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.
72 eval(const Symbol_table
*, const Layout
*);
74 // Return the value of an expression which is permitted to refer to
75 // the dot symbol. This sets *IS_ABSOLUTE to indicate whether this
76 // is an absolute value; it will be false if a non-absolute symbol
77 // was referenced in the expression; this is used to detect invalid
78 // uses when setting a section address.
80 eval_with_dot(const Symbol_table
*, const Layout
*, bool dot_has_value
,
81 uint64_t dot_value
, bool* is_absolute
);
83 // Return the value of an expression which may or may not be
84 // permitted to refer to the dot symbol, depending on
87 eval_maybe_dot(const Symbol_table
*, const Layout
*, bool is_dot_available
,
88 bool dot_has_value
, uint64_t dot_value
, bool* is_absolute
);
90 // Print the expression to the FILE. This is for debugging.
92 print(FILE*) const = 0;
95 struct Expression_eval_info
;
98 // Compute the value of the expression (implemented by child class).
99 // This is public rather than protected because it is called
100 // directly by children of Expression on other Expression objects.
102 value(const Expression_eval_info
*) = 0;
105 // May not be copied.
106 Expression(const Expression
&);
107 Expression
& operator=(const Expression
&);
111 // Version_script_info stores information parsed from the version
112 // script, either provided by --version-script or as part of a linker
113 // script. A single Version_script_info object per target is owned by
116 class Version_script_info
119 ~Version_script_info();
121 // Return whether any version were defined in the version script.
124 { return this->version_trees_
.empty(); }
126 // Return the version associated with the given symbol name.
127 // Strings are allocated out of the stringpool given in the
128 // constructor. Strings are allocated out of the stringpool given
129 // in the constructor.
131 get_symbol_version(const char* symbol
) const
132 { return get_symbol_version_helper(symbol
, true); }
134 // Return whether this symbol matches the local: section of a
135 // version script (it doesn't matter which).
137 symbol_is_local(const char* symbol
) const
139 return (get_symbol_version(symbol
).empty()
140 && !get_symbol_version_helper(symbol
, false).empty());
143 // Return the names of versions defined in the version script.
144 // Strings are allocated out of the stringpool given in the
146 std::vector
<std::string
>
147 get_versions() const;
149 // Return the list of dependencies for this version.
150 std::vector
<std::string
>
151 get_dependencies(const char* version
) const;
153 // The following functions should only be used by the bison helper
154 // functions. They allocate new structs whose memory belongs to
155 // Version_script_info. The bison functions copy the information
156 // from the version script into these structs.
157 struct Version_dependency_list
*
158 allocate_dependency_list();
160 struct Version_expression_list
*
161 allocate_expression_list();
164 allocate_version_tree();
166 // Print contents to the FILE. This is for debugging.
172 print_expression_list(FILE* f
, const Version_expression_list
*) const;
174 const std::string
& get_symbol_version_helper(const char* symbol
,
175 bool check_global
) const;
177 std::vector
<struct Version_dependency_list
*> dependency_lists_
;
178 std::vector
<struct Version_expression_list
*> expression_lists_
;
179 std::vector
<struct Version_tree
*> version_trees_
;
182 // This class manages assignments to symbols. These can appear in
183 // three different locations in scripts: outside of a SECTIONS clause,
184 // within a SECTIONS clause, and within an output section definition
185 // within a SECTIONS clause. This can also appear on the command line
186 // via the --defsym command line option.
188 class Symbol_assignment
191 Symbol_assignment(const char* name
, size_t namelen
, Expression
* val
,
192 bool provide
, bool hidden
)
193 : name_(name
, namelen
), val_(val
), provide_(provide
), hidden_(hidden
),
197 // Add the symbol to the symbol table.
199 add_to_table(Symbol_table
*);
201 // Finalize the symbol value.
203 finalize(Symbol_table
*, const Layout
*);
205 // Finalize the symbol value when it can refer to the dot symbol.
207 finalize_with_dot(Symbol_table
*, const Layout
*, bool dot_has_value
,
210 // Set the symbol value, but only if the value is absolute. This is
211 // used while processing a SECTIONS clause.
213 set_if_absolute(Symbol_table
*, const Layout
*, bool is_dot_available
,
214 bool dot_has_value
, uint64_t dot_value
);
216 // Print the assignment to the FILE. This is for debugging.
221 // Shared by finalize and finalize_with_dot.
223 finalize_maybe_dot(Symbol_table
*, const Layout
*, bool is_dot_available
,
224 bool dot_has_value
, uint64_t dot_value
);
226 // Sized version of finalize.
229 sized_finalize(Symbol_table
*, const Layout
*, bool is_dot_available
,
230 bool dot_has_value
, uint64_t dot_value
);
234 // Expression to assign to symbol.
236 // Whether the assignment should be provided (only set if there is
237 // an undefined reference to the symbol.
239 // Whether the assignment should be hidden.
241 // The entry in the symbol table.
245 // This class manages assertions in linker scripts. These can appear
246 // in all the places where a Symbol_assignment can appear.
248 class Script_assertion
251 Script_assertion(Expression
* check
, const char* message
,
253 : check_(check
), message_(message
, messagelen
)
256 // Check the assertion.
258 check(const Symbol_table
*, const Layout
*);
260 // Print the assertion to the FILE. This is for debugging.
265 // The expression to check.
267 // The message to issue if the expression fails.
268 std::string message_
;
271 // We can read a linker script in two different contexts: when
272 // initially parsing the command line, and when we find an input file
273 // which is actually a linker script. Also some of the data which can
274 // be set by a linker script can also be set via command line options
275 // like -e and --defsym. This means that we have a type of data which
276 // can be set both during command line option parsing and while
277 // reading input files. We store that data in an instance of this
278 // object. We will keep pointers to that instance in both the
279 // Command_line and Layout objects.
286 // The entry address.
289 { return this->entry_
.empty() ? NULL
: this->entry_
.c_str(); }
291 // Set the entry address.
293 set_entry(const char* entry
, size_t length
)
294 { this->entry_
.assign(entry
, length
); }
296 // Add a symbol to be defined.
298 add_symbol_assignment(const char* name
, size_t length
, Expression
* value
,
299 bool provide
, bool hidden
);
303 add_assertion(Expression
* check
, const char* message
, size_t messagelen
);
305 // Define a symbol from the command line.
307 define_symbol(const char* definition
);
309 // Add all symbol definitions to the symbol table.
311 add_symbols_to_table(Symbol_table
*);
313 // Finalize the symbol values. Also check assertions.
315 finalize_symbols(Symbol_table
*, const Layout
*);
317 // Version information parsed from a version script. Everything
318 // else has a pointer to this object.
320 version_script_info()
321 { return &this->version_script_info_
; }
323 // A SECTIONS clause parsed from a linker script. Everything else
324 // has a pointer to this object.
327 { return &this->script_sections_
; }
329 // Whether we saw a SECTIONS clause.
331 saw_sections_clause() const
332 { return this->script_sections_
.saw_sections_clause(); }
334 // Whether we saw a PHDRS clause.
336 saw_phdrs_clause() const
337 { return this->script_sections_
.saw_phdrs_clause(); }
339 // Set section addresses using a SECTIONS clause. Return the
340 // segment which should hold the file header and segment headers;
341 // this may return NULL, in which case the headers are not in a
344 set_section_addresses(Symbol_table
*, Layout
*);
346 // Print the script to the FILE. This is for debugging.
351 // We keep a list of symbol assignments which occur outside of a
353 typedef std::vector
<Symbol_assignment
*> Symbol_assignments
;
355 // We keep a list of all assertions whcih occur outside of a
357 typedef std::vector
<Script_assertion
*> Assertions
;
359 // The entry address. This will be empty if not set.
362 Symbol_assignments symbol_assignments_
;
363 // Assertions to check.
364 Assertions assertions_
;
365 // Version information parsed from a version script.
366 Version_script_info version_script_info_
;
367 // Information from any SECTIONS clauses.
368 Script_sections script_sections_
;
371 // FILE was found as an argument on the command line, but was not
372 // recognized as an ELF file. Try to read it as a script. We've
373 // already read BYTES of data into P. Return true if the file was
374 // handled. This has to handle /usr/lib/libc.so on a GNU/Linux
378 read_input_script(Workqueue
*, const General_options
&, Symbol_table
*, Layout
*,
379 Dirsearch
*, Input_objects
*, Input_group
*,
380 const Input_argument
*, Input_file
*, const unsigned char* p
,
381 off_t bytes
, Task_token
* this_blocker
,
382 Task_token
* next_blocker
);
384 // FILE was found as an argument to --script (-T).
385 // Read it as a script, and execute its contents immediately.
388 read_commandline_script(const char* filename
, Command_line
*);
390 // FILE was found as an argument to --version-script. Read it as a
391 // version script, and store its contents in
392 // cmdline->script_options()->version_script_info().
395 read_version_script(const char* filename
, Command_line
* cmdline
);
398 } // End namespace gold.
400 #endif // !defined(GOLD_SCRIPT_H)