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., 59 Temple Place - Suite 330, Boston, MA 02111-1307, 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_undefweak
, /* Symbol is weak and undefined. */
50 bfd_link_hash_defined
, /* Symbol is defined. */
51 bfd_link_hash_defweak
, /* Symbol is weak and defined. */
52 bfd_link_hash_common
, /* Symbol is common. */
53 bfd_link_hash_indirect
, /* Symbol is an indirect link. */
54 bfd_link_hash_warning
/* Like indirect, but warn if referenced. */
57 /* The linking routines use a hash table which uses this structure for
60 struct bfd_link_hash_entry
62 /* Base hash table entry structure. */
63 struct bfd_hash_entry root
;
64 /* Type of this entry. */
65 enum bfd_link_hash_type type
;
67 /* Undefined and common symbols 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.
77 Weak symbols are not kept on this list.
79 Defined and defweak symbols use this field as a reference marker.
80 If the field is not NULL, or this structure is the tail of the
81 undefined symbol list, the symbol has been referenced. If the
82 symbol is undefined and becomes defined, this field will
83 automatically be non-NULL since the symbol will have been on the
84 undefined symbol list. */
85 struct bfd_link_hash_entry
*next
;
86 /* A union of information depending upon the type. */
89 /* Nothing is kept for bfd_hash_new. */
90 /* bfd_link_hash_undefined, bfd_link_hash_undefweak. */
93 bfd
*abfd
; /* BFD symbol was found in. */
95 /* bfd_link_hash_defined, bfd_link_hash_defweak. */
98 bfd_vma value
; /* Symbol value. */
99 asection
*section
; /* Symbol section. */
101 /* bfd_link_hash_indirect, bfd_link_hash_warning. */
104 struct bfd_link_hash_entry
*link
; /* Real symbol. */
105 const char *warning
; /* Warning (bfd_link_hash_warning only). */
107 /* bfd_link_hash_common. */
110 /* The linker needs to know three things about common
111 symbols: the size, the alignment, and the section in
112 which the symbol should be placed. We store the size
113 here, and we allocate a small structure to hold the
114 section and the alignment. The alignment is stored as a
115 power of two. We don't store all the information
116 directly because we don't want to increase the size of
117 the union; this structure is a major space user in the
119 bfd_size_type size
; /* Common symbol size. */
120 struct bfd_link_hash_common_entry
122 unsigned int alignment_power
; /* Alignment. */
123 asection
*section
; /* Symbol section. */
129 /* This is the link hash table. It is a derived class of
132 struct bfd_link_hash_table
134 /* The hash table itself. */
135 struct bfd_hash_table table
;
136 /* The back end which created this hash table. This indicates the
137 type of the entries in the hash table, which is sometimes
138 important information when linking object files of different
140 const bfd_target
*creator
;
141 /* A linked list of undefined and common symbols, linked through the
142 next field in the bfd_link_hash_entry structure. */
143 struct bfd_link_hash_entry
*undefs
;
144 /* Entries are added to the tail of the undefs list. */
145 struct bfd_link_hash_entry
*undefs_tail
;
148 /* Look up an entry in a link hash table. If FOLLOW is true, this
149 follows bfd_link_hash_indirect and bfd_link_hash_warning links to
151 extern struct bfd_link_hash_entry
*bfd_link_hash_lookup
152 PARAMS ((struct bfd_link_hash_table
*, const char *, boolean create
,
153 boolean copy
, boolean follow
));
155 /* Traverse a link hash table. */
156 extern void bfd_link_hash_traverse
157 PARAMS ((struct bfd_link_hash_table
*,
158 boolean (*) (struct bfd_link_hash_entry
*, PTR
),
161 /* Add an entry to the undefs list. */
162 extern void bfd_link_add_undef
163 PARAMS ((struct bfd_link_hash_table
*, struct bfd_link_hash_entry
*));
165 /* This structure holds all the information needed to communicate
166 between BFD and the linker when doing a link. */
170 /* Function callbacks. */
171 const struct bfd_link_callbacks
*callbacks
;
172 /* true if BFD should generate a relocateable object file. */
173 boolean relocateable
;
174 /* true if BFD should generate a shared object. */
176 /* true if BFD should pre-bind symbols in a shared object. */
178 /* Which symbols to strip. */
179 enum bfd_link_strip strip
;
180 /* Which local symbols to discard. */
181 enum bfd_link_discard discard
;
182 /* The local symbol prefix to discard if using discard_l. */
183 unsigned int lprefix_len
;
185 /* true if symbols should be retained in memory, false if they
186 should be freed and reread. */
188 /* The list of input BFD's involved in the link. These are chained
189 together via the link_next field. */
191 /* If a symbol should be created for each input BFD, this is section
192 where those symbols should be placed. It must be a section in
193 the output BFD. It may be NULL, in which case no such symbols
194 will be created. This is to support CREATE_OBJECT_SYMBOLS in the
195 linker command language. */
196 asection
*create_object_symbols_section
;
197 /* Hash table handled by BFD. */
198 struct bfd_link_hash_table
*hash
;
199 /* Hash table of symbols to keep. This is NULL unless strip is
201 struct bfd_hash_table
*keep_hash
;
202 /* Hash table of symbols to report back via notice_callback. If
203 this is NULL no symbols are reported back. */
204 struct bfd_hash_table
*notice_hash
;
206 /* If a base output file is wanted, then this points to it */
210 /* This structures holds a set of callback functions. These are
211 called by the BFD linker routines. The first argument to each
212 callback function is the bfd_link_info structure being used. Each
213 function returns a boolean value. If the function returns false,
214 then the BFD function which called it will return with a failure
217 struct bfd_link_callbacks
219 /* A function which is called when an object is added from an
220 archive. ABFD is the archive element being added. NAME is the
221 name of the symbol which caused the archive element to be pulled
223 boolean (*add_archive_element
) PARAMS ((struct bfd_link_info
*,
226 /* A function which is called when a symbol is found with multiple
227 definitions. NAME is the symbol which is defined multiple times.
228 OBFD is the old BFD, OSEC is the old section, OVAL is the old
229 value, NBFD is the new BFD, NSEC is the new section, and NVAL is
230 the new value. OBFD may be NULL. OSEC and NSEC may be
231 bfd_com_section or bfd_ind_section. */
232 boolean (*multiple_definition
) PARAMS ((struct bfd_link_info
*,
240 /* A function which is called when a common symbol is defined
241 multiple times. NAME is the symbol appearing multiple times.
242 OBFD is the BFD of the existing symbol; it may be NULL if this is
243 not known. OTYPE is the type of the existing symbol, which may
244 be bfd_link_hash_defined, bfd_link_hash_defweak,
245 bfd_link_hash_common, or bfd_link_hash_indirect. If OTYPE is
246 bfd_link_hash_common, OSIZE is the size of the existing symbol.
247 NBFD is the BFD of the new symbol. NTYPE is the type of the new
248 symbol, one of bfd_link_hash_defined, bfd_link_hash_common, or
249 bfd_link_hash_indirect. If NTYPE is bfd_link_hash_common, NSIZE
250 is the size of the new symbol. */
251 boolean (*multiple_common
) PARAMS ((struct bfd_link_info
*,
254 enum bfd_link_hash_type otype
,
257 enum bfd_link_hash_type ntype
,
259 /* A function which is called to add a symbol to a set. ENTRY is
260 the link hash table entry for the set itself (e.g.,
261 __CTOR_LIST__). RELOC is the relocation to use for an entry in
262 the set when generating a relocateable file, and is also used to
263 get the size of the entry when generating an executable file.
264 ABFD, SEC and VALUE identify the value to add to the set. */
265 boolean (*add_to_set
) PARAMS ((struct bfd_link_info
*,
266 struct bfd_link_hash_entry
*entry
,
267 bfd_reloc_code_real_type reloc
,
268 bfd
*abfd
, asection
*sec
, bfd_vma value
));
269 /* A function which is called when the name of a g++ constructor or
270 destructor is found. This is only called by some object file
271 formats. CONSTRUCTOR is true for a constructor, false for a
272 destructor. This will use BFD_RELOC_CTOR when generating a
273 relocateable file. NAME is the name of the symbol found. ABFD,
274 SECTION and VALUE are the value of the symbol. */
275 boolean (*constructor
) PARAMS ((struct bfd_link_info
*,
277 const char *name
, bfd
*abfd
, asection
*sec
,
279 /* A function which is called when there is a reference to a warning
280 symbol. WARNING is the warning to be issued. */
281 boolean (*warning
) PARAMS ((struct bfd_link_info
*,
282 const char *warning
));
283 /* A function which is called when a relocation is attempted against
284 an undefined symbol. NAME is the symbol which is undefined.
285 ABFD, SECTION and ADDRESS identify the location from which the
286 reference is made. In some cases SECTION may be NULL. */
287 boolean (*undefined_symbol
) PARAMS ((struct bfd_link_info
*,
288 const char *name
, bfd
*abfd
,
289 asection
*section
, bfd_vma address
));
290 /* A function which is called when a reloc overflow occurs. NAME is
291 the name of the symbol or section the reloc is against,
292 RELOC_NAME is the name of the relocation, and ADDEND is any
293 addend that is used. ABFD, SECTION and ADDRESS identify the
294 location at which the overflow occurs; if this is the result of a
295 bfd_section_reloc_link_order or bfd_symbol_reloc_link_order, then
296 ABFD will be NULL. */
297 boolean (*reloc_overflow
) PARAMS ((struct bfd_link_info
*,
299 const char *reloc_name
, bfd_vma addend
,
300 bfd
*abfd
, asection
*section
,
302 /* A function which is called when a dangerous reloc is performed.
303 The canonical example is an a29k IHCONST reloc which does not
304 follow an IHIHALF reloc. MESSAGE is an appropriate message.
305 ABFD, SECTION and ADDRESS identify the location at which the
306 problem occurred; if this is the result of a
307 bfd_section_reloc_link_order or bfd_symbol_reloc_link_order, then
308 ABFD will be NULL. */
309 boolean (*reloc_dangerous
) PARAMS ((struct bfd_link_info
*,
311 bfd
*abfd
, asection
*section
,
313 /* A function which is called when a reloc is found to be attached
314 to a symbol which is not being written out. NAME is the name of
315 the symbol. ABFD, SECTION and ADDRESS identify the location of
316 the reloc; if this is the result of a
317 bfd_section_reloc_link_order or bfd_symbol_reloc_link_order, then
318 ABFD will be NULL. */
319 boolean (*unattached_reloc
) PARAMS ((struct bfd_link_info
*,
321 bfd
*abfd
, asection
*section
,
323 /* A function which is called when a symbol in notice_hash is
324 defined or referenced. NAME is the symbol. ABFD, SECTION and
325 ADDRESS are the value of the symbol. If SECTION is
326 bfd_und_section, this is a reference. */
327 boolean (*notice
) PARAMS ((struct bfd_link_info
*, const char *name
,
328 bfd
*abfd
, asection
*section
, bfd_vma address
));
331 /* The linker builds link_order structures which tell the code how to
332 include input data in the output file. */
334 /* These are the types of link_order structures. */
336 enum bfd_link_order_type
338 bfd_undefined_link_order
, /* Undefined. */
339 bfd_indirect_link_order
, /* Built from a section. */
340 bfd_fill_link_order
, /* Fill with a 16 bit constant. */
341 bfd_data_link_order
, /* Set to explicit data. */
342 bfd_section_reloc_link_order
, /* Relocate against a section. */
343 bfd_symbol_reloc_link_order
/* Relocate against a symbol. */
346 /* This is the link_order structure itself. These form a chain
347 attached to the section whose contents they are describing. */
349 struct bfd_link_order
351 /* Next link_order in chain. */
352 struct bfd_link_order
*next
;
353 /* Type of link_order. */
354 enum bfd_link_order_type type
;
355 /* Offset within output section. */
357 /* Size within output section. */
359 /* Type specific information. */
364 /* Section to include. If this is used, then
365 section->output_section must be the section the
366 link_order is attached to, section->output_offset must
367 equal the link_order offset field, and section->_raw_size
368 must equal the link_order size field. Maybe these
369 restrictions should be relaxed someday. */
374 /* Value to fill with. */
379 /* Data to put into file. The size field gives the number
380 of bytes which this field points to. */
385 /* Description of reloc to generate. Used for
386 bfd_section_reloc_link_order and
387 bfd_symbol_reloc_link_order. */
388 struct bfd_link_order_reloc
*p
;
393 /* A linker order of type bfd_section_reloc_link_order or
394 bfd_symbol_reloc_link_order means to create a reloc against a
395 section or symbol, respectively. This is used to implement -Ur to
396 generate relocs for the constructor tables. The
397 bfd_link_order_reloc structure describes the reloc that BFD should
398 create. It is similar to a arelent, but I didn't use arelent
399 because the linker does not know anything about most symbols, and
400 any asymbol structure it creates will be partially meaningless.
401 This information could logically be in the bfd_link_order struct,
402 but I didn't want to waste the space since these types of relocs
403 are relatively rare. */
405 struct bfd_link_order_reloc
408 bfd_reloc_code_real_type reloc
;
412 /* For type bfd_section_reloc_link_order, this is the section
413 the reloc should be against. This must be a section in the
414 output BFD, not any of the input BFDs. */
416 /* For type bfd_symbol_reloc_link_order, this is the name of the
417 symbol the reloc should be against. */
421 /* Addend to use. The object file should contain zero. The BFD
422 backend is responsible for filling in the contents of the object
423 file correctly. For some object file formats (e.g., COFF) the
424 addend must be stored into in the object file, and for some
425 (e.g., SPARC a.out) it is kept in the reloc. */
429 /* Allocate a new link_order for a section. */
430 extern struct bfd_link_order
*bfd_new_link_order
PARAMS ((bfd
*, asection
*));