1 /* bfdlink.h -- header file for BFD link routines
2 Copyright 1993 Free Software Foundation, Inc.
3 Written by Steve Chamberlain and Ian Lance Taylor, Cygnus Support.
5 This file is part of BFD, the Binary File Descriptor library.
7 This program is free software; you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 2 of the License, or
10 (at your option) any later version.
12 This program is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
17 You should have received a copy of the GNU General Public License
18 along with this program; if not, write to the Free Software
19 Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */
24 /* Which symbols to strip during a link. */
27 strip_none
, /* Don't strip any symbols. */
28 strip_debugger
, /* Strip debugging symbols. */
29 strip_some
, /* keep_hash is the list of symbols to keep. */
30 strip_all
/* Strip all symbols. */
33 /* Which local symbols to discard during a link. This is irrelevant
34 if strip_all is used. */
37 discard_none
, /* Don't discard any locals. */
38 discard_l
, /* Discard locals with a certain prefix. */
39 discard_all
/* Discard all locals. */
42 /* These are the possible types of an entry in the BFD link hash
45 enum bfd_link_hash_type
47 bfd_link_hash_new
, /* Symbol is new. */
48 bfd_link_hash_undefined
, /* Symbol seen before, but undefined. */
49 bfd_link_hash_weak
, /* Symbol is weak and undefined. */
50 bfd_link_hash_defined
, /* Symbol is defined. */
51 bfd_link_hash_common
, /* Symbol is common. */
52 bfd_link_hash_indirect
, /* Symbol is an indirect link. */
53 bfd_link_hash_warning
/* Like indirect, but warn if referenced. */
56 /* The linking routines use a hash table which uses this structure for
59 struct bfd_link_hash_entry
61 /* Base hash table entry structure. */
62 struct bfd_hash_entry root
;
63 /* Type of this entry. */
64 enum bfd_link_hash_type type
;
65 /* Whether this symbol has been written out. */
67 /* Undefined and common entries are kept in a linked list through
68 this field. This field is not in the union because that would
69 force us to remove entries from the list when we changed their
70 type, which would force the list to be doubly linked, which would
71 waste more memory. When an undefined or common symbol is
72 created, it should be added to this list, the head of which is in
73 the link hash table itself. As symbols are defined, they need
74 not be removed from the list; anything which reads the list must
75 doublecheck the symbol type. Weak symbols are not kept on this
77 struct bfd_link_hash_entry
*next
;
78 /* A union of information depending upon the type. */
81 /* Nothing is kept for bfd_hash_new. */
82 /* bfd_link_hash_undefined, bfd_link_hash_weak. */
85 bfd
*abfd
; /* BFD symbol was found in. */
87 /* bfd_link_hash_defined. */
90 bfd_vma value
; /* Symbol value. */
91 asection
*section
; /* Symbol section. */
93 /* bfd_link_hash_indirect, bfd_link_hash_warning. */
96 struct bfd_link_hash_entry
*link
; /* Real symbol. */
97 const char *warning
; /* Warning (bfd_link_hash_warning only). */
99 /* bfd_link_hash_common. */
102 bfd_vma size
; /* Common symbol size. */
103 asection
*section
; /* Symbol section. */
108 /* This is the link hash table. It is a derived class of
111 struct bfd_link_hash_table
113 /* The hash table itself. */
114 struct bfd_hash_table table
;
115 /* The back end which created this hash table. This indicates the
116 type of the entries in the hash table, which is sometimes
117 important information when linking object files of different
120 /* A linked list of undefined and common symbols, linked through the
121 next field in the bfd_link_hash_entry structure. */
122 struct bfd_link_hash_entry
*undefs
;
123 /* Entries are added to the tail of the undefs list. */
124 struct bfd_link_hash_entry
*undefs_tail
;
127 /* Look up an entry in a link hash table. If FOLLOW is true, this
128 follows bfd_link_hash_indirect and bfd_link_hash_warning links to
130 extern struct bfd_link_hash_entry
*bfd_link_hash_lookup
131 PARAMS ((struct bfd_link_hash_table
*, const char *, boolean create
,
132 boolean copy
, boolean follow
));
134 /* Traverse a link hash table. */
135 extern void bfd_link_hash_traverse
136 PARAMS ((struct bfd_link_hash_table
*,
137 boolean (*) (struct bfd_link_hash_entry
*, PTR
),
140 /* Add an entry to the undefs list. */
141 extern void bfd_link_add_undef
142 PARAMS ((struct bfd_link_hash_table
*, struct bfd_link_hash_entry
*));
144 /* This structure holds all the information needed to communicate
145 between BFD and the linker when doing a link. */
149 /* Function callbacks. */
150 const struct bfd_link_callbacks
*callbacks
;
151 /* true if BFD should generate a relocateable object file. */
152 boolean relocateable
;
153 /* Which symbols to strip. */
154 enum bfd_link_strip strip
;
155 /* Which local symbols to discard. */
156 enum bfd_link_discard discard
;
157 /* The local symbol prefix to discard if using discard_l. */
158 unsigned int lprefix_len
;
160 /* true if symbols should be retained in memory, false if they
161 should be freed and reread. */
163 /* The list of input BFD's involved in the link. These are chained
164 together via the link_next field. */
166 /* If a symbol should be created for each input BFD, this is section
167 where those symbols should be placed. It must be a section in
168 the output BFD. It may be NULL, in which case no such symbols
169 will be created. This is to support CREATE_OBJECT_SYMBOLS in the
170 linker command language. */
171 asection
*create_object_symbols_section
;
172 /* Hash table handled by BFD. */
173 struct bfd_link_hash_table
*hash
;
174 /* Hash table of symbols to keep. This is NULL unless strip is
176 struct bfd_hash_table
*keep_hash
;
177 /* Hash table of symbols to report back via notice_callback. If
178 this is NULL no symbols are reported back. */
179 struct bfd_hash_table
*notice_hash
;
182 /* This structures holds a set of callback functions. These are
183 called by the BFD linker routines. The first argument to each
184 callback function is the bfd_link_info structure being used. Each
185 function returns a boolean value. If the function returns false,
186 then the BFD function which called it will return with a failure
189 struct bfd_link_callbacks
191 /* A function which is called when an object is added from an
192 archive. ABFD is the archive element being added. NAME is the
193 name of the symbol which caused the archive element to be pulled
195 boolean (*add_archive_element
) PARAMS ((struct bfd_link_info
*,
198 /* A function which is called when a symbol is found with multiple
199 definitions. NAME is the symbol which is defined multiple times.
200 OBFD is the old BFD, OSEC is the old section, OVAL is the old
201 value, NBFD is the new BFD, NSEC is the new section, and NVAL is
202 the new value. OBFD may be NULL. OSEC and NSEC may be
203 bfd_com_section or bfd_ind_section. */
204 boolean (*multiple_definition
) PARAMS ((struct bfd_link_info
*,
212 /* A function which is called when a common symbol is defined
213 multiple times. NAME is the symbol appearing multiple times.
214 OBFD is the BFD of the existing symbol. OTYPE is the type of the
215 existing symbol, either bfd_link_hash_defined or
216 bfd_link_hash_common. If OTYPE is bfd_link_hash_common, OSIZE is
217 the size of the existing symbol. NBFD is the BFD of the new
218 symbol. NTYPE is the type of the new symbol, either
219 bfd_link_hash_defined or bfd_link_hash_common. If NTYPE is
220 bfd_link_hash_common, NSIZE is the size of the new symbol. */
221 boolean (*multiple_common
) PARAMS ((struct bfd_link_info
*,
224 enum bfd_link_hash_type otype
,
227 enum bfd_link_hash_type ntype
,
229 /* A function which is called to add a symbol to a set. ENTRY is
230 the link hash table entry for the set itself (e.g.,
231 __CTOR_LIST__). RELOC is the relocation to use for an entry in
232 the set when generating a relocateable file, and is also used to
233 get the size of the entry when generating an executable file.
234 ABFD, SEC and VALUE identify the value to add to the set. */
235 boolean (*add_to_set
) PARAMS ((struct bfd_link_info
*,
236 struct bfd_link_hash_entry
*entry
,
237 bfd_reloc_code_real_type reloc
,
238 bfd
*abfd
, asection
*sec
, bfd_vma value
));
239 /* A function which is called when the name of a g++ constructor or
240 destructor is found. This is only called by some object file
241 formats. CONSTRUCTOR is true for a constructor, false for a
242 destructor. This will use BFD_RELOC_CTOR when generating a
243 relocateable file. NAME is the name of the symbol found. ABFD,
244 SECTION and VALUE are the value of the symbol. */
245 boolean (*constructor
) PARAMS ((struct bfd_link_info
*,
247 const char *name
, bfd
*abfd
, asection
*sec
,
249 /* A function which is called when there is a reference to a warning
250 symbol. WARNING is the warning to be issued. */
251 boolean (*warning
) PARAMS ((struct bfd_link_info
*,
252 const char *warning
));
253 /* A function which is called when a relocation is attempted against
254 an undefined symbol. NAME is the symbol which is undefined.
255 ABFD, SECTION and ADDRESS identify the location from which the
256 reference is made. */
257 boolean (*undefined_symbol
) PARAMS ((struct bfd_link_info
*,
258 const char *name
, bfd
*abfd
,
259 asection
*section
, bfd_vma address
));
260 /* A function which is called when a reloc overflow occurs. NAME is
261 the name of the symbol or section the reloc is against,
262 RELOC_NAME is the name of the relocation, and ADDEND is any
263 addend that is used. ABFD, SECTION and ADDRESS identify the
264 location at which the overflow occurs; if this is the result of a
265 bfd_section_reloc_link_order or bfd_symbol_reloc_link_order, then
266 ABFD will be NULL. */
267 boolean (*reloc_overflow
) PARAMS ((struct bfd_link_info
*,
269 const char *reloc_name
, bfd_vma addend
,
270 bfd
*abfd
, asection
*section
,
272 /* A function which is called when a dangerous reloc is performed.
273 The canonical example is an a29k IHCONST reloc which does not
274 follow an IHIHALF reloc. MESSAGE is an appropriate message.
275 ABFD, SECTION and ADDRESS identify the location at which the
276 problem occurred; if this is the result of a
277 bfd_section_reloc_link_order or bfd_symbol_reloc_link_order, then
278 ABFD will be NULL. */
279 boolean (*reloc_dangerous
) PARAMS ((struct bfd_link_info
*,
281 bfd
*abfd
, asection
*section
,
283 /* A function which is called when a reloc is found to be attached
284 to a symbol which is not being written out. NAME is the name of
285 the symbol. ABFD, SECTION and ADDRESS identify the location of
286 the reloc; if this is the result of a
287 bfd_section_reloc_link_order or bfd_symbol_reloc_link_order, then
288 ABFD will be NULL. */
289 boolean (*unattached_reloc
) PARAMS ((struct bfd_link_info
*,
291 bfd
*abfd
, asection
*section
,
293 /* A function which is called when a symbol in notice_hash is
294 defined or referenced. NAME is the symbol. ABFD, SECTION and
295 ADDRESS are the value of the symbol. If SECTION is
296 bfd_und_section, this is a reference. */
297 boolean (*notice
) PARAMS ((struct bfd_link_info
*, const char *name
,
298 bfd
*abfd
, asection
*section
, bfd_vma address
));
301 /* The linker builds link_order structures which tell the code how to
302 include input data in the output file. */
304 /* These are the types of link_order structures. */
306 enum bfd_link_order_type
308 bfd_undefined_link_order
, /* Undefined. */
309 bfd_indirect_link_order
, /* Built from a section. */
310 bfd_fill_link_order
, /* Fill with a 16 bit constant. */
311 bfd_section_reloc_link_order
, /* Relocate against a section. */
312 bfd_symbol_reloc_link_order
/* Relocate against a symbol. */
315 /* This is the link_order structure itself. These form a chain
316 attached to the section whose contents they are describing. */
318 struct bfd_link_order
320 /* Next link_order in chain. */
321 struct bfd_link_order
*next
;
322 /* Type of link_order. */
323 enum bfd_link_order_type type
;
324 /* Offset within output section. */
326 /* Size within output section. */
328 /* Type specific information. */
333 /* Section to include. If this is used, then
334 section->output_section must be the section the
335 link_order is attached to, section->output_offset must
336 equal the link_order offset field, and section->_raw_size
337 must equal the link_order size field. Maybe these
338 restrictions should be relaxed someday. */
343 /* Value to fill with. */
348 /* Description of reloc to generate. Used for
349 bfd_section_reloc_link_order and
350 bfd_symbol_reloc_link_order. */
351 struct bfd_link_order_reloc
*p
;
356 /* A linker order of type bfd_section_reloc_link_order or
357 bfd_symbol_reloc_link_order means to create a reloc against a
358 section or symbol, respectively. This is used to implement -Ur to
359 generate relocs for the constructor tables. The
360 bfd_link_order_reloc structure describes the reloc that BFD should
361 create. It is similar to a arelent, but I didn't use arelent
362 because the linker does not know anything about most symbols, and
363 any asymbol structure it creates will be partially meaningless.
364 This information could logically be in the bfd_link_order struct,
365 but I didn't want to waste the space since these types of relocs
366 are relatively rare. */
368 struct bfd_link_order_reloc
371 bfd_reloc_code_real_type reloc
;
375 /* For type bfd_section_reloc_link_order, this is the section
376 the reloc should be against. This must be a section in the
377 output BFD, not any of the input BFDs. */
379 /* For type bfd_symbol_reloc_link_order, this is the name of the
380 symbol the reloc should be against. */
384 /* Addend to use. The object file should contain zero. The BFD
385 backend is responsible for filling in the contents of the object
386 file correctly. For some object file formats (e.g., COFF) the
387 addend must be stored into in the object file, and for some
388 (e.g., SPARC a.out) it is kept in the reloc. */
392 /* Allocate a new link_order for a section. */
393 extern struct bfd_link_order
*bfd_new_link_order
PARAMS ((bfd
*, asection
*));