source: rtems-tools/linkers/rld-symbols.h @ 59c3ebd

4.104.115
Last change on this file since 59c3ebd was 544de91, checked in by Chris Johns <chrisj@…>, on 12/28/12 at 23:20:22

Fix managing weak symbols.

Weak symbols where not being managed correctly. The symbols table
is now a class with externals and weaks as separate symtabs so
the externals can be searched first then the weaks and if not
found an unresolved error is raised. This was found creating
a libbsdport RAP file where the drivers in the all driver table
resolved to the weak symbols and so linking in nothing.

Fixing the weak symbols as found in the libbsdport library
triggered a new resolver bug. The object files now contain the
resolver state and this is used to determine if an object file
has been resolved or is currently being resolved avoiding
rescursive loops with dependent object files.

The resolver trace output is a little easier to read.

  • Property mode set to 100644
File size: 6.4 KB
Line 
1/*
2 * Copyright (c) 2011, Chris Johns <chrisj@rtems.org>
3 *
4 * Permission to use, copy, modify, and/or distribute this software for any
5 * purpose with or without fee is hereby granted, provided that the above
6 * copyright notice and this permission notice appear in all copies.
7 *
8 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
9 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
10 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
11 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
12 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
13 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
14 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
15 */
16/**
17 * @file
18 *
19 * @ingroup rtems-ld
20 *
21 * @brief RTEMS Linker symbols manages the symbols from all the object files.
22 *
23 */
24
25#if !defined (_RLD_SYMBOLS_H_)
26#define _RLD_SYMBOLS_H_
27
28#include <iostream>
29#include <list>
30#include <map>
31#include <string>
32
33#include <rld-elf-types.h>
34
35namespace rld
36{
37  /**
38   * Forward declarations.
39   */
40  namespace files
41  {
42    class object;
43  }
44
45  namespace symbols
46  {
47    /**
48     * A symbol.
49     */
50    class symbol
51    {
52    public:
53      /**
54       * Default constructor. No symbol has been defined.
55       */
56      symbol ();
57
58      /**
59       * Construct an exported symbol with a object file.
60       */
61      symbol (int                 index,
62              const std::string&  name,
63              files::object&      object,
64              const elf::elf_sym& esym);
65
66      /**
67       * Construct a symbol with no object file and an ELF index.
68       */
69      symbol (int index, const std::string& name, const elf::elf_sym& esym);
70
71      /**
72       * Construct a linker symbol that is internally created.
73       */
74      symbol (const std::string&  name,
75              const elf::elf_addr value = 0);
76
77      /**
78       * Construct a linker symbol that is internally created.
79       */
80      symbol (const char*   name,
81              elf::elf_addr value = 0);
82
83      /**
84       * The symbol's index in the symtab section of the ELF file.
85       */
86      int index () const;
87
88      /**
89       * The symbol's name.
90       */
91      const std::string& name () const;
92
93      /**
94       * The symbol's demangled name.
95       */
96      const std::string& demangled () const;
97
98      /**
99       * Is the symbol a C++ name ?
100       */
101      bool is_cplusplus () const;
102
103      /**
104       * The symbol's type.
105       */
106      int type () const;
107
108      /**
109       * The symbol's binding, ie local, weak, or global.
110       */
111      int binding () const;
112
113      /**
114       * The symbol's section index.
115       */
116      int section_index () const;
117
118      /**
119       * The value of the symbol.
120       */
121      elf::elf_addr value () const;
122
123      /**
124       * The data of the symbol.
125       */
126      uint32_t info () const;
127
128      /**
129       * The symbol's object file name.
130       */
131      files::object* object () const;
132
133      /**
134       * Set the symbol's object file name. Used when resolving unresolved
135       * symbols.
136       */
137      void set_object (files::object& obj);
138
139      /**
140       * The ELF symbol.
141       */
142      const elf::elf_sym& esym () const;
143
144      /**
145       * Return the number of references.
146       */
147      int references () const {
148        return references_;
149      }
150
151      /**
152       * Return the number of references.
153       */
154      void referenced ();
155
156      /**
157       * Less than operator for the map container.
158       */
159      bool operator< (const symbol& rhs) const;
160
161      /**
162       * Output to the a stream.
163       */
164      void output (std::ostream& out) const;
165
166    private:
167
168      int            index_;      //< The symbol's index in the ELF file.
169      std::string    name_;       //< The name of the symbol.
170      std::string    demangled_;  //< If a C++ symbol the demangled name.
171      files::object* object_;     //< The object file containing the symbol.
172      elf::elf_sym   esym_;       //< The ELF symbol.
173      int            references_; //< The number of times if it referenced.
174    };
175
176    /**
177     * Container of symbols. A bucket of symbols.
178     */
179    typedef std::list < symbol > bucket;
180
181    /**
182     * References to symbols. Should always point to symbols held in a bucket.
183     */
184    typedef std::list < symbol* > pointers;
185
186    /**
187     * A symbols table is a map container of symbols. Should always point to
188     * symbols held in a bucket.
189     */
190    typedef std::map < std::string, symbol* > symtab;
191
192    /**
193     * A symbols contains a symbol table of externals and weak symbols.
194     */
195    class table
196    {
197    public:
198      /**
199       * Construct a table.
200       */
201      table ();
202
203      /**
204       * Destruct a table.
205       */
206      ~table ();
207
208      /**
209       * Add an external symbol.
210       */
211      void add_external (symbol& sym);
212
213      /**
214       * Add a weak symbol.
215       */
216      void add_weak (symbol& sym);
217
218      /**
219       * Find an external symbol.
220       */
221      symbol* find_external (const std::string& name);
222
223      /**
224       * Find an weak symbol.
225       */
226      symbol* find_weak (const std::string& name);
227
228      /**
229       * Return the size of the symbols loaded.
230       */
231      size_t size () const;
232
233      /**
234       * Return the externals symbol table.
235       */
236      const symtab& externals () const;
237
238      /**
239       * Return the weaks symbol table.
240       */
241      const symtab& weaks () const;
242
243    private:
244
245      /**
246       * Cannot copy a table.
247       */
248      table (const table& orig);
249
250      /**
251       * A table of external symbols.
252       */
253      symtab _externals;
254
255      /**
256       * A table of weak symbols.
257       */
258      symtab _weaks;
259    };
260
261    /**
262     * Load a table from a buckey.
263     */
264    void load (bucket& bucket_, table& table_);
265
266    /**
267     * Load a table from a buckey.
268     */
269    void load (bucket& bucket_, symtab& table_);
270
271    /**
272     * Given a container of symbols return how many are referenced.
273     */
274    size_t referenced (pointers& symbols);
275
276    /**
277     * Output the symbol table.
278     */
279    void output (std::ostream& out, const table& symbols);
280
281    /**
282     * Output the symbol table.
283     */
284    void output (std::ostream& out, const symtab& symbols);
285  }
286}
287
288/**
289 * Output stream operator.
290 */
291static inline std::ostream& operator<< (std::ostream&               out,
292                                        const rld::symbols::symbol& sym) {
293  sym.output (out);
294  return out;
295}
296
297#endif
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