_to_table(Symbol_table*);
214 // Finalize the symbol value.
216 finalize(Symbol_table*, const Layout*);
218 // Finalize the symbol value when it can refer to the dot symbol.
220 finalize_with_dot(Symbol_table*, const Layout*, uint64_t dot_value,
221 Output_section* dot_section);
223 // Set the symbol value, but only if the value is absolute. This is
224 // used while processing a SECTIONS clause. We assume that dot is
225 // an absolute value here. We do not check assertions.
227 set_if_absolute(Symbol_table*, const Layout*, bool is_dot_available,
230 // Print the assignment to the FILE. This is for debugging.
235 // Shared by finalize and finalize_with_dot.
237 finalize_maybe_dot(Symbol_table*, const Layout*, bool is_dot_available,
238 uint64_t dot_value, Output_section* dot_section);
240 // Sized version of finalize.
243 sized_finalize(Symbol_table*, const Layout*, bool is_dot_available,
244 uint64_t dot_value, Output_section*);
248 // Expression to assign to symbol.
250 // Whether the assignment should be provided (only set if there is
251 // an undefined reference to the symbol.
253 // Whether the assignment should be hidden.
255 // The entry in the symbol table.
259 // This class manages assertions in linker scripts. These can appear
260 // in all the places where a Symbol_assignment can appear.
262 class Script_assertion
265 Script_assertion(Expression* check, const char* message,
267 : check_(check), message_(message, messagelen)
270 // Check the assertion.
272 check(const Symbol_table*, const Layout*);
274 // Print the assertion to the FILE. This is for debugging.
279 // The expression to check.
281 // The message to issue if the expression fails.
282 std::string message_;
285 // We can read a linker script in two different contexts: when
286 // initially parsing the command line, and when we find an input file
287 // which is actually a linker script. Also some of the data which can
288 // be set by a linker script can also be set via command line options
289 // like -e and --defsym. This means that we have a type of data which
290 // can be set both during command line option parsing and while
291 // reading input files. We store that data in an instance of this
292 // object. We will keep pointers to that instance in both the
293 // Command_line and Layout objects.
300 // Add a symbol to be defined.
302 add_symbol_assignment(const char* name, size_t length, Expression* value,
303 bool provide, bool hidden);
307 add_assertion(Expression* check, const char* message, size_t messagelen);
309 // Define a symbol from the command line.
311 define_symbol(const char* definition);
313 // Create sections required by any linker scripts.
315 create_script_sections(Layout*);
317 // Add all symbol definitions to the symbol table.
319 add_symbols_to_table(Symbol_table*);
321 // Finalize the symbol values. Also check assertions.
323 finalize_symbols(Symbol_table*, const Layout*);
325 // Version information parsed from a version script. Everything
326 // else has a pointer to this object.
328 version_script_info()
329 { return &this->version_script_info_; }
331 const Version_script_info*
332 version_script_info() const
333 { return &this->version_script_info_; }
335 // A SECTIONS clause parsed from a linker script. Everything else
336 // has a pointer to this object.
339 { return &this->script_sections_; }
341 // Whether we saw a SECTIONS clause.
343 saw_sections_clause() const
344 { return this->script_sections_.saw_sections_clause(); }
346 // Whether we saw a PHDRS clause.
348 saw_phdrs_clause() const
349 { return this->script_sections_.saw_phdrs_clause(); }
351 // Set section addresses using a SECTIONS clause. Return the
352 // segment which should hold the file header and segment headers;
353 // this may return NULL, in which case the headers are not in a
356 set_section_addresses(Symbol_table*, Layout*);
358 // Print the script to the FILE. This is for debugging.
363 // We keep a list of symbol assignments which occur outside of a
365 typedef std::vector<Symbol_assignment*> Symbol_assignments;
367 // We keep a list of all assertions whcih occur outside of a
369 typedef std::vector<Script_assertion*> Assertions;
371 // The entry address. This will be empty if not set.
374 Symbol_assignments symbol_assignments_;
375 // Assertions to check.
376 Assertions assertions_;
377 // Version information parsed from a version script.
378 Version_script_info version_script_info_;
379 // Information from any SECTIONS clauses.
380 Script_sections script_sections_;
383 // FILE was found as an argument on the command line, but was not
384 // recognized as an ELF file. Try to read it as a script. We've
385 // already read BYTES of data into P. Return true if the file was
386 // handled. This has to handle /usr/lib/libc.so on a GNU/Linux
390 read_input_script(Workqueue*, const General_options&, Symbol_table*, Layout*,
391 Dirsearch*, Input_objects*, Input_group*,
392 const Input_argument*, Input_file*, const unsigned char* p,
393 off_t bytes, Task_token* this_blocker,
394 Task_token* next_blocker);
396 // FILE was found as an argument to --script (-T).
397 // Read it as a script, and execute its contents immediately.
400 read_commandline_script(const char* filename, Command_line*);
402 // FILE was found as an argument to --version-script. Read it as a
403 // version script, and store its contents in
404 // cmdline->script_options()->version_script_info().
407 read_version_script(const char* filename, Command_line* cmdline);
410 } // End namespace gold.
412 #endif // !defined(GOLD_SCRIPT_H)